Thermally induced alkylation of diamond.

PubMed

Hoeb, Marco; Auernhammer, Marianne; Schoell, Sebastian J; Brandt, Martin S; Garrido, Jose A; Stutzmann, Martin; Sharp, Ian D

2010-12-21

We present an approach for the thermally activated formation of alkene-derived self-assembled monolayers on oxygen-terminated single and polycrystalline diamond surfaces. Chemical modification of the oxygen and hydrogen plasma-treated samples was achieved by heating in 1-octadecene. The resulting layers were characterized using X-ray photoelectron spectroscopy, thermal desorption spectroscopy, atomic force microscopy, Fourier transform infrared spectroscopy, and water contact angle measurements. This investigation reveals that alkenes selectively attach to the oxygen-terminated sites via covalent C-O-C bonds. The hydrophilic oxygen-terminated diamond is rendered strongly hydrophobic following this reaction. The nature of the process limits the organic layer growth to a single monolayer, and FTIR measurements reveal that such monolayers are dense and well ordered. In contrast, hydrogen-terminated diamond sites remain unaffected by this process. This method is thus complementary to the UV-initiated reaction of alkenes with diamond, which exhibits the opposite reactivity contrast. Thermal alkylation increases the range of available diamond functionalization strategies and provides a means of straightforwardly forming single organic layers in order to engineer the surface properties of diamond.

Nanodiamond finding in the hyblean shallow mantle xenoliths.

PubMed

Simakov, S K; Kouchi, A; Mel'nik, N N; Scribano, V; Kimura, Y; Hama, T; Suzuki, N; Saito, H; Yoshizawa, T

2015-06-01

Most of Earth's diamonds are connected with deep-seated mantle rocks; however, in recent years, μm-sized diamonds have been found in shallower metamorphic rocks, and the process of shallow-seated diamond formation has become a hotly debated topic. Nanodiamonds occur mainly in chondrite meteorites associated with organic matter and water. They can be synthesized in the stability field of graphite from organic compounds under hydrothermal conditions. Similar physicochemical conditions occur in serpentinite-hosted hydrothermal systems. Herein, we report the first finding of nanodiamonds, primarily of 6 and 10 nm, in Hyblean asphaltene-bearing serpentinite xenoliths (Sicily, Italy). The discovery was made by electron microscopy observations coupled with Raman spectroscopy analyses. The finding reveals new aspects of carbon speciation and diamond formation in shallow crustal settings. Nanodiamonds can grow during the hydrothermal alteration of ultramafic rocks, as well as during the lithogenesis of sediments bearing organic matter.

Tracing the depositional history of Kalimantan diamonds by zircon provenance and diamond morphology studies

NASA Astrophysics Data System (ADS)

Kueter, Nico; Soesilo, Joko; Fedortchouk, Yana; Nestola, Fabrizio; Belluco, Lorenzo; Troch, Juliana; Wälle, Markus; Guillong, Marcel; Von Quadt, Albrecht; Driesner, Thomas

2016-11-01

Diamonds in alluvial deposits in Southeast Asia are not accompanied by indicator minerals suggesting primary kimberlite or lamproite sources. The Meratus Mountains in Southeast Borneo (Province Kalimantan Selatan, Indonesia) provide the largest known deposit of these so-called "headless" diamond deposits. Proposals for the origin of Kalimantan diamonds include the adjacent Meratus ophiolite complex, ultra-high pressure (UHP) metamorphic terranes, obducted subcontinental lithospheric mantle and undiscovered kimberlite-type sources. Here we report results from detailed sediment provenance analysis of diamond-bearing Quaternary river channel material and from representative outcrops of the oldest known formations within the Alino Group, including the diamond-bearing Campanian-Maastrichtian Manunggul Formation. Optical examination of surfaces of diamonds collected from artisanal miners in the Meratus area (247 stones) and in West Borneo (Sanggau Area, Province Kalimantan Barat; 85 stones) points toward a classical kimberlite-type source for the majority of these diamonds. Some of the diamonds host mineral inclusions suitable for deep single-crystal X-ray diffraction investigation. We determined the depth of formation of two olivines, one coesite and one peridotitic garnet inclusion. Pressure of formation estimates for the peridotitic garnet at independently derived temperatures of 930-1250 °C are between 4.8 and 6.0 GPa. Sediment provenance analysis includes petrography coupled to analyses of detrital garnet and glaucophane. The compositions of these key minerals do not indicate kimberlite-derived material. By analyzing almost 1400 zircons for trace element concentrations with laser ablation ICP-MS (LA-ICP-MS) we tested the mineral's potential as an alternative kimberlite indicator. The screening ultimately resulted in a small subset of ten zircons with a kimberlitic affinity. Subsequent U-Pb dating resulting in Cretaceous ages plus a detailed chemical reflection make a kimberlitic origin unfavorable with respect to the regional geological history. Rather, trace elemental analyses (U, Th and Eu) suggest an eclogitic source for these zircons. The age distribution of detrital zircons allows in general a better understanding of collisional events that formed the Meratus orogen and identifies various North Australian Orogens as potential Pre-Mesozoic sediment sources. Our data support a model whereby the majority of Kalimantan diamonds were emplaced within the North Australian Craton by volcanic processes. Partly re-deposited into paleo-collectors or residing in their primary host, these diamond-deposits spread passively throughout Southeast Asia by terrane migration during the Gondwana breakup. Terrane amalgamation events largely metamorphosed these diamond-bearing lithologies while destroying the indicative mineral content. Orogenic uplift finally liberated their diamond-content into new, autochthonous placer deposits.

Carbon isotope fractionation during diamond growth in depleted peridotite: Counterintuitive insights from modelling water-maximum CHO fluids as multi-component systems

NASA Astrophysics Data System (ADS)

Stachel, T.; Chacko, T.; Luth, R. W.

2017-09-01

Because of the inability of depleted cratonic peridotites to effectively buffer oxygen fugacities when infiltrated by CHO or carbonatitic fluids, it has been proposed recently (Luth and Stachel, 2014) that diamond formation in peridotites typically does not occur by rock-buffered redox reactions as previously thought but by an oxygen-conserving reaction in which minor coexisting CH4 and CO2 components in a water-rich fluid react to form diamond (CO2 + CH4 = 2C + 2H2O). In such fluid-buffered systems, carbon isotope fractionation during diamond precipitation occurs in the presence of two dominant fluid carbon species. Carbon isotope modelling of diamond precipitation from mixed CH4- and CO2-bearing fluids reveals unexpected fundamental differences relative to diamond crystallization from a single carbon fluid species: (1) irrespective of which carbon fluid species (CH4 or CO2) is dominant in the initial fluid, diamond formation is invariably associated with progressive minor (<1‰) enrichment of diamond in 13C as crystallization proceeds. This is in contrast to diamond precipitation by rock-buffered redox processes from a fluid containing only a single carbon species, which can result in either progressive 13C enrichment (CO2 or carbonate fluids) or 13C depletion (CH4 fluids) in the diamond. (2) Fluid speciation is the key factor controlling diamond δ13 C values; as XCO2 (XCO2 = CO2/[CO2 + CH4]) in the initial fluid increases from 0.1 to 0.9 (corresponding to an increase in fO2 of 0.8 log units), the carbon isotope composition of the first-precipitated diamond decreases by 3.7‰. The tight mode in δ13C of - 5 ± 1 ‰ for diamonds worldwide places strict constraints on the dominant range of XCO2 in water-rich fluids responsible for diamond formation. Specifically, precipitation of diamonds with δ13C values in the range -4 to -6‰ from mantle-derived fluids with an average δ13C value of -5‰ (derived from evidence not related to diamonds) requires that diamond-forming fluids were relatively reduced and had methane as the dominant carbon species (XCO2 = 0.1-0.5). Application of our model to a recently published set of in-situ carbon isotope analyses for peridotitic diamonds from Marange, Zimbabwe (Smit et al., 2016), which contain CH4 fluid inclusions, allows us to perfectly match the observed co-variations in δ13 C, δ15 N and N content and at the same time explain the previously counter-intuitive observation of progressive 13C enrichment in diamonds that appear to have grown from a fluid with methane as the dominant carbon species. Similarly, the almost complete absence in the published record of progressive 13C depletion trends within diamonds likely reflects ubiquitous precipitation from CH4- and CO2-bearing water-rich fluids, rather than diamond formation exclusively by carbonate-bearing and CH4-free oxidized fluids or melts.

n-Type diamond and method for producing same

DOEpatents

Anderson, Richard J.

2002-01-01

A new n-type semiconducting diamond is disclosed, which is doped with n-type dopant atoms. Such diamond is advantageously formed by chemical vapor deposition from a source gas mixture comprising a carbon source compound for the diamond, and a volatile hot wire filament for the n-type impurity species, so that the n-type impurity atoms are doped in the diamond during its formation. A corresponding chemical vapor deposition method of forming the n-type semiconducting diamond is disclosed. The n-type semiconducting diamond of the invention may be usefully employed in the formation of diamond-based transistor devices comprising pn diamond junctions, and in other microelectronic device applications.

Finite element design for the HPHT synthesis of diamond

NASA Astrophysics Data System (ADS)

Li, Rui; Ding, Mingming; Shi, Tongfei

2018-06-01

The finite element method is used to simulate the steady-state temperature field in diamond synthesis cell. The 2D and 3D models of the China-type cubic press with large deformation of the synthesis cell was established successfully, which has been verified by situ measurements of synthesis cell. The assembly design, component design and process design for the HPHT synthesis of diamond based on the finite element simulation were presented one by one. The temperature field in a high-pressure synthetic cavity for diamond production is optimized by adjusting the cavity assembly. A series of analysis about the influence of the pressure media parameters on the temperature field are examined through adjusting the model parameters. Furthermore, the formation mechanism of wasteland was studied in detail. It indicates that the wasteland is inevitably exists in the synthesis sample, the distribution of growth region of the diamond with hex-octahedral is move to the center of the synthesis sample from near the heater as the power increasing, and the growth conditions of high quality diamond is locating at the center of the synthesis sample. These works can offer suggestion and advice to the development and optimization of a diamond production process.

Formation of nanodiamonds at near-ambient conditions via microplasma dissociation of ethanol vapour.

PubMed

Kumar, Ajay; Ann Lin, Pin; Xue, Albert; Hao, Boyi; Khin Yap, Yoke; Sankaran, R Mohan

2013-01-01

Clusters of diamond-phase carbon, known as nanodiamonds, exhibit novel mechanical, optical and biological properties that have elicited interest for a wide range of technological applications. Although diamond is predicted to be more stable than graphite at the nanoscale, extreme environments are typically used to produce nanodiamonds. Here we show that nanodiamonds can be stably formed in the gas phase at atmospheric pressure and neutral gas temperatures <100 °C by dissociation of ethanol vapour in a novel microplasma process. Addition of hydrogen gas to the process allows in flight purification by selective etching of the non-diamond carbon and stabilization of the nanodiamonds. The nanodiamond particles are predominantly between 2 and 5 nm in diameter, and exhibit cubic diamond, n-diamond and lonsdaleite crystal structures, similar to nanodiamonds recovered from meteoritic residues. These results may help explain the origin of nanodiamonds in the cosmos, and offer a simple and inexpensive route for the production of high-purity nanodiamonds.

Fabrication and characterization of a co-planar detector in diamond for low energy single ion implantation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abraham, John Bishoy Sam; Pacheco, Jose L.; Aguirre, Brandon Adrian

2016-08-09

We demonstrate low energy single ion detection using a co-planar detector fabricated on a diamond substrate and characterized by ion beam induced charge collection. Histograms are taken with low fluence ion pulses illustrating quantized ion detection down to a single ion with a signal-to-noise ratio of approximately 10. We anticipate that this detection technique can serve as a basis to optimize the yield of single color centers in diamond. In conclusion, the ability to count ions into a diamond substrate is expected to reduce the uncertainty in the yield of color center formation by removing Poisson statistics from the implantationmore » process.« less

Effect of diamond-like carbon thin film coated acrylic resin on candida albicans biofilm formation.

PubMed

Queiroz, José Renato Cavalcanti; Fissmer, Sara Fernanda; Koga-Ito, Cristiane Yumi; Salvia, Ana C R D; Massi, Marcos; Sobrinho, Argermiro Soares da Silva; Júnior, Lafayette Nogueira

2013-08-01

The purpose of this study was to evaluate the effect of diamond-like carbon thin films doped and undoped with silver nanoparticles coating poly(methyl methacrylate) (PMMA) on Candida albicans biofilm formation. The control of biofilm formation is important to prevent oral diseases in denture users. Forty-five PMMA disks were obtained, finished, cleaned in an ultrasonic bath, and divided into three groups: Gc, no surface coating (control group); Gdlc, coated with diamond-like carbon film; and Gag, coated with diamond-like carbon film doped with silver nanoparticles. The films were deposited using a reactive magnetron sputtering system (physical vapor deposition process). The specimens were characterized by optical profilometry, atomic force microscopy, and Rutherford backscattering spectroscopy analyses that determined differences in chemical composition and morphological structure. Following sterilization of the specimens by γ-ray irradiation, C. albicans (ATCC 18804) biofilms were formed by immersion in 2 ml of Sabouraud dextrose broth inoculated with a standardized fungal suspension. After 24 hours, the number of colony forming units (cfu) per specimen was counted. Data concerning biofilm formation were analyzed using ANOVA and the Tukey test (p < 0.05). C. albicans biofilm formation was significantly influenced by the films (p < 0.00001), reducing the number of cfu, while not affecting the roughness parameters (p > 0.05). The Tukey test showed no significant difference between Gdlc and Gag. Films deposited were extremely thin (∼50 nm). The silver particles presented a diameter between 60 and 120 nm and regular distribution throughout the film surface (to Gag). Diamond-like carbon films, doped or undoped with silver nanoparticles, coating the base of PMMA-based dentures could be an alternative procedure for preventing candidosis in denture users. © 2013 by the American College of Prosthodontists.

Investigation of nucleation and growth processes of diamond films by atomic force microscopy

NASA Technical Reports Server (NTRS)

George, M. A.; Burger, A.; Collins, W. E.; Davidson, J. L.; Barnes, A. V.; Tolk, N. H.

1994-01-01

The nucleation and growth of plasma-enhanced chemical-vapor deposited polycrystalline diamond films were studied using atomic force microscopy (AFM). AFM images were obtained for (1) nucleated diamond films produced from depositions that were terminated during the initial stages of growth, (2) the silicon substrate-diamond film interface side of diamond films (1-4 micrometers thick) removed from the original surface of the substrate, and (3) the cross-sectional fracture surface of the film, including the Si/diamond interface. Pronounced tip effects were observed for early-stage diamond nucleation attributed to tip convolution in the AFM images. AFM images of the film's cross section and interface, however, were not highly affected by tip convolution, and the images indicate that the surface of the silicon substrate is initially covered by a small grained polycrystalline-like film and the formation of this precursor film is followed by nucleation of the diamond film on top of this layer. X-ray photoelectron spectroscopy spectra indicate that some silicon carbide is present in the precursor layer.

Effects of rapid thermal annealing on the contact of tungsten/p-diamond

NASA Astrophysics Data System (ADS)

Zhao, D.; Li, F. N.; Liu, Z. C.; Chen, X. D.; Wang, Y. F.; Shao, G. Q.; Zhu, T. F.; Zhang, M. H.; Zhang, J. W.; Wang, J. J.; Wang, W.; Wang, H. X.

2018-06-01

The electrical properties, surface morphology and interface characteristics of W/p-diamond contact before and after annealing have been investigated. It is shown that the as-fabricated W/p-diamond contact exhibited non-linear behavior. After annealing at a temperature higher than 400 °C, the W/p-diamond contact showed ohmic behaviour. The specific contact resistance of W/p-diamond was 8.2 × 10-4 Ω·cm2 after annealing at 500 °C for 3 min in a N2 ambient, which was extracted from fitting the I-V relationship of TLM. It is noted that the RMS roughness increases with the annealing temperature increasing, which could be ascribed to the formation of WOX by the reaction of W and oxygen at high temperature. The XPS measurement showed that the barrier height of the W/p-diamond is 0.45 ± 0.12 eV after annealing at 500 °C. Furthermore, the formation of defects at the W/p-diamond interface, probably created by the formation of tungsten carbide during rapid thermal annealing, should be responsible for the ohmic formation of W/p-diamond after annealing at high temperature.

Field electron emission enhancement in lithium implanted and annealed nitrogen-incorporated nanocrystalline diamond films

NASA Astrophysics Data System (ADS)

Sankaran, K. J.; Srinivasu, K.; Yeh, C. J.; Thomas, J. P.; Drijkoningen, S.; Pobedinskas, P.; Sundaravel, B.; Leou, K. C.; Leung, K. T.; Van Bael, M. K.; Schreck, M.; Lin, I. N.; Haenen, K.

2017-06-01

The field electron emission (FEE) properties of nitrogen-incorporated nanocrystalline diamond films were enhanced due to Li-ion implantation/annealing processes. Li-ion implantation mainly induced the formation of electron trap centers inside diamond grains, whereas post-annealing healed the defects and converted the a-C phase into nanographite, forming conduction channels for effective transport of electrons. This resulted in a high electrical conductivity of 11.0 S/cm and enhanced FEE performance with a low turn-on field of 10.6 V/μm, a high current density of 25.5 mA/cm2 (at 23.2 V/μm), and a high lifetime stability of 1,090 min for nitrogen incorporated nanocrystalline diamond films.

Understanding ultrafine nanodiamond formation using nanostructured explosives

PubMed Central

Pichot, Vincent; Risse, Benedikt; Schnell, Fabien; Mory, Julien; Spitzer, Denis

2013-01-01

The detonation process is able to build new materials with a bottom-up approach. Diamond, the hardest material on earth, can be synthesized in this way. This unconventional synthesis route is possible due to the presence of carbon inside the high-explosive molecules: firing high-explosive mixtures with a negative oxygen balance in a non-oxidative environment leads to the formation of nanodiamond particles. Trinitrotoluene (TNT) and hexogen (RDX) are the explosives primarily used to synthesize nanodiamonds. Here we show that the use of nanostructured explosive charges leads to the formation of smaller detonation nanodiamonds, and it also provides new understanding of nanodiamond formation-mechanisms. The discontinuity of the explosive at the nanoscale level plays the key role in modifying the diamond particle size, and therefore varying the size with microstructured charges is impossible. PMID:23831716

Diamond formation due to a pH drop during fluid–rock interactions

DOE PAGES

Sverjensky, Dimitri A.; Huang, Fang

2015-11-03

Diamond formation has typically been attributed to redox reactions during precipitation from fluids or magmas. Either the oxidation of methane or the reduction of carbon dioxide has been suggested, based on simplistic models of deep fluids consisting of mixtures of dissolved neutral gas molecules without consideration of aqueous ions. The role of pH changes associated with water–silicate rock interactions during diamond formation is unknown. Here we show that diamonds could form due to a drop in pH during water–rock interactions. We use a recent theoretical model of deep fluids that includes ions, to show that fluid can react irreversibly withmore » eclogite at 900 °C and 5.0 GPa, generating diamond and secondary minerals due to a decrease in pH at almost constant oxygen fugacity. Overall, our results constitute a new quantitative theory of diamond formation as a consequence of the reaction of deep fluids with the rock types that they encounter during migration. Diamond can form in the deep Earth during water–rock interactions without changes in oxidation state.« less

Diamond formation due to a pH drop during fluid–rock interactions

PubMed Central

Sverjensky, Dimitri A.; Huang, Fang

2015-01-01

Diamond formation has typically been attributed to redox reactions during precipitation from fluids or magmas. Either the oxidation of methane or the reduction of carbon dioxide has been suggested, based on simplistic models of deep fluids consisting of mixtures of dissolved neutral gas molecules without consideration of aqueous ions. The role of pH changes associated with water–silicate rock interactions during diamond formation is unknown. Here we show that diamonds could form due to a drop in pH during water–rock interactions. We use a recent theoretical model of deep fluids that includes ions, to show that fluid can react irreversibly with eclogite at 900 °C and 5.0 GPa, generating diamond and secondary minerals due to a decrease in pH at almost constant oxygen fugacity. Overall, our results constitute a new quantitative theory of diamond formation as a consequence of the reaction of deep fluids with the rock types that they encounter during migration. Diamond can form in the deep Earth during water–rock interactions without changes in oxidation state. PMID:26529259

Novel phase of carbon, ferromagnetism, and conversion into diamond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Narayan, Jagdish, E-mail: narayan@ncsu.edu; Bhaumik, Anagh

2015-12-07

We report the discovery of a new phase of carbon (referred to as Q-carbon) and address fundamental issues related to direct conversion of carbon into diamond at ambient temperatures and pressures in air without any need for catalyst and presence of hydrogen. The Q-carbon is formed as result of quenching from super undercooled state by using high-power nanosecond laser pulses. We discuss the equilibrium phase diagram (P vs. T) of carbon and show that by rapid quenching kinetics can shift thermodynamic graphite/diamond/liquid carbon triple point from 5000 K/12 GPa to super undercooled carbon at atmospheric pressure in air. It is shown thatmore » nanosecond laser heating of diamond-like amorphous carbon on sapphire, glass, and polymer substrates can be confined to melt carbon in a super undercooled state. By quenching the carbon from the super undercooled state, we have created a new state of carbon (Q-carbon) from which nanodiamond, microdiamond, microneedles, and single-crystal thin films are formed depending upon the nucleation and growth times allowed for diamond formation. The Q-carbon quenched from liquid is a new state of solid carbon with a higher mass density than amorphous carbon and a mixture of mostly fourfold sp{sup 3} (75%–85%) with the rest being threefold sp{sup 2} bonded carbon (with distinct entropy). It is expected to have new and improved mechanical hardness, electrical conductivity, chemical, and physical properties, including room-temperature ferromagnetism (RTFM) and enhanced field emission. Here we present interesting results on RTFM, enhanced electrical conductivity and surface potential of Q-carbon to emphasize its unique properties. The Q-carbon exhibits robust bulk ferromagnetism with estimated Curie temperature of about 500 K and saturation magnetization value of 20 emu g{sup −1}. From the Q-carbon, diamond phase is nucleated and a variety of micro- and nanostructures and large-area single-crystal diamond sheets are grown by allowing growth times as needed. Subsequent laser pulses can be used to grow nanodiamond into microdiamond and nucleate other nanostructures of diamond on the top of existing microdiamond and create novel nanostructured materials. The microstructural details provide insights into the mechanism of formation of nanodiamond, microdiamond, nanoneedles, microneedles, and single-crystal thin films. This process allows carbon-to-diamond conversion and formation of useful nanostructures and microstructures at ambient temperatures in air at atmospheric pressure on practical and heat-sensitive substrates in a controlled way without need for any catalysts and hydrogen to stabilize sp{sup 3} bonding for diamond formation.« less

Novel phase of carbon, ferromagnetism, and conversion into diamond

NASA Astrophysics Data System (ADS)

Narayan, Jagdish; Bhaumik, Anagh

2015-12-01

We report the discovery of a new phase of carbon (referred to as Q-carbon) and address fundamental issues related to direct conversion of carbon into diamond at ambient temperatures and pressures in air without any need for catalyst and presence of hydrogen. The Q-carbon is formed as result of quenching from super undercooled state by using high-power nanosecond laser pulses. We discuss the equilibrium phase diagram (P vs. T) of carbon and show that by rapid quenching kinetics can shift thermodynamic graphite/diamond/liquid carbon triple point from 5000 K/12 GPa to super undercooled carbon at atmospheric pressure in air. It is shown that nanosecond laser heating of diamond-like amorphous carbon on sapphire, glass, and polymer substrates can be confined to melt carbon in a super undercooled state. By quenching the carbon from the super undercooled state, we have created a new state of carbon (Q-carbon) from which nanodiamond, microdiamond, microneedles, and single-crystal thin films are formed depending upon the nucleation and growth times allowed for diamond formation. The Q-carbon quenched from liquid is a new state of solid carbon with a higher mass density than amorphous carbon and a mixture of mostly fourfold sp3 (75%-85%) with the rest being threefold sp2 bonded carbon (with distinct entropy). It is expected to have new and improved mechanical hardness, electrical conductivity, chemical, and physical properties, including room-temperature ferromagnetism (RTFM) and enhanced field emission. Here we present interesting results on RTFM, enhanced electrical conductivity and surface potential of Q-carbon to emphasize its unique properties. The Q-carbon exhibits robust bulk ferromagnetism with estimated Curie temperature of about 500 K and saturation magnetization value of 20 emu g-1. From the Q-carbon, diamond phase is nucleated and a variety of micro- and nanostructures and large-area single-crystal diamond sheets are grown by allowing growth times as needed. Subsequent laser pulses can be used to grow nanodiamond into microdiamond and nucleate other nanostructures of diamond on the top of existing microdiamond and create novel nanostructured materials. The microstructural details provide insights into the mechanism of formation of nanodiamond, microdiamond, nanoneedles, microneedles, and single-crystal thin films. This process allows carbon-to-diamond conversion and formation of useful nanostructures and microstructures at ambient temperatures in air at atmospheric pressure on practical and heat-sensitive substrates in a controlled way without need for any catalysts and hydrogen to stabilize sp3 bonding for diamond formation.

Microinclusions in polycrystalline diamonds: insights into processes of diamond formation

NASA Astrophysics Data System (ADS)

Jacob, D. E.; Wirth, R.; Enzmann, F.; Schwarz, J. O.; Kronz, A.

2009-04-01

Polycrystalline diamond aggregates (framesites) contain silicates of eclogitic and peridotitic affinity (e.g. Kurat and Dobosi, 2000). The minerals occur mostly in interstices and are intimately intergrown with the diamonds, indicating contemporaneous crystallization within the diamond stability field in the Earth's mantle. In addition to silicates, rarer phases such as Fe-carbide can sometimes be found in framesites that record unusually low local oxygen fugacity at the time of their formation (Jacob et al., 2004). Furthermore, while most gem-sized diamonds have old, often Archaean formation ages, some polycrystalline diamond aggregates have been shown to form directly preceding the kimberlite eruption (Jacob et al., 2000). Thus, these samples may provide a unique source of information on the nature and timing of small scale processes that lead to diamond formation and complement evidence from gem-sized diamonds. Here, we present a study of micro- and nano-inclusions in diamonds from a polycrystalline diamond aggregate (framesite) from the Orapa Mine (Botswana) and combine results from TEM/FIB analyses with high-resolution computerized micro-tomography (HR-µCT) and electron microprobe analyses to further constrain the formation of diamond in the Earth's mantle. Results In total, 14 microinclusions from fifteen FIB foils were investigated. Micro- and nano-inclusions identified by TEM were smaller than 1µm down to ca. 50nm in size, and are both monomineralic and multi-phase. The cavities are often lath-shaped and oriented parallel to each other; many show lattice dislocations in the surrounding diamond. In addition, inclusions are found along open cracks within the diamond single crystals. Mineral phases in the microinclusions comprise rutile, omphacite and a FeS phase (pyrrhotite). The multiphase inclusions most often consist of cavities that are only partly occupied (less than 50% of the total space), suggesting that the empty space was originally filled by a fluid. One multiphase inclusion was found to be still fluid-bearing, showing characteristic continuous changes in diffraction contrast due to density fluctuations caused by the electron beam. No other elements than carbon were detected during AEM of this area which suggests that the fluid consists of relatively pure C-H-O species. In addition to the fluid, this inclusion contained fine-grained FeS, a silicate phase rich in Fe, P, Mg, Al, Ca and K and a quench phase, rich in Fe, P and Si. Macroinclusions (>5µm) are magnetite, often surrounded by hematite, FeS, low-Cr garnet (Py50Alm39Grs11) and omphacite (Jd23). Garnet and cpx were found as non-touching inclusions and yield 1256°C at 5 GPa. Most of the magnetite inclusions are single crystals and some are strongly deformed with signs of recrystallization. Hematite occurs as porous aggregates of nano-granules of ca. 5-7 nm sizes. High Resolution µ-Computer Tomography (HR-µCT) shows pores in the sample and the included mineral phases as areas of differing grey-values. These are a direct function of the specific x-ray density of the specific phase and can be used to differentiate oxides and silicates. Based on the 3D tomogram, the amount of pores per total volume of the diamond plus inclusion matrix is calculated to be 0.65 vol%, while magnetite inclusions amount to 3.16 vol%. The average equivalent radius of the magnetite grains (radius of a sphere with the same volume as the grain) is 17.8 µm, while that of the pores is 12.6µm. Discussion The occurrence of omphacite, rutile and FeS as microinclusions within the diamond crystals clearly shows that these phases are cogenetic to the diamonds. However, magnetite and hematite were only encountered as large inclusions in cavities that appear to be interstitial porosity. Moreover, analysis of the equivalent radius distribution of the pores and the magnetite inclusions derived from HR-µCT shows a complete overlap of the mode, indicating that magnetite preferentially fills the porosity in the sample. Furthermore, hematite occurs exclusively along the outer rim of the magnetite crystals and textural features suggest that this phase is a late replacement product of magnetite. This shows that the magnetite-bearing cavities were not shielded from the outside by the host diamond and may indicate that magnetite itself was introduced after diamond formation or during a secondary event that may still, however, have taken place at PT conditions of the diamond stability field. The microinclusion suite described here is distinct from that found in fibrous (e.g. Klein-BenDavid et al., 2007) and in microdiamonds (Kvasnytsya et al., 2006). Carbonates, halides and phosphates, that are typical for fibrous and microdiamonds were not encountered in our study. Instead, the microinclusion suite found in the framesite consists of the typical eclogitic minerals (rutile, garnet, omphacite, sulphide) plus a C-H-O fluid. Jacob et al., 2004. Contrib. Mineral. Petrol., 146, 566-576. Jacob et al., 2000. Science, 289, 1182-1185. Klein-BenDavid et al., 2007. Amer. Mineral. 91, 353-365. Kurat and Dobosi, 2000. Mineral. Petrol. 69, 143-159. Kvasnytsya et al., 2006. Ukrainian Geologist 2, 25-36.

Structural analysis of ion-implanted chemical-vapor-deposited diamond by transmission electron microscope

NASA Astrophysics Data System (ADS)

Jiang, N.; Deguchi, M.; Wang, C. L.; Won, J. H.; Jeon, H. M.; Mori, Y.; Hatta, A.; Kitabatake, M.; Ito, T.; Hirao, T.; Sasaki, T.; Hiraki, A.

1997-04-01

A transmission electron microscope (TEM) study of ion-implanted chemical-vapor-deposited (CVD) diamond is presented. CVD diamond used for transmission electron microscope observation was directly deposited onto Mo TEM grids. As-deposited specimens were irradiated by C (100 keV) ions at room temperature with a wide range of implantation doses (10 12-10 17/cm 2). Transmission electron diffraction (TED) patterns indicate that there exists a critical dose ( Dc) for the onset of amorphization of CVD diamond as a result of ion induced damage and the value of critical dose is confirmed to be about 3 × 10 15/cm 2. The ion-induced transformation process is clearly revealed by high resolution electron microscope (HREM) images. For a higher dose implantation (7 × 10 15/cm 2) a large amount of diamond phase is transformed into amorphous carbon and many tiny misoriented diamond blocks are found to be left in the amorphous solid. The average size of these misoriented diamond blocks is only about 1-2 nm. Further bombardment (10 17/cm 2) almost kills all of the diamond phase within the irradiated volume and moreover leads to local formation of micropolycrystalline graphite.

Radiation-induced diamond crystallization: Origin of carbonados and its implications on meteorite nano-diamonds

USGS Publications Warehouse

Ozima, M.; Tatsumoto, M.

1997-01-01

Ten carbonados from Central Africa were studied for U-Th-Pb systematics. To extract U, Th, and Pb from the samples, we developed a cold combustion technique wherein diamond was burnt in liquid oxygen. The technique gave low blanks; 25-50 pg for Pb, 3 pg for U, and 5 pg for Th. After very thorough acid treatments of the carbonados with hot HNO3, HF, and HCl over one week, most of U, Th, and Pb were removed from the samples. Lead in the acid-leached diamonds was highly radiogenic (206Pb/204Pb up to 470). However, the amounts of U and Th in the acid-leached diamonds are too low to account for the radiogenic Pb even if we assume 4.5 Ga for the age of the diamonds. Therefore, we conclude that the radiogenic Pb was implanted into the diamonds from surroundings by means of recoil energy of radioactive decays of U and Th. From the radiogenic lead isotopic composition, we estimate a minimum age of 2.6 Ga and a maximum age of 3.8 Ga for the formation of the carbonados. The above findings of the implantation of recoiled radiogenic Pb into carbonados is consistent with the process of radiation-induced crystallization which was proposed for carbonado by Kaminsky (1987). We show from some theoretical considerations that when highly energetic particles, such as those emitted from radioactive decay of U and Th, interact with carbonaceous materials, they give rise to cascades of atomic disturbance (over regions of about a few nanometer), and the disturbed atoms are likely to recrystallize to form micro-diamonds because of increasing surface energy due to small size. The radiation-induced diamond formation mechanism may be relevant to the origin of nano-diamonds in primitive meteorites. Copyright ?? 1997 Elsevier Science Ltd.

Phase diagram of carbon and the factors limiting the quantity and size of natural diamonds

NASA Astrophysics Data System (ADS)

Blank, Vladimir D.; Churkin, Valentin D.; Kulnitskiy, Boris A.; Perezhogin, Igor A.; Kirichenko, Alexey N.; Denisov, Viktor N.; Erohin, Sergey V.; Sorokin, Pavel B.; Popov, Mikhail Yu

2018-03-01

Phase diagrams of carbon, and those focusing on the graphite-to-diamond transitional conditions in particular, are of great interest for fundamental and applied research. The present study introduces a number of experiments carried out to convert graphite under high-pressure conditions, showing a formation of stable phase of fullerene-type onions cross-linked by sp3-bonds in the 55-115 GPa pressure range instead of diamonds formation (even at temperature 2000-3000 K) and the already formed diamonds turn into carbon onions. Our results refute the widespread idea that diamonds can form at any pressure from 2.2 to 1000 GPa. The phase diagram built within this study allows us not only to explain the existing numerous experimental data on the formation of diamond from graphite, but also to make assumptions about the conditions of its growth in Earth’s crust.

Geometry and material choices govern hard-rock drilling performance of PDC drag cutters.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wise, Jack LeRoy

2005-06-01

Sandia National Laboratories has partnered with industry on a multifaceted, baseline experimental study that supports the development of improved drag cutters for advanced drill bits. Different nonstandard cutter lots were produced and subjected to laboratory tests that evaluated the influence of selected design and processing parameters on cutter loads, wear, and durability pertinent to the penetration of hard rock with mechanical properties representative of formations encountered in geothermal or deep oil/gas drilling environments. The focus was on cutters incorporating ultrahard PDC (polycrystalline diamond compact) overlays (i.e., diamond tables) on tungsten-carbide substrates. Parameter variations included changes in cutter geometry, material composition,more » and processing conditions. Geometric variables were the diamond-table thickness, the cutting-edge profile, and the PDC/substrate interface configuration. Material and processing variables for the diamond table were, respectively, the diamond particle size and the sintering pressure applied during cutter fabrication. Complementary drop-impact, granite-log abrasion, linear cutting-force, and rotary-drilling tests examined the response of cutters from each lot. Substantial changes in behavior were observed from lot to lot, allowing the identification of features contributing major (factor of 10+) improvements in cutting performance for hard-rock applications. Recent field demonstrations highlight the advantages of employing enhanced cutter technology during challenging drilling operations.« less

Simulations of chemical vapor deposition diamond film growth using a kinetic Monte Carlo model and two-dimensional models of microwave plasma and hot filament chemical vapor deposition reactors

NASA Astrophysics Data System (ADS)

May, P. W.; Harvey, J. N.; Allan, N. L.; Richley, J. C.; Mankelevich, Yu. A.

2010-12-01

A one-dimensional kinetic Monte Carlo (KMC) model has been developed to simulate the chemical vapor deposition of a diamond (100) surface under conditions used to grow single-crystal diamond (SCD), microcrystalline diamond (MCD), nanocrystalline diamond (NCD), and ultrananocrystalline diamond (UNCD) films. The model considers adsorption, etching/desorption, lattice incorporation and surface migration but not defect formation or renucleation processes. Two methods have been devised for estimation of the gas phase concentrations of species at the growing diamond surface, and are used to determine adsorption rates for C1Hx hydrocarbons for the different conditions. The rate of migration of adsorbed carbon species is governed by the availability of neighboring radical sites, which, in turn, depend upon the rates of H abstraction and of surface-radical migration. The KMC model predicts growth rates and surface roughness for each of diamond types consistent with experiment. In the absence of defect formation and renucleation the average surface diffusion length, ℓ, is a key parameter controlling surface morphology. When ℓ <2, surface migration is limited by the lack of availability of surface radical sites, and the migrating surface species simply hop back and forth between two adjacent sites but do not travel far beyond their initial adsorption site. Thus, Eley-Rideal processes dominate the growth, leading to the rough surfaces seen in NCD and UNCD. The maximum or "intrinsic" surface roughness occurs for nominally zero-migration conditions (ℓ =0) with an rms value of approximately five carbon atoms. Conversely, when migration occurs over greater distances (ℓ >2), Langmuir-Hinshelwood processes dominate the growth producing the smoother surfaces of MCD and SCD. By extrapolation, we predict that atomically smooth surfaces over large areas should occur once migrating species can travel approximately five sites (ℓ ˜5). β-scission processes are found to be unimportant for MCD and SCD growth conditions, but can remove up to 5% of the adsorbing carbon for NCD and UNCD growth. C1Hx insertion reactions also contribute <1% to the growth for nearly all conditions, while C2Hx (x <2) insertion reactions are negligible due their very low concentrations at the surface. Finally, the predictions for growth rate and morphology for UNCD deposition in a microwave system were found to be anomalous compared to those for all the other growth conditions, suggesting that carbonaceous particulates created in these plasmas may significantly affect the gas chemistry.

Nature of diamonds in Yakutian eclogites: views from eclogite tomography and mineral inclusions in diamonds

NASA Astrophysics Data System (ADS)

Anand, Mahesh; Taylor, Lawrence A.; Misra, Kula C.; Carlson, William D.; Sobolev, Nikolai V.

2004-09-01

We have performed dissections of two diamondiferous eclogites (UX-1 and U33/1) from the Udachnaya kimberlite, Yakutia in order to understand the nature of diamond formation and the relationship between the diamonds, their mineral inclusions, and host eclogite minerals. Diamonds were carefully recovered from each xenolith, based upon high-resolution X-ray tomography images and three-dimensional models. The nature and physical properties of minerals, in direct contact with diamonds, were investigated at the time of diamond extraction. Polished sections of the eclogites were made, containing the mould areas of the diamonds, to further investigate the chemical compositions of the host minerals and the phases that were in contact with diamonds. Major- and minor-element compositions of silicate and sulfide mineral inclusions in diamonds show variations among each other, and from those in the host eclogites. Oxygen isotope compositions of one garnet and five clinopyroxene inclusions in diamonds from another Udachnaya eclogite (U51) span the entire range recorded for eclogite xenoliths from Udachnaya. In addition, the reported compositions of almost all clinopyroxene inclusions in U51 diamonds exhibit positive Eu anomaly. This feature, together with the oxygen isotopic characteristics, is consistent with the well-established hypothesis of subduction origin for Udachnaya eclogite xenoliths. It is intuitive to expect that all eclogite xenoliths in a particular kimberlite should have common heritage, at least with respect to their included diamonds. However, the variation in the composition of multiple inclusions within diamonds, and among diamonds, from the same eclogite indicates the involvement of complex processes in diamond genesis, at least in the eclogite xenoliths from Yakutia that we have studied.

Super-deep diamond genesis at Redox conditions of slab-mantle boundary

NASA Astrophysics Data System (ADS)

Gao, J.; Chen, B.; Wu, X.

2017-12-01

Diamond genesis is an intriguing issue for diamond resources and the deep carbon cycle of the Earth's interiors. Super-deep diamonds, representing only 6% of the global diamond population, often host inclusions with phase assemblages requiring a sublithospheric origin (>300 km). Being the windows for probing the deep Earth, super-deep diamonds with their distinctive micro-inclusions not only record a history of oceanic lithosphere subduction and upward transport at a depth of >250 km to even 1000 km, but indicate their genesis pertinent to mantle-carbonate melts in a Fe0-bufferred reduced condition. Our pilot experiments have evidenced the formation of diamonds from MgCO3-Fe0 system in a diamond anvil cell device at 25 GPa and 1800 K. Detailed experimental investigations of redox mechanism of MgCO3-Fe0 and CaCO3-Fe0 coupling have been conducted using multi-anvil apparatus. The conditions are set along the oceanic lithosphere subduction paths in the pressure-temperature range of 10-24 GPa and 1200-2000 K, covering the formation region of most super-deep diamonds. The clear reaction zones strongly support the redox reaction between carbonatitic slab and Fe0-bearing metals under mantle conditions. Our study has experimentally documented the possibility of super-deep diamond genesis at redox conditions of carbonateitic slab and Fe0-bearings. The kinetics of diamond formation as a function of pressure-temperature conditions are also discussed.

Diamond formation through isochemical cooling of CHO fluids vs redox buffering: examples from Marange peridotitic and Zimmi eclogitic diamonds

NASA Astrophysics Data System (ADS)

Smit, Karen V.; Stachel, Thomas; Stern, Richard A.; Shirey, Steven B.; Steele, Andrew

2017-04-01

Traditional models for diamond formation within the lithospheric mantle invoke either carbonate reduction or methane oxidation. Both these mechanisms require some oxygen exchange with the surrounding wall-rock at the site of diamond precipitation. However, peridotite does not have sufficient buffering capacity to allow for diamond formation via these traditional models and instead peridotitic diamonds may form through isochemical cooling of H2O-rich CHO fluids [1]. Marange mixed-habit diamonds from eastern Zimbabwe provide the first natural confirmation of this new diamond growth model [2]. Although Marange diamonds do not contain any silicate or sulphide inclusions, they contain Ni-N-vacancy complexes detected through photoluminescence (PL) spectroscopy that suggest the source fluids equilibrated in the Ni-rich depleted peridotitic lithosphere. Cuboid sectors also contain abundant micro-inclusions of CH4, the first direct observation of reduced CH4-rich fluids that are thought to percolate through the lithospheric mantle [2]. In fluid inclusion-free diamonds, core-to-rim trends in δ13C and N content are used to infer the speciation of the diamond-forming fluid. Core to rim trends of increasing δ13C with decreasing N content are interpreted as diamond growth from oxidized CO2- or carbonate-bearing fluids. Diamond growth from reduced species should show the opposite trends - decreasing δ13C from core to rim with decreasing N content. Within the CH4-bearing growth sectors of Marange diamonds, however, such a 'reduced' trend is not observed. Rather, δ13C increases from core to rim within a homogeneously grown zone [2]. These contradictory observations can be explained through either mixing between CH4- and CO2-rich end-members of hydrous fluids [2] or through closed system precipitation from an already mixed CH4-CO2 H2O-maximum fluid with XCO2 (CO2/[CO2+CH4]) between 0.3 and 0.7 [3]. These results demonstrate that Marange diamonds precipitated from cooling CH4-CO2-bearing hydrous fluids rather than through redox buffering. As this growth mechanism applies to both the fluid-rich cuboid and gem-like octahedral sectors of Marange diamonds, a non-redox model for diamond formation from mixed CH4-CO2 fluids is indicated for a wider range of gem-quality peridotitic diamonds. Indeed, at the redox conditions of global diamond-bearing lithospheric mantle (FMQ -2 to -4; [4]), CHO fluids are strongly water-dominated and contain both CH4 and CO2 as dominant carbon species [5]. By contrast diamond formation in eclogitic assemblages, through either redox buffering or cooling of carbon-bearing fluids, is not as well constrained. Zimmi diamonds from the West African craton have eclogitic sulphide inclusions (with low Ni and high Re/Os) and formed at 650 Ma, overlapping with the timing of subduction [6]. In one Zimmi diamond, a core to rim trend of decreasing δ13C (-23.4 to -24.5 ) and N content is indicative of formation from reduced C2H6/CH4-rich fluids, likely derived from oceanic crust recycled during Neoproterozoic subduction. Unlike mixed CH4-CO2 fluids near the water maximum, isochemical cooling or ascent of such reduced CHO fluids is not effficient at diamond precipitation. Furthermore, measurable carbon isotopic variations in diamond are not predicted in this model and therefore cannot be reconciled with the ˜1 ‰ internal variation seen. Consequently, this Zimmi eclogitic diamond likely formed through redox buffering of reduced subduction-related fluids, infiltrating into sulphide-bearing eclogite. References 1. Luth and Stachel, 2014. CMP, 168, 1083 2. Smit et al., 2016. Lithos, 265, 68-81 3. Stachel et al., in review 4. Stagno et al., 2013. Nature, 493, 84-88 5. Zhang and Duan, 2009. GCA 73, 2089-2102 6. Smit et al., 2016. Precamb Res, 286, 152-166

The uniquely high-temperature character of Cullinan diamonds: A signature of the Bushveld mantle plume?

NASA Astrophysics Data System (ADS)

Korolev, N. M.; Kopylova, M.; Bussweiler, Y.; Pearson, D. G.; Gurney, J.; Davidson, J.

2018-04-01

The mantle beneath the Cullinan kimberlite (formerly known as "Premier") is a unique occurrence of diamondiferous cratonic mantle where diamonds were generated contemporaneously and shortly following a mantle upwelling that led to the formation of a Large Igneous Province that produced the world's largest igneous intrusion - the 2056 Ma Bushveld Igneous Complex (BIC). We studied 332 diamond inclusions from 202 Cullinan diamonds to investigate mantle thermal effects imposed by the formation of the BIC. The overwhelming majority of diamonds come from three parageneses: (1) lithospheric eclogitic (69%), (2) lithospheric peridotitic (21%), and (3) sublithospheric mafic (9%). The lithospheric eclogitic paragenesis is represented by clinopyroxene, garnet, coesite and kyanite. Main minerals of the lithospheric peridotitic paragenesis are forsterite, enstatite, Cr-pyrope, Cr-augite and spinel; the sublithospheric mafic association includes majorite, CaSiO3 phases and omphacite. Diamond formation conditions were calculated using an Al-in-olivine thermometer, a garnet-clinopyroxene thermometer, as well as majorite and Raman barometers. The Cullinan diamonds may be unique on the global stage in recording a cold geotherm of 40 mW/m2 in cratonic lithosphere that was in contact with underlying convecting mantle at temperatures of 1450-1550 °C. The studied Cullinan diamonds contain a high proportion of inclusions equilibrated at temperatures exceeding the ambient 1327 °C adiabat, i.e. 54% of eclogitic diamonds and 41% of peridotitic diamonds. By contrast, ≤ 1% of peridotitic diamond inclusions globally yield equally high temperatures. We propose that the Cullinan diamond inclusions recorded transient, slow-dissipating thermal perturbations associated with the plume-related formation of the 2 Ga Bushveld igneous province. The presence of inclusions in diamond from the mantle transition zone at 300-650 km supports this view. Cullinan xenoliths indicative of the thermal state of the cratonic lithosphere at 1.2 Ga are equilibrated at the relatively low temperatures, not exceeding adiabatic. The ability of diamonds to record super-adiabatic temperatures may relate to their entrainment from the deeper, hotter parts of the upper mantle un-sampled by the kimberlite in the form of xenoliths or their equilibration in a younger lithosphere after a decay of the thermal disturbance.

Erbium ion implantation into diamond - measurement and modelling of the crystal structure.

PubMed

Cajzl, Jakub; Nekvindová, Pavla; Macková, Anna; Malinský, Petr; Sedmidubský, David; Hušák, Michal; Remeš, Zdeněk; Varga, Marián; Kromka, Alexander; Böttger, Roman; Oswald, Jiří

2017-02-22

Diamond is proposed as an extraordinary material usable in interdisciplinary fields, especially in optics and photonics. In this contribution we focus on the doping of diamond with erbium as an optically active centre. In the theoretical part of the study based on DFT simulations we have developed two Er-doped diamond structural models with 0 to 4 carbon vacancies in the vicinity of the Er atom and performed geometry optimizations by the calculation of cohesive energies and defect formation energies. The theoretical results showed an excellent agreement between the calculated and experimental cohesive energies for the parent diamond. The highest values of cohesive energies and the lowest values of defect formation energies were obtained for models with erbium in the substitutional carbon position with 1 or 3 vacancies in the vicinity of the erbium atom. From the geometry optimization the structural model with 1 vacancy had an octahedral symmetry whereas the model with 3 vacancies had a coordination of 10 forming a trigonal structure with a hexagonal ring. In the experimental part, erbium doped diamond crystal samples were prepared by ion implantation of Er + ions using ion implantation fluences ranging from 1 × 10 14 ions per cm 2 to 5 × 10 15 ions per cm 2 . The experimental results revealed a high degree of diamond structural damage after the ion implantation process reaching up to 69% of disordered atoms in the samples. The prepared Er-doped diamond samples annealed at the temperatures of 400, 600 and 800 °C in a vacuum revealed clear luminescence, where the 〈110〉 cut sample has approximately 6-7 times higher luminescence intensity than the 〈001〉 cut sample with the same ion implantation fluence. The reported results are the first demonstration of the Er luminescence in the single crystal diamond structure for the near-infrared spectral region.

Fabrication of microchannels in polycrystalline diamond using pre-fabricated Si substrates

NASA Astrophysics Data System (ADS)

Chandran, Maneesh; Elfimchev, Sergey; Michaelson, Shaul; Akhvlediani, Rozalia; Ternyak, Orna; Hoffman, Alon

2017-10-01

In this paper, we report on a simple, feasible method to fabricate microchannels in diamond. Polycrystalline diamond microchannels were produced by fabricating trenches in a Si wafer and subsequently depositing a thin layer of diamond onto this substrate using the hot filament vapor deposition technique. Fabrication of trenches in the Si substrate at different depths was carried out by standard photolithography, and the subsequent deposition of the diamond layer was performed by the hot filament chemical vapor deposition technique. The growth mechanism of diamond that leads to the formation of closed diamond microchannels is discussed in detail based on the Knudsen number and growth chemistry of diamond. Variations in the crystallite size, crystalline quality, and thickness of the diamond layer along the trench depths were systematically analyzed using cross-sectional scanning electron microscopy and Raman spectroscopy. Defect density and formation of non-diamond forms of carbon in the diamond layer were found to increase with the trench depth, which sets a limit of 5-45 μm trench depth (or an aspect ratio of 1-9) for the fabrication of diamond microchannels using this method under the present conditions.

Creation of deep blue light emitting nitrogen-vacancy center in nanosized diamond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Himics, L., E-mail: himics.laszlo@wigner.mta.hu; Tóth, S.; Veres, M.

2014-03-03

This paper reports on the formation of complex defect centers related to the N3 center in nanosized diamond by employing plasma immersion and focused ion beam implantation methods. He{sup +} ion implantation into nanosized diamond “layer” was performed with the aim of creating carbon atom vacancies in the diamond structure, followed by the introduction of molecular N{sub 2}{sup +} ion and heat treatment in vacuum at 750 °C to initiate vacancy diffusion. To decrease the sp{sup 2} carbon content of nanosized diamond formed during the implantation processes, a further heat treatment at 450 °C in flowing air atmosphere was used. The modificationmore » of the bonding properties after each step of defect creation was monitored by Raman scattering measurements. The fluorescence measurements of implanted and annealed nanosized diamond showed the appearance of an intensive and narrow emission band with fine structures at 2.98 eV, 2.83 eV, and 2.71 eV photon energies.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sverjensky, Dimitri A.; Huang, Fang

Diamond formation has typically been attributed to redox reactions during precipitation from fluids or magmas. Either the oxidation of methane or the reduction of carbon dioxide has been suggested, based on simplistic models of deep fluids consisting of mixtures of dissolved neutral gas molecules without consideration of aqueous ions. The role of pH changes associated with water–silicate rock interactions during diamond formation is unknown. Here we show that diamonds could form due to a drop in pH during water–rock interactions. We use a recent theoretical model of deep fluids that includes ions, to show that fluid can react irreversibly withmore » eclogite at 900 °C and 5.0 GPa, generating diamond and secondary minerals due to a decrease in pH at almost constant oxygen fugacity. Overall, our results constitute a new quantitative theory of diamond formation as a consequence of the reaction of deep fluids with the rock types that they encounter during migration. Diamond can form in the deep Earth during water–rock interactions without changes in oxidation state.« less

Origin of a needle-like granular structure for ultrananocrystalline diamond films grown in a N2/CH4 plasma

NASA Astrophysics Data System (ADS)

Sankaran, K. J.; Kurian, J.; Chen, H. C.; Dong, C. L.; Y Lee, C.; Tai, N. H.; Lin, I. N.

2012-09-01

Microstructural evolution as a function of substrate temperature (TS) for conducting ultrananocrystalline diamond (UNCD) films is systematically studied. Variation of the sp2 graphitic and sp3 diamond content with TS in the films is analysed from the Raman and near-edge x-ray absorption fine structure spectra. Morphological and microstructural studies confirm that at TS = 700 °C well-defined acicular structures evolve. These nanowire structures comprise sp3 phased diamond, encased in a sheath of sp2 bonded graphitic phase. TS causes a change in morphology and thereby the various properties of the films. For TS = 800 °C the acicular grain growth ceases, while that for TS = 700 °C ceases only upon termination of the deposition process. The grain-growth process for the unique needle-like granular structure is proposed such that the CN species invariably occupy the tip of the nanowire, promoting an anisotropic grain-growth process and the formation of acicular structure of the grains. The electron field emission studies substantiate that the films grown at TS = 700 °C are the most conducting, with conduction mediated through the graphitic phase present in the films.

Dense plasma chemistry of hydrocarbons at conditions relevant to planetary interiors and inertial confinement fusion

NASA Astrophysics Data System (ADS)

Kraus, Dominik

2017-10-01

Carbon-hydrogen demixing and subsequent diamond precipitation has been predicted to strongly participate in shaping the internal structure and evolution of icy giant planets like Neptune and Uranus. The very same dense plasma chemistry is also a potential concern for CH plastic ablator materials in inertial confinement fusion (ICF) experiments where similar conditions are present during the first compression stage of the imploding capsule. Here, carbon-hydrogen demixing may enhance the hydrodynamic instabilities occurring in the following compression stages. First experiments applying dynamic compression and ultrafast in situ X-ray diffraction at SLAC's Linac Coherent Light Source demonstrated diamond formation from polystyrene (CH) at 150 GPa and 5000 K. Very recent experiments have now investigated the influence of oxygen, which is highly abundant in icy giant planets on the phase separation process. Compressing PET (C5H4O2) and PMMA(C5H8O2), we find again diamond formation at pressures above 150 GPa and temperatures of several thousand kelvins, showing no strong effect due to the presence of oxygen. Thus, diamond precipitation deep inside icy giant planets seems very likely. Moreover, small-angle X-ray scattering (SAXS) was added to the platform, which determines an upper limit for the diamond particle size, while the width of the diffraction features provides a lower limit. We find that diamond particles of several nanometers in size are formed on a nanosecond timescale. Finally, spectrally resolved X-ray scattering is used to scale amorphous diffraction signals and allows for determining the amount of carbon-hydrogen demixing inside the compressed samples even if no crystalline diamond is formed. This whole set of diagnostics provides unprecedented insights into the nanosecond kinetics of dense plasma chemistry.

Atomistic aspects of ductile responses of cubic silicon carbide during nanometric cutting

PubMed Central

2011-01-01

Cubic silicon carbide (SiC) is an extremely hard and brittle material having unique blend of material properties which makes it suitable candidate for microelectromechanical systems and nanoelectromechanical systems applications. Although, SiC can be machined in ductile regime at nanoscale through single-point diamond turning process, the root cause of the ductile response of SiC has not been understood yet which impedes significant exploitation of this ceramic material. In this paper, molecular dynamics simulation has been carried out to investigate the atomistic aspects of ductile response of SiC during nanometric cutting process. Simulation results show that cubic SiC undergoes sp3-sp2 order-disorder transition resulting in the formation of SiC-graphene-like substance with a growth rate dependent on the cutting conditions. The disorder transition of SiC causes the ductile response during its nanometric cutting operations. It was further found out that the continuous abrasive action between the diamond tool and SiC causes simultaneous sp3-sp2 order-disorder transition of diamond tool which results in graphitization of diamond and consequent tool wear. PMID:22078069

Atomistic aspects of ductile responses of cubic silicon carbide during nanometric cutting.

PubMed

Goel, Saurav; Luo, Xichun; Reuben, Robert L; Rashid, Waleed Bin

2011-11-11

Cubic silicon carbide (SiC) is an extremely hard and brittle material having unique blend of material properties which makes it suitable candidate for microelectromechanical systems and nanoelectromechanical systems applications. Although, SiC can be machined in ductile regime at nanoscale through single-point diamond turning process, the root cause of the ductile response of SiC has not been understood yet which impedes significant exploitation of this ceramic material. In this paper, molecular dynamics simulation has been carried out to investigate the atomistic aspects of ductile response of SiC during nanometric cutting process. Simulation results show that cubic SiC undergoes sp3-sp2 order-disorder transition resulting in the formation of SiC-graphene-like substance with a growth rate dependent on the cutting conditions. The disorder transition of SiC causes the ductile response during its nanometric cutting operations. It was further found out that the continuous abrasive action between the diamond tool and SiC causes simultaneous sp3-sp2 order-disorder transition of diamond tool which results in graphitization of diamond and consequent tool wear.

A novel electroless method to prepare a platinum electrocatalyst on diamond for fuel cell applications

NASA Astrophysics Data System (ADS)

Lyu, Xiao; Hu, Jingping; Foord, John S.; Wang, Qiang

2013-11-01

A novel electroless deposition method was demonstrated to prepare a platinum electrocatalyst on boron doped diamond (BDD) substrates without the need for pre-activation. This green method addresses the uniformity and particle size issues associated with electrodeposition and circumvents the pre-activation procedure which is necessary for conventional electroless deposition. The inert BDD substrate formed a galvanic couple with an iron wire, to overcome the activation barrier associated with conventional electroless deposition on diamond, leading to the formation of Pt nanoparticles on the electrode surface in a galvanic process coupled to a chemical process. When sodium hypophosphite was employed as the reducing agent to drive the electroless reaction Pt deposits which were contaminated with iron and phosphorus resulted. In contrast, the reducing agent ascorbic acid gave rise to high purity Pt nanoparticles. Optimal deposition conditions with respect to bath temperature, pH value and stabilizing additives are identified. Using this approach, high purity and uniformly distributed platinum nanoparticles are obtained on the diamond electrode surface, which demonstrate a high electrochemical activity towards methanol oxidation.

Chromatographic study of formation conditions of rhombododecahedral diamond crystals

NASA Astrophysics Data System (ADS)

Zhimulev, E. I.; Sonin, V. M.; Chepurov, A. I.; Tomilenko, A. A.

2009-06-01

The results of chromatographic study of the formation of rhombododecahedral diamonds synthesized in the Fe-Ni-(Ti)-C system at 5.5-6.0 GPa and 1350-1450°C are presented, including crystals with rounded surfaces of the rhombododecahedron with parallel striation, which are morphological analogues of natural diamonds abundant at various kimberlite, lamproite, and placer deposits. Chromatography was performed at 150°C with mechanical breakup of diamonds. The stable release of methane when diamonds of habit {110} are crushed is established. It is concluded that the appearance of the habit rhombododecahedron may be related not only to the effect of temperature and pressure on crystal growth but also to reductive conditions of crystallization. At the same time, the appearance of significant amounts of hydrocarbons in the system probably results in stopping of the growth of faces {110} and {100} and, instead, formation of specific surfaces that are composed of microscopic accessories faced by planes {111}.

Cavitations synthesis of carbon nanostructures

NASA Astrophysics Data System (ADS)

Voropaev, S.

2011-04-01

Originally an idea of diamonds production by hydrodynamical cavitation was presented by academician E M Galimov. He supposed the possibility of nature diamonds formation at fast magma flowing in kimberlitic pipes during bubbles collapse. This hypothesis assumes a number of processes, which were not under consideration until now. It concerns cavitation under high pressure, growth and stability of the gas- and vapors bubbles, their evolution, and corresponding physical- and chemical processes inside. Experimental setup to reproduce the high pressure and temperature reaction centers by means of the cavitation following the above idea was created. A few crystalline nanocarbon forms were successfully recovered after treatment of benzene (C6H6).

The modeling and synthesis of nanodiamonds by laser ablation of graphite and diamond-like carbon in liquid-confined ambient

NASA Astrophysics Data System (ADS)

Basso, L.; Gorrini, F.; Bazzanella, N.; Cazzanelli, M.; Dorigoni, C.; Bifone, A.; Miotello, A.

2018-01-01

Nanodiamonds have attracted considerable interest for their potential applications in quantum computation, sensing, and bioimaging. However, synthesis of nanodiamonds typically requires high pressures and temperatures, and is still a challenge. Here, we demonstrate production of nanodiamonds by pulsed laser ablation of graphite and diamond-like carbon in water. Importantly, this technique enables production of nanocrystalline diamonds at room temperature and standard pressure conditions. Moreover, we propose a method for the purification of nanodiamonds from graphitic and amorphous carbon phases that do not require strong acids and harsh chemical conditions. Finally, we present a thermodynamic model that describes the formation of nanodiamonds during pulsed laser ablation. We show that synthesis of the crystalline phase is driven by a graphite-liquid-diamond transition process that occurs at the extreme thermodynamic conditions reached inside the ablation plume.

X-Ray Tomography of Diamondiferous Eclogites: Clues to the Origin of Diamonds.

NASA Astrophysics Data System (ADS)

Taylor, L. A.; Ketcham, R. A.

2009-05-01

During the last decade or so, considerable new and significant data have been gathered concerning the origin of diamonds. This has come from the mantle xenoliths that are the rocks in which the diamonds originated, namely eclogites and peridotites, the host rocks for diamonds in the mantle. Upon rising through the crust to the surface in their kimberlite magmatic carriers and subsequent weathering on the surface, the weak olivine commonly alters, thereby reducing the crushing strength of the peridotite xenoliths. However, the eclogite xenoliths often retain enough toughness to resist total shattering after initial crushing during diamond recovery process. Subjecting these eclogite nodules to X-rays (e.g., 1.54 Å Cu K) can reveal the bright-blue fluorescence of any diamonds exposed at the surface of the xenoliths. Slow and careful extraction can result in recovery of large diamonds. Many of these unique rocks are the ones upon which we have performed High- Resolution X-ray Computed Tomography (HRXCT) at UT Austin. These data have formed the basis for further eclogite dissections and diamond polishing at UT Knoxville. The size of the diamondiferous eclogites that were scanned by HRXCT are from 20 g to 8.8 kg, all with many diamonds ranging from <1 mm to >1 cm, most octahedral, several with mineral inclusions. These diamondiferous eclogites have both textures and fabrics that provide evidence indicating the secondary formation of the diamonds. These include lineations of diamonds along zones of metasomatic alteration, former zones of enhanced permeability; the non-association of sulfides (po, pn, cpy) with the diamonds, versus sulfide-immiscible melt for the diamond origin; lack of any diamonds in direct contact with the primary garnets or clinopyroxenes; and the presence of some dodecahedral diamonds, indicative of resorption processes, typically attributed to the kimberlite melt. Indeed, these eclogites are not igneous in origin, but metamorphic products of their subducted oceanic crustal protoliths. In addition, detailed studies of the extracted diamonds supply more unexpected results. Polished diamonds examined with cathodoluminescence show evidence for a torturous life of cubic nucleation, growth, resorption, octahedral growth, resorption, and even plastic deformation. These are anomalous observations of diamonds supposedly formed along with the primary minerals in their eclogite hosts. The mineral inclusions in the diamonds reveal additional compelling clues of their origin. Multiple clinopyroxene inclusions can have different compositions within a single diamond, different between diamonds, and even different from that of the host. It is proposed that diamonds present in mantle eclogite xenoliths are secondary, having little to do with their hosts, formed by metasomatic fluids penetrating the eclogites along zones of permeability, and causing extensive secondary alteration and even partial melting of the primary garnets and omphacites.

Natural diamond formation by self-redox of ferromagnesian carbonate

NASA Astrophysics Data System (ADS)

Chen, Ming; Shu, Jinfu; Xie, Xiande; Tan, Dayong; Mao, Ho-kwang

2018-03-01

Formation of natural diamonds requires the reduction of carbon to its bare elemental form, and pressures (P) greater than 5 GPa to cross the graphite–diamond transition boundary. In a study of shocked ferromagnesian carbonate at the Xiuyan impact crater, we found that the impact pressure–temperature (P-T) of 25–45 GPa and 800–900 °C were sufficient to decompose ankerite Ca(Fe2+,Mg)(CO3)2 to form diamond in the absence of another reductant. The carbonate self-reduced to diamond by concurrent oxidation of Fe2+ to Fe3+ to form a high-P polymorph of magnesioferrite, MgFe3+2O4. Discovery of the subsolidus carbonate self-reduction mechanism indicates that diamonds could be ubiquitously present as a dominant host for carbon in the Earth’s lower mantle.

A novel Mo-W interlayer approach for CVD diamond deposition on steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kundrát, Vojtěch; Sullivan, John; Ye, Haitao, E-mail: h.ye@aston.ac.uk

Steel is the most widely used material in engineering for its cost/performance ratio and coatings are routinely applied on its surface to further improve its properties. Diamond coated steel parts are an option for many demanding industrial applications through prolonging the lifetime of steel parts, enhancement of tool performance as well as the reduction of wear rates. Direct deposition of diamond on steel using conventional chemical vapour deposition (CVD) processes is known to give poor results due to the preferential formation of amorphous carbon on iron, nickel and other elements as well as stresses induced from the significant difference inmore » the thermal expansion coefficients of those materials. This article reports a novel approach of deposition of nanocrystalline diamond coatings on high-speed steel (M42) substrates using a multi-structured molybdenum (Mo) – tungsten (W) interlayer to form steel/Mo/Mo-W/W/diamond sandwich structures which overcome the adhesion problem related to direct magnetron sputtering deposition of pure tungsten. Surface, interface and tribology properties were evaluated to understand the role of such an interlayer structure. The multi-structured Mo-W interlayer has been proven to improve the adhesion between diamond films and steel substrates by acting as an effective diffusion barrier during the CVD diamond deposition.« less

A novel Mo-W interlayer approach for CVD diamond deposition on steel

NASA Astrophysics Data System (ADS)

Kundrát, Vojtěch; Zhang, Xiaoling; Cooke, Kevin; Sun, Hailin; Sullivan, John; Ye, Haitao

2015-04-01

Steel is the most widely used material in engineering for its cost/performance ratio and coatings are routinely applied on its surface to further improve its properties. Diamond coated steel parts are an option for many demanding industrial applications through prolonging the lifetime of steel parts, enhancement of tool performance as well as the reduction of wear rates. Direct deposition of diamond on steel using conventional chemical vapour deposition (CVD) processes is known to give poor results due to the preferential formation of amorphous carbon on iron, nickel and other elements as well as stresses induced from the significant difference in the thermal expansion coefficients of those materials. This article reports a novel approach of deposition of nanocrystalline diamond coatings on high-speed steel (M42) substrates using a multi-structured molybdenum (Mo) - tungsten (W) interlayer to form steel/Mo/Mo-W/W/diamond sandwich structures which overcome the adhesion problem related to direct magnetron sputtering deposition of pure tungsten. Surface, interface and tribology properties were evaluated to understand the role of such an interlayer structure. The multi-structured Mo-W interlayer has been proven to improve the adhesion between diamond films and steel substrates by acting as an effective diffusion barrier during the CVD diamond deposition.

Micro and nanocrystalline diamond formation on reticulated vitreous carbon substrate

NASA Astrophysics Data System (ADS)

Diniz, A. V.; Trava-Airoldi, V. J.; Corat, E. J.; Ferreira, N. G.

2005-10-01

High diamond nucleation and a three-dimensional growth on reticulated vitreous carbon substrate are obtained by chemical vapor deposition. Scanning electron microscopy images show continuous films covering the whole substrate including the center of 3.5 mm thick porous samples. It is evident the nanocrystalline diamond (NCD) film formation on deeper substrate regions. The grain size can vary from nano to micro scale for deposition time of 20 h. Raman spectra of sample regions closer to filaments exhibit well-defined diamond line. For central regions of sample (depth between 1.0 and 2.0 mm) Raman spectra also confirm NCD film.

Anisotropic diamond etching through thermochemical reaction between Ni and diamond in high-temperature water vapour.

PubMed

Nagai, Masatsugu; Nakanishi, Kazuhiro; Takahashi, Hiraku; Kato, Hiromitsu; Makino, Toshiharu; Yamasaki, Satoshi; Matsumoto, Tsubasa; Inokuma, Takao; Tokuda, Norio

2018-04-27

Diamond possesses excellent physical and electronic properties, and thus various applications that use diamond are under development. Additionally, the control of diamond geometry by etching technique is essential for such applications. However, conventional wet processes used for etching other materials are ineffective for diamond. Moreover, plasma processes currently employed for diamond etching are not selective, and plasma-induced damage to diamond deteriorates the device-performances. Here, we report a non-plasma etching process for single crystal diamond using thermochemical reaction between Ni and diamond in high-temperature water vapour. Diamond under Ni films was selectively etched, with no etching at other locations. A diamond-etching rate of approximately 8.7 μm/min (1000 °C) was successfully achieved. To the best of our knowledge, this rate is considerably greater than those reported so far for other diamond-etching processes, including plasma processes. The anisotropy observed for this diamond etching was considerably similar to that observed for Si etching using KOH.

Transformation of shock-compressed graphite to hexagonal diamond in nanoseconds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Turneaure, Stefan J.; Sharma, Surinder M.; Volz, Travis J.

2017-10-01

The graphite-to-diamond transformation under shock compression has been of broad scientific interest since 1961. The formation of hexagonal diamond (HD) is of particular interest because it is expected to be harder than cubic diamond and due to its use in terrestrial sciences as a marker at meteorite impact sites. However, the formation of diamond having a fully hexagonal structure continues to be questioned and remains unresolved. Using real-time (nanosecond), in situ x-ray diffraction measurements, we show unequivocally that highly oriented pyrolytic graphite, shock-compressed along the c axis to 50 GPa, transforms to highly oriented elastically strained HD with the (100)HDmore » plane parallel to the graphite basal plane.« less

Topological Quantum Information Processing Mediated Via Hybrid Topogical Insulator Structures

DTIC Science & Technology

2014-03-28

formation, manipulation, entanglement and detection of Majorana fermions in diamond-topological insulator - superconductor heterojunctions. Furthermore...between Superconductors and Topological Insulators Recent advances have revealed a new type of information processing, topological quantum...Topological Insulator - Superconductor Heterostructures," Physical Review B 84, 144507 (2011). 7 Hsiang-Hsuan Hung, Pouyan Ghaemi, Taylor L

Structural defects in natural plastically deformed diamonds: Evidence from EPR spectroscopy

NASA Astrophysics Data System (ADS)

Mineeva, R. M.; Titkov, S. V.; Speransky, A. V.

2009-06-01

Structural defects formed as a result of plastic deformation in natural diamond crystals have been studied by EPR spectroscopy. The spectra of brown, pink-brown, black-brown, pink-purple, and gray plastically deformed diamonds of type Ia from deposits in Yakutia and the Urals were recorded. The results of EPR spectroscopy allowed us to identify various deformation centers in the structure of natural diamonds and to show that nitrogen centers were transformed under epigenetic mechanical loading. Abundant A centers, consisting of two isomorphic nitrogen atoms located in neighboring structural sites, were destroyed as a result of this process to form a series of N1, N4, W7, M2, and M3 nitrogen centers. Such centers are characterized by an anisotropic spatial distribution and a positive charge, related to the mechanism of their formation. In addition, N2 centers (probably, deformation-produced dislocations decorated by nitrogen) were formed in all plastically deformed diamonds and W10 and W35 centers (the models have not been finally ascertained) were formed in some of them. It has been established that diamonds with various types of deformation-induced color contain characteristic associations of these deformation centers. The diversity of associations of deformation centers indicates appreciable variations in conditions of disintegration of deep-seated rocks, transfer of diamonds to the Earth’s surface, and formation of kimberlitic deposits. Depending on the conditions of mechanical loading, the diamond crystals were plastically deformed by either dislocation gliding or mechanical twinning. Characteristic features of plastic deformation by dislocation gliding are the substantial prevalence of the N2 centers over other deformation centers and the occurrence of the high-spin W10 and W35 centers. The attributes of less frequent plastic deformation by mechanical twinning are unusual localization of the M2 centers and, in some cases, the N1 centers in microtwinned lamellae. Numerous data on models of deformation centers in natural diamonds, including the M2 and M3 centers, which were observed in the studied collection for the first time, are discussed.

Formation of the Fe,Mg-Silicates, Fe0, and Graphite (Diamond) Assemblage as a Result of Cohenite Oxidation under Lithospheric Mantle Conditions

NASA Astrophysics Data System (ADS)

Bataleva, Yu. V.; Palyanov, Yu. N.; Borzdov, Yu. M.; Zdrokov, E. V.; Novoselov, I. D.; Sobolev, N. V.

2018-03-01

Experimental studies in the Fe3C-SiO2-MgO system ( P = 6.3 GPa, T = 1100-1500°C, t = 20-40 h) have been carried out. It has been established that carbide-oxide interaction resulted in the formation of Fe-orthopyroxene, graphite, wustite, and cohenite (1100 and 1200°C), as well as a Fe-C-O melt (1300-1500°C). The main processes occurring in the system at 1100 and 1200°C are the oxidation of cohenite, the extraction of carbon from carbide, and the crystallization of metastable graphite, as well as the formation of ferrosilicates. At T ≥ 1300°C, graphite crystallization and diamond growth occur as a result of the redox interaction of a predominantly metallic melt (Fe-C-O) with oxides and silicates. The carbide-oxide interaction studied can be considered as the basis for modeling a number of carbon-producing processes in the lithospheric mantle at fO2 values near the iron-wustite buffer.

Carolinas Coastal Change Processes Project data report for observations near Diamond Shoals, North Carolina, January-May 2009

USGS Publications Warehouse

Armstrong, Brandy N.; Warner, John C.; Voulgaris, George; List, Jeffrey H.; Thieler, E. Robert; Martini, Marinna A.; Montgomery, Ellyn T.

2011-01-01

This Open-File Report provides information collected for an oceanographic field study that occurred during January - May 2009 to investigate processes that control the sediment transport dynamics at Diamond Shoals, North Carolina. The objective of this report is to make the data available in digital form and to provide information to facilitate further analysis of the data. The report describes the background, experimental setup, equipment, and locations of the sensor deployments. The edited data are presented in time-series plots for rapid visualization of the data set, and in data files that are in the Network Common Data Format (netcdf). Supporting observational data are also included.

Mixed fluid sources involved in diamond growth constrained by Sr-Nd-Pb-C-N isotopes and trace elements

NASA Astrophysics Data System (ADS)

Klein-BenDavid, Ofra; Pearson, D. Graham; Nowell, Geoff M.; Ottley, Chris; McNeill, John C. R.; Cartigny, Pierre

2010-01-01

Sub-micrometer inclusions in diamonds carry high-density fluids (HDF) from which the host diamonds have precipitated. The chemistry of these fluids is our best opportunity of characterizing the diamond-forming environment. The trace element patterns of diamond fluids vary within a limited range and are similar to those of carbonatitic/kimberlitic melts that originate from beneath the lithospheric mantle. A convecting mantle origin for the fluid is also implied by C isotopic compositions and by a preliminary Sr isotopic study (Akagi, T., Masuda, A., 1988. Isotopic and elemental evidence for a relationship between kimberlite and Zaire cubic diamonds. Nature 336, 665-667.). Nevertheless, the major element chemistry of HDFs is very different from that of kimberlites and carbonatites, varying widely and being characterized by extreme K enrichment (up to ˜ 39 wt.% on a water and carbonate free basis) and high volatile contents. The broad spectrum of major element compositions in diamond-forming fluids has been related to fluid-rock interaction and to immiscibility processes. Elemental signatures can be easily modified by a variety of mantle processes whereas radiogenic isotopes give a clear fingerprint of the time-integrated evolution of the fluid source region. Here we present the results of the first multi radiogenic-isotope (Sr, Nd, Pb) and trace element study on fluid-rich diamonds, implemented using a newly developed off-line laser sampling technique. The data are combined with N and C isotope analysis of the diamond matrix to better understand the possible sources of fluid involved in the formation of these diamonds. Sr isotope ratios vary significantly within single diamonds. The highly varied but unsupported Sr isotope ratios cannot be explained by immiscibility processes or fluid-mineral elemental fractionations occurring at the time of diamond growth. Our results demonstrate the clear involvement of a mixed fluid, with one component originating from ancient incompatible element-enriched parts of the lithospheric mantle while the trigger for releasing this fluid source was probably carbonatitic/kimberlitic melts derived from greater depths. We suggest that phlogopite mica was an integral part of the enriched lithospheric fluid source and that breakdown of this mica releases K and radiogenic Sr into a fluid phase. The resulting fluids operate as a major metasomatic agent in the sub-continental lithospheric mantle as reflected by the isotopic composition and trace element patterns of G10 garnets.

High-density fluids and the growth of monocrystalline diamonds

NASA Astrophysics Data System (ADS)

Weiss, Y.; Kiflawi, I.; Davies, N.; Navon, O.

2014-09-01

The chemical nature and composition of the growth medium of monocrystalline (MC) diamonds is still a matter of debate, partially because carbonate-bearing high-density fluids (HDFs) that are common in fibrous diamonds have not been found in MC diamonds. Here we report the first finding of HDF microinclusions in a MC octahedral diamond from Finsch, South Africa and in the MC octahedral core of a coated diamond from Kankan, Guinea; both diamonds carry nitrogen in B-centers. Numerous microinclusions in diamond Finsch_2a_cap1 are restricted to two thin layers parallel to the (1 1 1) face, ∼20 and 200 μm from the diamond rim. Low-Mg carbonatitic HDFs are found along the inner layer while the outer layer trapped saline compositions. The major and trace element compositions of the inclusions and their infrared spectra are highly similar to those of microinclusions found in fibrous diamonds. A few isolated microinclusions of saline compositions are scattered around a sulfide inclusion in the center of the octahedral core of diamond ON-KAN-383. This evidence for the involvement of oxidized fluids in the formation of MC diamonds adds to previous reports on the antiquity of HDFs in fibrous diamonds, the presence of carbonate and halide phases in inclusions in MC diamonds and the similarity of trace element pattern of a MC diamond to those of low-Mg carbonatitic HDF in fibrous diamonds. In addition, we show that the interaction of HDFs with depleted garnets can produce sinusoidal REE patterns which are one of the primary features of lherzolitic and harzburgitic garnet inclusions in MC diamonds. Together, these observations suggest that HDFs are involved in the formation of many types of diamonds from the Archaean to the Phanerozoic. HDFs are trapped in large quantities during rapid, fibrous growth, but must also be present during the growth of many MC diamonds.

Calculation of intrinsic stresses in the diamond-like coatings produced by plasma ion deposition in modes of DC and pulse bias potentials

NASA Astrophysics Data System (ADS)

Kalinichenko, A. A.; Perepelkin, S. S.; Strel'nitskij, V. E.

2015-04-01

The formula derivation for calculation of intrinsic stress in diamond-like coatings deposited from the ion flux in modes of continuous and pulsed potentials in view of process of defects formation is given. The criterion of applicability of obtained formula allowing to determine critical parameters of the pulsed potential mode is suggested. Results of calculation of stresses in diamond-like coatings at deposition of low-energy ions C+ from filtered vacuum arc plasma are adduced. The influence of the bias potential, repetition frequency and pulse duration, on the value of intrinsic stress is discussed. Qualitative agreement of calculated stress and experimental data is stated. The important role of deposition temperature in control of intrinsic stress in deposited coating is noted.

Determining the microwave coupling and operational efficiencies of a microwave plasma assisted chemical vapor deposition reactor under high pressure diamond synthesis operating conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nad, Shreya; Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824; Gu, Yajun

2015-07-15

The microwave coupling efficiency of the 2.45 GHz, microwave plasma assisted diamond synthesis process is investigated by experimentally measuring the performance of a specific single mode excited, internally tuned microwave plasma reactor. Plasma reactor coupling efficiencies (η) > 90% are achieved over the entire 100–260 Torr pressure range and 1.5–2.4 kW input power diamond synthesis regime. When operating at a specific experimental operating condition, small additional internal tuning adjustments can be made to achieve η > 98%. When the plasma reactor has low empty cavity losses, i.e., the empty cavity quality factor is >1500, then overall microwave discharge coupling efficienciesmore » (η{sub coup}) of >94% can be achieved. A large, safe, and efficient experimental operating regime is identified. Both substrate hot spots and the formation of microwave plasmoids are eliminated when operating within this regime. This investigation suggests that both the reactor design and the reactor process operation must be considered when attempting to lower diamond synthesis electrical energy costs while still enabling a very versatile and flexible operation performance.« less

Invasion of Hydrous Fluids Predates Kimberlite Formation

NASA Astrophysics Data System (ADS)

Kopylova, M. G.; Wang, Q.; Smith, E. M.

2017-12-01

Petrological observations on diamonds and peridotite xenoliths in kimberlites point towards an influx of hydrous metasomatic fluids shortly predating kimberlite formation. Diamonds may grow at different times within the same segment of the cratonic mantle, and diamonds that form shortly before (<5-7 My) the kimberlite entrainment host the more hydrous fluid inclusions. Younger fibrous diamonds typically contain 10-25 wt.% water in fluid inclusions, while older octahedrally-grown diamonds host "dry" N2-CO2 fluids. Our recent studies of fluids in diamond now show that many different kinds of diamonds can contain fluid inclusions. Specifically, we found a new way to observe and analyze fluids in octahedrally-grown, non-fibrous diamonds by examining healed fractures. This is a new textural context for fluid inclusions that reveals a valuable physical record of infiltrating mantle fluids, that postdate diamond growth, but equilibrate within the diamond stability field at depths beyond 150 km. Another sign of the aqueous fluids influx is the formation of distinct peridotite textures shortly predating the kimberlite. Kimberlites entrain peridotite xenoliths with several types of textures: older coarse metamorphic textures and younger, sheared textures. The preserved contrast in grain sizes between porphyroclasts and neoblasts in sheared peridotites constrain the maximum duration of annealing. Experimental estimates of the annealing time vary from 7x107 sec (2 years) to 106 years (1 My) depending on olivine hydration, strain rate, pressure, temperature and, ultimately, the annealing mechanism. Kimberlite sampling of sheared peridotites from the lithosphere- asthenosphere boundary (LAB) implies their formation no earlier than 1 My prior to the kimberlite ascent. Water contents of olivine measured by FTIR spectrometry using polarized light demonstrated contrasting hydration of coarse and sheared samples. Olivine from sheared peridotite samples has the average water content of 78±3 ppm, in contrast to the less hydrated coarse peridotites (33±6 ppm). LAB hydration results in the lower viscosity of the mantle (1-4 orders of magnitude) translating into 10-104- fold increase in strain rate if stress, its duration, pressure, temperature and the deformation mechanism are assumed constant.

Investigation on the formation of lonsdaleite from graphite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greshnyakov, V. A.; Belenkov, E. A., E-mail: belenkov@csu.ru

2017-02-15

Structural stability and the possible pathways to experimental formation of lonsdaleite—a hexagonal 2H polytype of diamond—have been studied in the framework of the density functional theory (DFT). It is established that the structural transformation of orthorhombic Cmmm graphite to 2H polytype of diamond must take place at a pressure of 61 GPa, while the formation of lonsdaleite from hexagonal P6/mmm graphite must take place at 56 GPa. The minimum potential barrier height separating the 2H polytype state from graphite is only 0.003 eV/atom smaller than that for the cubic diamond. The high potential barrier is indicative of the possibility ofmore » stable existence of the hexagonal diamond under normal conditions. In this work, we have also analyzed the X-ray diffraction and electron-microscopic data available for nanodiamonds found in meteorite impact craters in search for the presence of hexagonal diamond. Results of this analysis showed that pure 3C and 2H polytypes are not contained in the carbon materials of impact origin, the structure of nanocrystals found representing diamonds with randomly packed layers. The term “lonsdaleite,” used to denote carbon materials found in meteorite impact craters and diamond crystals with 2H polytype structure, is rather ambiguous, since no pure hexagonal diamond has been identified in carbon phases found at meteorite fall sites.« less

A novel procedure to obtain nanocrystalline diamond/porous silicon composite by chemical vapor deposition/infiltration processes.

PubMed

Miranda, C R B; Azevedo, A F; Baldan, M R; Beloto, A F; Ferreira, N G

2009-06-01

Nanocrystalline diamond (NCD) films were formed on porous silicon (PS) substrate by Chemical Vapor Deposition/Infiltration (CVD/CVI) process using a hot filament reactor. This innovative procedure is determinant to grow a controlled three-dimensional diamond structure with diamond grains formation in the pores, covering uniformly the different growth planes. In this CVI process, a piece of reticulated vitreous carbon (RVC) was used, under de PS substrate, as an additional solid source of hydrocarbon that ensures the production of pertinent carbon growth species directly on PS and into its pores. PS substrates were obtained by anodization etching process of n-type silicon wafer in a hydrofluoric acid (HF) solution containing acetonitrile (CH3CN) which result in an uniform and well controlled porous distribution and size when compared with the usual ethanol solution. Depositions were performed using Ar-H2-CH4 where the methane concentration varied from 0 up to 1.0 vol%, to analyze the influence of RVC use as an additional carbon source on growth mechanism. Scanning Electron Microscopy (SEM) and Field Emission Gun (FEG) were used to investigate PS and NCD film morphology. SEM images of NCD showed faceted nanograins with average size from 5 to 16 nm and uniform surface texture covering all the supports among the pores resulting in an apparent micro honeycomb structure. Raman spectra confirmed the existence of sp2-bonded carbon at the grain boundaries. The spectra showed a peak that may be deconvoluted in two components at 1332 cm(-1) (diamond) and 1345 cm(-1) (D band). Two shoulders at 1150 and 1490 cm(-1) also appear and are assigned to transpolyacetylene (TPA) segments at the grain boundaries of NCD surfaces. In addition, X-ray diffraction analyses of all films presented characteristic diamond diffraction peaks corresponding to (111), (220) and (311).

Diamond Head Revisited with Ammonium Dichromate.

ERIC Educational Resources Information Center

Arrigoni, Edward

1981-01-01

The classroom demonstration using ammonium dichromate to simulate a volcanic eruption can be modified into a more dramatic and accurate representation of the geologic processes involved in the formation of a volcanic crater. The materials, demonstration setup, safety procedures, and applications to instruction are presented. (Author/WB)

Layer Protecting the Surface of Zirconium Used in Nuclear Reactors.

PubMed

Ashcheulov, Petr; Skoda, Radek; Skarohlíd, Jan; Taylor, Andrew; Fendrych, Frantisek; Kratochvílová, Irena

2016-01-01

Zirconium alloys have very useful properties for nuclear facilities applications having low absorption cross-section of thermal electrons, high ductility, hardness and corrosion resistance. However, there is also a significant disadvantage: it reacts with water steam and during this (oxidative) reaction it releases hydrogen gas, which partly diffuses into the alloy forming zirconium hydrides. A new strategy for surface protection of zirconium alloys against undesirable oxidation in nuclear reactors by polycrystalline diamond film has been patented- Czech patent 305059: Layer protecting the surface of zirconium alloys used in nuclear reactors and PCT patent: Layer for protecting surface of zirconium alloys (Patent Number: WO2015039636-A1). The zirconium alloy surface was covered by polycrystalline diamond layer grown in plasma enhanced chemical vapor deposition apparatus with linear antenna delivery system. Substantial progress in the description and understanding of the polycrystalline diamond/ zirconium alloys interface and material properties under standard and nuclear reactors conditions (irradiation, hot steam oxidation experiments and heating-quenching cycles) was made. In addition, process technology for the deposition of protective polycrystalline diamond films onto the surface of zirconium alloys was optimized. Zircaloy2 nuclear fuel pins were covered by 300 nm thick protective polycrystalline diamond layer (PCD) using plasma enhanced chemical vapor deposition apparatus with linear antenna delivery system. The polycrystalline diamond layer protects the zirconium alloy surface against undesirable oxidation and consolidates its chemical stability while preserving its functionality. PCD covered Zircaloy2 and standard Zircaloy2 pins were for 30 min. oxidized in 1100°C hot steam. Under these conditions α phase of zirconium changes to β phase (more opened for oxygen/hydrogen diffusion). PCD anticorrosion protection of Zircaloy nuclear fuel assemblies can significantly prolong lifetime of Zirconium alloy in nuclear reactors even above Zirconium phase transition temperatures. Even after ion beam irradiation (10 dpa, 3 MeV Fe(2+)) the diamond film still shows satisfactory structural integrity with both sp(3) and sp(2) carbon phases. Zircaloy2 under the carbon-based protective layer after hot steam oxidation test differed from the original Zircaloy2 material composition only very slightly, proving that the diamond coating increases the material resistance to high temperature oxidation. Zirconium alloys nuclear fuel pins' surfaces were covered by compact and homogeneous polycrystalline diamond layers consisting of sp(3) and sp(2) carbon phases with a high crystalline diamond content and low roughness. Diamond withstands very high temperatures, has excellent thermal conductivity and low chemical reactivity, it does not degrade over time and (important for the nuclear fuel cladding) being pure carbon, it has perfect neutron cross-section properties. Moreover, polycrystalline diamond layers consisting of crystalline (sp(3)) and amorphous (sp(2)) carbon phases could have suitable thermal expansion. Zirconium alloys coated with polycrystalline diamond film are protected against undesirable changes and processes. Further, the polycrystalline diamond layer prevents the reaction between the alloy surface and water vapor. During such reaction, water molecules dissociate and initiate formation of zirconium dioxide and hydrogen, accompanied by the release of large amount of heat. Thus the protective layer prevents the formation of hydrogen and the release of reaction heat. Few relevant patents to the topic have been reviewed and cited.

Improvement on electrical conductivity and electron field emission properties of Au-ion implanted ultrananocrystalline diamond films by using Au-Si eutectic substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sankaran, K. J.; Institute for Materials Research; Sundaravel, B.

2015-08-28

In the present work, Au-Si eutectic layer was used to enhance the electrical conductivity/electron field emission (EFE) properties of Au-ion implanted ultrananocrystalline diamond (Au-UNCD) films grown on Si substrates. The electrical conductivity was improved to a value of 230 (Ω cm){sup −1}, and the EFE properties was enhanced reporting a low turn-on field of 2.1 V/μm with high EFE current density of 5.3 mA/cm{sup 2} (at an applied field of 4.9 V/μm) for the Au-UNCD films. The formation of SiC phase circumvents the formation of amorphous carbon prior to the nucleation of diamond on Si substrates. Consequently, the electron transport efficiency of themore » UNCD-to-Si interface increases, thereby improving the conductivity as well as the EFE properties. Moreover, the salient feature of these processes is that the sputtering deposition of Au-coating for preparing the Au-Si interlayer, the microwave plasma enhanced chemical vapor deposition process for growing the UNCD films, and the Au-ion implantation process for inducing the nanographitic phases are standard thin film preparation techniques, which are simple, robust, and easily scalable. The availability of these highly conducting UNCD films with superior EFE characteristics may open up a pathway for the development of high-definition flat panel displays and plasma devices.« less

Transformation of shock-compressed graphite to hexagonal diamond in nanoseconds

PubMed Central

Turneaure, Stefan J.; Sharma, Surinder M.; Volz, Travis J.; Winey, J. M.; Gupta, Yogendra M.

2017-01-01

The graphite-to-diamond transformation under shock compression has been of broad scientific interest since 1961. The formation of hexagonal diamond (HD) is of particular interest because it is expected to be harder than cubic diamond and due to its use in terrestrial sciences as a marker at meteorite impact sites. However, the formation of diamond having a fully hexagonal structure continues to be questioned and remains unresolved. Using real-time (nanosecond), in situ x-ray diffraction measurements, we show unequivocally that highly oriented pyrolytic graphite, shock-compressed along the c axis to 50 GPa, transforms to highly oriented elastically strained HD with the (100)HD plane parallel to the graphite basal plane. These findings contradict recent molecular dynamics simulation results for the shock-induced graphite-to-diamond transformation and provide a benchmark for future theoretical simulations. Additionally, our results show that an earlier report of HD forming only above 170 GPa for shocked pyrolytic graphite may lead to incorrect interpretations of meteorite impact events. PMID:29098183

Transformation of shock-compressed graphite to hexagonal diamond in nanoseconds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Turneaure, Stefan J.; Sharma, Surinder M.; Volz, Travis J.

The graphite-to-diamond transformation under shock compression has been of broad scientific interest since 1961. The formation of hexagonal diamond (HD) is of particular interest because it is expected to be harder than cubic diamond and due to its use in terrestrial sciences as a marker at meteorite impact sites. However, the formation of diamond having a fully hexagonal structure continues to be questioned and remains unresolved. Using real-time (nanosecond), in situ x-ray diffraction measurements, we show unequivocally that highly oriented pyrolytic graphite, shock-compressed along the c axis to 50 GPa, transforms to highly oriented elastically strained HD with the (100)HDmore » plane parallel to the graphite basal plane. These findings contradict recent molecular dynamics simulation results for the shock-induced graphite-to-diamond transformation and provide a benchmark for future theoretical simulations. Additionally, our results show that an earlier report of HD forming only above 170 GPa for shocked pyrolytic graphite may lead to incorrect interpretations of meteorite impact events.« less

Transformation of shock-compressed graphite to hexagonal diamond in nanoseconds

DOE PAGES

Turneaure, Stefan J.; Sharma, Surinder M.; Volz, Travis J.; ...

2017-10-27

The graphite-to-diamond transformation under shock compression has been of broad scientific interest since 1961. The formation of hexagonal diamond (HD) is of particular interest because it is expected to be harder than cubic diamond and due to its use in terrestrial sciences as a marker at meteorite impact sites. However, the formation of diamond having a fully hexagonal structure continues to be questioned and remains unresolved. Using real-time (nanosecond), in situ x-ray diffraction measurements, we show unequivocally that highly oriented pyrolytic graphite, shock-compressed along the c axis to 50 GPa, transforms to highly oriented elastically strained HD with the (100)HDmore » plane parallel to the graphite basal plane. These findings contradict recent molecular dynamics simulation results for the shock-induced graphite-to-diamond transformation and provide a benchmark for future theoretical simulations. Additionally, our results show that an earlier report of HD forming only above 170 GPa for shocked pyrolytic graphite may lead to incorrect interpretations of meteorite impact events.« less

Direct conversion of h-BN into c-BN and formation of epitaxial c-BN/diamond heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Narayan, Jagdish, E-mail: narayan@ncsu.edu; Bhaumik, Anagh; Xu, Weizong

2016-05-14

We have created a new state of BN (named Q-BN) through rapid melting and super undercooling and quenching by using nanosecond laser pulses. Phase pure c-BN is formed either by direct quenching of super undercooled liquid or by nucleation and growth from Q-BN. Thus, a direct conversion of hexagonal boron nitride (h-BN) into phase-pure cubic boron nitride (c-BN) is achieved by nanosecond pulsed laser melting at ambient temperatures and atmospheric pressure in air. According to the P-T phase diagram, the transformation from h-BN into c-BN under equilibrium processing can occur only at high temperatures and pressures, as the hBN-cBN-Liquid triplemore » point is at 3500 K/9.5 GPa or 3700 K/7.0 GPa with a recent theoretical refinement. Using nonequilibrium nanosecond laser melting, we have created super undercooled state and shifted this triple point to as low as 2800 K and atmospheric pressure. The rapid quenching from super undercooled state leads to the formation of a new phase, named as Q-BN. We present detailed characterization of Q-BN and c-BN layers by using Raman spectroscopy, high-resolution scanning electron microscopy, electron-back-scatter diffraction, high-resolution TEM, and electron energy loss spectroscopy, and discuss the mechanism of formation of nanodots, nanoneedles, microneedles, and single-crystal c-BN on sapphire substrate. We have also deposited diamond by pulsed laser deposition of carbon on c-BN and created c-BN/diamond heterostructures, where c-BN acts as a template for epitaxial diamond growth. We discuss the mechanism of epitaxial c-BN and diamond growth on lattice matching c-BN template under pulsed laser evaporation of amorphous carbon, and the impact of this discovery on a variety of applications.« less

Diamond ages from Victor (Superior Craton): Intra-mantle cycling of volatiles (C, N, S) during supercontinent reorganisation

NASA Astrophysics Data System (ADS)

Aulbach, S.; Creaser, Robert A.; Stachel, Thomas; Heaman, Larry M.; Chinn, Ingrid L.; Kong, Julie

2018-05-01

The central Superior Craton hosts both the diamondiferous 1.1 Ga Kyle Lake and Jurassic Attawapiskat kimberlites. A major thermal event related to the Midcontinent Rift at ca. 1.1 Ga induced an elevated geothermal gradient that largely destroyed an older generation of diamonds, raising the question of when, and how, the diamond inventory beneath Attawapiskat was formed. We determined Re-Os isotope systematics of sulphides included in diamonds from Victor by isotope dilution negative thermal ionisation mass spectrometry in order to obtain insights into the age and nature of the diamond source in the context of regional tectonothermal evolution. Regression of the peridotitic inclusion data (n = 14 of 16) yields a 718 ± 49 Ma age, with an initial 187Os/188Os ratio of 0.1177 ± 0.0016, i.e. depleted at the time of formation (γOs -3.7 ± 1.3). Consequently, Re depletion model ages calculated for these samples are systematically overestimated. Given that reported 187Os/188Os in olivine from Attawapiskat xenoliths varies strongly (0.1012-0.1821), the low and nearly identical initial Os of sulphide inclusions combined with their high 187Re/188Os (median 0.34) suggest metasomatic formation from a mixed source. This was likely facilitated by percolation of amounts of melt sufficient to homogenise Os, (re)crystallise sulphide and (co)precipitate diamond; that is, the sulphide inclusions and their diamond host are synchronous if not syngenetic. The ∼720 Ma age corresponds to rifting beyond the northern craton margin during Rodinia break-up. This suggests mobilisation of volatiles (C, N, S) and Os due to attendant mantle stretching and metasomatism by initially oxidising and S-undersaturated melts, which ultimately produced lherzolitic diamonds with high N contents compared to older Kyle Lake diamonds. Thus, some rift-influenced settings are prospective with respect to diamond formation. They are also important sites of hidden, intra-lithospheric volatile redistribution that can be revealed by diamond studies. Later emplacement of the Attawapiskat kimberlites, linking the carbon cycle to the surface, was associated with renewed disturbance during passage of the Great Meteor Hotspot. Lherzolitic diamond formation from oxidising small-volume melts may be the expression of an early and deep stage of the lithospheric conditioning required for the successful eruption of kimberlites, which complements the late and shallow emplacement of volatile-rich metasomes after upward displacement of a redox freezing front.

Trace-element patterns of fibrous and monocrystalline diamonds: Insights into mantle fluids

NASA Astrophysics Data System (ADS)

Rege, S.; Griffin, W. L.; Pearson, N. J.; Araujo, D.; Zedgenizov, D.; O'Reilly, S. Y.

2010-08-01

During their growth diamonds may trap micron-scale inclusions of the fluids from which they grew, and these "time capsules" provide insights into the metasomatic processes that have modified the subcontinental lithospheric mantle. LAM-ICPMS analysis of trace elements in > 500 fibrous and monocrystalline diamonds worldwide has been used to understand the nature of these fluids. Analyses of fibrous diamonds define two general types of pattern, a "fibrous-high" (FH) one with high contents of LREE, Ba and K, and a "fibrous-low" (FL) pattern characterized by depletion in LREE/MREE, Ba and K, negative anomalies in Sr and Y, and subchondritic Zr/Hf and Nb/Ta. Both types may be found in fibrous diamonds from single deposits, and in three Yakutian pipes some diamonds show abrupt transitions from inclusion-rich cores with FH patterns to clearer rims with FL patterns. Most monocrystalline diamonds show FL-type patterns, but some have patterns that resemble those of FH fibrous diamonds. Peridotitic and eclogitic monocrystalline diamonds may show either patterns with relatively flat REE, or patterns with more strongly depleted LREE. Kimberlites that contain peridotitic diamonds with "high" patterns also contain eclogitic diamonds with "high" patterns. Strong similarities in the patterns of these two groups of diamonds may suggest high fluid/rock ratios. Many diamonds of the "superdeep" paragenesis have trace-element patterns similar to those of other monocrystalline diamonds. This may be evidence that the trace-element compositions of deep-seated fluids are generally similar to those that form diamonds in the subcontinental lithospheric mantle. The element fractionations observed between the FH and FL patterns are consistent with the immiscible separation of a silicic fluid from a carbonatite-silicate fluid, leaving a residual carbonatitic fluid strongly enriched in LREE, Ba and alkalies. This model would suggest that most monocrystalline diamonds crystallized from the more silicic fraction. Comparison with studies of single fluid inclusions in fibrous diamonds suggests that the FH patterns reflect trapped inclusions of high-Mg and low-Mg carbonatitic high-density fluids. In terms of the rock-forming elements, the fluids that precipitated the rims of some fibrous diamonds (FL pattern) and most monocrystalline diamonds are broadly similar to some hydro-silicic high-density fluids found in fibrous diamonds. However, there are still significant differences between the trace-element patterns of most monocrystalline diamonds and known high-density fluids, and further research is required to understand the formation and growth of these diamonds.

Infrared spectral and carbon isotopic characteristics of micro- and macro-diamonds from the Panda kimberlite (Central Slave Craton, Canada)

NASA Astrophysics Data System (ADS)

Melton, G. L.; Stachel, T.; Stern, R. A.; Carlson, J.; Harris, J. W.

2013-09-01

One hundred and twenty-one micro-diamonds (< 1 mm) and 90 macro-diamonds (2.5 mm to 3.4 mm) from the Panda kimberlite (Ekati mine, Central Slave Craton, Canada) were analyzed for nitrogen content, nitrogen aggregation state (%B) and platelet and hydrogen peak areas (cm- 2). Micro-diamond nitrogen concentrations range from < 10 at. ppm to 1696 at. ppm (median = 805 at. ppm) and the median aggregation state is 23%B. Macro-diamonds range from < 10 at. ppm to 1260 at. ppm (median = 187 at. ppm) nitrogen and have a median nitrogen aggregation of 26%B. Platelet and hydrogen peaks were observed in 37% and 79% of the micro-diamonds and 79% and 56% of the macro-diamonds, respectively. Nitrogen based time averaged residence temperatures indicate that micro- and macro-diamonds experienced similar thermal mantle residence histories, both populations displaying bimodal residence temperature distributions with a gap between 1130 °C and 1160 °C (at 3.5 Ga residence). In addition, SIMS carbon isotopic analyses for the micro-diamonds were obtained: δ13C compositions range from - 6.9‰ to + 1.8‰ (median = - 4.3‰). CL imaging reveals distinct growth layers that in some samples differ by > 2‰, but mostly vary by < 0.5‰. Comparison of only the “gem-quality” samples (n = 49 micro- and 90 macro-diamonds) between the two diamond sets, indicates a statistically significant shift of + 1.3‰ in average δ13C from macro- to micro-diamonds and this shift documents distinct diamond forming fluids, fractionation process or growth histories. A broad transition to heavier isotopic values is also observed in connection to decreasing mantle residence temperatures. The bimodal mantle residence temperature distribution may coincide with the transition from highly depleted shallow to more fertile deep lithospheric mantle observed beneath the Central Slave Craton. The increase in δ13C with decreasing residence temperature (proxy for decreasing depth) is interpreted to reflect diamond formation from a carbonate-bearing metasomatic fluid/melt that isotopically evolves as it percolates upward through the lithosphere.

Proceedings of the Seventh Applied Diamond Conference/Third Frontier Carbon Technology Joint Conference (ADC/FCT 2003). Supplement 1

NASA Technical Reports Server (NTRS)

Murakawa, M. (Editor); Miyoshi, K. (Editor); Koga, Y. (Editor); Schaefer, L. (Editor); Tzeng, Y. (Editor)

2003-01-01

This document contains 2 reports which were presented at the Seventh Applied Diamond Conference/Third Frontier Carbon Technology Joint Conference. The topics discuss the formation of C-N nanofibers as well as the characterization of diamond thin films.

Diamonds in ophiolites: Contamination or a new diamond growth environment?

NASA Astrophysics Data System (ADS)

Howell, D.; Griffin, W. L.; Yang, J.; Gain, S.; Stern, R. A.; Huang, J.-X.; Jacob, D. E.; Xu, X.; Stokes, A. J.; O'Reilly, S. Y.; Pearson, N. J.

2015-11-01

For more than 20 years, the reported occurrence of diamonds in the chromites and peridotites of the Luobusa massif in Tibet (a complex described as an ophiolite) has been widely ignored by the diamond research community. This skepticism has persisted because the diamonds are similar in many respects to high-pressure high-temperature (HPHT) synthetic/industrial diamonds (grown from metal solvents), and the finding previously has not been independently replicated. We present a detailed examination of the Luobusa diamonds (recovered from both peridotites and chromitites), including morphology, size, color, impurity characteristics (by infrared spectroscopy), internal growth structures, trace-element patterns, and C and N isotopes. A detailed comparison with synthetic industrial diamonds shows many similarities. Cubo-octahedral morphology, yellow color due to unaggregated nitrogen (C centres only, Type Ib), metal-alloy inclusions and highly negative δ13C values are present in both sets of diamonds. The Tibetan diamonds (n = 3) show an exceptionally large range in δ15N (-5.6 to + 28.7 ‰) within individual crystals, and inconsistent fractionation between {111} and {100} growth sectors. This in contrast to large synthetic HPHT diamonds grown by the temperature gradient method, which have with δ15N = 0 ‰ in {111} sectors and + 30 ‰ in {100} sectors, as reported in the literature. This comparison is limited by the small sample set combined with the fact the diamonds probably grew by different processes. However, the Tibetan diamonds do have generally higher concentrations and different ratios of trace elements; most inclusions are a NiMnCo alloy, but there are also some small REE-rich phases never seen in HPHT synthetics. These characteristics indicate that the Tibetan diamonds grew in contact with a C-saturated Ni-Mn-Co-rich melt in a highly reduced environment. The stable isotopes indicate a major subduction-related contribution to the chemical environment. The unaggregated nitrogen, combined with the lack of evidence for resorption or plastic deformation, suggests a short (geologically speaking) residence in the mantle. Previously published models to explain the occurrence of the diamonds, and other phases indicative of highly reduced conditions and very high pressures, have failed to take into account the characteristics of the diamonds and the implications for their formation. For these diamonds to be seriously considered as the result of a natural growth environment requires a new understanding of mantle conditions that could produce them.

Formation of nanodiamond films from aqueous suspensions during spin coating

NASA Astrophysics Data System (ADS)

Lebedev-Stepanov, P. V.; Molchanov, S. P.; Vasil'ev, A. L.; Mitrokhin, V. P.; Yurasik, G. A.; Aleksenskii, A. E.; Dideikin, A. T.

2016-03-01

The formation of multifunctional ordered arrays of detonation diamond particles is studied during self-assembling in spin coating of films of evaporating microdroplets. It is shown that the most homogeneous layer of diamond particles on a crystalline silicon substrate forms at a rate of substrate rotation of 8000 min-1, whereas a relation between the distribution of particles and the radius is clearly detected at rates of about 2000 min-1. As the rate of substrate rotation increases from 2500 to 8000 min-1, the density of the coating of a silicon substrate with diamond nanoparticles decreases approximately threefold. A model is proposed to estimate the increase in the number of individual diamond "points" with the substrate rotation frequency.

Mechanochemical formation of heterogeneous diamond structures during rapid uniaxial compression in graphite

NASA Astrophysics Data System (ADS)

Kroonblawd, Matthew P.; Goldman, Nir

2018-05-01

We predict mechanochemical formation of heterogeneous diamond structures from rapid uniaxial compression in graphite using quantum molecular dynamics simulations. Ensembles of simulations reveal the formation of different diamondlike products starting from thermal graphite crystal configurations. We identify distinct classes of final products with characteristic probabilities of formation, stress states, and electrical properties and show through simulations of rapid quenching that these products are nominally stable and can be recovered at room temperature and pressure. Some of the diamond products exhibit significant disorder and partial closure of the energy gap between the highest-occupied and lowest-unoccupied molecular orbitals (i.e., the HOMO-LUMO gap). Seeding atomic vacancies in graphite significantly biases toward forming products with small HOMO-LUMO gap. We show that a strong correlation between the HOMO-LUMO gap and disorder in tetrahedral bonding configurations informs which kinds of structural defects are associated with gap closure. The rapid diffusionless transformation of graphite is found to lock vacancy defects into the final diamond structure, resulting in configurations that prevent s p3 bonding and lead to localized HOMO and LUMO states with a small gap.

Diamond film deposition on WC-Co and steel substrates with a CrN interlayer for tribological applications

NASA Astrophysics Data System (ADS)

Chandran, Maneesh; Hoffman, Alon

2016-06-01

The most renowned property of diamond is its exceptional hardness. By depositing diamond films on tungsten carbide (WC-Co) and steel substrates, the hardness of diamond can be combined with the toughness of these materials, resulting in an excellent wear resistance material for tribological applications. However, poor adhesion of diamond coating on these substrates leads to a lesser lifetime for the diamond coated tools than expected. The prime reasons for the lack of proper adhesion are the preferential formation of graphitic layer at the interface due to the catalytic activities of cobalt/iron and the interfacial residual stresses due to the mismatch in thermal expansion coefficients of diamond (1.5  ×  10-6 K-1) and WC-Co (5.2  ×  10-6 K-1) or steel (12  ×  10-6 K-1). In this review, we discuss the possibility of using a Cr-N interlayer as a diffusion barrier to prevent the catalytic activities of cobalt/iron and also to relax the interfacial residual stresses to some extent to enhance the adhesion of diamond coatings on these substrates. An overview of the most pertinent results of the last two decades, including the recent progress is introduced. We describe in detail how the Cr-N interlayer with the desired properties is fabricated. We give a concise overview of diamond deposition process, including the methods to vary the grain size from microcrystalline to nanocrystalline, which are suitable for some tribological applications. We describe in detail on surface and interface analysis, residual stress measurements, assessment adhesion strength and tribological performance of diamond coated WC-Co and steel substrates using various characterization techniques. We conclude by highlighting the current progress and future perspectives of diamond coatings on these substrates for tribological applications.

Diamond formation in the deep lower mantle: a high-pressure reaction of MgCO3 and SiO2

PubMed Central

Maeda, Fumiya; Ohtani, Eiji; Kamada, Seiji; Sakamaki, Tatsuya; Hirao, Naohisa; Ohishi, Yasuo

2017-01-01

Diamond is an evidence for carbon existing in the deep Earth. Some diamonds are considered to have originated at various depth ranges from the mantle transition zone to the lower mantle. These diamonds are expected to carry significant information about the deep Earth. Here, we determined the phase relations in the MgCO3-SiO2 system up to 152 GPa and 3,100 K using a double sided laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction. MgCO3 transforms from magnesite to the high-pressure polymorph of MgCO3, phase II, above 80 GPa. A reaction between MgCO3 phase II and SiO2 (CaCl2-type SiO2 or seifertite) to form diamond and MgSiO3 (bridgmanite or post-perovsktite) was identified in the deep lower mantle conditions. These observations suggested that the reaction of the MgCO3 phase II with SiO2 causes formation of super-deep diamond in cold slabs descending into the deep lower mantle. PMID:28084421

Interplay between discharge physics, gas phase chemistry and surface processes in hydrocarbon plasmas

NASA Astrophysics Data System (ADS)

Hassouni, Khaled

2013-09-01

In this paper we present two examples that illustrate two different contexts of the interplay between plasma-surface interaction process and discharge physics and gas phase chemistry in hydrocarbon discharges. In the first example we address the case of diamond deposition processes and illustrate how a detailed investigation of the discharge physics, collisional processes and transport phenomena in the plasma phase make possible to accurately predict the key local-parameters, i.e., species density at the growing substrate, as function of the macroscopic process parameters, thus allowing for a precise control of diamond deposition process. In the second example, we illustrate how the interaction between a rare gas pristine discharge and carbon (graphite) electrode induce a dramatic change on the discharge nature, i.e., composition, ionization kinetics, charge equilibrium, etc., through molecular growth and clustering processes, solid particle formation and dusty plasma generation. Work done in collaboration with Alix Gicquel, Francois Silva, Armelle Michau, Guillaume Lombardi, Xavier Bonnin, Xavier Duten, CNRS, Universite Paris 13.

Effect of graphite particle size and content on the formation mechanism of detonation polycrystalline diamond

NASA Astrophysics Data System (ADS)

Tong, Y.; Cao, Y.; Liu, R.; Shang, S. Y.; Huang, F. L.

2018-03-01

The formation mechanism of detonation polycrystalline diamond (DPD) generated from the detonation of a mixed RDX/graphite explosive is investigated. It is found experimentally that the DPD conversion rate decreases with both the content and the particle size of the graphite. Moreover, the particle sizes of the generated DPD powder are analyzed, which shows that, with the decrease in the graphite particle size, the mean number diameter of DPD decreases, but the mean volume diameter increases. In addition, with the help of scanning electron microscopy, it is observed that the in situ phase change occurs in the graphite particles, by which the small particles combine to form numerous large DPD particles. Based on both the experimental data and the classical ZND detonation model, we divide such a DPD synthesis process into two stages: In the first stage, the in situ phase change from graphite to diamond is dominant, supplemented by some coalescence growth at high pressure and temperature, which is affected mainly by the detonation performance of the mixed explosive under consideration. In the second stage, the graphitization of DPD caused by the residual heat is dominant, which is affected mainly by the unloading rate of the particle temperature.

Ultrafast transformation of graphite to diamond: an ab initio study of graphite under shock compression.

PubMed

Mundy, Christopher J; Curioni, Alessandro; Goldman, Nir; Will Kuo, I-F; Reed, Evan J; Fried, Laurence E; Ianuzzi, Marcella

2008-05-14

We report herein ab initio molecular dynamics simulations of graphite under shock compression in conjunction with the multiscale shock technique. Our simulations reveal that a novel short-lived layered diamond intermediate is formed within a few hundred of femtoseconds upon shock loading at a shock velocity of 12 kms (longitudinal stress>130 GPa), followed by formation of cubic diamond. The layered diamond state differs from the experimentally observed hexagonal diamond intermediate found at lower pressures and previous hydrostatic calculations in that a rapid buckling of the graphitic planes produces a mixture of hexagonal and cubic diamond (layered diamond). Direct calculation of the x-ray absorption spectra in our simulations reveals that the electronic structure of the final state closely resembles that of compressed cubic diamond.

Deterministic Nanopatterning of Diamond Using Electron Beams.

PubMed

Bishop, James; Fronzi, Marco; Elbadawi, Christopher; Nikam, Vikram; Pritchard, Joshua; Fröch, Johannes E; Duong, Ngoc My Hanh; Ford, Michael J; Aharonovich, Igor; Lobo, Charlene J; Toth, Milos

2018-03-27

Diamond is an ideal material for a broad range of current and emerging applications in tribology, quantum photonics, high-power electronics, and sensing. However, top-down processing is very challenging due to its extreme chemical and physical properties. Gas-mediated electron beam-induced etching (EBIE) has recently emerged as a minimally invasive, facile means to dry etch and pattern diamond at the nanoscale using oxidizing precursor gases such as O 2 and H 2 O. Here we explain the roles of oxygen and hydrogen in the etch process and show that oxygen gives rise to rapid, isotropic etching, while the addition of hydrogen gives rise to anisotropic etching and the formation of topographic surface patterns. We identify the etch reaction pathways and show that the anisotropy is caused by preferential passivation of specific crystal planes. The anisotropy can be controlled by the partial pressure of hydrogen and by using a remote RF plasma source to radicalize the precursor gas. It can be used to manipulate the geometries of topographic surface patterns as well as nano- and microstructures fabricated by EBIE. Our findings constitute a comprehensive explanation of the anisotropic etch process and advance present understanding of electron-surface interactions.

Silicon Sheet Growth Development for the Large Area Sheet Task of the Low Cost Solar Array Project. Heat Exchanger Method - Ingot Casting Fixed Abrasive Method - Multi-Wire Slicing

NASA Technical Reports Server (NTRS)

Schmid, F.; Khattak, C. P.

1978-01-01

Solar cells fabricated from HEM cast silicon yielded up to 15% conversion efficiencies. This was achieved in spite of using unpurified graphite parts in the HEM furnace and without optimization of material or cell processing parameters. Molybdenum retainers prevented SiC formation and reduced carbon content by 50%. The oxygen content of vacuum cast HEM silicon is lower than typical Czochralski grown silicon. Impregnation of 45 micrometers diamonds into 7.5 micrometers copper sheath showed distortion of the copper layer. However, 12.5 micrometers and 15 micrometers copper sheath can be impregnated with 45 micrometers diamonds to a high concentration. Electroless nickel plating of wires impregnated only in the cutting edge showed nickel concentration around the diamonds. This has the possibility of reducing kerf. The high speed slicer fabricated can achieve higher speed and longer stroke with vibration isolation.

Optical patterning of trapped charge in nitrogen-doped diamond

NASA Astrophysics Data System (ADS)

Dhomkar, Siddharth; Jayakumar, Harishankar; Pagliero, Daniela; Laraoui, Abdelghani; Albu, Remus; Manson, Neil; Doherty, Marcus; Henshaw, Jacob; Meriles, Carlos

The nitrogen-vacancy (NV) center in diamond is emerging as a promising platform for solid-state quantum information processing and nanoscale metrology. Of interest in these applications is the manipulation of the NV charge state, which can be attained by optical illumination. Here we use two-color optical microscopy to investigate the dynamics of NV photo-ionization, charge diffusion, and trapping in type-1b diamond. We combine fixed-point laser excitation and scanning fluorescence imaging to locally alter the concentration of negatively charged NVs and to subsequently probe the corresponding redistribution of charge. We uncover the formation of various spatial patterns of trapped charge, which we semi-quantitatively reproduce via a model of the interplay between photo-excited carriers and atomic defects in the diamond lattice. Further, by using the NV as a local probe, we map the relative fraction of positively charged nitrogen upon localized optical excitation. These observations may prove important to various technologies, including the transport of quantum information between remote NVs and the development of three-dimensional, charge-based memories. We acknowledge support from the National Science Foundation through Grant NSF-1314205.

Iron Oxide Nanoparticles Employed as Seeds for the Induction of Microcrystalline Diamond Synthesis

PubMed Central

2008-01-01

Iron nanoparticles were employed to induce the synthesis of diamond on molybdenum, silicon, and quartz substrates. Diamond films were grown using conventional conditions for diamond synthesis by hot filament chemical vapor deposition, except that dispersed iron oxide nanoparticles replaced the seeding. X-ray diffraction, visible, and ultraviolet Raman Spectroscopy, energy-filtered transmission electron microscopy , electron energy-loss spectroscopy, and X-ray photoelectron spectroscopy (XPS) were employed to study the carbon bonding nature of the films and to analyze the carbon clustering around the seed nanoparticles leading to diamond synthesis. The results indicate that iron oxide nanoparticles lose the O atoms, becoming thus active C traps that induce the formation of a dense region of trigonally and tetrahedrally bonded carbon around them with the ensuing precipitation of diamond-type bonds that develop into microcrystalline diamond films under chemical vapor deposition conditions. This approach to diamond induction can be combined with dip pen nanolithography for the selective deposition of diamond and diamond patterning while avoiding surface damage associated to diamond-seeding methods.

Direct observation and mechanism of increased emission sites in Fe-coated microcrystalline diamond films

NASA Astrophysics Data System (ADS)

Panda, Kalpataru; Sundaravel, B.; Panigrahi, B. K.; Huang, Pin-Chang; Shih, Wen-Ching; Chen, Huang-Chin; Lin, I.-Nan

2012-06-01

The electron field emission (EFE) properties of microcrystalline diamond (MCD) films are significantly enhanced due to the Fe coating and post-annealing processes. The 900 °C post-annealed Fe coated diamond films exhibit the best EFE properties, with a turn on field (E0) of 3.42 V/μm and attain EFE current density (Je) of 170 μA/cm2 at 7.5 V/μm. Scanning tunnelling spectroscopy (STS) in current imaging tunnelling spectroscopy mode clearly shows the increased number density of emission sites in Fe-coated and post-annealed MCD films than the as-prepared ones. Emission is seen from the boundaries of the Fe (or Fe3C) nanoparticles formed during the annealing process. In STS measurement, the normalized conductance dI /dV/I/V versus V curves indicate nearly metallic band gap, at the boundaries of Fe (or Fe3C) nanoparticles. Microstructural analysis indicates that the mechanism for improved EFE properties is due to the formation of nanographite that surrounds the Fe (or Fe3C) nanoparticles.

Formation and Evolution of the Continental Lithospheric Mantle: Perspectives From Radiogenic Isotopes of Silicate and Sulfide Inclusions in Macrodiamonds

NASA Astrophysics Data System (ADS)

Shirey, S. B.; Richardson, S. H.

2007-12-01

Silicate and sulfide inclusions that occur in diamonds comprise the oldest (>3 Ga), deepest (>140 km) samples of mantle-derived minerals available for study. Their relevance to the evolution of the continental lithosphere is clear because terrestrial macrodiamonds are confined to regions of the Earth with continental lithospheric mantle keels. The goals of analytical work on inclusions in diamond are to obtain paragenesis constraints, radiogenic ages, and initial isotopic compositions. The purpose is to place diamond formation episodes into the broader framework of the geological processes that create and modify the continental lithosphere and to relate the source of the C and N in diamond-forming fluids to understanding the Earth's C and N cycles in the Archean. Although sulfide and silicate inclusions rarely occur in the same diamond, they both can be grouped according to their geochemical similarity with the chief rock types that comprise the mantle keel: peridotite and eclogite. Silicate inclusions are classified as harzburgitic (depleted; olivine > Fo91, garnet Cr2O3 > 3 wt% and CaO from 0 to 5 wt%), lherzolitic (fertile), or eclogitic (basaltic; garnet Cr2O3 < 2 wt% and CaO from 3 to 15 wt%, clinopyroxene with higher Na2O, Al2O3, and FeO); they are amenable for trace element study by SIMS and for Sm-Nd and Rb-Sr analysis by conventional P-TIMS after grouping by mineralogical similarity. Sulfide inclusions (chiefly FeS with lesser Ni, Cu, and Co) are classified as peridotitic (Ni > 14 wt%; Os > 2 ppm) versus eclogitic (Ni < 10 wt%; Os < 200 ppb); single sulfides are amenable for S isotopic study by SIMS or TIMS, and Re-Os analysis by N-TIMS. Work on inclusions in diamonds depends on the distribution of mined, diamond-bearing kimberlites, and the generosity of mining companies because of the extreme rarity of inclusions in suites of mostly gem-quality diamonds. Most isotopic work has been on the Kaapvaal-Zimbabwe craton with lesser work on the Slave, Siberian, and Australian cratons. Sm-Nd ages on silicate suites and Re-Os ages on sulfide suites confirm diamond formation from the Mesoarchean though the Neoproterozoic. Most important are the systematics across cratons in the context of crustal geology that lead to generalities about craton evolution. Inclusion suites date mantle keels as Mesoarchean and clearly point to subduction as the major process to form the earliest continental nuclei and to amalgamate the cratons in their present form. This is evident from the elevated initial Os isotopic compositions in 3.5 Ga Slave (Panda) and 2.9 Ga Kaapvaal (Kimberley) sulfides, the low Sm/Nd and elevated initial Sr isotopic compositions of 3.4 Ga Kaapvaal (Kimberley) harzburgitic garnets, the preponderance of 2.9 Ga eclogitic sulfides in every western Kaapvaal craton locality, and the occurrence of surficial, volcanogenic S in Kaapvaal (Orapa) sulfides. The continental lithosphere was accessible to melts and fluids from the asthenosphere throughout the Proterozoic as evident from silicate and sulfide inclusion suites of 0.9 to 2.0 Ga age in every locality studied in the Kaapvaal craton. The correspondence of silicate inclusion type with current seismic velocity structure of the Kaapvaal mantle keel shows that its structure is at least Bushveld age (2 Ga) and due to compositional differences. Seismic velocity structures of continental mantle keels may be more a function of their geologic history than current temperature distribution.

Orientation relationship between diamond and magnesiochromite inclusions

NASA Astrophysics Data System (ADS)

Alvaro, Matteo; Angel, Ross; Nimis, Paolo; Milani, Sula; Harris, Jeff; Nestola, Fabrizio

2017-04-01

The correct determination of the relative crystallographic orientations of single crystals has many applications. When single crystals undergo phase transitions, especially at high pressures, the relative orientations of the two phases yields insights into transition mechanisms (Dobson et al 2013). On the other hand, determination of the crystallographic orientations of minerals included in diamonds can provide insights into the mechanisms of their entrapment and the timing of their formation relative to the host diamond (e.g. Nestola et al. 2014, Milani et al. 2016). The reported occurrence of non-trivial orientations for some minerals in diamonds, suggesting an epitaxial relationship, has long been considered to reflect contemporaneous growth of the diamond and the inclusion (e.g. syngenesis). Correct interpretation of such orientations requires (i) a statistically significant crystallographic data set for single and multiple inclusions in a large number of diamonds, and (ii) a robust data-processing method, capable of removing ambiguities derived from the high symmetry of the diamond and the inclusion. We have developed a software to perform such processing (OrientXplot, Angel et al. 2015), starting from crystallographic orientation matrixes obtained by X-ray diffractometry or EBSD data. Previous studies of inclusions in lithospheric diamonds, by single-crystal X-ray diffraction and EBSD, indicate a wide variety in the orientations of different inclusion phases with respect to their diamond host (Futergendler & Frank-Kamenetsky 1961; Frank-Kamenetsky 1964; Wiggers de Vries et al. 2011; Nestola et al. 2014, Milani et al. 2016). For example, olivine inclusions in lithospheric diamonds from Udachnaya do not show any preferred orientations with respect to their diamond hosts, but multiple inclusions in a single diamond often show very similar orientations within few degrees. In the present work on magnesiochromite inclusions in diamonds from Udachnaya, there is a partial orientation between inclusion and host. A (111) plane of each inclusion is sub-parallel to a {111} plane of their diamond host, but with random orientations of the magnesiochromite [100], [010] and [001] relative to the diamond. In one case, where a single inclusion comprised a magnesiochromite-olivine touching pair, the magnesiochromite was oriented as noted above and the olivine showed a random orientation. The implications of these observations for the mechanisms of diamond growth will be explored and the results will be compared and combined with previous work. This work was supported by ERC starting grant "INDIMEDEA" (307322) to F. Nestola and by the MIUR-SIR grant "MILE DEEp" (RBSI140351) to M. Alvaro. References Angel R. J. et al., J. Appl. Crystallogr. 48, 1330-1334 (2015). Wiggers de Vries D.F. et al., Contrib Mineral Petr 161, 565-579 (2011). Dobson D. P. et al., Nat. Geosci. 6, 575-578 (2013). Frank-Kamenetsky V.A. The nature of structural impurities and inclusions in minerals. Leningrad, Gos. Univ. (1964) Futergendler S.I. and Frank-Kamenetsky V.A. Zap Vsesoyuzn Mineral Obs 90, 230 (1961). Nestola F. et al., Int. Geol. Rev. 56(13), 1658-1667 (2014).

Investigations on diamond nanostructuring of different morphologies by the reactive-ion etching process and their potential applications.

PubMed

Kunuku, Srinivasu; Sankaran, Kamatchi Jothiramalingam; Tsai, Cheng-Yen; Chang, Wen-Hao; Tai, Nyan-Hwa; Leou, Keh-Chyang; Lin, I-Nan

2013-08-14

We report the systematic studies on the fabrication of aligned, uniform, and highly dense diamond nanostructures from diamond films of various granular structures. Self-assembled Au nanodots are used as a mask in the self-biased reactive-ion etching (RIE) process, using an O2/CF4 process plasma. The morphology of diamond nanostructures is a close function of the initial phase composition of diamond. Cone-shaped and tip-shaped diamond nanostructures result for microcrystalline diamond (MCD) and nanocrystalline diamond (NCD) films, whereas pillarlike and grasslike diamond nanostructures are obtained for Ar-plasma-based and N2-plasma-based ultrananocrystalline diamond (UNCD) films, respectively. While the nitrogen-incorporated UNCD (N-UNCD) nanograss shows the most-superior electron-field-emission properties, the NCD nanotips exhibit the best photoluminescence properties, viz, different applications need different morphology of diamond nanostructures to optimize the respective characteristics. The optimum diamond nanostructure can be achieved by proper choice of granular structure of the initial diamond film. The etching mechanism is explained by in situ observation of optical emission spectrum of RIE plasma. The preferential etching of sp(2)-bonded carbon contained in the diamond films is the prime factor, which forms the unique diamond nanostructures from each type of diamond films. However, the excited oxygen atoms (O*) are the main etching species of diamond film.

Direct Coating of Nanocrystalline Diamond on Steel

NASA Astrophysics Data System (ADS)

Tsugawa, Kazuo; Kawaki, Shyunsuke; Ishihara, Masatou; Hasegawa, Masataka

2012-09-01

Nanocrystalline diamond films have been successfully deposited on stainless steel substrates without any substrate pretreatments to promote diamond nucleation, including the formation of interlayers. A low-temperature growth technique, 400 °C or lower, in microwave plasma chemical vapor deposition using a surface-wave plasma has cleared up problems in diamond growth on ferrous materials, such as the surface graphitization, long incubation time, substrate softening, and poor adhesion. The deposited nanocrystalline diamond films on stainless steel exhibit good adhesion and tribological properties, such as a high wear resistance, a low friction coefficient, and a low aggression strength, at room temperature in air without lubrication.

Regional patterns in the paragenesis and age of inclusions in diamond, diamond composition, and the lithospheric seismic structure of Southern Africa

NASA Astrophysics Data System (ADS)

Shirey, Steven B.; Harris, Jeffrey W.; Richardson, Stephen H.; Fouch, Matthew; James, David E.; Cartigny, Pierre; Deines, Peter; Viljoen, Fanus

2003-12-01

The Archean lithospheric mantle beneath the Kaapvaal-Zimbabwe craton of Southern Africa shows ±1% variations in seismic P-wave velocity at depths within the diamond stability field (150-250 km) that correlate regionally with differences in the composition of diamonds and their syngenetic inclusions. Seismically slower mantle trends from the mantle below Swaziland to that below southeastern Botswana, roughly following the surface outcrop pattern of the Bushveld-Molopo Farms Complex. Seismically slower mantle also is evident under the southwestern side of the Zimbabwe craton below crust metamorphosed around 2 Ga. Individual eclogitic sulfide inclusions in diamonds from the Kimberley area kimberlites, Koffiefontein, Orapa, and Jwaneng have Re-Os isotopic ages that range from circa 2.9 Ga to the Proterozoic and show little correspondence with these lithospheric variations. However, silicate inclusions in diamonds and their host diamond compositions for the above kimberlites, Finsch, Jagersfontein, Roberts Victor, Premier, Venetia, and Letlhakane do show some regional relationship to the seismic velocity of the lithosphere. Mantle lithosphere with slower P-wave velocity correlates with a greater proportion of eclogitic versus peridotitic silicate inclusions in diamond, a greater incidence of younger Sm-Nd ages of silicate inclusions, a greater proportion of diamonds with lighter C isotopic composition, and a lower percentage of low-N diamonds whereas the converse is true for diamonds from higher velocity mantle. The oldest formation ages of diamonds indicate that the mantle keels which became continental nuclei were created by middle Archean (3.2-3.3 Ga) mantle depletion events with high degrees of melting and early harzburgite formation. The predominance of sulfide inclusions that are eclogitic in the 2.9 Ga age population links late Archean (2.9 Ga) subduction-accretion events involving an oceanic lithosphere component to craton stabilization. These events resulted in a widely distributed younger Archean generation of eclogitic diamonds in the lithospheric mantle. Subsequent Proterozoic tectonic and magmatic events altered the composition of the continental lithosphere and added new lherzolitic and eclogitic diamonds to the already extensive Archean diamond suite.

Appropriate salt concentration of nanodiamond colloids for electrostatic self-assembly seeding of monosized individual diamond nanoparticles on silicon dioxide surfaces.

PubMed

Yoshikawa, Taro; Zuerbig, Verena; Gao, Fang; Hoffmann, René; Nebel, Christoph E; Ambacher, Oliver; Lebedev, Vadim

2015-05-19

Monosized (∼4 nm) diamond nanoparticles arranged on substrate surfaces are exciting candidates for single-photon sources and nucleation sites for ultrathin nanocrystalline diamond film growth. The most commonly used technique to obtain substrate-supported diamond nanoparticles is electrostatic self-assembly seeding using nanodiamond colloidal suspensions. Currently, monodisperse nanodiamond colloids, which have a narrow distribution of particle sizes centering on the core particle size (∼4 nm), are available for the seeding technique on different substrate materials such as Si, SiO2, Cu, and AlN. However, the self-assembled nanoparticles tend to form small (typically a few tens of nanometers or even larger) aggregates on all of those substrate materials. In this study, this major weakness of self-assembled diamond nanoparticles was solved by modifying the salt concentration of nanodiamond colloidal suspensions. Several salt concentrations of colloidal suspensions were prepared using potassium chloride as an inserted electrolyte and were examined with respect to seeding on SiO2 surfaces. The colloidal suspensions and the seeded surfaces were characterized by dynamic light scattering and atomic force microscopy, respectively. Also, the interaction energies between diamond nanoparticles in each of the examined colloidal suspensions were compared on the basis of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. From these investigations, it became clear that the appropriate salt concentration suppresses the formation of small aggregates during the seeding process owing to the modified electrostatic repulsive interaction between nanoparticles. Finally, monosized (<10 nm) individual diamond nanoparticles arranged on SiO2 surfaces have been successfully obtained.

Local formation of nitrogen-vacancy centers in diamond by swift heavy ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwartz, J.; Aloni, S.; Ogletree, D. F.

2014-12-03

In this paper, we exposed nitrogen-implanted diamonds to beams of swift heavy ions (~1 GeV, ~4 MeV/u) and find that these irradiations lead directly to the formation of nitrogen vacancy (NV) centers, without thermal annealing. We compare the photoluminescence intensities of swift heavy ion activated NV - centers to those formed by irradiation with low-energy electrons and by thermal annealing. NV - yields from irradiations with swift heavy ions are 0.1 of yields from low energy electrons and 0.02 of yields from thermal annealing. We discuss possible mechanisms of NV center formation by swift heavy ions such as electronic excitationsmore » and thermal spikes. While forming NV centers with low efficiency, swift heavy ions could enable the formation of three dimensional NV - assemblies over relatively large distances of tens of micrometers. Finally and further, our results show that NV center formation is a local probe of (partial) lattice damage relaxation induced by electronic excitations from swift heavy ions in diamond.« less

Formation of the nitrogen aggregates in annealed diamond by neutron irradiation

NASA Astrophysics Data System (ADS)

Mita, Y.; Nisida, Y.; Okada, M.

2018-02-01

Neutron heavy irradiation was performed on synthetic diamonds contain nitrogen atoms in isolated substitutional form (called "type Ib diamond") and they were annealed under a pressure of 6 GPa. A large number of nitrogen B-aggregate which consists of four substitutional nitrogen atoms symmetrically surrounding a vacancy was formed within 30 m from single nitrogen atoms. Furthermore it is observed that, in these diamonds, single nitrogen atoms coexist with the B-aggregates, which is unexplainable by the simple nitrogen aggregation model.

The influence of sterilization on nitrogen-included ultrananocrystalline diamond for biomedical applications.

PubMed

Tong, Wei; Tran, Phong A; Turnley, Ann M; Aramesh, Morteza; Prawer, Steven; Brandt, Milan; Fox, Kate

2016-04-01

Diamond has shown great potential in different biomedical applications, but the effects of sterilization on its properties have not been investigated. Here, we studied the influence of five sterilization techniques (solvent cleaning, oxygen plasma, UV irradiation, autoclave and hydrogen peroxide) on nitrogen-included ultrananocrystalline diamond. The chemical modification of the diamond surface was evaluated using X-ray photoelectron spectroscopy and water contact angle measurements. Different degrees of surface oxidation and selective sp(2) bonded carbon etching were found following all sterilization techniques, resulting in an increase of hydrophilicity. Higher viabilities of in vitro mouse 3T3 fibroblasts and rat cortical neuron cells were observed on oxygen plasma, autoclave and hydrogen peroxide sterilized diamond, which correlated with their higher hydrophilicity. By examination of apatite formation in simulated body fluid, in vivo bioactivity was predicted to be best on those surfaces which have been oxygen plasma treated and lowest on those which have been exposed to UV irradiation. The charge injection properties were also altered by the sterilization process and there appears to be a correlation between these changes and the degree of oxygen termination of the surface. We find that the modification brought by autoclave, oxygen plasma and hydrogen peroxide were most consistent with the use of N-UNCD in biological applications as compared to samples sterilized by solvent cleaning or UV exposure or indeed non-sterilized. A two-step process of sterilization by hydrogen peroxide following oxygen plasma treatment was then suggested. However, the final choice of sterilization technique will depend on the intended end application. Copyright © 2015 Elsevier B.V. All rights reserved.

Study on Platinum Coating Depth in Focused Ion Beam Diamond Cutting Tool Milling and Methods for Removing Platinum Layer.

PubMed

Choi, Woong Kirl; Baek, Seung Yub

2015-09-22

In recent years, nanomachining has attracted increasing attention in advanced manufacturing science and technologies as a value-added processes to control material structures, components, devices, and nanoscale systems. To make sub-micro patterns on these products, micro/nanoscale single-crystal diamond cutting tools are essential. Popular non-contact methods for the macro/micro processing of diamond composites are pulsed laser ablation (PLA) and electric discharge machining (EDM). However, for manufacturing nanoscale diamond tools, these machining methods are not appropriate. Despite diamond's extreme physical properties, diamond can be micro/nano machined relatively easily using a focused ion beam (FIB) technique. In the FIB milling process, the surface properties of the diamond cutting tool is affected by the amorphous damage layer caused by the FIB gallium ion collision and implantation and these influence the diamond cutting tool edge sharpness and increase the processing procedures. To protect the diamond substrate, a protection layer-platinum (Pt) coating is essential in diamond FIB milling. In this study, the depth of Pt coating layer which could decrease process-induced damage during FIB fabrication is investigated, along with methods for removing the Pt coating layer on diamond tools. The optimum Pt coating depth has been confirmed, which is very important for maintaining cutting tool edge sharpness and decreasing processing procedures. The ultra-precision grinding method and etching with aqua regia method have been investigated for removing the Pt coating layer. Experimental results show that when the diamond cutting tool width is bigger than 500 nm, ultra-precision grinding method is appropriate for removing Pt coating layer on diamond tool. However, the ultra-precision grinding method is not recommended for removing the Pt coating layer when the cutting tool width is smaller than 500 nm, because the possibility that the diamond cutting tool is damaged by the grinding process will be increased. Despite the etching method requiring more procedures to remove the Pt coating layer after FIB milling, it is a feasible method for diamond tools with under 500 nm width.

Power MEMS Development

DTIC Science & Technology

2011-05-01

wafer pair through further processing. Initial cracking issues were identified due to liquid penetration between the wafers during wet processing...free-standing MCD films we needed to address crack formation in the diamond and the Si substrate, which we observed during our initial growths due to...NCD film grown using the heated stage, and finally the thick MCD film grown on the cooled stage. We also found that the control of cracking in the

Degradation of caffeine by conductive diamond electrochemical oxidation.

PubMed

Indermuhle, Chloe; Martín de Vidales, Maria J; Sáez, Cristina; Robles, José; Cañizares, Pablo; García-Reyes, Juan F; Molina-Díaz, Antonio; Comninellis, Christos; Rodrigo, Manuel A

2013-11-01

The use of Conductive-Diamond Electrochemical Oxidation (CDEO) and Sonoelectrochemical Oxidation (CDSEO) has been evaluated for the removal of caffeine of wastewater. Effects of initial concentration, current density and supporting electrolyte on the process efficiency are assessed. Results show that caffeine is very efficiently removed with CDEO and that depletion of caffeine has two stages depending on its concentration. At low concentrations, opposite to what it is expected in a mass-transfer controlled process, the efficiency increases with current density very significantly, suggesting a very important role of mediated oxidation processes on the removal of caffeine. In addition, the removal of caffeine is faster than TOC, indicating the formation of reaction intermediates. The number and relative abundance of them depend on the operating conditions and supporting electrolyte used. In chloride media, removal of caffeine is faster and more efficiently, although the occurrence of more intermediates takes place. CDSEO does not increase the efficiency of caffeine removal, but it affects to the formation of intermediates. A detailed characterization of intermediates by liquid chromatography time-of-flight mass spectrometry seems to indicate that the degradation of caffeine by CDEO follows an oxidation pathway similar to mechanism proposed by other advanced oxidation processes. Copyright © 2013 Elsevier Ltd. All rights reserved.

Formation of carbon nanoclusters by implantation of keV carbon ions in fused silica followed by thermal annealing

NASA Astrophysics Data System (ADS)

Olivero, P.; Peng, J. L.; Liu, A.; Reichart, P.; McCallum, J. C.; Sze, J. Y.; Lau, S. P.; Tay, B. K.; Kalish, R.; Dhar, S.; Feldman, Leonard; Jamieson, David N.; Prawer, Steven

2005-02-01

In the last decade, the synthesis and characterization of nanometer sized carbon clusters have attracted growing interest within the scientific community. This is due to both scientific interest in the process of diamond nucleation and growth, and to the promising technological applications in nanoelectronics and quantum communications and computing. Our research group has demonstrated that MeV carbon ion implantation in fused silica followed by thermal annealing in the presence of hydrogen leads to the formation of nanocrystalline diamond, with cluster size ranging from 5 to 40 nm. In the present paper, we report the synthesis of carbon nanoclusters by the implantation into fused silica of keV carbon ions using the Plasma Immersion Ion Implantation (PIII) technique, followed by thermal annealing in forming gas (4% 2H in Ar). The present study is aimed at evaluating this implantation technique that has the advantage of allowing high fluence-rates on large substrates. The carbon nanostructures have been characterized with optical absorption and Raman spectroscopies, cross sectional Transmission Electron Microscopy (TEM), and Parallel Electron Energy Loss Spectroscopy (PEELS). Nuclear Reaction Analysis (NRA) has been employed to evaluate the deuterium incorporation during the annealing process, as a key mechanism to stabilize the formation of the clusters.

Process for making a cesiated diamond film field emitter and field emitter formed therefrom

DOEpatents

Anderson, D.F.; Kwan, S.W.

1999-03-30

A process for making a cesiated diamond film comprises (a) depositing a quantity of cesium iodide on the diamond film in a vacuum of between about 10{sup {minus}4} Torr and about 10{sup {minus}7} Torr, (b) increasing the vacuum to at least about 10{sup {minus}8} Torr, and (c) imposing an electron beam upon the diamond film, said electron beam having an energy sufficient to dissociate said cesium iodide and to incorporate cesium into interstices of the diamond film. The cesiated diamond film prepared according to the process has an operating voltage that is reduced by a factor of at least approximately 2.5 relative to conventional, non-cesiated diamond film field emitters. 2 figs.

Process for making a cesiated diamond film field emitter and field emitter formed therefrom

DOEpatents

Anderson, David F.; Kwan, Simon W.

1999-01-01

A process for making a cesiated diamond film comprises (a) depositing a quantity of cesium iodide on the diamond film in a vacuum of between about 10.sup.-4 Torr and about 10.sup.-7 Torr, (b) increasing the vacuum to at least about 10.sup.-8 Torr, and (c) imposing an electron beam upon the diamond film, said electron beam having an energy sufficient to dissociate said cesium iodide and to incorporate cesium into interstices of the diamond film. The cesiated diamond film prepared according to the process has an operating voltage that is reduced by a factor of at least approximately 2.5 relative to conventional, non-cesiated diamond film field emitters.

Morphological Features of Diamond Crystals Dissolved in Fe0.7S0.3 Melt at 4 GPa and 1400°C

NASA Astrophysics Data System (ADS)

Sonin, V. M.; Zhimulev, E. I.; Pomazanskiy, B. S.; Zemnuhov, A. L.; Chepurov, A. A.; Afanasiev, V. P.; Chepurov, A. I.

2018-01-01

An experimental study of the dissolution of natural and synthetic diamonds in a sulfur-bearing iron melt (Fe0.7S0.3) with high P-T parameters (4 GPa, 1400°C) was performed. The results demonstrated that under these conditions, octahedral crystals with flat faces and rounded tetrahexahedral diamond crystals are transformed into rounded octahedroids, which have morphological characteristics similar to those of natural diamonds from kimberlite. It was suggested that, taking into account the complex history of individual natural diamond crystals, including the dissolution stages, sulfur-bearing metal melts up to sulfide melts were not only diamond-forming media during the early evolution of the Earth, but also natural solvents of diamond in the mantle environment before the formation of kimberlitic melts.

Enhancement of structure images of interstellar diamond microcrystals by image processing

NASA Technical Reports Server (NTRS)

O'Keefe, Michael A.; Hetherington, Crispin; Turner, John; Blake, David; Freund, Friedemann

1988-01-01

Image processed high resolution TEM images of diamond crystals found in oxidized acid residues of carbonaceous chondrites are presented. Two models of the origin of the diamonds are discussed. The model proposed by Lewis et al. (1987) supposes that the diamonds formed under low pressure conditions, whereas that of Blake et al (1988) suggests that the diamonds formed due to particle-particle collisions behind supernova shock waves. The TEM images of the diamond presented support the high pressure model.

Size-dependent reactivity of diamond nanoparticles.

PubMed

Williams, Oliver A; Hees, Jakob; Dieker, Christel; Jäger, Wolfgang; Kirste, Lutz; Nebel, Christoph E

2010-08-24

Photonic active diamond nanoparticles attract increasing attention from a wide community for applications in drug delivery and monitoring experiments as they do not bleach or blink over extended periods of time. To be utilized, the size of these diamond nanoparticles needs to be around 4 nm. Cluster formation is therefore the major problem. In this paper we introduce a new technique to modify the surface of particles with hydrogen, which prevents cluster formation in buffer solution and which is a perfect starting condition for chemical surface modifications. By annealing aggregated nanodiamond powder in hydrogen gas, the large (>100 nm) aggregates are broken down into their core ( approximately 4 nm) particles. Dispersion of these particles into water via high power ultrasound and high speed centrifugation, results in a monodisperse nanodiamond colloid, with exceptional long time stability in a wide range of pH, and with high positive zeta potential (>60 mV). The large change in zeta potential resulting from this gas treatment demonstrates that nanodiamond particle surfaces are able to react with molecular hydrogen at relatively low temperatures, a phenomenon not witnessed with larger (20 nm) diamond particles or bulk diamond surfaces.

Plasma boriding of a cobalt-chromium alloy as an interlayer for nanostructured diamond growth

NASA Astrophysics Data System (ADS)

Johnston, Jamin M.; Jubinsky, Matthew; Catledge, Shane A.

2015-02-01

Chemical vapor deposited (CVD) diamond coatings can potentially improve the wear resistance of cobalt-chromium medical implant surfaces, but the high cobalt content in these alloys acts as a catalyst to form graphitic carbon. Boriding by high temperature liquid baths and powder packing has been shown to improve CVD diamond compatibility with cobalt alloys. We use the microwave plasma-enhanced (PE) CVD process to deposit interlayers composed primarily of the borides of cobalt and chromium. The use of diborane (B2H6) in the plasma feedgas allows for the formation of a robust boride interlayer for suppressing graphitic carbon during subsequent CVD of nano-structured diamond (NSD). This metal-boride interlayer is shown to be an effective diffusion barrier against elemental cobalt for improving nucleation and adhesion of NSD coatings on a CoCrMo alloy. Migration of elemental cobalt to the surface of the interlayer is significantly reduced and undetectable on the surface of the subsequently-grown NSD coating. The effects of PECVD boriding are compared for a range of substrate temperatures and deposition times and are evaluated using glancing-angle X-ray diffraction (XRD), cross-sectional scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and micro-Raman spectroscopy. Boriding of CoCrMo results in adhered nanostructured diamond coatings with low surface roughness.

Transient photoresponse of nitrogen-doped ultrananocrystalline diamond electrodes in saline solution

NASA Astrophysics Data System (ADS)

Ahnood, Arman; Simonov, Alexandr N.; Laird, Jamie S.; Maturana, Matias I.; Ganesan, Kumaravelu; Stacey, Alastair; Ibbotson, Michael R.; Spiccia, Leone; Prawer, Steven

2016-03-01

Beyond conventional electrically-driven neuronal stimulation methods, there is a growing interest in optically-driven approaches. In recent years, nitrogen-doped ultrananocrystalline diamond (N-UNCD) has emerged as a strong material candidate for use in electrically-driven stimulation electrodes. This work investigates the electrochemical activity of N-UNCD in response to pulsed illumination, to assess its potential for use as an optically-driven stimulation electrode. Whilst N-UNCD in the as-grown state exhibits a weak photoresponse, the oxygen plasma treated film exhibits two orders of magnitude enhancement in its sub-bandgap open circuit photovoltage response. The enhancement is attributed to the formation of a dense network of oxygen-terminated diamond nanocrystals at the N-UNCD surface. Electrically connected to the N-UNCD bulk via sub-surface graphitic grain boundaries, these diamond nanocrystals introduce a semiconducting barrier between the sub-surface graphitic semimetal and the electrolyte solution, leading to a photovoltage under irradiation with wavelengths of λ = 450 nm and shorter. Within the safe optical exposure limit of 2 mW mm-2, charge injection capacity of 0.01 mC cm-2 is achieved using a 15 × 15 μm electrode, meeting the requirements for extracellular and intercellular stimulation. The nanoscale nature of processes presented here along with the diamond's biocompatibility and biostability open an avenue for the use of oxygen treated N-UNCD as optically driven stimulating electrodes.

Structure, properties, and possible mechanisms of formation of diamond-like phases

NASA Astrophysics Data System (ADS)

Belenkov, E. A.; Greshnyakov, V. A.

2016-10-01

An analysis was performed for relations between the structural parameters and the properties of 36 carbon diamond-like phases consisting of atoms occupying crystallographically equivalent positions. It was found that the crystal lattices of these phases were in stressed states with respect to the cubic diamond lattice. The density of diamond-like phases, their sublimation energies, bulk moduli, hardnesses, and band gaps depend on the deformation parameters Def and Str. The most stable phases must be phases with minimal parameters Def and Str and also with ring parameter Rng that is most close to the corresponding parameter of cubic diamond. The structures and energy characteristics of fullerites, nanotube bundles, and graphene layers of which diamond-like phases can be obtained as a result of polymerization at high pressures have been calculated.

Optical patterning of trapped charge in nitrogen-doped diamond

NASA Astrophysics Data System (ADS)

Jayakumar, Harishankar; Henshaw, Jacob; Dhomkar, Siddharth; Pagliero, Daniela; Laraoui, Abdelghani; Manson, Neil B.; Albu, Remus; Doherty, Marcus W.; Meriles, Carlos A.

2016-08-01

The nitrogen-vacancy (NV) centre in diamond is emerging as a promising platform for solid-state quantum information processing and nanoscale metrology. Of interest in these applications is the manipulation of the NV charge, which can be attained by optical excitation. Here, we use two-colour optical microscopy to investigate the dynamics of NV photo-ionization, charge diffusion and trapping in type-1b diamond. We combine fixed-point laser excitation and scanning fluorescence imaging to locally alter the concentration of negatively charged NVs, and to subsequently probe the corresponding redistribution of charge. We uncover the formation of spatial patterns of trapped charge, which we qualitatively reproduce via a model of the interplay between photo-excited carriers and atomic defects. Further, by using the NV as a probe, we map the relative fraction of positively charged nitrogen on localized optical excitation. These observations may prove important to transporting quantum information between NVs or to developing three-dimensional, charge-based memories.

Diamond-like-carbon nanoparticle production and agglomeration following UV multi-photon excitation of static naphthalene/helium gas mixtures

NASA Astrophysics Data System (ADS)

Walsh, A. J.; Tielens, A. G. G. M.; Ruth, A. A.

2016-07-01

We report the formation of nanoparticles with significant diamond character after UV multi-photon laser excitation of gaseous naphthalene, buffered in static helium gas, at room temperature. The nanoparticles are identified in situ by their absorption and scattering spectra between 400 and 850 nm, which are modeled using Mie theory. Comparisons of the particles' spectroscopic and optical properties with those of carbonaceous materials indicate a sp3/sp2 hybridization ratio of 8:1 of the particles formed. The particle extinction in the closed static (unstirred) gas-phase system exhibits a complex and quasi-oscillatory time dependence for the duration of up to several hours with periods ranging from seconds to many minutes. The extinction dynamics of the system is based on a combination of transport features and particle interaction, predominantly agglomeration. The relatively long period of agglomeration allows for a unique analysis of the agglomeration process of diamond-like carbon nanoparticles in situ.

Optical patterning of trapped charge in nitrogen-doped diamond.

PubMed

Jayakumar, Harishankar; Henshaw, Jacob; Dhomkar, Siddharth; Pagliero, Daniela; Laraoui, Abdelghani; Manson, Neil B; Albu, Remus; Doherty, Marcus W; Meriles, Carlos A

2016-08-30

The nitrogen-vacancy (NV) centre in diamond is emerging as a promising platform for solid-state quantum information processing and nanoscale metrology. Of interest in these applications is the manipulation of the NV charge, which can be attained by optical excitation. Here, we use two-colour optical microscopy to investigate the dynamics of NV photo-ionization, charge diffusion and trapping in type-1b diamond. We combine fixed-point laser excitation and scanning fluorescence imaging to locally alter the concentration of negatively charged NVs, and to subsequently probe the corresponding redistribution of charge. We uncover the formation of spatial patterns of trapped charge, which we qualitatively reproduce via a model of the interplay between photo-excited carriers and atomic defects. Further, by using the NV as a probe, we map the relative fraction of positively charged nitrogen on localized optical excitation. These observations may prove important to transporting quantum information between NVs or to developing three-dimensional, charge-based memories.

Optical patterning of trapped charge in nitrogen-doped diamond

PubMed Central

Jayakumar, Harishankar; Henshaw, Jacob; Dhomkar, Siddharth; Pagliero, Daniela; Laraoui, Abdelghani; Manson, Neil B.; Albu, Remus; Doherty, Marcus W.; Meriles, Carlos A.

2016-01-01

The nitrogen-vacancy (NV) centre in diamond is emerging as a promising platform for solid-state quantum information processing and nanoscale metrology. Of interest in these applications is the manipulation of the NV charge, which can be attained by optical excitation. Here, we use two-colour optical microscopy to investigate the dynamics of NV photo-ionization, charge diffusion and trapping in type-1b diamond. We combine fixed-point laser excitation and scanning fluorescence imaging to locally alter the concentration of negatively charged NVs, and to subsequently probe the corresponding redistribution of charge. We uncover the formation of spatial patterns of trapped charge, which we qualitatively reproduce via a model of the interplay between photo-excited carriers and atomic defects. Further, by using the NV as a probe, we map the relative fraction of positively charged nitrogen on localized optical excitation. These observations may prove important to transporting quantum information between NVs or to developing three-dimensional, charge-based memories. PMID:27573190

Local formation of nitrogen-vacancy centers in diamond by swift heavy ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwartz, J.; Ilmenau University of Technology, Department of Microelectronics and Nanoelectric Systems, 98684 Ilmenau; Aloni, S.

2014-12-07

We exposed nitrogen-implanted diamonds to beams of swift heavy ions (∼1 GeV, ∼4 MeV/u) and find that these irradiations lead directly to the formation of nitrogen vacancy (NV) centers, without thermal annealing. We compare the photoluminescence intensities of swift heavy ion activated NV{sup −} centers to those formed by irradiation with low-energy electrons and by thermal annealing. NV{sup −} yields from irradiations with swift heavy ions are 0.1 of yields from low energy electrons and 0.02 of yields from thermal annealing. We discuss possible mechanisms of NV center formation by swift heavy ions such as electronic excitations and thermal spikes. While formingmore » NV centers with low efficiency, swift heavy ions could enable the formation of three dimensional NV{sup −} assemblies over relatively large distances of tens of micrometers. Further, our results show that NV center formation is a local probe of (partial) lattice damage relaxation induced by electronic excitations from swift heavy ions in diamond.« less

Fluorinated diamond particles bonded in a filled fluorocarbon resin matrix

DOEpatents

Taylor, G.W.; Roybal, H.E.

1983-11-14

A method of producing fluorinated diamond particles bonded in a filled fluorocarbon resin matrix. Simple hot pressing techniques permit the formation of such matrices from which diamond impregnated grinding tools and other articles of manufacture can be produced. Teflon fluorocarbon resins filled with Al/sub 2/O/sub 3/ yield grinding tools with substantially improved work-to-wear ratios over grinding wheels known in the art.

Fluorinated diamond particles bonded in a filled fluorocarbon resin matrix

DOEpatents

Taylor, Gene W.; Roybal, Herman E.

1985-01-01

A method of producing fluorinated diamond particles bonded in a filled fluorocarbon resin matrix. Simple hot pressing techniques permit the formation of such matrices from which diamond impregnated grinding tools and other articles of manufacture can be produced. Teflon fluorocarbon resins filled with Al.sub.2 O.sub.3 yield grinding tools with substantially improved work-to-wear ratios over grinding wheels known in the art.

Growth and tribological properties of diamond films on silicon and tungsten carbide substrates

NASA Astrophysics Data System (ADS)

Radhika, R.; Ramachandra Rao, M. S.

2016-11-01

Hot filament chemical vapor deposition technique was used to deposit microcrystalline diamond (MCD) and nanocrystalline diamond (NCD) films on silicon (Si) and tungsten carbide (WC-6Co) substrates. Friction coefficient of larger diamond grains deposited on WC-6Co substrate shows less value approximately 0.2 while this differs marginally on films grown on Si substrate. The study claims that for a less friction coefficient, the grain size is not necessarily smaller. However, the less friction coefficient (less than 0.1 saturated value) in MCD and NCD deposited on Si is explained by the formation of graphitized tribolayer. This layer easily forms when diamond phase is thermodynamically unstable.

Diamond Composite Films for Protective Coatings on Metals and Method of Formation

NASA Technical Reports Server (NTRS)

Ong, Tiong P. (Inventor); Shing, Yuh-Han (Inventor)

1997-01-01

Composite films consisting of diamond crystallites and hard amorphous films such as diamond-like carbon, titanium nitride, and titanium oxide are provided as protective coatings for metal substrates against extremely harsh environments. A composite layer having diamond crystallites and a hard amorphous film is affixed to a metal substrate via an interlayer including a bottom metal silicide film and a top silicon carbide film. The interlayer is formed either by depositing metal silicide and silicon carbide directly onto the metal substrate, or by first depositing an amorphous silicon film, then allowing top and bottom portions of the amorphous silicon to react during deposition of the diamond crystallites, to yield the desired interlayer structure.

Enhancement of oxidation resistance via a self-healing boron carbide coating on diamond particles

PubMed Central

Sun, Youhong; Meng, Qingnan; Qian, Ming; Liu, Baochang; Gao, Ke; Ma, Yinlong; Wen, Mao; Zheng, Weitao

2016-01-01

A boron carbide coating was applied to diamond particles by heating the particles in a powder mixture consisting of H3BO3, B and Mg. The composition, bond state and coverage fraction of the boron carbide coating on the diamond particles were investigated. The boron carbide coating prefers to grow on the diamond (100) surface than on the diamond (111) surface. A stoichiometric B4C coating completely covered the diamond particle after maintaining the raw mixture at 1200 °C for 2 h. The contribution of the boron carbide coating to the oxidation resistance enhancement of the diamond particles was investigated. During annealing of the coated diamond in air, the priory formed B2O3, which exhibits a self-healing property, as an oxygen barrier layer, which protected the diamond from oxidation. The formation temperature of B2O3 is dependent on the amorphous boron carbide content. The coating on the diamond provided effective protection of the diamond against oxidation by heating in air at 1000 °C for 1 h. Furthermore, the presence of the boron carbide coating also contributed to the maintenance of the static compressive strength during the annealing of diamond in air. PMID:26831205

Enhancement of oxidation resistance via a self-healing boron carbide coating on diamond particles.

PubMed

Sun, Youhong; Meng, Qingnan; Qian, Ming; Liu, Baochang; Gao, Ke; Ma, Yinlong; Wen, Mao; Zheng, Weitao

2016-02-02

A boron carbide coating was applied to diamond particles by heating the particles in a powder mixture consisting of H3BO3, B and Mg. The composition, bond state and coverage fraction of the boron carbide coating on the diamond particles were investigated. The boron carbide coating prefers to grow on the diamond (100) surface than on the diamond (111) surface. A stoichiometric B4C coating completely covered the diamond particle after maintaining the raw mixture at 1200 °C for 2 h. The contribution of the boron carbide coating to the oxidation resistance enhancement of the diamond particles was investigated. During annealing of the coated diamond in air, the priory formed B2O3, which exhibits a self-healing property, as an oxygen barrier layer, which protected the diamond from oxidation. The formation temperature of B2O3 is dependent on the amorphous boron carbide content. The coating on the diamond provided effective protection of the diamond against oxidation by heating in air at 1000 °C for 1 h. Furthermore, the presence of the boron carbide coating also contributed to the maintenance of the static compressive strength during the annealing of diamond in air.

Direct observation of inversion capacitance in p-type diamond MOS capacitors with an electron injection layer

NASA Astrophysics Data System (ADS)

Matsumoto, Tsubasa; Kato, Hiromitsu; Makino, Toshiharu; Ogura, Masahiko; Takeuchi, Daisuke; Yamasaki, Satoshi; Imura, Masataka; Ueda, Akihiro; Inokuma, Takao; Tokuda, Norio

2018-04-01

The electrical properties of Al2O3/p-type diamond (111) MOS capacitors were studied with the goal of furthering diamond-based semiconductor research. To confirm the formation of an inversion layer in the p-type diamond body, an n-type layer for use as a minority carrier injection layer was selectively deposited onto p-type diamond. To form the diamond MOS capacitors, Al2O3 was deposited onto OH-terminated diamond using atomic layer deposition. The MOS capacitor showed clear inversion capacitance at 10 Hz. The minority carrier injection from the n-type layer reached the inversion n-channel diamond MOS field-effect transistor (MOSFET). Using the high-low frequency capacitance method, the interface state density, D it, within an energy range of 0.1-0.5 eV from the valence band edge energy, E v, was estimated at (4-9) × 1012 cm-2 eV-1. However, the high D it near E v remains an obstacle to improving the field effect mobility for the inversion p-channel diamond MOSFET.

78 FR 40627 - Prohibitions and Conditions on the Importation and Exportation of Rough Diamonds

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-08

... November 5, 2002, the launch of the Kimberley Process Certification Scheme (KPCS) for rough diamonds. Under... implements the Kimberley Process Certification Scheme (KPCS) for rough diamonds. The KPCS is a process, based... not been controlled through the Kimberley Process Certification Scheme. By Executive Order 13312 dated...

Low-damage direct patterning of silicon oxide mask by mechanical processing

PubMed Central

2014-01-01

To realize the nanofabrication of silicon surfaces using atomic force microscopy (AFM), we investigated the etching of mechanically processed oxide masks using potassium hydroxide (KOH) solution. The dependence of the KOH solution etching rate on the load and scanning density of the mechanical pre-processing was evaluated. Particular load ranges were found to increase the etching rate, and the silicon etching rate also increased with removal of the natural oxide layer by diamond tip sliding. In contrast, the local oxide pattern formed (due to mechanochemical reaction of the silicon) by tip sliding at higher load was found to have higher etching resistance than that of unprocessed areas. The profile changes caused by the etching of the mechanically pre-processed areas with the KOH solution were also investigated. First, protuberances were processed by diamond tip sliding at lower and higher stresses than that of the shearing strength. Mechanical processing at low load and scanning density to remove the natural oxide layer was then performed. The KOH solution selectively etched the low load and scanning density processed area first and then etched the unprocessed silicon area. In contrast, the protuberances pre-processed at higher load were hardly etched. The etching resistance of plastic deformed layers was decreased, and their etching rate was increased because of surface damage induced by the pre-processing. These results show that etching depth can be controlled by controlling the etching time through natural oxide layer removal and mechanochemical oxide layer formation. These oxide layer removal and formation processes can be exploited to realize low-damage mask patterns. PMID:24948891

Diamond MEMS: wafer scale processing, devices, and technology insertion

NASA Astrophysics Data System (ADS)

Carlisle, J. A.

2009-05-01

Diamond has long held the promise of revolutionary new devices: impervious chemical barriers, smooth and reliable microscopic machines, and tough mechanical tools. Yet it's been an outsider. Laboratories have been effectively growing diamond crystals for at least 25 years, but the jump to market viability has always been blocked by the expense of diamond production and inability to integrate with other materials. Advances in chemical vapor deposition (CVD) processes have given rise to a hierarchy of carbon films ranging from diamond-like carbon (DLC) to vapor-deposited diamond coatings, however. All have pros and cons based on structure and cost, but they all share some of diamond's heralded attributes. The best performer, in theory, is the purest form of diamond film possible, one absent of graphitic phases. Such a material would capture the extreme hardness, high Young's modulus and chemical inertness of natural diamond. Advanced Diamond Technologies Inc., Romeoville, Ill., is the first company to develop a distinct chemical process to create a marketable phase-pure diamond film. The material, called UNCD® (for ultrananocrystalline diamond), features grain sizes from 3 to 300 nm in size, and layers just 1 to 2 microns thick. With significant advantages over other thin films, UNCD is designed to be inexpensive enough for use in atomic force microscopy (AFM) probes, microelectromechanical machines (MEMS), cell phone circuitry, radio frequency devices, and even biosensors.

Development of program package for investigation and modeling of carbon nanostructures in diamond like carbon films with the help of Raman scattering and infrared absorption spectra line resolving

NASA Astrophysics Data System (ADS)

Hayrapetyan, David B.; Hovhannisyan, Levon; Mantashyan, Paytsar A.

2013-04-01

The analysis of complex spectra is an actual problem for modern science. The work is devoted to the creation of a software package, which analyzes spectrum in the different formats, possesses by dynamic knowledge database and self-study mechanism, performs automated analysis of the spectra compound based on knowledge database by application of certain algorithms. In the software package as searching systems, hyper-spherical random search algorithms, gradient algorithms and genetic searching algorithms were used. The analysis of Raman and IR spectrum of diamond-like carbon (DLC) samples were performed by elaborated program. After processing the data, the program immediately displays all the calculated parameters of DLC.

Upper mantle fluids evolution, diamond formation, and mantle metasomatism

NASA Astrophysics Data System (ADS)

Huang, F.; Sverjensky, D. A.

2017-12-01

During mantle metasomatism, fluid-rock interactions in the mantle modify wall-rock compositions. Previous studies usually either investigated mineral compositions in xenoliths and xenocrysts brought up by magmas, or examined fluid compositions preserved in fluid inclusions in diamonds. However, a key study of Panda diamonds analysed both mineral and fluid inclusions in the diamonds [1] which we used to develop a quantitative characterization of mantle metasomatic processes. In the present study, we used an extended Deep Earth Water model [2] to simulate fluid-rock interactions at upper mantle conditions, and examine the fluids and mineral assemblages together simultaneously. Three types of end-member fluids in the Panda diamond fluid inclusions include saline, rich in Na+K+Cl; silicic, rich in Si+Al; and carbonatitic, rich in Ca+Mg+Fe [1, 3]. We used the carbonatitic end-member to represent fluid from a subducting slab reacting with an excess of peridotite + some saline fluid in the host environment. During simultaneous fluid mixing and reaction with the host rock, the logfO2 increased by about 1.6 units, and the pH increased by 0.7 units. The final minerals were olivine, garnet and diamond. The Mg# of olivine decreased from 0.92 to 0.85. Garnet precipitated at an early stage, and its Mg# also decreased with reaction progress, in agreement with the solid inclusions in the Panda diamonds. Phlogopite precipitated as an intermediate mineral and then disappeared. The aqueous Ca, Mg, Fe, Si and Al concentrations all increased, while Na, K, and Cl concentrations decreased during the reaction, consistent with trends in the fluid inclusion compositions. Our study demonstrates that fluids coming from subducting slabs could trigger mantle metasomatism, influence the compositions of sub-lithospherc cratonic mantle, precipitate diamonds, and change the oxygen fugacity and pH of the upper mantle fluids. [1] Tomlinson et al. EPSL (2006); [2] Sverjensky, DA et al., GCA (2014), Huang, F, Ph. D. thesis, Johns Hopkins University, (2017); [3] Shirey et al., Rev. Mineral. Geochem. (2013)

The nature and origin of interstellar diamond

NASA Technical Reports Server (NTRS)

Blake, David F.; Freund, Friedemann; Shipp, Ruth; Krishnan, Kannan F. M.; Echer, Charles J.

1988-01-01

The C-delta component of the Allende meteorite is a microscopic diamond some of whose properties seem in conflict with those expected of diamond. High spatial resolution analytical data are presented here which may help explain such results. Surface and interfacial carbon atoms in the component, which may comprise as much as 25 percent of the total, impart an 'amorphous' character to some spectral data. These data support the proposed high-pressure conversion of amorphous carbon and graphite into diamonds due to grain-grain collisions in the ISM, although a low-pressure mechanism of formation cannot be ruled out.

Role of fluid in the mechanism of formation of volcaniclastic and coherent kimberlite facies: a diamond perspective

NASA Astrophysics Data System (ADS)

Fedortchouk, Yana; Chinn, Ingrid

2016-04-01

Dissolution features on diamonds recovered from kimberlites vary depending on the dissolution conditions and can be used as a reliable proxy for volatiles and their role in kimberlite emplacement. Volatiles determine the mechanism of magma emplacement; variation in volatile content and CO2/CO2+H2O ratio may affect the geology of kimberlite bodies and formation of coherent vs. volcaniclastic kimberlite facies. Here we examine the evolution of a kimberlite system during ascent using the resorption morphology of its diamond population. We use 655 macro-diamonds from a complex kimberlite pipe in the Orapa kimberlite field (Botswana) to examine the role of volatiles in the formation of the three facies comprising this pipe: two coherent kimberlite facies (CKA and CKB) and one massive volcaniclastic facies (MVK). The diamonds come from three drillholes through each of the studied kimberlite facies. Separate diamond samples derived from 2 - 13 m intervals were combined into 40 m depth intervals for statistical purposes. Four independent morphological methods allowed us to reliably discriminate products of resorption in kimberlite magma from resorption in the mantle, and use the former in our study. We found that the proportion of diamonds with kimberlitic resorption is the lowest in CKA - 22%, medium in MVK - 50%, and highest in CKB - 73%, and it increases with depth in each of the drillholes. Each kimberlite facies shows its own style of kimberlite-induced resorption on rounded tetrahexahedron (THH) diamonds: glossy surfaces in MVK, rough corroded surfaces in CKB, and combination of glossy surfaces with chains of circular pits in CKA, where these pits represent the initial stages of development of corrosive features observed on CKB diamonds. Based on the results of our previous experimental studies we propose that resorption of MVK diamonds is a product of interaction with COH fluid, resorption of CKB diamonds is a product of interaction with a volatile-undersaturated melt (possibly carbonatitic), and CKA diamonds show an overprint of melt-controlled resorption over a fluid-controlled resorption. We propose an early separation of the fluid phase during the ascent of this kimberlite magma, segregation of this fluid and rise towards the top of the magma column. Over-pressurisation caused by the expansion of this fluid worked as a driving force for the magma ascent acceleration. The magma column has separated into two parts: (1) the bubble-rich magma towards the top, explosive emplacement of which formed the MVK facies, followed by the "tailing" bubble-poor magma quietly arriving to form the CKA facies, and (2) magma that lost volatiles to the upwardly escaping bubbles, in which a slower ascent caused more intensive diamond resorption and delayed emplacement, forming the CKB facie. It is possible that formation, buoyancy, and growth of fluid bubbles controls the ascent of the kimberlite magma, where emplacement of bubble-rich magma forms volcaniclastic kimberlite facies, while fast rise of the bubbles through the magma column separates the fluid-rich phase that moves up preparing the conduit in the surrounding rocks and forms an explosive pipe at the surface, from a volatile-depleted magma, which slowly rises and fills the pipe with CK kimberlite facies.

Sedimentary processes in the Carnot Formation (Central African Republic) related to the palaeogeographic framework of Central Africa

NASA Astrophysics Data System (ADS)

Censier, Claude; Lang, Jacques

1999-08-01

The depositional environment, provenance and processes of emplacement of the detrital material of the Mesozoic Carnot Formation are defined, by bedding and sedimentological analysis of its main facies, and are reconstructed within the palaeogeographic framework of Central Africa. The clastic material was laid down between probably the Albian and the end of the Cretaceous, in a NNW-oriented braided stream fluvial system that drained into the Doba Trough (Chad) and probably also into the Touboro Basin (Cameroon). The material was derived from weathering of the underlying Devonian-Carboniferous Mambéré Glacial Formation and of the Precambrian schist-quartzite complex located to the south of the Carnot Formation. These results provide useful indications as to the provenance of diamonds mined in the southwest Central African Republic.

Metal-Silicate Partitioning of Various Siderophile Elements at High Pressure and High Temperatures: a Diamond Anvil Cell Study

NASA Astrophysics Data System (ADS)

Badro, J.; Blanchard, I.; Siebert, J.

2015-12-01

Core formation is the major chemical fractionation that occurred on Earth. This event is widely believed to have happened at pressures of at least 40 GPa and temperatures exceeding 3000 K. It has left a significant imprint on the chemistry of the mantle by removing most of the siderophile (iron-loving) elements from it. Abundances of most siderophile elements in the bulk silicate Earth are significantly different than those predicted from experiments at low P-T. Among them, vanadium, chromium, cobalt and gallium are four siderophile elements which abundances in the mantle have been marked by core formation processes. Thus, understand their respective abundance in the mantle can help bringing constraints on the conditions of Earth's differentiation. We performed high-pressure high-temperature experiments using laser heating diamond anvil cell to investigate the metal-silicate partitioning of those four elements. Homogeneous glasses doped in vanadium, chromium, cobalt and gallium were synthesized using a levitation furnace and load inside the diamond anvil cell along with metallic powder. Samples were recovered using a Focused Ion Beam and chemically analyzed using an electron microprobe. We investigate the effect of pressure, temperature and metal composition on the metal-silicate partitioning of V, Cr, Co and Ga. Three previous studies focused on V, Cr and Co partitioning at those conditions of pressure and temperature, but none explore gallium partitioning at the relevant extreme conditions of core formation. We will present the first measurements of gallium metal-silicate partitioning performed at the appropriate conditions of pressure and temperature of Earth's differentiation.

Simulation and Experimental Study on Surface Formation Mechanism in Machining of SiCp/Al Composites

NASA Astrophysics Data System (ADS)

Du, Jinguang; Zhang, Haizhen; He, Wenbin; Ma, Jun; Ming, Wuyi; Cao, Yang

2018-03-01

To intuitively reveal the surface formation mechanism in machining of SiCp/Al composites, in this paper the removal mode of reinforced particle and aluminum matrix, and their influence on surface formation mechanism were analyzed by single diamond grit cutting simulation and single diamond grit scratch experiment. Simulation and experiment results show that when the depth of cut is small, the scratched surface of the workpiece is relatively smooth; however, there are also irregular pits on the machined surface. When increasing the depth of cut, there are many obvious laminar structures on the scratched surface, and the surface appearance becomes coarser. When the cutting speed is small, the squeezing action of abrasive grit on SiC particles plays a dominant role in the extrusion of SiC particles. When increasing the cutting speed, SiC particles also occur broken or fractured; but the machined surface becomes smooth. When machining SiCp/Al composites, the SiC may happen in such removal ways, such as fracture, debonding, broken, sheared, pulled into and pulled out, etc. By means of reasonably developing micro cutting finite element simulation model of SiCp/Al composites could be used to analyze the surface formation process and particle removal way in different machining conditions.

Drilling of optical glass with electroplated diamond tools

NASA Astrophysics Data System (ADS)

Wang, A. J.; Luan, C. G.; Yu, A. B.

2010-10-01

K9 optical glass drilling experiments were carried out. Bright nickel electroplated diamond tools with small slots and under heat treatment in different temperature were fabricated. Scan electro microscope was applied to analyze the wear of electroplated diamond tool. The material removal rate and grinding ratio were calculated. Machining quality was observed. Bond coating hardness was measured. The experimental results show that coolant is needed for the drilling processes of optical glasses. Heat treatment temperature of diamond tool has influence on wearability of diamond tool and grinding ratio. There were two wear types of electroplated diamond tool, diamond grit wear and bond wear. With the machining processes, wear of diamond grits included fracture, blunt and pull-out, and electroplated bond was gradually worn out. High material removal rates could be obtained by using diamond tool with suitable slot numbers. Bright nickel coating bond presents smallest grains and has better mechanical properties. Bright nickel electroplated diamond tool with slot structure and heat treatment under 200°C was suitable for optical glass drilling.

Determination of high-strength materials diamond grinding rational modes

NASA Astrophysics Data System (ADS)

Arkhipov, P. V.; Lobanov, D. V.; Rychkov, D. A.; Yanyushkin, A. S.

2018-03-01

The analysis of methods of high-strength materials abrasive processing is carried out. This method made it possible to determine the necessary directions and prospects for the development of shaping combined methods. The need to use metal bonded diamond abrasive tools in combination with a different kind of energy is noted to improve the processing efficiency and reduce the complexity of operations. The complex of experimental research on revealing the importance of mechanical and electrical components of cutting regimes, on the cutting ability of diamond tools, as well as the need to reduce the specific consumption of an abrasive wheel as one of the important economic indicators of the processing process is performed. It is established that combined diamond grinding with simultaneous continuous correction of the abrasive wheel contributes to an increase in the cutting ability of metal bonded diamond abrasive tools when processing high-strength materials by an average of 30% compared to diamond grinding. Particular recommendations on the designation of technological factors are developed depending on specific production problems.

Alluvial Diamond Resource Potential and Production Capacity Assessment of Ghana

USGS Publications Warehouse

Chirico, Peter G.; Malpeli, Katherine C.; Anum, Solomon; Phillips, Emily C.

2010-01-01

In May of 2000, a meeting was convened in Kimberley, South Africa, and attended by representatives of the diamond industry and leaders of African governments to develop a certification process intended to assure that rough, exported diamonds were free of conflictual concerns. This meeting was supported later in 2000 by the United Nations in a resolution adopted by the General Assembly. By 2002, the Kimberley Process Certification Scheme (KPCS) was ratified and signed by both diamond-producing and diamond-importing countries. Over 70 countries were included as members at the end of 2007. To prevent trade in 'conflict' diamonds while protecting legitimate trade, the KPCS requires that each country set up an internal system of controls to prevent conflict diamonds from entering any imported or exported shipments of rough diamonds. Every diamond or diamond shipment must be accompanied by a Kimberley Process (KP) certificate and be contained in tamper-proof packaging. The objective of this study was to assess the alluvial diamond resource endowment and current production capacity of the alluvial diamond-mining sector in Ghana. A modified volume and grade methodology was used to estimate the remaining diamond reserves within the Birim and Bonsa diamond fields. The production capacity of the sector was estimated using a formulaic expression of the number of workers reported in the sector, their productivity, and the average grade of deposits mined. This study estimates that there are approximately 91,600,000 carats of alluvial diamonds remaining in both the Birim and Bonsa diamond fields: 89,000,000 carats in the Birim and 2,600,000 carats in the Bonsa. Production capacity is calculated to be 765,000 carats per year, based on the formula used and available data on the number of workers and worker productivity. Annual production is highly dependent on the international diamond market and prices, the numbers of seasonal workers actively mining in the sector, and environmental conditions, which influence seasonal farming.

Triphasic Tooling with Small Oriented Diamond Tip for Turning and Smoothing Lightweight Mirrors

NASA Technical Reports Server (NTRS)

Voronov, O. A.; Tompa, G. S.; Kear, B. H.; Veress, V.

2004-01-01

We are developing a new method for the growth of small diamond crystals at very high temperatures and pressures directly from a carbon melt. A prototype "Supercell" has been developed for this purpose. This system is capable of high rate crystal growth in relatively large working volumes. The resulting high quality diamond crystals will be incorporated into a triphasic diamond/titanium carbide/titanium composite tool, with an oriented diamond crystal at its tip. High pressure is needed to prevent degradation of diamond at high temperature, and to ensure the formation of a crack & composite structure. After grinding and polishing, the composite material will be joined to a steel holder, thus forming a diamond-tipped tool for turning and smoothing of a mirror surface. A properly oriented single-crystal diamond cuts and smoothes much better than a conventional polycrystalline diamond crystal. This is because the hardness depends on crystallographic orientation-the difference corresponds to 60-100 GPa on the Knoop scale. Our goal is to achieve surface roughness of about 1 nm, which will be accomplished by precision cutting and smoothing. The hardness of the functionally-graded diamond/titanium carbide/titanium composite tool varies from 100 GPa at its tip to 15 GPa at its base. Previous work has shown that the mass of machined material using an oriented-diamond tool is much larger than that for a standard diamond-metal composite tool.

Process for ultra smooth diamond coating on metals and uses thereof

NASA Technical Reports Server (NTRS)

Vohra, Yogesh K. (Inventor); Catledge, Shane A. (Inventor)

2001-01-01

The present invention provides a new process to deposit well adhered ultra smooth diamond films on metals by adding nitrogen gas to the methane/hydrogen plasma created by a microwave discharge. Such diamond coating process is useful in tribological/wear resistant applications in bio-implants, machine tools, and magnetic recording industry.

31 CFR 592.201 - Prohibited importation and exportation of any rough diamond; permitted importation or exportation...

Code of Federal Regulations, 2010 CFR

2010-07-01

..., unless the rough diamond has been controlled through the Kimberley Process Certification Scheme. (b) The... States of any rough diamond not controlled through the Kimberley Process Certification Scheme do not... Process Certification Scheme and thus is not permitted, except in the following circumstance. The...

Deformation-related spectroscopic features in natural Type Ib-IaA diamonds from Zimmi (West African craton)

NASA Astrophysics Data System (ADS)

Smit, Karen V.; D'Haenens-Johansson, Ulrika F. S.; Howell, Daniel; Loudin, Lorne C.; Wang, Wuyi

2018-06-01

Zimmi diamonds (Sierra Leone) have 500 million year mantle residency times whose origin is best explained by rapid tectonic exhumation to shallower depths in the mantle, associated with continental collision but prior to kimberlite eruption. Here we present spectroscopic data for a new suite of Zimmi sulphide-bearing diamonds that allow us to evaluate the link between their spectroscopic features and their unusual geological history. Cathodoluminesence (CL) imaging of these diamonds revealed irregular patterns with abundant deformation lamellae, associated with the diamonds' tectonic exhumation. Vacancies formed during deformation were subsequently naturally annealed to form vacancy clusters, NV0/- centres and H3 (NVN0). The brownish-yellow to greenish-yellow colours observed in Zimmi Ib-IaA diamonds result from visible absorption by a combination of isolated substitutional nitrogen ( {N}S^0 ) and deformation-related vacancy clusters. Colour-forming centres and other spectroscopic features can all be attributed to the unique geological history of Zimmi Ib-IaA diamonds and their rapid exhumation after formation.

Twinning of cubic diamond explains reported nanodiamond polymorphs

NASA Astrophysics Data System (ADS)

Németh, Péter; Garvie, Laurence A. J.; Buseck, Peter R.

2015-12-01

The unusual physical properties and formation conditions attributed to h-, i-, m-, and n-nanodiamond polymorphs has resulted in their receiving much attention in the materials and planetary science literature. Their identification is based on diffraction features that are absent in ordinary cubic (c-) diamond (space group: Fd-3m). We show, using ultra-high-resolution transmission electron microscope (HRTEM) images of natural and synthetic nanodiamonds, that the diffraction features attributed to the reported polymorphs are consistent with c-diamond containing abundant defects. Combinations of {113} reflection and <011> rotation twins produce HRTEM images and d-spacings that match those attributed to h-, i-, and m-diamond. The diagnostic features of n-diamond in TEM images can arise from thickness effects of c-diamonds. Our data and interpretations strongly suggest that the reported nanodiamond polymorphs are in fact twinned c-diamond. We also report a new type of twin (<11> rotational), which can give rise to grains with dodecagonal symmetry. Our results show that twins are widespread in diamond nanocrystals. A high density of twins could strongly influence their applications.

Osteoblast adhesion to orthopaedic implant alloys: Effects of cell adhesion molecules and diamond-like carbon coating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kornu, R.; Kelly, M.A.; Smith, R.L.

1996-11-01

In total joint arthroplasty, long-term outcomes depend in part on the biocompatibility of implant alloys. This study analyzed effects of surface finish and diamond-like carbon coating on osteoblast cell adhesion to polished titanium-aluminum-vanadium and polished or grit-blasted cobalt-chromium-molybdenum alloys. Osteoblast binding was tested in the presence and absence of the cell adhesion proteins fibronectin, laminin, fibrinogen, and vitronectin and was quantified by measurement of DNA content. Although adherence occurred in serum-free medium, maximal osteoblast binding required serum and was similar for titanium and cobalt alloys at 2 and 12 hours. With the grit-blasted cobalt alloy, cell binding was reduced 48%more » (p < 0.05) by 24 hours. Coating the alloys with diamond-like carbon did not alter osteoblast adhesion, whereas fibronectin pretreatment increased cell binding 2.6-fold (p < 0.05). In contrast, fibrinogen, vitronectin, and laminin did not enhance cell adhesion. These results support the hypothesis that cell adhesion proteins can modify cell binding to orthopaedic alloys. Although osteoblast binding was not affected by the presence of diamond-like carbon, this coating substance may influence other longer term processes, such as bone formation, and deserves further study. 40 refs., 4 figs.« less

High-pressure behaviour of Cr-Fe-Mg-Al spinels: applications to diamond geobarometry

NASA Astrophysics Data System (ADS)

Periotto, Benedetta; Bruschini, Enrico; Nestola, Fabrizio; Lenaz, Davide; Princivalle, Francesco; Andreozzi, Giovanni B.; Bosi, Ferdinando

2014-05-01

Spinels belonging to the chromite - magnesiochromite - hercynite (FeCr2O4-MgCr2O4-FeAl2O4) system are among the most common inclusions found in diamonds (Stachel and Harris 2008). In particular, although FeCr2O4 and MgCr2O4 components sum to between 85 and 88% of spinels found in diamonds, hercynite FeAl2O4 plays a not negligible role in determining their thermo-elastic properties with concentrations reaching 7-9 % (other minor end-members like MgAl2O4, MgFe2O4 and Fe2O3 rarely reach 2-3% in total, see Lenaz et al. 2009). Recent studies were focused on the determination of the diamond formation pressure by the so-called "elastic method" (see for example Nestola et al. 2011 and references therein). It was demonstrated that accurate and precise thermo-elastic parameters are fundamental to minimize the uncertainty of formation pressure. In this work we have determined the equations of state at room temperature of three synthetic spinel end-members chromite - magnesiochromite - hercynite and one natural spinel crystal extracted from a diamond (from Udachnaya mine, Siberia, Russia) by single-crystal X-ray diffraction in situ at high-pressure. A diamond-anvil cell was mounted on a STADI IV diffractometer equipped with a point detector and motorized by SINGLE software (Angel and Finger 2011). The natural crystal was investigated to test (and possibly validate) the "empirical prediction model", capable to provide bulk modulus and its first pressure derivative only knowing the composition of the spinels found in diamonds. Such prediction model could be used to obtain pressure of formation for the diamond-spinel pair through the elastic method. Details and results will be discussed. The research was funded by the ERC Starting Grant to FN (grant agreement n° 307322). References Angel R.J., Finger L.W. (2011) SINGLE A program to control single-crystal diffractometers. Journal of Applied Crystallography, 44, 247-251. Lenaz D., Logvinova A.M., Princivalle F., Sobolev N. (2009) Structural parameters of chromite included in diamond and kimberlites from Siberia: a new tool for discriminating source. American Mineralogist, 94, 1067-1070. Nestola F., Nimis P., Ziberna L., Longo M., Marzoli A., Harris J.W., Manghnani M.H., Fedortchouk Y. (2011) First crystal-structure determination of olivine in diamond: composition and implications for provenance in the Earth's mantle. Earth and Planetary Science Letters, 305, 249-255. Stachel, T., and Harris, J.W. (2008) The origin of cratonic diamonds - constraints from mineral inclusions. Ore Geology Reviews, 34, 5-32.

Fabrication of diamond shells

DOEpatents

Hamza, Alex V.; Biener, Juergen; Wild, Christoph; Woerner, Eckhard

2016-11-01

A novel method for fabricating diamond shells is introduced. The fabrication of such shells is a multi-step process, which involves diamond chemical vapor deposition on predetermined mandrels followed by polishing, microfabrication of holes, and removal of the mandrel by an etch process. The resultant shells of the present invention can be configured with a surface roughness at the nanometer level (e.g., on the order of down to about 10 nm RMS) on a mm length scale, and exhibit excellent hardness/strength, and good transparency in the both the infra-red and visible. Specifically, a novel process is disclosed herein, which allows coating of spherical substrates with optical-quality diamond films or nanocrystalline diamond films.

Alluvial diamond resource potential and production capacity assessment of the Central African Republic

USGS Publications Warehouse

Chirico, Peter G.; Barthelemy, Francis; Ngbokoto, Francois A.

2010-01-01

In May of 2000, a meeting was convened in Kimberley, South Africa, and attended by representatives of the diamond industry and leaders of African governments to develop a certification process intended to assure that rough, exported diamonds were free of conflict concerns. This meeting was supported later in 2000 by the United Nations in a resolution adopted by the General Assembly. By 2002, the Kimberly Process Certification Scheme (KPCS) was ratified and signed by diamond-producing and diamond-importing countries. Over 70 countries were included as members of the KPCS at the end of 2007. To prevent trade in "conflict diamonds" while protecting legitimate trade, the KPCS requires that each country set up an internal system of controls to prevent conflict diamonds from entering any imported or exported shipments of rough diamonds. Every diamond or diamond shipment must be accompanied by a Kimberley Process (KP) certificate and be contained in tamper-proof packaging. The objective of this study was (1) to assess the naturally occurring endowment of diamonds in the Central African Republic (potential resources) based on geological evidence, previous studies, and recent field data and (2) to assess the diamond-production capacity and measure the intensity of mining activity. Several possible methods can be used to estimate the potential diamond resource. However, because there is generally a lack of sufficient and consistent data recording all diamond mining in the Central African Republic and because time to conduct fieldwork and accessibility to the diamond mining areas are limited, two different methodologies were used: the volume and grade approach and the content per kilometer approach. Estimates are that approximately 39,000,000 carats of alluvial diamonds remain in the eastern and western zones of the CAR combined. This amount is roughly twice the total amount of diamonds reportedly exported from the Central African Republic since 1931. Production capacity is calculated to be 840,000 carats per year, a number that is nearly twice the 450,000 carats per year reported annually by the Central African Republic. The difference in the two numbers reflects the lack of sufficient data on diamond resource grades, worker productivity, and the number and locations of sites being worked.

Self-sharpening-effect of nickel-diamond coatings sprayed by HVOF

NASA Astrophysics Data System (ADS)

Tillmann, W.; Brinkhoff, A.; Schaak, C.; Zajaczkowski, J.

2017-03-01

The durability of stone working and drilling tools is an increasingly significant requirement in industrial applications. These tools are mainly produced by brazing diamond metal matrix composites inserts to the tool body. These inserts are produced by sintering diamonds and metal powder (e.g. nickel). If the wear is too high, the diamonds will break out of the metal matrix and other diamonds will be uncovered. This effect is called self-sharpening. But diamonds are difficult to handle because of their thermal sensitivity. Due to their high thermal influence, manufacturing costs, and complicate route of manufacturing (first sintering, then brazing), there is a great need for alternative production methods for such tools. One alternative to produce wear-resistant and self-sharpening coatings are thermal spray processes as examined in this paper. An advantage of thermal spray processes is their smaller thermal influence on the diamond, due to the short dwelling time in the flame. To reduce the thermal influence during spraying, nickel coated diamonds were used in the HVOF-process (high velocity oxygen fuel process). The wear resistance was subsequently investigated by means of a standardized ball-on-disc test. Furthermore, a SEM (scanning electron microscope) was used to gain information about the wear-mechanism and the self-sharpening effect of the coating.

15 CFR 30.70 - Violation of the Clean Diamond Trade Act.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 15 Commerce and Foreign Trade 1 2013-01-01 2013-01-01 false Violation of the Clean Diamond Trade... Clean Diamond Trade Act. Public Law 108-19, the Clean Diamond Trade Act (the Act), section 8(c... diamonds, including those with respect to the validation of the Kimberley Process Certificate by the...

15 CFR 30.70 - Violation of the Clean Diamond Trade Act.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 15 Commerce and Foreign Trade 1 2012-01-01 2012-01-01 false Violation of the Clean Diamond Trade... Clean Diamond Trade Act. Public Law 108-19, the Clean Diamond Trade Act (the Act), section 8(c... diamonds, including those with respect to the validation of the Kimberley Process Certificate by the...

15 CFR 30.70 - Violation of the Clean Diamond Trade Act.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Violation of the Clean Diamond Trade... Clean Diamond Trade Act. Public Law 108-19, the Clean Diamond Trade Act (the Act), section 8(c... diamonds, including those with respect to the validation of the Kimberley Process Certificate by the...

15 CFR 30.70 - Violation of the Clean Diamond Trade Act.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 15 Commerce and Foreign Trade 1 2014-01-01 2014-01-01 false Violation of the Clean Diamond Trade... Clean Diamond Trade Act. Public Law 108-19, the Clean Diamond Trade Act (the Act), section 8(c... diamonds, including those with respect to the validation of the Kimberley Process Certificate by the...

Development of CVD Diamond for Industrial Applications Final Report CRADA No. TC-2047-02

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caplan, M.; Olstad, R.; Jory, H.

2017-09-08

This project was a collaborative effort to develop and demonstrate a new millimeter microwave assisted chemical vapor deposition(CVD) process for manufacturing large diamond disks with greatly reduced processing times and costs from those now available. In the CVD process, carbon based gases (methane) and hydrogen are dissociated into plasma using microwave discharge and then deposited layer by layer as polycrystalline diamond onto a substrate. The available low frequency (2.45GHz) microwave sources used elsewhere (De Beers) result in low density plasmas and low deposition rates: 4 inch diamond disks take 6-8 weeks to process. The new system developed in this projectmore » uses a high frequency 30GHz Gyrotron as the microwave source and a quasi-optical CVD chamber resulting in a much higher density plasma which greatly reduced the diamond processing times (1-2 weeks)« less

Effects of low-energy electron irradiation on formation of nitrogen–vacancy centers in single-crystal diamond

DOE PAGES

Schwartz, J.; Aloni, S.; Ogletree, D. F.; ...

2012-04-20

Exposure to beams of low-energy electrons (2-30 keV) in a scanning electron microscope locally induces formation of NV-centers without thermal annealing in diamonds that have been implanted with nitrogen ions. In this study, we find that non-thermal, electron-beam-induced NV-formation is about four times less efficient than thermal annealing. But NV-center formation in a consecutive thermal annealing step (800°C) following exposure to low-energy electrons increases by a factor of up to 1.8 compared to thermal annealing alone. Finally, these observations point to reconstruction of nitrogen-vacancy complexes induced by electronic excitations from low-energy electrons as an NV-center formation mechanism and identify localmore » electronic excitations as a means for spatially controlled room-temperature NV-center formation.« less

Grain-size-dependent diamond-nondiamond composite films: characterization and field-emission properties.

PubMed

Pradhan, Debabrata; Lin, I Nan

2009-07-01

Diamond films with grain sizes in the range of 5-1000 nm and grain boundaries containing nondiamond carbon are deposited on a silicon substrate by varying the deposition parameters. The overall morphologies of the as-deposited diamond-nondiamond composite films are examined by scanning electron microscopy and atomic force microscopy, which show a decrease in the surface roughness with a decrease in the diamond grain size. Although the Raman spectra show predominately nondiamond carbon features in the diamond films with smaller grain sizes, glancing-angle X-ray diffraction spectra show the absence of graphitic carbon features and the presence of very small amorphous carbon diffraction features. The CH4 percentage (%) in Ar and H2 plasma during deposition plays a crucial role in the formation of diamond films with different grain sizes and nondiamond carbon contents, which, in turn, determines the field-emission behavior of the corresponding diamond films. The smaller the grain size of the diamond, the lower is the turn-on field for electron emission. A lower turn-on field is obtained from the diamond films deposited with 2-5% CH4 than from the films deposited with either 1% or 7.5% CH4 in the Ar medium. A current density greater than 1 mA/cm2 (at 50 V/microm) is obtained from diamond films deposited with a higher percentage of CH4. A model is suggested for the field-emission mechanism from the diamond-nondiamond composite films with different diamond grain sizes and nondiamond contents.

Diamond bio electronics.

PubMed

Linares, Robert; Doering, Patrick; Linares, Bryant

2009-01-01

The use of diamond for advanced applications has been the dream of mankind for centuries. Until recently this dream has been realized only in the use of diamond for gemstones and abrasive applications where tons of diamonds are used on an annual basis. Diamond is the material system of choice for many applications, but its use has historically been limited due to the small size, high cost, and inconsistent (and typically poor) quality of available diamond materials until recently. The recent development of high quality, single crystal diamond crystal growth via the Chemical Vapor Deposition (CVD) process has allowed physcists and increasingly scientists in the life science area to think beyond these limitations and envision how diamond may be used in advanced applications ranging from quantum computing, to power generation and molecular imaging, and eventually even diamond nano-bots. Because of diamond's unique properties as a bio-compatible material, better understanding of diamond's quantum effects and a convergence of mass production, semiconductor-like fabrication process, diamond now promises a unique and powerful key to the realization of the bio-electronic devices being envisioned for the new era of medical science. The combination of robust in-the-body diamond based sensors, coupled with smart bio-functionalized diamond devices may lead to diamond being the platform of choice for bio-electronics. This generation of diamond based bio-electronic devices would contribute substantially to ushering in a paradigm shift for medical science, leading to vastly improved patient diagnosis, decrease of drug development costs and risks, and improved effectiveness of drug delivery and gene therapy programs through better timed and more customized solutions.

Impact resistance and energies of intermetallic bonded diamond composites and polycrystalline diamond compacts and their comparison

NASA Astrophysics Data System (ADS)

Gorla, Sai Prasanth

Chemistry of intermetallic bonded diamond is studied. The impact resistance and energies of intermetallic bonded diamond is compared to current poly crystalline diamond compacts. IBD's are found to have high standards of hardness and have more impact energies absorbed. Intermetallic bonded diamond composite comprises of diamond particles dispersed in Tungsten carbide using Nickel aluminide (Ni3Al) as binder. In previous research conducted on IBD's, diamonds are successfully dispersed in intermetallic alloy of nickel aluminide and processed at 1350°C such that diamond particles remain intact without forming graphite. Composites are formed by milling, pressing the intermetallic binder and diamond particles and sintering at high temperature conditions.

Correlated carbon and oxygen isotope signatures in eclogitic diamonds with coesite inclusions: A SIMS investigation of diamonds from Guaniamo, Argyle and Orapa mines

NASA Astrophysics Data System (ADS)

Schulze, D. J.; Page, Z.; Harte, B.; Valley, J.; Channer, D.; Jaques, L.

2006-12-01

Using ion microprobes and secondary-ion mass spectrometry we have analyzed the carbon and oxygen isotopic composition of eclogite-suite diamonds and their coesite inclusions, respectively, from three suites of diamonds of Proterozoic age. Extremely high (for the mantle) oxygen isotope values (delta 18O of +10.2 to +16.9 per mil VSMOW) are preserved in coesites included in eclogitic diamonds from Guaniamo, Venezuela (Schulze et al., Nature, 2003), providing compelling evidence for an origin of their eclogite hosts by subduction of sea water altered ocean floor basalts. In situ SIMS analyses of their host diamonds yield carbon isotope values (delta 13C) of -12 to -18 per mil PDB. SIMS analyses of coesite inclusions from Argyle, Australia diamonds previously analyzed by combustion methods for d13C composition (Jaques et al., Proc. 4th Kimb. Conf, 1989), also yield anomalously high d18O values (+6.8 to +16.0 per mil VSMOW), that correlate with the anomalously low carbon isotope values (-10.3 to -14.1 per mil PDB). One coesite-bearing diamond from Orapa, Botswana analyzed in situ by SIMS has a d18O value of the coesite of +8.5 per mil VSMOW and a d13C value of the adjacent diamond host of -9.0 per mil PDB. A second Orapa stone has a SIMS carbon isotope compositional range of d13C = -14 to -16 per mil PDB, but the coesite is too small for ion probe analysis. At each of these localities, carbon isotope values of coesite-bearing diamonds that are lower than typical of mantle carbon are correlated with oxygen isotope compositions of included coesites that are substantially above the common mantle oxygen isotope range. Such results are not in accord with diamond genesis models involving formation of eclogitic diamonds from igneous melts undergoing fractionation in the mantle or by crystallization from primordial inhomogeneities in Earth's mantle. By analogy with the oxygen isotope compositions of altered ocean floor basalts and Alpine (subduction zone) eclogites they are, however, consistent with a subduction origin for these eclogite assemblages from altered ocean floor basaltic protoliths, and thus the simplest explanation for the source of the low carbon isotope values of these diamonds is formation from biogenic carbon accumulated on or near the ocean floor and subducted to the depths of eclogite and diamond stability with the altered basalts. Significantly these results, which were not predicted from studies of diamond-bearing eclogites, apply to the mantle beneath three different continental crustal blocks of both Proterozoic (Guaniamo and Argyle) and Archean/Proterozoic (Orapa) age.

Diamond anvil cells using boron-doped diamond electrodes covered with undoped diamond insulating layer

NASA Astrophysics Data System (ADS)

Matsumoto, Ryo; Yamashita, Aichi; Hara, Hiroshi; Irifune, Tetsuo; Adachi, Shintaro; Takeya, Hiroyuki; Takano, Yoshihiko

2018-05-01

Diamond anvil cells using boron-doped metallic diamond electrodes covered with undoped diamond insulating layers have been developed for electrical transport measurements under high pressure. These designed diamonds were grown on a bottom diamond anvil via a nanofabrication process combining microwave plasma-assisted chemical vapor deposition and electron beam lithography. The resistance measurements of a high-quality FeSe superconducting single crystal under high pressure were successfully demonstrated by just putting the sample and gasket on the bottom diamond anvil directly. The superconducting transition temperature of the FeSe single crystal was increased to up to 43 K by applying uniaxial-like pressure.

Mineral inclusions and geochemical characteristics of microdiamonds from the DO27, A154, A21, A418, DO18, DD17 and Ranch Lake kimberlites at Lac de Gras, Slave Craton, Canada

NASA Astrophysics Data System (ADS)

Davies, Rondi M.; Griffin, William L.; O'Reilly, Suzanne Y.; Doyle, Buddy J.

2004-09-01

A mineral inclusion, carbon isotope, nitrogen content, nitrogen aggregation state and morphological study of 576 microdiamonds from the DO27, A154, A21, A418, DO18, DD17 and Ranch Lake kimberlites at Lac de Gras, Slave Craton, was conducted. Mineral inclusion data show the diamonds are largely eclogitic (64%), followed by peridotitic (25%) and ultradeep (11%). The paragenetic abundances are similar to macrodiamonds from the DO27 kimberlite (Davies, R.M., Griffin, W.L., O'Reilly, S.Y., 1999. Diamonds from the deep: pipe DO27, Slave craton, Canada. In: Gurney, J.J., Gurney, J.L., Pascoe, M.D., Richardson, S.H. (Eds.), The J. B. Dawson Vol., Proc. 7th Internat. Kimberlite Conf., Red Roof Designs, Cape Town, pp. 148-155) but differ to diamonds from nearby kimberlites at Ekati (e.g., Lithos (2004); Tappert, R., Stachel, T., Harris, J.W., Brey, G.P., 2004. Mineral Inclusions in Diamonds from the Panda Kimberlite, S. P., Canada. 8th International Kimberlite Conference, extended abstracts) and Snap Lake to the south (Dokl. Earth Sci. 380 (7) (2001) 806), that are dominated by peridotitic stones. Eclogitic diamonds with variable inclusion compositions and temperatures of formation (1040-1300 °C) crystallised at variable lithospheric depths sometimes in changing chemical environments. A large range to very 13C-depleted C-isotope compositions ( δ13C=-35.8‰ to -2.2‰) and an NMORB bulk composition, calculated from trace elements in garnet and clinopyroxene inclusions, are consistent with an origin from subducted oceanic crust and sediments. Carbon isotopes in the peridotitic diamonds have mantle compositions ( δ13C mode -4.0‰). Mineral inclusion compositions are largely harzburgitic. Variable temperatures of formation (garnet TNi=800-1300 °C) suggest the peridotitic diamonds originate from the shallow ultra-depleted and deeper less depleted layers of the central Slave lithosphere. Carbon isotopes ( δ13C av.=-5.1‰) and mineral inclusions in the ultradeep diamonds suggest they formed in peridotitic mantle (˜670 km). The diamonds may have been entrained in a plume and subcreted to the base of the central Slave lithosphere. Poorly aggregated nitrogen (IaA without platelets) in a large number of eclogitic (67%) and peridotitic (32%) diamonds, with similar nitrogen contents, indicates the diamonds were stored in the mantle at low temperatures (1060-<1100 °C) following crystallisation in the Archean. Type IaA diamonds have largely cubo-octahedral growth forms, and Type II and Type IaAB diamonds, with higher nitrogen aggregation states, mostly have octahedral morphologies. However, no correlation between these groups and their mineral inclusion compositions, C-isotopes, and N-contents rules out the possibility of unique source origins and suggests eclogitic and peridotitic diamonds experienced variable mantle thermal states. Variation in mineral inclusion chemistries in single diamonds, possible overgrowths of 13C-depleted eclogitic diamond on diamonds with peridotitic and ultradeep inclusions, and Type I ultradeep diamond with low N-aggregation is consistent with diamond growth over time in changing chemical environments.

X-ray topographic study of diamonds: implications for the genetic nature of inclusions in diamond

NASA Astrophysics Data System (ADS)

Agrosì, Giovanna; Nestola, Fabrizio; Tempesta, Gioacchino; Bruno, Marco; Scandale, Eugenio; Harris, Jeff W.

2014-05-01

In recent years, several studies have focused on the growth conditions of the diamonds through the analysis of the mineral inclusions trapped in them (Howell, 2012 and references therein). Nevertheless, to obtain rigorous information about chemical and physical conditions of diamond formation, it is crucial to determine if the crystallization of the inclusions occurred before (protogenetic nature), during (syngenetic nature) or after (epigenetic nature) the growth of diamond (Wiggers de Vries et al., 2011). X-ray topography (XRDT) can be a helpful tool to verify the genetic nature of inclusions in diamond. This technique characterizes the extended defects and reconstructs the growth history of the samples (Agrosì et al., 2013 and references therein) and, consequently contributes to elucidation of the relationship between the inclusions and the host-diamond. With this aim a diamond from the Udachnaya kimberlite, Siberia, was investigated. The diamond crystal was the one previously studied by Nestola et al. (2011) who performed in-situ crystal structure refinement of the inclusions to obtain data about the formation pressure. The inclusions were iso-oriented olivines that did not show evident cracks and subsequently could not be considered epigenetic. Optical observations revealed an anomalous birefringence in the adjacent diamond and the inclusions had typical "diamond-imposed cubo-octahedral" shape for the largest olivine. The diffraction contrast study shows that the diamond exhibits significant deformation fields related to plastic post growth deformation. The crystallographic direction of strains was established applying the extinction criterion. Section topographs were taken to minimize the overlapping of the strain field associate with the different defects and revealed that no dislocations nucleated from the olivine inclusions. Generally, when a solid inclusion has been incorporated in the growing crystal, the associated volume distortion can be minimized by means the nucleation of dislocations and/or twinning (Agrosì et al., 2013). In our case, the specific and significant features - the olivine inclusions showing a "diamond imposed cubo-octahedral shape" and no dislocation nucleation - that characterize this sample will be discussed in detail. References: F Nestola, P Nimis, L Ziberna, M Longo, A Marzoli, JW Harris, MH Manghnani (2011): Earth and Planetary Science Letters 305 (1), 249-255. Howell, D. (2012): Eur. J. Mineral., 24, 575-585. Wiggers de Vries D.F., Drury M.R., de Winter D.A. M., Bulanova G P., Pearson D. G., Davies G. R. (2011): Contrib. Mineral. Petrol. 161, 565-579. Agrosì G., Tempesta G., Scandale E., Harris J.W. (2013): Eur. J. Mineral, 25 (4), 551-559.

Development and testing of a Mudjet-augmented PDC bit.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Black, Alan; Chahine, Georges; Raymond, David Wayne

2006-01-01

This report describes a project to develop technology to integrate passively pulsating, cavitating nozzles within Polycrystalline Diamond Compact (PDC) bits for use with conventional rig pressures to improve the rock-cutting process in geothermal formations. The hydraulic horsepower on a conventional drill rig is significantly greater than that delivered to the rock through bit rotation. This project seeks to leverage this hydraulic resource to extend PDC bits to geothermal drilling.

Interface Properties of Wide Bandgap Semiconductor Structures

DTIC Science & Technology

1993-12-01

oxyacetylene torch and a water cooled substrate. Studying and controlling this chemical vapor deposition (CVD) process, however, can be frustrating because the...the carbide heat of formation. The precursors of chlorinated methylsilanes coupled with bias were used to deposit C films on Si(100). Textured C (lll...films were also achieved using an oxyacetylene torch . Cu forms an epitaxial rectifyingIcontact to diamond with a Schottky barrier height (SBH) of

A methodology for conducting national-scale alluvial diamond resource potential and production capacity assessments, with a focus on artisanal mining

USGS Publications Warehouse

Chirico, Peter G.; Malpeli, Katherine C.

2012-01-01

In May of 2000, a meeting was convened in Kimberley, South Africa, by representatives of the diamond industry and leaders of African governments to develop a certification process intended to assure that export shipments of rough diamonds were free of conflict concerns. Outcomes of the meeting were formally supported later in December of 2000 by the United Nations in a resolution adopted by the General Assembly. By 2002, the Kimberley Process Certification Scheme was ratified and signed by diamond-producing and diamond-importing countries. As of August 2012, the Kimberley Process (KP) had 51 participants representing 77 countries. It is often difficult to obtain independent verification of the diamond production statistics that are provided to the KP. However, some degree of independent verification can be obtained through an understanding of a country’s naturally occurring endowment of diamonds and the intensity of mining activities. Studies that integrate these two components can produce a range of estimated values for a country’s diamond production, and these estimates can then be compared to the production statistics released by that country. This methodology is used to calculate (1) the diamond resource potential of a country, which refers to the total number of carats estimated to be remaining in the country, and (2) the diamond production capacity of a country, which is the current volume of diamonds that may realistically be produced per year utilizing current human and physical resources. The following sections outline the methodology used by the U.S. Geological Survey (USGS) to perform diamond assessments in Mali, the Central African Republic, Ghana, and Guinea.

Summary of the diamond resource potential and production capacity assessment of Guinea

USGS Publications Warehouse

Chirico, Peter G.; Malpeli, Katherine C.

2012-01-01

In May of 2000, a meeting was convened in Kimberley, South Africa, by representatives of the diamond industry and leaders of African governments to develop a certification process intended to assure that export shipments of rough diamonds were free of conflict concerns. Outcomes of the meeting were formally supported later in December of 2000 by the United Nations in a resolution adopted by the General Assembly. By 2002, the Kimberley Process Certification Scheme (KPCS) was ratified and signed by diamond-producing and diamond-importing countries. As of August 2012, the Kimberley Process (KP) had 51 participants representing 77 countries. With the passing of the AD, the Plenary agreed that further efforts should be made to assess Guinea's diamond production capacity. In support of this objective, the U.S. Geological Survey (USGS) partnered with the Kimberley Process Working Group of Diamond Experts (WGDE) and Guinea's Ministry of Mines and Geology (MMG) to conduct a field campaign in Guinea from April 24 through May 2, 2010. The field team was composed of Mark Van Bockstael of the WGDE, Peter Chirico of the USGS, and several geologists from the MMG. The team visited diamond mining sites in western Guinea's Kindia, Forècariah, Coyah, and Tèlimèlè Prefectures, in which the Guinean government identified newly discovered deposits mined by artisans. Several mining sites within the Kissidougou Prefecture in southeastern Guinea were also visited as part of this study. Geologic and geomorphic information on the diamond deposits was collected at each site. The fieldwork conducted during this trip served as a means of acquiring critical data needed to conduct a full assessment of diamond resources and production capacity.

Long-term culture of pluripotent stem-cell-derived human neurons on diamond--A substrate for neurodegeneration research and therapy.

PubMed

Nistor, Paul A; May, Paul W; Tamagnini, Francesco; Randall, Andrew D; Caldwell, Maeve A

2015-08-01

Brain Computer Interfaces (BCI) currently represent a field of intense research aimed both at understanding neural circuit physiology and at providing functional therapy for traumatic or degenerative neurological conditions. Due to its chemical inertness, biocompatibility and stability, diamond is currently being actively investigated as a potential substrate material for culturing cells and for use as the electrically active component of a neural sensor. Here we provide a protocol for the differentiation of mature, electrically active neurons on microcrystalline synthetic thin-film diamond substrates starting from undifferentiated pluripotent stem cells. Furthermore, we investigate the optimal characteristics of the diamond microstructure for long-term neuronal sustainability. We also analyze the effect of boron as a dopant for such a culture. We found that the diamond crystalline structure has a significant influence on the neuronal culture unlike the boron doping. Specifically, small diamond microcrystals promote higher neurite density formation. We find that boron incorporated into the diamond does not influence the neurite density and has no deleterious effect on cell survival. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Study on effect of plasma surface treatments for diamond deposition by DC arc plasmatron.

PubMed

Kang, In-Je; Joa, Sang-Beom; Lee, Heon-Ju

2013-11-01

To improve the thermal conductivity and wear resistance of ceramic materials in the field of renewable energy technologies, diamond coating by plasma processing has been carried out in recent years. This study's goal is to improve diamond deposition on Al2O3 ceramic substrates by plasma surface treatments. Before diamond deposition was carried out in a vacuum, plasma surface treatments using Ar gas were conducted to improve conditions for deposition. We also conducted plasma processing for diamond deposition on Al2O3 ceramic substrates using a DC arc Plasmatron. The Al2O3 ceramic substrates with diamond film (5 x 15 mm2), were investigated by SEM (Scanning Electron Microscopy), AFM (Atomic Force Microscopy) and XRD (X-ray Diffractometer). Then, the C-H stretching of synthetic diamond films by FTIR (Fourier Transform Infrared Spectroscopy) was studied. We identified nanocrystalline diamond films on the Al2O3 ceramic substrates. The results showed us that the deposition rate of diamond films was 2.3 microm/h after plasma surface treatments. Comparing the above result with untreated ceramic substrates, the deposition rate improved with the surface roughness of the deposited diamond films.

Bases of the Mantle-Carbonatite Conception of Diamond Genesis

NASA Astrophysics Data System (ADS)

Litvin, Yuriy; Spivak, Anna; Kuzyura, Anastasia

2016-04-01

In the mantle-carbonatite conception of diamond genesis, the results of physic-chemical experiments are coordinated with the data of analytic mineralogy of primary inclusions in natural diamonds. Generalization of the solutions of principal genetic problems constitutes the bases of the conception. The solutions are following: (1) it is grounded that diamond-parental melts of the upper mantle have peridotite/eclogite - carbonatite - carbon compositions, of the transition zone - (wadsleite↔ringwoodite) - majorite - stishovite - carbonatite - carbon compositions, and of the lower mantle - periclase/wustite - bridgmanite - Ca-perovskite -stishovite - carbonatite - carbon compositions; (2) a construction of generalized diagrams for the diamond-parental media, which reveal changeable compositions of the growth melts of diamonds and associated phases, their genetic relations to the mantle substance, and classification connections of the primary inclusions in natural diamonds; (3) experimental equilibrium phase diagrams of syngenesis of diamonds and primary inclusions, which characterize the nucleation and growth conditions of diamonds and a capture of paragenetic and xenogenetic minerals by the growing diamonds; (4) a determination of the phase diagrams of diamonds and inclusions syngenesis under the regime of fractional crystallization, which discover the regularities of ultrabasic-basic evolution and paragenesis transitions in the diamond-forming systems of the upper and lower mantle. The evidence of the physic-chemically united mode of diamond genesis at the mantle depths with different mineralogy is obtained. References. Litvin Yu.A. (2007). High-pressure mineralogy of diamond genesis. In: Advances in High-Pressure Mineralogy (edited by Eiji Ohtani), Geological Society of America Special paper 421, 83-103. Litvin Yu.A. (2012). Experimental study of physic-chemical conditions of natural diamond formation on an example of the eclogite-carbonatite-sulphide-diamond system. Geology of Ore Deposits. 54(6), 523-539. Litvin Yu.A., Spivak A.V., Solopova N.A., Dubrovinsky L.S. (2014). On origin of lower-mantle diamonds and their primary inclusions. Physics of the Earth and Planetary Interiors, 228 (The Liebermann Volume), 176-185. http://dx.doi.org/10.1016/j/pepi/2013.12.007

Influence of the current density on the electrochemical treatment of concentrated 1-butyl-3-methylimidazolium chloride solutions on diamond electrodes.

PubMed

Marcionilio, Suzana M L de Oliveira; Alves, Gisele M; E Silva, Rachel B Góes; Marques, Pablo J Lima; Maia, Poliana D; Neto, Brenno A D; Linares, José J

2016-10-01

This paper focuses on the influence of the current density treatment of a concentrated 1-butyl-3-methylimidazolium chloride (BMImCl) solution on an electrochemical reactor with a boron-doped diamond (BDD) anode. The decrease in the total organic carbon (TOC) and the BMImCl concentration demonstrate the capability of BDD in oxidizing ionic liquids (ILs) and further mineralizing (to CO2 and NO3 (-)) more rapidly at higher current densities in spite of the reduced current efficiency of the process. Moreover, the presence of Cl(-) led to the formation of oxychlorinated anions (mostly ClO3 (-) and ClO4 (-)) and, in combination with the ammonia generated in the cathode from the nitrate reduction, chloramines, more intensely at higher current density. Finally, the analysis of the intermediates formed revealed no apparent influence of the current density on the BMImCl degradation mechanism. The current density presents therefore a complex influence on the IL treatment process that is discussed throughout this paper.

Effect of the cathode material on the removal of nitrates by electrolysis in non-chloride media.

PubMed

Lacasa, Engracia; Cañizares, Pablo; Llanos, Javier; Rodrigo, Manuel A

2012-04-30

In this work, the effect of the cathode material (conductive diamond, stainless steel, silicon carbide, graphite or lead) and the current density (150-1400 A m(-2)) on the removal of nitrates from aqueous solutions is studied by electrolysis in non-divided electrochemical cells equipped with conductive diamond anodes, using sodium sulphate as the electrolyte. The results show that the cathode material very strongly influences both the process performance and the product distribution. The main products obtained are gaseous nitrogen (NO, N(2)O and NO(2)) and ammonium ions. Nitrate removal follows first order kinetics, which indicates that the electrolysis process is controlled by mass transfer. Furthermore, the stainless steel and graphite cathodes show a great selectivity towards the production of ammonium ions, whereas the silicon carbide cathode leads to the highest formation of gaseous nitrogen, which production is promoted at low current densities. Copyright © 2012 Elsevier B.V. All rights reserved.

Fabrication of Hierarchical Layer-by-Layer Assembled Diamond-based Core-Shell Nanocomposites as Highly Efficient Dye Absorbents for Wastewater Treatment

NASA Astrophysics Data System (ADS)

Zhao, Xinna; Ma, Kai; Jiao, Tifeng; Xing, Ruirui; Ma, Xilong; Hu, Jie; Huang, Hao; Zhang, Lexin; Yan, Xuehai

2017-03-01

The effective chemical modification and self-assembly of diamond-based hierarchical composite materials are of key importance for a broad range of diamond applications. Herein, we report the preparation of novel core-shell diamond-based nanocomposites for dye adsorption toward wastewater treatment through a layer-by-layer (LbL) assembled strategy. The synthesis of the reported composites began with the carboxyl functionalization of microdiamond by the chemical modification of diamond@graphene oxide composite through the oxidation of diamond@graphite. The carboxyl-terminated microdiamond was then alternatively immersed in the aqueous solution of amine-containing polyethylenimine and carboxyl-containing poly acrylic acid, which led to the formation of adsorption layer on diamond surface. Alternating (self-limiting) immersions in the solutions of the amine-containing and carboxyl-containing polymers were continued until the desired number of shell layers were formed around the microdiamond. The obtained core-shell nanocomposites were successfully synthesized and characterized by morphological and spectral techniques, demonstrating higher surface areas and mesoporous structures for good dye adsorption capacities than nonporous solid diamond particles. The LbL-assembled core-shell nanocomposites thus obtained demonstrated great adsorption capacity by using two model dyes as pollutants for wastewater treatment. Therefore, the present work on LbL-assembled diamond-based composites provides new alternatives for developing diamond hybrids as well as nanomaterials towards wastewater treatment applications.

In situ observation of shear-driven amorphization in silicon crystals.

PubMed

He, Yang; Zhong, Li; Fan, Feifei; Wang, Chongmin; Zhu, Ting; Mao, Scott X

2016-10-01

Amorphous materials are used for both structural and functional applications. An amorphous solid usually forms under driven conditions such as melt quenching, irradiation, shock loading or severe mechanical deformation. Such extreme conditions impose significant challenges on the direct observation of the amorphization process. Various experimental techniques have been used to detect how the amorphous phases form, including synchrotron X-ray diffraction, transmission electron microscopy (TEM) and Raman spectroscopy, but a dynamic, atomistic characterization has remained elusive. Here, by using in situ high-resolution TEM (HRTEM), we show the dynamic amorphization process in silicon nanocrystals during mechanical straining on the atomic scale. We find that shear-driven amorphization occurs in a dominant shear band starting with the diamond-cubic (dc) to diamond-hexagonal (dh) phase transition and then proceeds by dislocation nucleation and accumulation in the newly formed dh-Si phase. This process leads to the formation of an amorphous Si (a-Si) band, embedded with dh-Si nanodomains. The amorphization of dc-Si via an intermediate dh-Si phase is a previously unknown pathway of solid-state amorphization.

Composite material having high thermal conductivity and process for fabricating same

DOEpatents

Colella, N.J.; Davidson, H.L.; Kerns, J.A.; Makowiecki, D.M.

1998-07-21

A process is disclosed for fabricating a composite material such as that having high thermal conductivity and having specific application as a heat sink or heat spreader for high density integrated circuits. The composite material produced by this process has a thermal conductivity between that of diamond and copper, and basically consists of coated diamond particles dispersed in a high conductivity metal, such as copper. The composite material can be fabricated in small or relatively large sizes using inexpensive materials. The process basically consists, for example, of sputter coating diamond powder with several elements, including a carbide forming element and a brazeable material, compacting them into a porous body, and infiltrating the porous body with a suitable braze material, such as copper-silver alloy, thereby producing a dense diamond-copper composite material with a thermal conductivity comparable to synthetic diamond films at a fraction of the cost. 7 figs.

Process for fabricating composite material having high thermal conductivity

DOEpatents

Colella, Nicholas J.; Davidson, Howard L.; Kerns, John A.; Makowiecki, Daniel M.

2001-01-01

A process for fabricating a composite material such as that having high thermal conductivity and having specific application as a heat sink or heat spreader for high density integrated circuits. The composite material produced by this process has a thermal conductivity between that of diamond and copper, and basically consists of coated diamond particles dispersed in a high conductivity metal, such as copper. The composite material can be fabricated in small or relatively large sizes using inexpensive materials. The process basically consists, for example, of sputter coating diamond powder with several elements, including a carbide forming element and a brazeable material, compacting them into a porous body, and infiltrating the porous body with a suitable braze material, such as copper-silver alloy, thereby producing a dense diamond-copper composite material with a thermal conductivity comparable to synthetic diamond films at a fraction of the cost.

Composite material having high thermal conductivity and process for fabricating same

DOEpatents

Colella, Nicholas J.; Davidson, Howard L.; Kerns, John A.; Makowiecki, Daniel M.

1998-01-01

A process for fabricating a composite material such as that having high thermal conductivity and having specific application as a heat sink or heat spreader for high density integrated circuits. The composite material produced by this process has a thermal conductivity between that of diamond and copper, and basically consists of coated diamond particles dispersed in a high conductivity metal, such as copper. The composite material can be fabricated in small or relatively large sizes using inexpensive materials. The process basically consists, for example, of sputter coating diamond powder with several elements, including a carbide forming element and a brazeable material, compacting them into a porous body, and infiltrating the porous body with a suitable braze material, such as copper-silver alloy, thereby producing a dense diamond-copper composite material with a thermal conductivity comparable to synthetic diamond films at a fraction of the cost.

Propagation of threading dislocations in heteroepitaxial diamond films with (111) orientation and their role in the formation of intrinsic stress

NASA Astrophysics Data System (ADS)

Gallheber, B.-C.; Klein, O.; Fischer, M.; Schreck, M.

2017-06-01

In the present study, systematic correlations were revealed between the propagation direction of threading dislocations, the off-axis growth conditions, and the stress state of heteroepitaxial diamond on Ir/YSZ/Si(111). Measurements of the strain tensor ɛ ⃡ by X-ray diffraction and the subsequent calculation of the tensor of intrinsic stress σ ⃡ showed stress-free samples as well as symmetric biaxial stress states for on-axis samples. Transmission electron microscopy (TEM) lamellas were prepared for plan-view studies along the [ 1 ¯ 1 ¯ 1 ¯ ] direction and for cross-section investigations along the [11 2 ¯ ] and [1 1 ¯ 0] zone axes. For samples grown on-axis with parameters which avoid the formation of intrinsic stress, the majority of dislocations have line vectors clearly aligned along [111]. A sudden change to conditions that promote stress formation is correlated with an abrupt bending of the dislocations away from [111]. This behaviour is in nice agreement with the predictions of a model that attributes formation of intrinsic stress to an effective climb of dislocations. Further growth experiments under off-axis conditions revealed the generation of stress states with pronounced in-plane anisotropy of several Gigapascal. Their formation is attributed to the combined action of two basic processes, i.e., the step flow driven dislocation tilting and the temperature dependent effective climb of dislocations. Again, our interpretation is supported by the dislocation propagation derived from TEM observations.

Analysis of synthetic diamond single crystals by X-ray topography and double-crystal diffractometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prokhorov, I. A., E-mail: igor.prokhorov@mail.ru; Ralchenko, V. G.; Bolshakov, A. P.

2013-12-15

Structural features of diamond single crystals synthesized under high pressure and homoepitaxial films grown by chemical vapor deposition (CVD) have been analyzed by double-crystal X-ray diffractometry and topography. The conditions of a diffraction analysis of diamond crystals using Ge monochromators have been optimized. The main structural defects (dislocations, stacking faults, growth striations, second-phase inclusions, etc.) formed during crystal growth have been revealed. The nitrogen concentration in high-pressure/high-temperature (HPHT) diamond substrates is estimated based on X-ray diffraction data. The formation of dislocation bundles at the film-substrate interface in the epitaxial structures has been revealed by plane-wave topography; these dislocations are likelymore » due to the relaxation of elastic macroscopic stresses caused by the lattice mismatch between the substrate and film. The critical thicknesses of plastic relaxation onset in CVD diamond films are calculated. The experimental techniques for studying the real diamond structure in optimizing crystal-growth technology are proven to be highly efficient.« less

Electrically conductive diamond electrodes

DOEpatents

Swain, Greg [East Lansing, MI; Fischer, Anne [Arlington, VA; Bennett, Jason [Lansing, MI; Lowe, Michael [Holt, MI

2009-05-19

An electrically conductive diamond electrode and process for preparation thereof is described. The electrode comprises diamond particles coated with electrically conductive doped diamond preferably by chemical vapor deposition which are held together with a binder. The electrodes are useful for oxidation reduction in gas, such as hydrogen generation by electrolysis.

Cathodoluminescence of diamond as an indicator of its metamorphic history

NASA Astrophysics Data System (ADS)

Kopylova, Maya; Bruce, Loryn; Longo, Micaela; Ryder, John; Dobrzhinetskaya, Larissa

2010-05-01

Diamond displays a supreme resistance to chemical and mechanical weathering, ensuring its survival through complex and prolonged crustal processes, including metamorphism and exhumation. For these reasons, volcanic sources and secondary and tertiary collectors for detrital placer diamonds, like Ural or Bingara diamonds, may be difficult to determine. If metamorphic processes leave their marks on diamond, they can be used to reconstruct crustal geologic processes and ages of primary diamondiferous volcanics. Four diamond suites extracted from metamorphic rocks have been characterized using optical CL, infrared and CL spectroscopy, and photoluminescence at the liquid nitrogen temperature. The studied diamonds are from the ~2.7 Ga sedimentary conglomerate and lamprophyric breccia metamorphosed in the greenschist facies (Wawa, Northern Ontario, Canada) during the 2.67 Ga Kenoran orogeny, and from the ultra-high pressure (UHP) terranes of Kokchetav (Kazakhstan) and Erzgebirge (Germany) exhumated in the Paleozoic. Wawa diamonds (Type IaAB and Type II) displayed green, yellow, orange, and red CL colours controlled by the CL emittance at 520, 576 nm, and between 586 and 664 nm. The UHP terranes diamonds show much weaker CL; few luminescent stones display CL peaks at 395, 498, 528 nm and a broad band at 580-668 nm. In contrast, most common diamonds found in unmetamorphosed rocks, i.e. octahedrally grown Type IaAB stones, luminescence blue emitting light at ~415-440 nm and 480-490 nm. There is a noticeable difference between cathodoluminescence of these diamonds and diamonds in metamorphic rocks. The studied diamonds that experienced metamorphism show a shift of CL emission to longer wavelengths (above 520 nm) and to green, yellow and red CL colours. Photoluminescence has the high resolution necessary to assign luminescence to specific optical centers of diamond. Diamonds in metamorphic rocks contain H3 (pairs of substitutional nitrogen atoms separated by a vacancy) and NVo optical centers (neutrally charged complexes of a vacancy and a single nitrogen). We ascribe the effect of metamorphism on the diamond CL to low-T, low-P deformation that creates lattice dislocations and vacancies. These combine with substitutional N to make and enhance optical centers. The metamorphism-induced CL anneals when diamonds are stored at high-T mantle conditions, as the mobility of dislocations at T>750oC quenches the luminescence. Indeed, all studied diamonds that displayed unusual green, yellow and red CL were found in low and medium grade metamorphic rocks, i.e. Wawa greenschists (T<350oC and P< 3 kb) and Kokchetav and Erzgebirge UHP terranes retrograded in the amphibolite facies (T<750oC, P<14 kb) Our study suggest that a low abundance of octahedrally grown Type IaAB diamonds with blue CL colours among detrital diamonds may indicate that the stones may have once been a part of a low- or medium-grade metamorphic terrane. The CL characteristics superimposed by metamorphism could survive through billions of years of the geological history if not annealed by a high -T process. The discovered record of metamorphism in the diamond crystal lattice provides an opportunity for a better reconstruction of the crustal history and provenance studies of diamond.

PROCESS FOR COLORING DIAMONDS

DOEpatents

Dugdale, R.A.

1960-07-19

A process is given for coloring substantially colorless diamonds in the blue to blue-green range and comprises the steps of irradiating the colorless diamonds with electrons having an energy within the range 0.5 to 2 Mev to obtain an integrated electron flux of between 1 and 2 x 10/sup 18/ thc diamonds may be irradiated 1 hr when they take on a blue color with a slight green tint: After being heated at about 500 deg C for half an hour they become pure blue. Electrons within this energy range contam sufficient energy to displace the diamond atoms from their normal lattice sites into interstitial sites, thereby causing the color changes.

Regional sub-cratonic mantle heterogeneities under the Kaapvaal craton recorded by sulfide inclusions in diamond.

NASA Astrophysics Data System (ADS)

Thomassot, E.; Lorand, J. P.

2016-12-01

Sulfide inclusions in diamonds (SID) have been trapped by their host at depth greater than 150 km and then protected from alteration or reequilibration processes. Subsequently, depending on their initial composition, there have experienced multiple exsolution events at temperatures between 650°C and 200°C. Mineralogical and isotopic composition of SID thus directly reflects their sources whereas their texture give information on the exhumation history of their diamond host. Our samples originating from Koffiefontein, De Beers Pool and Jwaneng kimberlites, include both peridotitic (P-type, n=6) and eclogitic (E-type, n=151) sulfides. P-type sulfides are monosulfide solid solutions (exsolved from a nickeliferous monosulfide solid solution, mss, stable at T>300°C). Their Ni and Cr content indicate that the sublithospheric mantle under Koffiefontein (Ni=26wt%; Cr=0.36 wt%) is more refractory than De Beers Pool (Ni=24wt%; Cr=0.28wt%) and Jwaneng (Ni=17wt%; Cr=0.22wt%). Sulfides from De Beers Pool have S/Se (3900±100) greater than the chondritic values ( 2540) pointing to a metasomatic overprint predating the formation of diamonds. S-isotopic composition (d34S=-0.9 ± 0.5‰, Δ33S=0‰) are homogeneous, and consistent with the composition of MORB. E-type sulfides are unmixed assemblage of chalcopyrite (crystallized from an intermediate solid solution formed at T 650°C) pentlandite (T° from 260 to >200°C) and pyrrhotite. Comparing the chemical composition of the unmixed phases with experimental data, we determined a blocking T° for E-type assemblages ranging from 540°C at Koffiefontein, to less than 200°C at Jwaneng and DeBeersPool. E-type sulfides thus confirm the chemical heterogeneity from one mine to the other, with d34S extended to fractionated values (-9 to +11‰). Our study indicates that SID are robust probes to explore regional scale mantle heterogeneities likely associated to discrete depletion events and possible recycling of ancient sediment, predating the formation of diamonds. Major, trace element and isotopes data will be presented at the conference in order to support this conclusion.

High resolution structural characterisation of laser-induced defect clusters inside diamond

NASA Astrophysics Data System (ADS)

Salter, Patrick S.; Booth, Martin J.; Courvoisier, Arnaud; Moran, David A. J.; MacLaren, Donald A.

2017-08-01

Laser writing with ultrashort pulses provides a potential route for the manufacture of three-dimensional wires, waveguides, and defects within diamond. We present a transmission electron microscopy study of the intrinsic structure of the laser modifications and reveal a complex distribution of defects. Electron energy loss spectroscopy indicates that the majority of the irradiated region remains as sp3 bonded diamond. Electrically conductive paths are attributed to the formation of multiple nano-scale, sp2-bonded graphitic wires and a network of strain-relieving micro-cracks.

Deposition and micro electrical discharge machining of CVD-diamond layers incorporated with silicon

NASA Astrophysics Data System (ADS)

Kühn, R.; Berger, T.; Prieske, M.; Börner, R.; Hackert-Oschätzchen, M.; Zeidler, H.; Schubert, A.

2017-10-01

In metal forming, lubricants have to be used to prevent corrosion or to reduce friction and tool wear. From an economical and ecological point of view, the aim is to avoid the usage of lubricants. For dry deep drawing of aluminum sheets it is intended to apply locally micro-structured wear-resistant carbon based coatings onto steel tools. One type of these coatings are diamond layers prepared by chemical vapor deposition (CVD). Due to the high strength of diamond, milling processes are unsuitable for micro-structuring of these layers. In contrast to this, micro electrical discharge machining (micro EDM) is a suitable process for micro-structuring CVD-diamond layers. Due to its non-contact nature and its process principle of ablating material by melting and evaporating, it is independent of the hardness, brittleness or toughness of the workpiece material. In this study the deposition and micro electrical discharge machining of silicon incorporated CVD-diamond (Si-CVD-diamond) layers were presented. For this, 10 µm thick layers were deposited on molybdenum plates by a laser-induced plasma CVD process (LaPlas-CVD). For the characterization of the coatings RAMAN- and EDX-analyses were conducted. Experiments in EDM were carried out with a tungsten carbide tool electrode with a diameter of 90 µm to investigate the micro-structuring of Si-CVD-diamond. The impact of voltage, discharge energy and tool polarity on process speed and resulting erosion geometry were analyzed. The results show that micro EDM is a suitable technology for micro-structuring of silicon incorporated CVD-diamond layers.

Surface structuring of boron doped CVD diamond by micro electrical discharge machining

NASA Astrophysics Data System (ADS)

Schubert, A.; Berger, T.; Martin, A.; Hackert-Oschätzchen, M.; Treffkorn, N.; Kühn, R.

2018-05-01

Boron doped diamond materials, which are generated by Chemical Vapor Deposition (CVD), offer a great potential for the application on highly stressed tools, e. g. in cutting or forming processes. As a result of the CVD process rough surfaces arise, which require a finishing treatment in particular for the application in forming tools. Cutting techniques such as milling and grinding are hardly applicable for the finish machining because of the high strength of diamond. Due to its process principle of ablating material by melting and evaporating, Electrical Discharge Machining (EDM) is independent of hardness, brittleness or toughness of the workpiece material. EDM is a suitable technology for machining and structuring CVD diamond, since boron doped CVD diamond is electrically conductive. In this study the ablation characteristics of boron doped CVD diamond by micro electrical discharge machining are investigated. Experiments were carried out to investigate the influence of different process parameters on the machining result. The impact of tool-polarity, voltage and discharge energy on the resulting erosion geometry and the tool wear was analyzed. A variation in path overlapping during the erosion of planar areas leads to different microstructures. The results show that micro EDM is a suitable technology for finishing of boron doped CVD diamond.

Alluvial diamond resource potential and production capacity assessment of Mali

USGS Publications Warehouse

Chirico, Peter G.; Barthelemy, Francis; Kone, Fatiaga

2010-01-01

In May of 2000, a meeting was convened in Kimberley, South Africa, and attended by representatives of the diamond industry and leaders of African governments to develop a certification process intended to assure that rough, exported diamonds were free of conflictual concerns. This meeting was supported later in 2000 by the United Nations in a resolution adopted by the General Assembly. By 2002, the Kimberley Process Certification Scheme (KPCS) was ratified and signed by diamond-producing and diamond-importing countries. Over 70 countries were included as members of the KPCS at the end of 2007. To prevent trade in "conflict diamonds" while protecting legitimate trade, the KPCS requires that each country set up an internal system of controls to prevent conflict diamonds from entering any imported or exported shipments of rough diamonds. Every diamond or diamond shipment must be accompanied by a Kimberley Process (KP) certificate and be contained in tamper-proof packaging. The objective of this study was (1) to assess the naturally occurring endowment of diamonds in Mali (potential resources) based on geological evidence, previous studies, and recent field data and (2) to assess the diamond-production capacity and measure the intensity of mining activity. Several possible methods can be used to estimate the potential diamond resource. However, because there is generally a lack of sufficient and consistent data recording all diamond mining in Mali and because time to conduct fieldwork and accessibility to the diamond mining areas are limited, four different methodologies were used: the cylindrical calculation of the primary kimberlitic deposits, the surface area methodology, the volume and grade approach, and the content per kilometer approach. Approximately 700,000 carats are estimated to be in the alluvial deposits of the Kenieba region, with 540,000 carats calculated to lie within the concentration grade deposits. Additionally, 580,000 carats are estimated to have been released from the primary kimberlites in the region. Therefore, the total estimated diamond resources in the Kenieba region are thought to be nearly 1,300,000 carats. The Bougouni zones are estimated to have 1,000,000 carats with more than half, 630,000 carats, contained in concentrated deposits. When combined, the Kenieba and Bougouni regions of Mali are estimated to be host to 2,300,000 carats of diamonds.

Aminosilane multilayer formed on a single-crystalline diamond surface with controlled nanoscopic hardness and bioactivity by a wet process.

PubMed

Amemiya, Yosuke; Hatakeyama, Akiko; Shimamoto, Nobuo

2009-01-06

Diamond could be an excellent support for nanodevices utilizing biomolecules if it is covered with a polymer layer immobilizing a variety of biomolecules. We report a wet method to form a 3-aminopropyltriethoxysilane (APTES) multilayer with a controlled hardness, roughness, and capacity for immobilizing protein. The method is feasible in typical biochemical laboratories where biomolecules are prepared. Atomic force microscopy (AFM) revealed that the surface geometries and nanoscopic hardness of the multilayers on an oxygen-terminated single-crystalline diamond surface depended on the dielectric constant of the solvent; the smaller the constant, the harder the layer. The hard multilayers had holes and APTES aggregates on the surfaces, while less hard ones had homogeneous surfaces with rare holes and little aggregates. The secondary deposition of APTES in a solvent with a large dielectric constant on a hard multilayer removed the holes, and further treatment of the multilayer in acidic ethanol solution diminished the aggregates. Such a surface can immobilize streptavidin with enough specificity against nonspecific adsorption using a combination of polyethylene glycol reagents. The results of a scratching test and nanoindentation test with AFM provided consistent results, suggesting some universality of the scratching test independent of the tip structure of the cantilever. The mechanism of formation of multilayers on the diamond surface and their binding to it is discussed.

Diamond and moissanite in ophiolitic mantle rocks and podiform chromitites: A deep carbon source?

NASA Astrophysics Data System (ADS)

Yang, J.; Xu, X.; Wiedenbeck, M.; Trumbull, R. B.; Robinson, P. T.

2010-12-01

Diamonds are known from a variety of occurreces, mainly from mantle-derived kimberlites, meteorite impact craters, and continental deep subduction and collision zones. Recently, an unusual mineral group was discovered in the Luobusa ophiolitic chromitites from the Yarlung Zangbu suture, Tibet, which probably originated from a depth of over 300 km in the mantle. Minerals of deep origin include coesite apparently pseudomorphing stishovite, and diamond as individual grains or inclusions in OsIr alloy. To determine if such UHP and unusual minerals occur elsewhere, we collected about 1.5 t of chromitite from two orebodies in an ultramafic body in the Polar Urals. Thus far, more than 60 different mineral species have been separated from these ores. The most exciting discovery is the common occurrence of diamond, a typical UHP mineral in the Luobusa chromitites. These minerals are very similar in composition and structure to those reported from the Luobusa chromitites. So far diamond and/or moissanite have been discovered from many different ophiolitic ultramafic rocks, including in-situ grains in polished chromitite fragments. These discoveries demonstrate that the Luobusa ophiolite is not a unique diamond-bearing massif. Secondary ion mass spectrometric (SIMS) analysis shows that the ophiolite-hosted diamond has a distinctive 13C-depleted isotopic composition (δ13C from -18 to -28‰, n=70), compatible to the ophiolite-hosted moissanite (δ13C from -18 to -35‰, n=36), both are much lighter than the main carbon reservoir in the upper mantle (δ13C near -5‰). The compiled data from moissanite from kimberlites and other mantle settings share the characteristic of strongly 13C-depleted isotopic composition. This suggests that diamond and moissanite originates from a separate carbon reservoir in the mantle or that its formation involved strong isotopic fractionation. Subduction of biogenic carbonaceous material could potentially satisfy both the unusual isotopic and redox constraints on diamond and moissanite formation, but this material would need to stay chemically isolated from the upper mantle until it reached the high-T stability field of diamond and moissanite. The origin of diamond and moissanite in the mantle is still unsolved, but all evidence from the upper mantle indicates that they cannot have formed there, except under special and local redox conditions. We suggest, alternatively, that diamond and moissanite may have formed in the lower mantle, where the existence of 13C-depleted carbon is strongly suspected.

Use of natural diamonds to monitor 14C AMS instrument backgrounds

NASA Astrophysics Data System (ADS)

Taylor, R. E.; Southon, John

2007-06-01

To examine one component of the instrument-based background in the University of California Keck Carbon Cycle AMS spectrometer, we have obtained measurements on a set of natural diamonds pressed into sample holders. Natural diamond samples (N = 14) from different sources within rock formations with geological ages greatly in excess of 100 Ma yielded a range of currents (∼110-250 μA 12C- where filamentous graphite typically yields ∼150 μA 12C-) and apparent 14C ages (64.9 ± 0.4 ka BP [0.00031 ± 0.00002 fm] to 80.0 ± 1.1 ka BP [0.00005 ± 0.00001 fm]). Six fragments cut from a single diamond exhibited essentially identical 14C values - 69.3 ± 0.5 ka-70.6 ± 0.5 ka BP. The oldest 14C age equivalents were measured on natural diamonds which exhibited the highest current yields.

"Fullerene-like" Raman bands in UHP metamorphic diamonds: Metastable intermediate phases for diamond formation

NASA Astrophysics Data System (ADS)

Harada, Y.; Igarashi, M.; Hashiguchi, Y.; Ogasawara, Y.

2011-12-01

Mysterious Raman bands at 1430-1480 cm-1 suggesting carbon (or carbon-bearing) species have been discovered in UHP metamorphic microdiamonds entirely enclosed in dolomite marble from Kokchetav Massif (Igarashi et al., 2011). Such Raman bands first discovered at some domains in a T-type (see Ishida et al., 2003) diamond in dolomite marble in 2005, but we have not reported this because of the possibility of misidentification by contamination. Later, similar bands were also found in the rim and the core of S-type and R-type. The relative intensities of these Raman bands to diamond (at 1332 cm-1) were 10-40 % in average (max. 90-110 %) and FWHMs are broad (25-45 cm-1). The possibility of the appearance of these Raman bands was low. As we used ordinary polished thin sections (thickness: 25 μm) and the organic materials used in thin section making have Raman bands at ca. 1450 cm-1, we carefully examined observed Raman spectra and the positions of the source materials of these bands to exclude the possibility of contaminations. Examined microdiamond grains are entirely enclosed in the host garnet, and no crack was observed in the host. We conducted 2D Raman mappings at different depths with 2 μm intervals. The result showed that the domains having these Raman bands were located within diamond grains and limited area (1-3 μm). These bands were never detected from outside diamond grains (e.g., host garnet). Thus, the unknown Raman bands at 1430-1480 cm-1 were attributed to some materials inside microdiamonds entirely included in the host garnet. The possibility of contamination was denied. Recently, we found similar Raman bands in the microdiamonds in garnet in Grt-Bt gneiss. Examined microdiamonds are entirely enclosed in garnet grain and no extra phase observed near laser spots in these microdiamond grains under an optical microscope. The Raman bands at 1430-1480 cm-1 were found from 4 microdiamond grains. The peak positions and FWHMs of these bands were as follows: (a) 1433, 31 (b) 1456, 35 (b) 1458, 41 (c) 1461, 31 (e) 1462 cm-1, 44 cm-1. Their intensities to the host diamond were 10-20 % in average. The mappings at different depths also showed very limited source space inside microdiamond grains. Although it is difficult to identify the source materials only by Raman spectroscopy, we considered that the Raman bands could be attributed to some carbon or carbon-bearing species which were relicts as metastable intermediate phases for microdiamond formation under UHP. Fullerenes are speculated as possible carbon materials for those bands. The band at 1470 cm-1 is similar to Ag (2) band of C60 fullerene. The large FWHM and the variation of peak positions at 1430-1480 cm-1 may be caused by aggregations of several species of fullerenes. If our speculation is correct, metamorphic diamond could have the possibility of preservation of intermediate carbon phases in diamond because the duration for diamond growth was much shorter than kimberlitic diamonds. We should pay attentions to such extra materials inside diamonds in order to clarify the real image of the diamond formation.

Is Absence of Evidence of UHPM Evidence of Absence: Did Conditions on Earth Before the Ediacaran Period Allow Formation of UHP Rocks but Only Rarely Their Exhumation?

NASA Astrophysics Data System (ADS)

Brown, M.

2008-12-01

UHPM provides petrologic evidence of transport of continental lithosphere to asthenospheric depth and return of some of these materials to crustal depth. The rock record registers UHPM since the Ediacaran Period, and studies of inclusion assemblages in zircon have increased the evidence of UHPM in Phanerozoic orogens and enabled an assessment of the real estate involved. Plots of apparent thermal gradient vs. age of metamorphism and P vs. age of metamorphism reveal two dramatic changes in inferred thermal environment and inferred depth of metamorphism from which continental lithosphere has been recovered during Earth evolution. First, from the Mesoarchean Era to the Neoproterozoic Era, sutures in subduction-to- collision orogens are marked by eclogite and high-pressure granulite metamorphism (characterized by apparent thermal gradients of 750-350 C/GPa). The P of metamorphism in sutures jumped from <1 GPa during the Eoarchean-Paleoarchean up to 2 GPa during the Paleoproterozoic. Second, from the Cryogenian- Ediacaran to the present, many sutures in subduction-to-collision orogens, and sometimes intracratonic sutures in the overriding plate, are marked by UHPM (characterized by apparent thermal gradients of <350 C/GPa) with P of metamorphism >2.7GPa. Given this pattern of secular change to colder apparent thermal gradients in sutures, the recent discovery of diamonds in zircons of crustal paragenesis in Neoarchean sedimentary rocks is surprising. Maybe UHPM has been possible since the Neoarchean but the evidence was rarely exhumed or if exhumed maybe the evidence was rarely preserved? The Appalachian/Caledonian-Variscide-Altaid and the Cimmerian-Himalayan-Alpine orogenic systems were formed by successive closure of short-lived oceans by transfer and suturing of ribbon-continent terranes derived from the Gondwanan side. Subduction of young ocean lithosphere followed by choking of the subduction channel by arc or terrane collision limited transport of water to the mantle wedge, and suppressed development of small-scale convection, arc magmatism and backarc formation. This allowed the retro- continental margin to remain strong, which favored efficient exhumation of UHPM rocks (Warren et al., 2008, EPSL). How should we interpret the presence of diamonds in detrital zircons (age range 3,050-4,260 Ma) from the Narryer terrane? Menneken et al. (2007, Nature) argue that the age range indicates repeated conditions for diamond formation (or recycling of ancient diamond) and that diamonds imply thick continental lithosphere and crust-mantle interactions since 4,260 Ma! This implies thermal environments and tectonics in the Hadean and Archean Eons similar to the Phanerozoic Eon. However, these ancient zircons originally crystallized from low-T melts (Watson and Harrison, 2006, Science) and the 'age' of the diamonds is only constrained to be > the age of deposition and <3,050 Ma. Williams (2007, Science) suggests that C was introduced as graphite precipitated from COH fluid in fractures/imperfections in zircon prior to deep burial to form diamond during a single event. COH fluid was involved in the formation of diamonds from Phanerozoic UHPM localities, so the hypothesis is viable if an appropriate tectonic model can be developed. I will present a model for the formation and exhumation of an overriding plate source terrane for the diamond-bearing detrital zircons that is consistent with periodic changes in the tectonic regime of Earth (Brown, 2006, Geology), and the geology and likely tectonic setting of the Narryer Terrane-Yilgarn Craton during the Neoarchean. Finally, I will speculate about UMPM during the Proterozoic and exhumation vs. relamination (Hacker et al., Eos, 2007).

Synthesis of Diamond Nanoplatelets/Carbon Nanowalls on Graphite Substrate by MPCVD

NASA Astrophysics Data System (ADS)

Zhang, Wei; Lyu, Jilei; Lin, Xiaoqi; Zhu, Jinfeng; Man, Weidong; Jiang, Nan

2015-07-01

The films composed of carbon nanowalls and diamond nanoplatelets, respectively, can be simultaneously formed on graphite substrate by controlling the hydrogen etching rate during microwave plasma chemical vapor deposition. To modulate the etching rate, two kinds of substrate design were used: a bare graphite plate and a graphite groove covered with a single crystal diamond sheet. After deposition at 1200°C for 3 hours, we find that dense diamond nanoplatelets were grown on the bare graphite, whereas carbon nanowalls were formed on the grooved surface, indicating that not only reaction temperature but also etching behavior is a key factor for nanostructure formation. supported by the Public Welfare Technology Application Projects of Zhejiang Province, China (No. 2013C33G3220012)

Tailoring nanocrystalline diamond coated on titanium for osteoblast adhesion.

PubMed

Pareta, Rajesh; Yang, Lei; Kothari, Abhishek; Sirinrath, Sirivisoot; Xiao, Xingcheng; Sheldon, Brian W; Webster, Thomas J

2010-10-01

Diamond coatings with superior chemical stability, antiwear, and cytocompatibility properties have been considered for lengthening the lifetime of metallic orthopedic implants for over a decade. In this study, an attempt to tailor the surface properties of diamond films on titanium to promote osteoblast (bone forming cell) adhesion was reported. The surface properties investigated here included the size of diamond surface features, topography, wettability, and surface chemistry, all of which were controlled during microwave plasma enhanced chemical-vapor-deposition (MPCVD) processes using CH4-Ar-H2 gas mixtures. The hardness and elastic modulus of the diamond films were also determined. H2 concentration in the plasma was altered to control the crystallinity, grain size, and topography of the diamond coatings, and specific plasma gases (O2 and NH3) were introduced to change the surface chemistry of the diamond coatings. To understand the impact of the altered surface properties on osteoblast responses, cell adhesion tests were performed on the various diamond-coated titanium. The results revealed that nanocrystalline diamond (grain sizes <100 nm) coated titanium dramatically increased surface hardness, and the introduction of O2 and NH3 during the MPCVD process promoted osteoblast adhesion on diamond and, thus, should be further studied for improving orthopedic applications. Copyright 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.

CVD diamond substrate for microelectronics. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burden, J.; Gat, R.

1996-11-01

Chemical Vapor Deposition (CVD) of diamond films has evolved dramatically in recent years, and commercial opportunities for diamond substrates in thermal management applications are promising. The objective of this technology transfer initiative (TTI) is for Applied Science and Technology, Inc. (ASTEX) and AlliedSignal Federal Manufacturing and Technologies (FM&T) to jointly develop and document the manufacturing processes and procedures required for the fabrication of multichip module circuits using CVD diamond substrates, with the major emphasis of the project concentrating on lapping/polishing prior to metallization. ASTEX would provide diamond films for the study, and FM&T would use its experience in lapping, polishing,more » and substrate metallization to perform secondary processing on the parts. The primary goal of the project was to establish manufacturing processes that lower the manufacturing cost sufficiently to enable broad commercialization of the technology.« less

In-Situ Chemical Analyses of Mineral Inclusions in Diamonds in Kimberlitic Eclogites From Yakutia

NASA Astrophysics Data System (ADS)

ANAND, M.; MISRA, K. C.; TAYLOR, L. A.; SOBOLEV, N. V.

2001-12-01

Mineral inclusions in diamonds (DIs) are stated to provide P-T-X-t information regarding the formation of the diamonds and the nature of the upper mantle. In an endeavor to further understand the importance of diamonds and their DIs in relation to their host rocks, we have investigated several diamondiferous eclogites from Yakutia, first by HRXC tomography (Taylor et al., 2001, this meeting) and then by dissection of the eclogites into their individual minerals. The mineralogy of the host eclogite is presented by Misra et al. (2001, this meeting). Two of the diamondiferous eclogite xenoliths, although weighing but 66 g and 42 g, contain 74 and 47 macro-diamonds, resp. Based on HRXCT imaging, appropriate sections were selected in the eclogite to extract diamonds with minimum loss of material. In the majority of cases, diamonds occur as perfect octahedron with well developed crystal faces. In some cases, however, diamonds occur as macles (twinned xls). The size range of the diamonds is 1-6 mm. Optical examination reveals the sulfides as the most common DIs in these diamonds, followed by clinopyroxenes and garnets. Each diamond was cut and polished along relatively soft directions parallel to either (001) or (110) faces so as to expose DIs for in-situ analyses. Examination by cathodoluminescence (CL) on an EMP demonstrated that the majority of the diamonds have minute, optically invisible, cracks from the DIs to the surfaces of the diamonds - i.e., the possibility of an open system. These diamonds show complicated growth histories and contain DIs that are in some cases, found to be associated with secondary alteration. In addition, the DIs in each diamond, examined in-situ are of different composition from the host and different from DIs in other diamonds, a relationship reported earlier (Taylor et al., 2000, Int'l Geol Rev). These observations raise serious doubts about the significance of DIs and the pristinity and syngenesis of DIs removed by the typical diamond~crushing procedure. Therefore, extreme caution must be taken when interpreting any of the P-T-X-t conditions of diamond growth, based on DIs.

Study of the triton-burnup process in different JET scenarios using neutron monitor based on CVD diamond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nemtsev, G., E-mail: g.nemtsev@iterrf.ru; Amosov, V.; Meshchaninov, S.

We present the results of analysis of triton burn-up process using the data from diamond detector. Neutron monitor based on CVD diamond was installed in JET torus hall close to the plasma center. We measure the part of 14 MeV neutrons in scenarios where plasma current varies in a range of 1-3 MA. In this experiment diamond neutron monitor was also able to detect strong gamma bursts produced by runaway electrons arising during the disruptions. We can conclude that CVD diamond detector will contribute to the study of fast particles confinement and help predict the disruption events in future tokamaks.

A large planetary body inferred from diamond inclusions in a ureilite meteorite.

PubMed

Nabiei, Farhang; Badro, James; Dennenwaldt, Teresa; Oveisi, Emad; Cantoni, Marco; Hébert, Cécile; El Goresy, Ahmed; Barrat, Jean-Alix; Gillet, Philippe

2018-04-17

Planetary formation models show that terrestrial planets are formed by the accretion of tens of Moon- to Mars-sized planetary embryos through energetic giant impacts. However, relics of these large proto-planets are yet to be found. Ureilites are one of the main families of achondritic meteorites and their parent body is believed to have been catastrophically disrupted by an impact during the first 10 million years of the solar system. Here we studied a section of the Almahata Sitta ureilite using transmission electron microscopy, where large diamonds were formed at high pressure inside the parent body. We discovered chromite, phosphate, and (Fe,Ni)-sulfide inclusions embedded in diamond. The composition and morphology of the inclusions can only be explained if the formation pressure was higher than 20 GPa. Such pressures suggest that the ureilite parent body was a Mercury- to Mars-sized planetary embryo.

Nitrogen termination of single crystal (100) diamond surface by radio frequency N{sub 2} plasma process: An in-situ x-ray photoemission spectroscopy and secondary electron emission studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chandran, Maneesh, E-mail: maneesh@tx.technion.ac.il, E-mail: choffman@tx.technion.ac.il; Shasha, Michal; Michaelson, Shaul

2015-09-14

In this letter, we report the electronic and chemical properties of nitrogen terminated (N-terminated) single crystal (100) diamond surface, which is a promising candidate for shallow NV{sup −} centers. N-termination is realized by an indirect RF nitrogen plasma process without inducing a large density of surface defects. Thermal stability and electronic property of N-terminated diamond surface are systematically investigated under well-controlled conditions by in-situ x-ray photoelectron spectroscopy and secondary electron emission. An increase in the low energy cut-off of the secondary electron energy distribution curve (EDC), with respect to a bare diamond surface, indicates a positive electron affinity of themore » N-terminated diamond. Exposure to atomic hydrogen results in reorganization of N-terminated diamond to H-terminated diamond, which exhibited a negative electron affinity surface. The change in intensity and spectral features of the secondary electron EDC of the N-terminated diamond is discussed.« less

The use of CVD diamond burs for ultraconservative cavity preparations: a report of two cases.

PubMed

Carvalho, Carlos Augusto R; Fagundes, Ticiane C; Barata, Terezinha J E; Trava-Airoldi, Vladimir Jesus; Navarro, Maria Fidela L

2007-01-01

During the past decades, scientific developments in cutting instruments have changed the conventional techniques used to remove caries lesions. Ultrasound emerged as an alternative for caries removal since the 1950s. However, the conventional technology for diamond powder aggregation with nickel metallic binders could not withstand ultrasonic power. Around 5 years ago, an alternative approach using chemical vapor deposition (CVD) resulted in synthetic diamond technology. CVD diamond burs are obtained with high adherence of the diamond as a unique stone on the metallic surface with excellent abrading performance. This technology allows for diamond deposition with coalescent granulation in different formats of substrates. When connected to an ultrasonic handpiece, CVD diamond burs become an option for cavity preparation, maximizing preservation of tooth structure. Potential advantages such as reduced noise, minimal damage to the gingival tissue, extended bur durability, improved proximal cavity access, reduced risk of hitting the adjacent tooth resulting from the high inclination angles, and minimal patient's risk of metal contamination. These innovative instruments also potentially eliminate some problems regarding decreased cutting efficiency of conventional diamond burs. This clinical report presents the benefits of using CVD diamond burs coupled with an ultrasonic handpiece in the treatment of incipient caries. CVD diamond burs coupled with an ultrasonic device offer a promising alternative for removal of carious lesions when ultraconservative cavity preparations are required. Additionally, this system provides a less-painful technique for caries removal, with minimal noise.

ZnS/diamond composite coatings for infrared transmission applications formed by the aerosol deposition method

NASA Astrophysics Data System (ADS)

Johnson, Scooter D.; Kub, Fritz J.; Eddy, Charles R.

2013-06-01

The deposition of nano-crystalline ZnS/diamond composite protective coatings on silicon, sapphire, and ZnS substrates, as a preliminary step to coating infrared transparent ZnS substrates from powder mixtures by the aerosol deposition method is presented. Advantages of the aerosol deposition method include the ability to form dense, nanocrystalline lms up to hundreds of microns thick at room temperature and at a high deposition rate on a variety of substrates. Deposition is achieved by creating a pressure gradient that accelerates micrometer- scale particles in an aerosol to high velocity. Upon impact with the target substrate the particles fracture and embed. Continued deposition forms the thick compacted lm. Deposition from an aerosolized mixture of ZnS and diamond powders onto all targets results in linear trend from apparent sputter erosion of the substrate at 100% diamond to formation of a lm with increasing fractions of ZnS. The crossover from abrasion to lm formation on sapphire occurs above about 50% ZnS and a mixture of 90% ZnS and 10% diamond forms a well-adhered lm of about 0.7 μm thickness at a rate of 0.14 μm/min. Resulting lms are characterized by scanning electron microscopy, pro lometry, infrared transmission spectroscopy, and x-ray photoemission spectroscopy. These initial lms mark progress toward the future goal of coating ZnS substrates for abrasion resistance.

Graphite to ultrafine nanocrystalline diamond phase transition model and growth restriction mechanism induced by nanosecond laser processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, X. D., E-mail: renxd@mail.ujs.edu.cn; Liu, R.; Zheng, L. M.

2015-10-05

To have a clear insight into nanocrystal growth from graphite to diamond upon high energy pulsed laser irradiation of graphite suspension, synthesis of ultrafine nanocrystalline diamonds with laser energy set up from 0.3 J to 12 J, repetition rate of 10 Hz has been studied. The method allows synthesizing ultrafine nanocrystalline particles continuously at the ambient temperature and normal pressure. The particle size is shown independent of laser energy, which is ultrafine and ranges in 2–6 nm. The theoretical grown size of nano-diamonds is found in well agreement with the experiment results. Four kinds of production were found: nano-diamond, spherical carbon nano-particles, flocculent amorphousmore » carbon, and graphene nano-ribbon rolls. A solid-vapor-plasma-liquid coexistence model describing phase transition from graphite to diamond induced by nanosecond laser processing was proposed. Graphene nano-ribbon rolls might be the intermediate phase in the conversion from graphite to diamond.« less

Thermal conductance of metal–diamond interfaces at high pressure

DOE PAGES

Hohensee, Gregory T.; Wilson, R. B.; Cahill, David G.

2015-03-06

The thermal conductance of interfaces between metals and diamond, which has a comparatively high Debye temperature, is often greater than can be accounted for by two phonon-processes. The high pressures achievable in a diamond anvil cell can significantly extend the metal phonon density of states to higher frequencies, and can also suppress extrinsic effects by greatly stiffening interface bonding. Here we report time-domain thermoreflectance measurements of metal-diamond interface thermal conductance up to 50 GPa in the DAC for Pb, Au 0.95Pd 0.05, Pt, and Al films deposited on Type 1A natural [100] and Type 2A synthetic [110] diamond anvils. Inmore » all cases, the thermal conductances increase weakly or saturate to similar values at high pressure. Lastly, our results suggest that anharmonic conductance at metal-diamond interfaces is controlled by partial transmission processes, where a diamond phonon that inelastically scatters at the interface absorbs or emits a metal phonon.« less

Fluidized bed deposition of diamond

DOEpatents

Laia, Jr., Joseph R.; Carroll, David W.; Trkula, Mitchell; Anderson, Wallace E.; Valone, Steven M.

1998-01-01

A process for coating a substrate with diamond or diamond-like material including maintaining a substrate within a bed of particles capable of being fluidized, the particles having substantially uniform dimensions and the substrate characterized as having different dimensions than the bed particles, fluidizing the bed of particles, and depositing a coating of diamond or diamond-like material upon the substrate by chemical vapor deposition of a carbon-containing precursor gas mixture, the precursor gas mixture introduced into the fluidized bed under conditions resulting in excitation mechanisms sufficient to form the diamond coating.

Chalcophile and siderophile elements in sulphide inclusions in eclogitic diamonds and metal cycling in a Paleoproterozoic subduction zone

NASA Astrophysics Data System (ADS)

Aulbach, Sonja; Stachel, Thomas; Seitz, Hans-Michael; Brey, Gerhard P.

2012-09-01

In the central Slave craton, eclogitic diamonds are suggested to have formed during Paleoproterozoic subduction in a meta-gabbroic substrate representing former lower oceanic crust that interacted with serpentinite-derived fluids at high fluid-rock ratios. In order to assess the behaviour of chalcophile and siderophile elements (CSE) during this process, we measured trace-element concentrations of sulphide inclusions in diamonds from the Diavik mine by laser ablation ICPMS. The nitrogen systematics of the diamonds (average N concentration of ˜600 ppm and aggregation state 4% N as B-aggregates) indicate average mantle residence temperatures of ˜1050 °C for a 1.85 Ga formation age, corresponding ˜170 km depth. Based on the available evidence from natural samples and experiments, we suggest that the highly siderophile elements (HSE: Os, Ir, Ru, Rh, Pd, Pt, Re) except Au behaved largely conservatively during fluid-induced metamorphism, which may point to a reducing and Cl-poor nature of the fluid. The abundances of the moderately siderophile and chalcophile elements Cr, Co, Ni, Cu, Ag, Sn, Mo and W may also have changed little, whereas As, Sb, Tl, Pb and Bi may have been mobilised from the subducting lower oceanic crust. The partitioning of CSE in eclogite and geochemical behaviour during oceanic crust formation was assessed for inferred conservative elements. Assuming an average sulphide mode of 0.3 wt.% for the oceanic crust, its abundances of HSE, Cu, Mo, Se and Te can mostly be accounted for by sulphide minerals alone. Lithophile behaviour of W, Cd, In and Sn and enrichment in residual melts may explain their lower abundances in the gabbroic eclogitic sulphide inclusions compared to MORB sulphide. These elements, as well as Cr, Co, Ni, Zn and Ga require additional host phases both in eclogite, where rutile partitions significant amounts of Cr, Zn, W, Ga and Sn, and in the oceanic crust.

Engineered arrays of nitrogen-vacancy color centers in diamond based on implantation of CN- molecules through nanoapertures

NASA Astrophysics Data System (ADS)

Spinicelli, P.; Dréau, A.; Rondin, L.; Silva, F.; Achard, J.; Xavier, S.; Bansropun, S.; Debuisschert, T.; Pezzagna, S.; Meijer, J.; Jacques, V.; Roch, J.-F.

2011-02-01

We report a versatile method for engineering arrays of nitrogen-vacancy (NV) color centers in diamond at the nanoscale. The defects were produced in parallel by ion implantation through 80 nm diameter apertures patterned using electron beam lithography in a polymethyl methacrylate (PMMA) layer deposited on a diamond surface. The implantation was performed with CN- molecules that increased the NV defect-formation yield. This method could enable the realization of a solid-state coupled-spin array and could be used for positioning an optically active NV center on a photonic microstructure.

Bactericidal activity of biomimetic diamond nanocone surfaces.

PubMed

Fisher, Leanne E; Yang, Yang; Yuen, Muk-Fung; Zhang, Wenjun; Nobbs, Angela H; Su, Bo

2016-03-17

The formation of biofilms on implant surfaces and the subsequent development of medical device-associated infections are difficult to resolve and can cause considerable morbidity to the patient. Over the past decade, there has been growing recognition that physical cues, such as surface topography, can regulate biological responses and possess bactericidal activity. In this study, diamond nanocone-patterned surfaces, representing biomimetic analogs of the naturally bactericidal cicada fly wing, were fabricated using microwave plasma chemical vapor deposition, followed by bias-assisted reactive ion etching. Two structurally distinct nanocone surfaces were produced, characterized, and the bactericidal ability examined. The sharp diamond nanocone features were found to have bactericidal capabilities with the surface possessing the more varying cone dimension, nonuniform array, and decreased density, showing enhanced bactericidal ability over the more uniform, highly dense nanocone surface. Future research will focus on using the fabrication process to tailor surface nanotopographies on clinically relevant materials that promote both effective killing of a broader range of microorganisms and the desired mammalian cell response. This study serves to introduce a technology that may launch a new and innovative direction in the design of biomaterials with capacity to reduce the risk of medical device-associated infections.

Toward deep blue nano hope diamonds: heavily boron-doped diamond nanoparticles.

PubMed

Heyer, Steffen; Janssen, Wiebke; Turner, Stuart; Lu, Ying-Gang; Yeap, Weng Siang; Verbeeck, Jo; Haenen, Ken; Krueger, Anke

2014-06-24

The production of boron-doped diamond nanoparticles enables the application of this material for a broad range of fields, such as electrochemistry, thermal management, and fundamental superconductivity research. Here we present the production of highly boron-doped diamond nanoparticles using boron-doped CVD diamond films as a starting material. In a multistep milling process followed by purification and surface oxidation we obtained diamond nanoparticles of 10-60 nm with a boron content of approximately 2.3 × 10(21) cm(-3). Aberration-corrected HRTEM reveals the presence of defects within individual diamond grains, as well as a very thin nondiamond carbon layer at the particle surface. The boron K-edge electron energy-loss near-edge fine structure demonstrates that the B atoms are tetrahedrally embedded into the diamond lattice. The boron-doped diamond nanoparticles have been used to nucleate growth of a boron-doped diamond film by CVD that does not contain an insulating seeding layer.

All-Diamond Microelectrodes as Solid State Probes for Localized Electrochemical Sensing.

PubMed

Silva, Eduardo L; Gouvêa, Cristol P; Quevedo, Marcela C; Neto, Miguel A; Archanjo, Braulio S; Fernandes, António J S; Achete, Carlos A; Silva, Rui F; Zheludkevich, Mikhail L; Oliveira, Filipe J

2015-07-07

The fabrication of an all-diamond microprobe is demonstrated for the first time. This ME (microelectrode) assembly consists of an inner boron doped diamond (BDD) layer and an outer undoped diamond layer. Both layers were grown on a sharp tungsten tip by chemical vapor deposition (CVD) in a stepwise manner within a single deposition run. BDD is a material with proven potential as an electrochemical sensor. Undoped CVD diamond is an insulating material with superior chemical stability in comparison to conventional insulators. Focused ion beam (FIB) cutting of the apex of the ME was used to expose an electroactive BDD disk. By cyclic voltammetry, the redox reaction of ferrocenemethanol was shown to take place at the BDD microdisk surface. In order to ensure that the outer layer was nonelectrically conductive, a diffusion barrier for boron atoms was established seeking the formation of boron-hydrogen complexes at the interface between the doped and the undoped diamond layers. The applicability of the microelectrodes in localized corrosion was demonstrated by scanning amperometric measurements of oxygen distribution above an Al-Cu-CFRP (Carbon Fiber Reinforced Polymer) galvanic corrosion cell.

Ultimate Atomic Bling: Nanotechnology of Diamonds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahl, Jeremy

2010-05-25

Diamonds exist in all sizes, from the Hope Diamond to minuscule crystals only a few atoms across. The smallest of these diamonds are created naturally by the same processes that make petroleum. Recently, researchers discovered that these 'diamondoids' are formed in many different structural shapes, and that these shapes can be used like LEGO blocks for nanotechnology. This talk will discuss the discovery of these nano-size diamonds and highlight current SLAC/Stanford research into their applications in electronics and medicine.

A theoretical and experimental study on the pulsed laser dressing of bronze-bonded diamond grinding wheels

NASA Astrophysics Data System (ADS)

Deng, H.; Chen, G. Y.; Zhou, C.; Zhou, X. C.; He, J.; Zhang, Y.

2014-09-01

A series of theoretical analyses and experimental investigations were performed to examine a pulsed fiber-laser tangential profiling and radial sharpening technique for bronze-bonded diamond grinding wheels. The mechanisms for the pulsed laser tangential profiling and radial sharpening of grinding wheels were theoretically analyzed, and the four key processing parameters that determine the quality, accuracy, and efficiency of pulsed laser dressing, namely, the laser power density, laser spot overlap ratio, laser scanning track line overlap ratio, and number of laser scanning cycles, were proposed. Further, by utilizing cylindrical bronze wheels (without diamond grains) and bronze-bonded diamond grinding wheels as the experimental subjects, the effects of these four processing parameters on the removal efficiency and the surface smoothness of the bond material after pulsed laser ablation, as well as the effects on the contour accuracy of the grinding wheels, the protrusion height of the diamond grains, the sharpness of the grain cutting edges, and the graphitization degree of the diamond grains after pulsed laser dressing, were explored. The optimal values of the four key processing parameters were identified.

Monocrystalline CVD-diamond optics for high-power laser applications

NASA Astrophysics Data System (ADS)

Holly, C.; Traub, M.; Hoffmann, D.; Widmann, C.; Brink, D.; Nebel, C.; Gotthardt, T.; Sözbir, M. C.; Wenzel, C.

2016-03-01

The potential of diamond as an optical material for high-power laser applications in the wavelength regime from the visible spectrum (VIS) to the near infrared (NIR) is investigated. Single-crystal diamonds with lateral dimensions up to 7×7mm2 are grown with microwave plasma assisted chemical vapor deposition (MPACVD) in parallel with up to 60 substrates and are further processed to spherical optics for beam guidance and shaping. The synthetic diamonds offer superior thermal, mechanical and optical properties, including low birefringence, scattering and absorption, also around 1 μm wavelength. We present dielectric (AR and HR) coated single-crystal diamond optics which are tested under high laser power in the multi-kW regime. The thermally induced focal shift of the diamond substrates is compared to the focal shift of a standard collimating and focusing unit for laser cutting made of fused silica optics. Due to the high thermal conductivity and low absorption of the diamond substrates compared to the fused silica optics no additional focal shift caused by a thermally induced refractive index change in the diamond is observed in our experiments. We present experimental results regarding the performance of the diamond substrates with and without dielectric coatings under high power and the influences of growth induced birefringence on the optical quality. Finally, we discuss the potential of the presented diamond lenses for high-power applications in the field of laser materials processing.

Synthesis and characterization of a nanocrystalline diamond aerogel

PubMed Central

Pauzauskie, Peter J.; Crowhurst, Jonathan C.; Worsley, Marcus A.; Laurence, Ted A.; Kilcoyne, A. L. David; Wang, Yinmin; Willey, Trevor M.; Visbeck, Kenneth S.; Fakra, Sirine C.; Evans, William J.; Zaug, Joseph M.; Satcher, Joe H.

2011-01-01

Aerogel materials have myriad scientific and technological applications due to their large intrinsic surface areas and ultralow densities. However, creating a nanodiamond aerogel matrix has remained an outstanding and intriguing challenge. Here we report the high-pressure, high-temperature synthesis of a diamond aerogel from an amorphous carbon aerogel precursor using a laser-heated diamond anvil cell. Neon is used as a chemically inert, near-hydrostatic pressure medium that prevents collapse of the aerogel under pressure by conformally filling the aerogel’s void volume. Electron and X-ray spectromicroscopy confirm the aerogel morphology and composition of the nanodiamond matrix. Time-resolved photoluminescence measurements of recovered material reveal the formation of both nitrogen- and silicon- vacancy point-defects, suggesting a broad range of applications for this nanocrystalline diamond aerogel. PMID:21555550

Synthesis and characterization of a nanocrystalline diamond aerogel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pauzauskie, Peter J.; Crowhurst, Jonathan C.; Worsley, Marcus A.

2011-07-06

Aerogel materials have myriad scientific and technological applications due to their large intrinsic surface areas and ultralow densities. However, creating a nanodiamond aerogel matrix has remained an outstanding and intriguing challenge. Here we report the high-pressure, high-temperature synthesis of a diamond aerogel from an amorphous carbon aerogel precursor using a laser-heated diamond anvil cell. Neon is used as a chemically inert, near-hydrostatic pressure medium that prevents collapse of the aerogel under pressure by conformally filling the aerogel's void volume. Electron and X-ray spectromicroscopy confirm the aerogel morphology and composition of the nanodiamond matrix. Time-resolved photoluminescence measurements of recovered material revealmore » the formation of both nitrogen- and silicon- vacancy point-defects, suggesting a broad range of applications for this nanocrystalline diamond aerogel.« less

Electron emission from diamond films seeded using kitchen-wrap polyethylene

NASA Astrophysics Data System (ADS)

Varshney, D.; Makarov, V. I.; Saxena, P.; Guinel, M. J. F.; Kumar, A.; Scott, J. F.; Weiner, B. R.; Morell, G.

2011-03-01

Diamond has many potential electronic applications, but the diamond seeding methods are generally harsh on the substrates rendering them unsuitable for integration in electronics. We report a non-abrasive, scalable and economic process of diamond film seeding using kitchen-wrap polyethylene employing hot filament chemical vapour reaction of H2S/CH4/H2 gas mixtures on Cu substrates. The fabricated diamond films were characterized with scanning electron microscopy, transmission electron microscopy and Raman spectroscopy, which confirm that the deposited film consists of a microcrystalline diamond of size in the range 0.5-1.0 µm. The synthesized diamond films exhibit a turn-on field of about 8.5 V µm-1 and long-term stability. Diamond film synthesis using polyethylene will enable the integration of diamond heat sinks into high-power and high-temperature electronic devices.

Surface Roughness of Various Diamond-Like Carbon Films

NASA Astrophysics Data System (ADS)

Liu, Dongping; Liu, Yanhong; Chen, Baoxiang

2006-11-01

Atomic force microscopy is used to estimate and compare the surface morphology of hydrogenated and hydrogen-free diamond-like carbon (DLC) films. The films were prepared by using DC magnetron sputtering of a graphite target, pulsed cathodic carbon arcs, electron cyclotron resonance (ECR), plasma source ion implantation and dielectric barrier discharge (DBD). The difference in the surface structure is presented for each method of deposition. The influences of various discharge parameters on the film surface properties are discussed based upon the experimental results. The coalescence process via the diffusion of adsorbed carbon species is responsible for the formation of hydrogen-free DLC films with rough surfaces. The films with surface roughness at an atomic level can be deposited by energetic ion impacts in a highly ionized carbon plasma. The dangling bonds created by atomic hydrogen lead to the uniform growth of hydrocarbon species at the a-C:H film surfaces of the ECR or DBD plasmas.

Electron beam pumped semiconductor laser

NASA Technical Reports Server (NTRS)

Hug, William F. (Inventor); Reid, Ray D. (Inventor)

2009-01-01

Electron-beam-pumped semiconductor ultra-violet optical sources (ESUVOSs) are disclosed that use ballistic electron pumped wide bandgap semiconductor materials. The sources may produce incoherent radiation and take the form of electron-beam-pumped light emitting triodes (ELETs). The sources may produce coherent radiation and take the form of electron-beam-pumped laser triodes (ELTs). The ELTs may take the form of electron-beam-pumped vertical cavity surface emitting lasers (EVCSEL) or edge emitting electron-beam-pumped lasers (EEELs). The semiconductor medium may take the form of an aluminum gallium nitride alloy that has a mole fraction of aluminum selected to give a desired emission wavelength, diamond, or diamond-like carbon (DLC). The sources may be produced from discrete components that are assembled after their individual formation or they may be produced using batch MEMS-type or semiconductor-type processing techniques to build them up in a whole or partial monolithic manner, or combination thereof.

Boron doped diamond synthesized from detonation nanodiamond in a C-O-H fluid at high pressure and high temperature

NASA Astrophysics Data System (ADS)

Shakhov, Fedor M.; Abyzov, Andrey M.; Takai, Kazuyuki

2017-12-01

Boron doped diamond (BDD) was synthesized under high pressure and high temperature (HPHT) of 7 GPa, 1230 °C in a short time of 10 s from a powder mixtures of detonation nanodiamond (DND), pentaerythritol C5H8(OH)4 and amorphous boron. SEM, TEM, XRD, XPS, FTIR and Raman spectroscopy indicated that BDD nano- and micro-crystals have formed by consolidation of DND particles (4 nm in size). XRD showed the enlargement of crystallites size to 6-80 nm and the increase in diamond lattice parameter by 0.02-0.07% without appearance of any microstrains. Raman spectroscopy was used to estimate the content of boron atoms embedded in the diamond lattice. It was found that the Raman diamond peak shifts significantly from 1332 cm-1 to 1290 cm-1 without appearance of any non-diamond carbon. The correlation between Raman peak position, its width, and boron content in diamond is proposed. Hydrogenated diamond carbon in significant amount was detected by IR spectroscopy and XPS. Due to the doping with boron content of about 0.1 at%, the electrical conductivity of the diamond achieved approximately 0.2 Ω-1 cm-1. Reaction mechanism of diamond growth (models of recrystallization and oriented attachment) is discussed, including the initial stages of pentaerythritol pyrolysis and thermal desorption of functional groups from the surface of DND particles with the generation of supercritical fluid of low-molecular substances (H2O, CH4, CO, CO2, etc.), as well as byproducts formation (B2O3, B4C).

The stability of a crystal with diamond structure for patchy particles with tetrahedral symmetry.

PubMed

Noya, Eva G; Vega, Carlos; Doye, Jonathan P K; Louis, Ard A

2010-06-21

The phase diagram of model anisotropic particles with four attractive patches in a tetrahedral arrangement has been computed at two different values of the range of the potential, with the aim of investigating the conditions under which a diamond crystal can be formed. We find that the diamond phase is never stable for our longer-ranged potential. At low temperatures and pressures, the fluid freezes into a body-centered-cubic solid that can be viewed as two interpenetrating diamond lattices with a weak interaction between the two sublattices. Upon compression, an orientationally ordered face-centered-cubic crystal becomes more stable than the body-centered-cubic crystal, and at higher temperatures, a plastic face-centered-cubic phase is stabilized by the increased entropy due to orientational disorder. A similar phase diagram is found for the shorter-ranged potential, but at low temperatures and pressures, we also find a region over which the diamond phase is thermodynamically favored over the body-centered-cubic phase. The higher vibrational entropy of the diamond structure with respect to the body-centered-cubic solid explains why it is stable even though the enthalpy of the latter phase is lower. Some preliminary studies on the growth of the diamond structure starting from a crystal seed were performed. Even though the diamond phase is never thermodynamically stable for the longer-ranged model, direct coexistence simulations of the interface between the fluid and the body-centered-cubic crystal and between the fluid and the diamond crystal show that at sufficiently low pressures, it is quite probable that in both cases the solid grows into a diamond crystal, albeit involving some defects. These results highlight the importance of kinetic effects in the formation of diamond crystals in systems of patchy particles.

Substantiation of Epitaxial Growth of Diamond Crystals on the Surface of Carbide Fe3AlC0.66 Phase Nanoparticles.

PubMed

Dzevin, Ievgenij M; Mekhed, Alexander A

2017-12-01

Samples of Fe-Al-C alloys of varying composition were synthesized under high pressures and temperatures. From X-ray analysis data, only K-phase with usual for it average parameter of elemental lattice cell, a = 0.376 nm, carbide Fe 3 C and cubic diamond reflexes were present before and after cooling to the temperature of liquid nitrogen.Calculations were made of the parameters of unit cells, the enthalpy of formation of the Fe 3 AlC, Fe 3.125 Al 0.825 C 0.5 , Fe 3.5 Al 0.5 C 0.5 , Fe 3.5 Al 0.5 C, Fe 3 Al 0.66 C 0.66 , and Fe 3 AlC 0.66 unit cells and crystallographic planes were identified on which epitaxial growth of the diamond phase was possible, using density functional theory as implemented in the WIEN2k package.The possibility of epitaxial growth of diamond crystals on Fe 3 AlC 0.66 (K-phase) nanoparticles was, therefore, demonstrated. The [200] plane was established to be the most suitable plane for diamond growth, having four carbon atoms arranged in a square and a central vacancy which can be occupied by carbon during thermal-and-pressure treatment. Distances between carbon atoms in the [200] plane differ by only 5% from distances between the carbon atoms of a diamond. The electronic structure and energetic parameters of the substrate were also investigated. It was shown that the substrate with at least four intermediate layers of K-phase exhibits signs of stability such as negative enthalpy of formation and the Fermi level falling to minimum densities of states.

Lu-Hf, in-situ Sr and Pb isotope and trace element systematics for mantle eclogites from the Diavik diamond mine: Evidence for Paleoproterozoic subduction beneath the Slave craton, Canada

NASA Astrophysics Data System (ADS)

Schmidberger, Stefanie S.; Simonetti, Antonio; Heaman, Larry M.; Creaser, Robert A.; Whiteford, Sean

2007-02-01

Lu-Hf, Sm-Nd and in-situ clinopyroxene Sr and Pb isotope systematics, and mineral major and in-situ trace element compositions were obtained for a suite of non-diamond and diamond-bearing eclogites from the Diavik kimberlites (A154; 55 Ma old), Slave craton (Canada). Temperature estimates of last equilibration in the lithosphere for the non-diamond-bearing Diavik eclogites define two groups; low-temperature (800-1050 °C) and high-temperature eclogites (1100-1300 °C). Most diamond-eclogites indicate temperatures similar to those of the high-temperature eclogites. Isotopic and major and trace element systematics for the non-diamond- and diamond-bearing eclogites indicate overlapping chemical compositions suggesting similar rock formational histories. Calculated whole rock major and trace element abundances using chemical and modal abundances for constituent minerals exhibit broad similarities with mafic cumulates from ophiolite sequences. Most importantly the calculated whole rock eclogite compositions display positive Sr and Eu anomalies, typically interpreted as the result of plagioclase accumulation in cumulate rocks of oceanic crust sequences. Initial whole rock Hf isotopic values and in-situ Sr isotope data from clinopyroxene grains provide evidence that the eclogites were derived from precursor rocks with depleted mantle isotope characteristics. These combined results support the interpretation that the eclogites from Diavik represent remnants of subducted oceanic crust. Lu-Hf isotope systematics indicate that the oceanic protolith for the eclogites formed in the Paleoproterozoic at ˜ 2.1 Ga, which is in agreement with the in-situ Pb isotope data from clinopyroxene. This result also corroborates the ˜ 2.1 Ga Lu-Hf model ages recorded by mantle zircons from eclogite found within the Jericho kimberlite in the northern Slave Province (˜ 200 km northwest of Diavik). The results from both studies indicate a link between eclogite formation and Paleoproterozoic subduction of oceanic lithosphere along the present-day western margin of the Archean Slave craton.

Ultratough CVD single crystal diamond and three dimensional growth thereof

DOEpatents

Hemley, Russell J [Washington, DC; Mao, Ho-kwang [Washington, DC; Yan, Chih-shiue [Washington, DC

2009-09-29

The invention relates to a single-crystal diamond grown by microwave plasma chemical vapor deposition that has a toughness of at least about 30 MPa m.sup.1/2. The invention also relates to a method of producing a single-crystal diamond with a toughness of at least about 30 MPa m.sup.1/2. The invention further relates to a process for producing a single crystal CVD diamond in three dimensions on a single crystal diamond substrate.

Electrochemical oxidation of tramadol in low-salinity reverse osmosis concentrates using boron-doped diamond anodes.

PubMed

Lütke Eversloh, Christian; Schulz, Manoj; Wagner, Manfred; Ternes, Thomas A

2015-04-01

The electrochemical treatment of low-salinity reverse osmosis (RO) concentrates was investigated using tramadol (100 μM) as a model substance for persistent organic contaminants. Galvanostatic degradation experiments using boron-doped diamond electrodes at different applied currents were conducted in RO concentrates as well as in ultra-pure water containing either sodium chloride or sodium sulfate. Kinetic investigations revealed a significant influence of in-situ generated active chlorine besides direct anodic oxidation. Therefore, tramadol concentrations decreased more rapidly at elevated chloride content. Nevertheless, reduction of total organic carbon (TOC) was found to be comparatively low, demonstrating that transformation rather than mineralization was taking place. Early stage product formation could be attributed to both direct and indirect processes, including demethylation, hydroxylation, dehydration, oxidative aromatic ring cleavage and halogenation reactions. The latter led to various halogenated derivatives and resulted in AOX (adsorbable organic halogens) formation in the lower mg/L-range depending on the treatment conditions. Characterisation of transformation products (TPs) was achieved via MS(n) experiments and additional NMR measurements. Based on identification and quantification of the main TPs in different matrices and on additional potentiostatic electrolysis, a transformation pathway was proposed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Trace elements in Gem-Quality Diamonds - Origin and evolution of diamond-forming fluid inclusions

NASA Astrophysics Data System (ADS)

Pearson, Graham; Krebs, Mandy; Stachel, Thomas; Woodland, Sarah; Chinn, Ingrid; Kong, Julie

2017-04-01

In the same way that melt inclusions in phenocrysts have expanded our idea of melt formation and evolution in basalts, studying fluids trapped in diamonds is providing important new constraints on the nature of diamond-forming fluids. Fibrous and cloudy diamonds trap a high but variable density of fluid inclusions and so have been extensively studied using major and trace element compositions. In contrast, constraining the nature of the diamond-forming fluid for high purity gem-quality diamonds has been restricted by the rarity of available high quality trace element data. This is due to the extremely low concentrations of impurities that gem diamonds contain - often in the ppt range. The recent discovery of fluids in gem diamonds showing similar major element chemistry to fluid-rich diamonds suggest that many diamonds may share a common spectrum of parental fluids. Here we test this idea further. Recent advances in analytical techniques, in particular the development of the "off-line" laser ablation pre-concentration approach, have allowed fully quantitative trace element data to be recovered from "fluid-poor", high quality gem diamonds. We present trace element data for gem diamonds from a variety of locations from Canada, S. Africa and Russia, containing either silicate or sulphide inclusions to examine possible paragenetic or genetic differences between fluids. REE abundance in the "gem" diamonds vary from 0.1 to 0.0001 x chondrite. To a first order, we observe the same spectrum of trace element compositions in the gem diamonds as that seen in fluid-rich "fibrous" diamonds, supporting a common origin for the fluids. REE patterns range from extremely flat (Ce/Yb)n 2.5 to 5 (commonly in sulphide-bearing diamonds) to >70, the latter having significantly greater inter-element HFSE/LILE fractionation. In general, the fluids from the sulphide-bearing diamonds are less REE-enriched than the silicate-bearing diamonds, but the ranges overlap significantly. The very large range in REE fractionation mimics very closely that produced in high pressure (5-6 GPa) experimental melts of CO2-H2O fluxed peridotite. Hence, the elemental characteristics of the fluids could be reconciled by the diamonds growing from such melts over a range of T and hence F, with the sulphide-bearing diamonds generally being produced by larger fraction (higher T) melts that have reacted less with their wall rocks. It is also possible that the less REE enriched fluids are consistent with derivation from more reduced CH4-bearing fluids that have lower solute capacity than oxidised fluids. This option is being evaluated.

The influence of the focus position on laser machining and laser micro-structuring monocrystalline diamond surface

NASA Astrophysics Data System (ADS)

Wu, Mingtao; Guo, Bing; Zhao, Qingliang; Fan, Rongwei; Dong, Zhiwei; Yu, Xin

2018-06-01

Micro-structured surface on diamond is widely used in microelectronics, optical elements, MEMS and NEMS components, ultra-precision machining tools, etc. The efficient micro-structuring of diamond material is still a challenging task. In this article, the influence of the focus position on laser machining and laser micro-structuring monocrystalline diamond surface were researched. At the beginning, the ablation threshold and its incubation effect of monocrystalline diamond were determined and discussed. As the accumulated laser pulses ranged from 40 to 5000, the laser ablation threshold decreased from 1.48 J/cm2 to 0.97 J/cm2. Subsequently, the variation of the ablation width and ablation depth in laser machining were studied. With enough pulse energy, the ablation width mainly depended on the laser propagation attributes while the ablation depth was a complex function of the focus position. Raman analysis was used to detect the variation of the laser machined diamond surface after the laser machining experiments. Graphite formation was discovered on the machined diamond surface and graphitization was enhanced after the defocusing quantity exceeded 45 μm. At last, several micro-structured surfaces were successfully fabricated on diamond surface with the defined micro-structure patterns and structuring ratios just by adjusting the defocusing quantity. The experimental structuring ratio was consistent with the theoretical analysis.

Formation of diamonds in laser-compressed hydrocarbons at planetary interior conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kraus, D.; Vorberger, J.; Pak, A.

The effects of hydrocarbon reactions and diamond precipitation on the internal structure and evolution of icy giant planets such as Neptune and Uranus have been discussed for more than three decades. Inside these celestial bodies, simple hydrocarbons such as methane, which are highly abundant in the atmospheres, are believed to undergo structural transitions that release hydrogen from deeper layers and may lead to compact stratified cores. Indeed, from the surface towards the core, the isentropes of Uranus and Neptune intersect a temperature–pressure regime in which methane first transforms into a mixture of hydrocarbon polymers, whereas, in deeper layers, a phasemore » separation into diamond and hydrogen may be possible. Here in this paper, we show experimental evidence for this phase separation process obtained by in situ X-ray diffraction from polystyrene (C 8H 8) n samples dynamically compressed to conditions around 150 GPa and 5,000 K; these conditions resemble the environment around 10,000 km below the surfaces of Neptune and Uranus. Our findings demonstrate the necessity of high pressures for initiating carbon–hydrogen separation and imply that diamond precipitation may require pressures about ten times as high as previously indicated by static compression experiments. In conclusion, our results will inform mass–radius relationships of carbon-bearing exoplanets, provide constraints for their internal layer structure and improve evolutionary models of Uranus and Neptune, in which carbon–hydrogen separation could influence the convective heat transport.« less

Formation of diamonds in laser-compressed hydrocarbons at planetary interior conditions

DOE PAGES

Kraus, D.; Vorberger, J.; Pak, A.; ...

2017-08-21

The effects of hydrocarbon reactions and diamond precipitation on the internal structure and evolution of icy giant planets such as Neptune and Uranus have been discussed for more than three decades. Inside these celestial bodies, simple hydrocarbons such as methane, which are highly abundant in the atmospheres, are believed to undergo structural transitions that release hydrogen from deeper layers and may lead to compact stratified cores. Indeed, from the surface towards the core, the isentropes of Uranus and Neptune intersect a temperature–pressure regime in which methane first transforms into a mixture of hydrocarbon polymers, whereas, in deeper layers, a phasemore » separation into diamond and hydrogen may be possible. Here in this paper, we show experimental evidence for this phase separation process obtained by in situ X-ray diffraction from polystyrene (C 8H 8) n samples dynamically compressed to conditions around 150 GPa and 5,000 K; these conditions resemble the environment around 10,000 km below the surfaces of Neptune and Uranus. Our findings demonstrate the necessity of high pressures for initiating carbon–hydrogen separation and imply that diamond precipitation may require pressures about ten times as high as previously indicated by static compression experiments. In conclusion, our results will inform mass–radius relationships of carbon-bearing exoplanets, provide constraints for their internal layer structure and improve evolutionary models of Uranus and Neptune, in which carbon–hydrogen separation could influence the convective heat transport.« less

Effect Of Chromium Underlayer On The Properties Of Nano-Crystalline Diamond Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garratt, Elias; AlFaify, Salem; Yoshitake, T.

2013-01-11

This paper investigated the effect of chromium underlayer on the structure, microstructure and composition of the nano-crystalline diamond films. Nano-crystalline diamond thin films were deposited at high temperature in microwave-induced plasma diluted with nitrogen, on silicon substrate with a thin film of chromium as an underlayer. The composition, structure and microstructure of the deposited layers were analyzed using non-Rutherford Backscattering Spectrometry, Raman Spectroscopy, Near-Edge X-Ray Absorption Fine Structure, X-ray Diffraction and Atomic Force Microscopy. Nanoindentation studies showed that the films deposited on chromium underlayer have higher hardness values compared to those deposited on silicon without an underlayer. Diamond and graphiticmore » phases of the films evaluated by x-ray and optical spectroscopic analysis determined consistency between sp2 and sp3 phases of carbon in chromium sample to that of diamond grown on silicon. Diffusion of chromium was observed using ion beam analysis which was correlated with the formation of chromium complexes by x-ray diffraction.« less

Effect of chromium underlayer on the properties of nano-crystalline diamond films

NASA Astrophysics Data System (ADS)

Garratt, E.; AlFaify, S.; Yoshitake, T.; Katamune, Y.; Bowden, M.; Nandasiri, M.; Ghantasala, M.; Mancini, D. C.; Thevuthasan, S.; Kayani, A.

2013-01-01

This paper investigated the effect of chromium underlayer on the structure, microstructure, and composition of the nano-crystalline diamond films. Nano-crystalline diamond thin films were deposited at high temperature in microwave-induced plasma diluted with nitrogen, on single crystal silicon substrate with a thin film of chromium as an underlayer. Characterization of the film was implemented using non-Rutherford backscattering spectrometry, Raman spectroscopy, near-edge x-ray absorption fine structure, x-ray diffraction, and atomic force microscopy. Nanoindentation studies showed that the films deposited on chromium underlayer have higher hardness values compared to those deposited on silicon without an underlayer. Diamond and graphitic phases of the films evaluated by x-ray and optical spectroscopic analyses determined consistency between the sp2 and sp3 phases of carbon in chromium sample to that of diamond grown on silicon. Diffusion of chromium was observed using ion beam analysis which was correlated with the formation of chromium complexes by x-ray diffraction.

Synthesis of diamond films at low temperature and study of nonlinear dynamic synthesis process

NASA Astrophysics Data System (ADS)

Zhao, Qingxun; Shang, Yong; Dong, Lifang; Fu, Guangsheng; Yan, Zheng; Yang, Jingfa

2002-09-01

In this paper, the experimental synthesis of diamond films and optical emission spectroscopy (OES) of the gaseous phase species are studied in the range of substrate temperature from Ts = 300°C to 850°C. The high quality sub-microcrystalline diamond films are successfully deposited at substrate temperature (330 ≍ 340)°C by adopting glow plasma assisted hot filament chemical vapor deposition (GPCVD). For the first time, in situ OES is applied to diagnose weak signal of GPCVD system when CH4 and H2 are used as the input gas, and the reactive species are identified in diamond growth processes. A primary model of diamond films growing at low temperature is presented by studying dynamic behavior for nonequilibrium plasma reactions.

Kankan diamonds (Guinea) III: δ13C and nitrogen characteristics of deep diamonds

NASA Astrophysics Data System (ADS)

Stachel, T.; Harris, J. W.; Aulbach, S.; Deines, P.

Diamonds from the Kankan area in Guinea formed over a large depth profile beginning within the cratonic mantle lithosphere and extending through the asthenosphere and transition zone into the lower mantle. The carbon isotopic composition, the concentration of nitrogen impurities and the nitrogen aggregation level of diamonds representing this entire depth range have been determined. Peridotitic and eclogitic diamonds of lithospheric origin from Kankan have carbon isotopic compositions (δ13C: peridotitic -5.4 to -2.2‰ eclogitic -19.7 to -0.7‰) and nitrogen characteristics (N: peridotitic 17-648 atomic ppm; eclogitic 0-1,313 atomic ppm; aggregation from IaA to IaB) which are generally typical for diamonds of these two suites worldwide. Geothermobarometry of peridotitic and eclogitic inclusion parageneses (worldwide sources) indicates that both suites formed under very similar conditions within the cratonic lithosphere, which is not consistent with a derivation of diamonds with light carbon isotopic composition from subducted organic matter within subducting oceanic slabs. Diamonds containing majorite garnet inclusions fall to the isotopically heavy side (δ13C: -3.1‰ to +0.9‰) of the worldwide diamond population. Nitrogen contents are low (0-126 atomic ppm) and one of the two nitrogen-bearing diamonds shows such a low level of nitrogen aggregation (30% B-centre) that it cannot have been exposed to ambient temperatures of the transition zone (>=1,400 °C) for more than 0.2 Ma. This suggests rapid upward transport and formation of some Kankan diamonds pene-contemporaneous to Cretaceous kimberlite activity. Similar to these diamonds from the asthenosphere and the transition zone, lower mantle diamonds show a small shift towards isotopic heavy compositions (-6.6 to -0.5‰, mode at -3.5‰). As already observed for other mines, the nitrogen contents of lower mantle diamonds were below detection (using FTIRS). The mutual shift of sublithospheric diamonds towards isotopic heavier compositions suggests a common carbon source, which may have inherited an isotopic heavy composition from a component consisting of subducted carbonates.

Kankan diamonds (Guinea) III: δ13C and nitrogen characteristics of deep diamonds

NASA Astrophysics Data System (ADS)

Stachel, T.; Harris, J. W.; Aulbach, S.; Deines, P.

2001-08-01

Diamonds from the Kankan area in Guinea formed over a large depth profile beginning within the cratonic mantle lithosphere and extending through the asthenosphere and transition zone into the lower mantle. The carbon isotopic composition, the concentration of nitrogen impurities and the nitrogen aggregation level of diamonds representing this entire depth range have been determined. Peridotitic and eclogitic diamonds of lithospheric origin from Kankan have carbon isotopic compositions (δ13C: peridotitic -5.4 to -2.2‰ eclogitic -19.7 to -0.7‰) and nitrogen characteristics (N: peridotitic 17-648 atomic ppm; eclogitic 0-1,313 atomic ppm; aggregation from IaA to IaB) which are generally typical for diamonds of these two suites worldwide. Geothermobarometry of peridotitic and eclogitic inclusion parageneses (worldwide sources) indicates that both suites formed under very similar conditions within the cratonic lithosphere, which is not consistent with a derivation of diamonds with light carbon isotopic composition from subducted organic matter within subducting oceanic slabs. Diamonds containing majorite garnet inclusions fall to the isotopically heavy side (δ13C: -3.1‰ to +0.9‰) of the worldwide diamond population. Nitrogen contents are low (0-126 atomic ppm) and one of the two nitrogen-bearing diamonds shows such a low level of nitrogen aggregation (30% B-centre) that it cannot have been exposed to ambient temperatures of the transition zone (>=1,400 °C) for more than 0.2 Ma. This suggests rapid upward transport and formation of some Kankan diamonds pene-contemporaneous to Cretaceous kimberlite activity. Similar to these diamonds from the asthenosphere and the transition zone, lower mantle diamonds show a small shift towards isotopic heavy compositions (-6.6 to -0.5‰, mode at -3.5‰). As already observed for other mines, the nitrogen contents of lower mantle diamonds were below detection (using FTIRS). The mutual shift of sublithospheric diamonds towards isotopic heavier compositions suggests a common carbon source, which may have inherited an isotopic heavy composition from a component consisting of subducted carbonates.

Formation of nanocrystalline diamond in polymer like carbon films deposited by plasma CVD.

PubMed

Bhaduri, A; Chaudhuri, P

2009-09-01

Conventional plasma enhanced chemical vapour deposition (PECVD) method is generally not suitable for the growth of nanocrystalline diamond (NCD) films. However, our study shows that conditions favourable for powder formation help to grow large amount of nanocrystallites in conventional PECVD. With CH4 as the carbon source gas, dilution with Ar and moderate (50 W) rf power enhances formations of powders (nanoparticles) and C2 dimers within the plasma. On the other hand, with pure CH4 or with hydrogen diluted CH4, powder formation as also NCD growth is hindered. It is proposed that the nanoparticles formed in the plasma act as the "islands" while the C2 dimers are the "seeds" for the NCD growth. The structure of the films deposited on the grounded anode under different conditions of dilution has been studied. It is observed that with high Ar dilution the films contain NCD embedded in polymer like carbon (PLC) matrix.

Carbon and nitrogen isotope systematics in diamond: Different sensitivities to isotopic fractionation or a decoupled origin?

NASA Astrophysics Data System (ADS)

Hogberg, K.; Stachel, T.; Stern, R. A.

2016-11-01

Using stable isotope data obtained on multiple aliquots of diamonds from worldwide sources, it has been argued that carbon and nitrogen in diamond are decoupled. Here we re-investigate the carbon-nitrogen relationship based on the most comprehensive microbeam data set to date of stable isotopes and nitrogen concentrations in diamonds (n = 94) from a single locality. Our diamond samples, derived from two kimberlites in the Chidliak Field (NE Canada), show large variability in δ13C (- 28.4 ‰ to - 1.1‰, mode at - 5.8‰), δ15N (- 5.8 to + 18.8‰, mode at - 3.0‰) and nitrogen contents ([N]; 3800 to less than 1 at.ppm). In combination, cathodoluminescence imaging and microbeam analyses reveal that the diamonds grew from multiple fluid pulses, with at least one major hiatus documented in some samples that was associated with a resorption event and an abrupt change from low δ13C and [N] to mantle-like δ13C and high [N]. Overall, δ13C appears to be uncorrelated to δ15N and [N] on both the inter- and intra-diamond levels. Co-variations of δ15N-log[N], however, result in at least two parallel, negatively correlated linear arrays, which are also present on the level of the individual diamonds falling on these two trends. These arrays emerge from the two principal data clusters, are characterized by slightly negative and slightly positive δ15N (about - 3 and + 2‰, respectively) and variable but overall high [N]. Using published values for the diamond-fluid nitrogen isotope fractionation factor and nitrogen partition coefficient, these trends are perfectly reproduced by a Rayleigh fractionation model. Overall, three key elements are identified in the formation of the diamond suite studied: (1.) a low δ13C and low [N] component that possibly is directly associated with an eclogitic diamond substrate or introduced during an early stage fluid event. (2.) Repeated influx of a variably nitrogen-rich mantle fluid (mildly negative δ13C and δ15N). (3.) In waning stages of influx, availability of the mantle-type fluid at the site of diamond growth became limited, leading to Rayleigh fractionation. These fractionation trends are clearly depicted by δ15N-[N] but are not detected when examining co-variation diagrams involving δ13C. Also on the level of individual diamonds, large (≥ 5‰) variations in δ15N are associated with δ13C values that typically are constant within analytical uncertainty. The much smaller isotope fractionation factor for carbon (considering carbonate- or methane-rich fluids as possible carbon sources) compared to nitrogen leads to an approximately one order of magnitude lower sensitivity of δ13C values to Rayleigh fractionation processes (i.e. during fractionation, a 1‰ change in δ13C is associated with a 10‰ change in δ15N). As a consequence, even minor heterogeneity in the primary isotopic composition of diamond forming carbon (e.g., due to addition of minor subducted carbon) will completely blur any possible co-variations with δ15N or [N]. We suggest this strong difference in isotope effects for C and N to be the likely cause of observations of an apparently decoupled behaviour of carbon and nitrogen isotopes in diamond.

On the Fabrication and Behavior of Diamond Microelectromechanical Sensors (DMEMS)

NASA Technical Reports Server (NTRS)

Holmes, K.; Davidson, J. L.; Kang, W. P.; Howell, M.

2001-01-01

CVD (chemically vapor deposited) diamond films can be processed similar to "conventional" semiconductor device fabrication and as such can be used to achieve microelectromechanical structures (MEMS) also similar to, for example, silicon technology. Very small cantilever beams, membranes, stripes, tips, etc. can be constructed in doped and undoped diamond films and offer an array of choices in diamond with its known superior properties such as elastic modulus, high temperature semiconduction, high thermal conductivity, very low coefficient of expansion and numerous other diamond parameters. This paper will review the construction and behavior of the second generation DMEMS devices comprised as an accelerometer with a diamond diaphragm for use in very high G applications and a diamond pressure sensor for very high temperature and frequency response.

Structures and Mechanical Properties of Natural and Synthetic Diamonds

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1998-01-01

A revolution in the diamond technology is in progress, as the low-pressure process becomes an industrial reality. It will soon be possible to take advantage of the demanding properties of diamond to develop a myriad of new applications, particularly for self-lubricating, wear-resistant, and superhard coatings. The production of large diamond films or sheets at low cost, a distinct possibility in the not-too-distant future, may drastically change tribology technology, particularly regarding solid lubricants and lubricating materials and systems. This paper reviews the structures and properties of natural and synthetic diamonds to gain a better understanding of the tribological properties of diamond and related materials. Atomic and crystal structure, impurities, mechanical properties, and indentation hardness of diamond are described.

D.C. Arcjet Diamond Deposition

NASA Astrophysics Data System (ADS)

Russell, Derrek Andrew

1995-01-01

Polycrystalline diamond films synthesized by a D.C. (direct current) arcjet device was reported for the first time in 1988. This device is capable of higher diamond growth rates than any other form of diamond CVD (chemical vapor deposition) process due to its inherent versatility with regard to the enthalpy and fluid properties of the diamond-depositing vapor. Unfortunately, the versatility of this type of device is contrasted by many difficulties such as arc stability and large heat fluxes which make applying it toward diamond deposition a difficult problem. The purpose of this work was to convert the dc arcjet, which is primarily a metallurgical device, into a commercially viable diamond CVD process. The project was divided into two parts: process development and diagnostics. The process development effort concentrated on the certain engineering challenges. Among these was a novel arcjet design that allowed the carbon-source gas to be injected downstream of the tungsten cathode while still facilitating mixture with the main gas feed. Another engineering accomplishment was the incorporation of a water -cooled substrate cooler/spinner that maintained the substrate at the proper temperature, provided the substrate with a large thermal time constant to reduce thermal shock of the diamond film, and enabled the system to achieve a four -inch diameter growth area. The process diagnostics effort concentrated on measurements aimed at developing a fundamental understanding of the properties of the plasma jet such as temperature, plasma density, Mach number, pressure at the substrate, etc. The plasma temperature was determined to be 5195 K by measuring the rotational temperature of C _2 via optical emission spectroscopy. The Mach number of the plasma jet was determined to be ~6.0 as determined by the ratio of the stagnation pressures before and after the shock wave in the plasma jet. The C_2 concentration in the plasma jet was determined to be {~10 }^{12} cm^ {-3} by counting the number of radiated Swan band photons. This is big enough to account for a significant amount (10%) of the diamond growth.

Molecular dynamics simulations of shock compressed heterogeneous materials. II. The graphite/diamond transition case for astrophysics applications

NASA Astrophysics Data System (ADS)

Pineau, N.; Soulard, L.; Colombet, L.; Carrard, T.; Pellé, A.; Gillet, Ph.; Clérouin, J.

2015-03-01

We present a series of molecular dynamics simulations of the shock compression of copper matrices containing a single graphite inclusion: these model systems can be related to some specific carbon-rich rocks which, after a meteoritic impact, are found to contain small fractions of nanodiamonds embedded in graphite in the vicinity of high impedance minerals. We show that the graphite to diamond transformation occurs readily for nanometer-sized graphite inclusions, via a shock accumulation process, provided the pressure threshold of the bulk graphite/diamond transition is overcome, independently of the shape or size of the inclusion. Although high diamond yields (˜80%) are found after a few picoseconds in all cases, the transition is non-isotropic and depends substantially on the relative orientation of the graphite stack with respect to the shock propagation, leading to distinct nucleation processes and size-distributions of the diamond grains. A substantial regraphitization process occurs upon release and only inclusions with favorable orientations likely lead to the preservation of a fraction of this diamond phase. These results agree qualitatively well with the recent experimental observations of meteoritic impact samples.

Studies of carbon incorporation on the diamond [100] surface during chemical vapor deposition using density functional theory.

PubMed

Cheesman, Andrew; Harvey, Jeremy N; Ashfold, Michael N R

2008-11-13

Accurate potential energy surface calculations are presented for many of the key steps involved in diamond chemical vapor deposition on the [100] surface (in its 2 x 1 reconstructed and hydrogenated form). The growing diamond surface was described by using a large (approximately 1500 atoms) cluster model, with the key atoms involved in chemical steps being described by using a quantum mechanical (QM, density functional theory, DFT) method and the bulk of the atoms being described by molecular mechanics (MM). The resulting hybrid QM/MM calculations are more systematic and/or at a higher level of theory than previous work on this growth process. The dominant process for carbon addition, in the form of methyl radicals, is predicted to be addition to a surface radical site, opening of the adjacent C-C dimer bond, insertion, and ultimate ring closure. Other steps such as insertion across the trough between rows of dimer bonds or addition to a neighboring dimer leading to formation of a reconstruction on the next layer may also contribute. Etching of carbon can also occur; the most likely mechanism involves loss of a two-carbon moiety in the form of ethene. The present higher-level calculations confirm that migration of inserted carbon along both dimer rows and chains should be relatively facile, with barriers of approximately 150 kJ mol (-1) when starting from suitable diradical species, and that this step should play an important role in establishing growth of smooth surfaces.

Treating soil-washing fluids polluted with oxyfluorfen by sono-electrolysis with diamond anodes.

PubMed

Vieira Dos Santos, E; Sáez, C; Cañizares, P; Martínez-Huitle, C A; Rodrigo, M A

2017-01-01

This works is focused on the treatment by sono-electrolysis of the liquid effluents produced during the Surfactant-Aided Soil-Washing (SASW) of soils spiked with herbicide oxyfluorfen. Results show that this combined technology is very efficient and attains the complete mineralization of the waste, regardless of the surfactant/soil radio applied in the SASW process (which is the main parameter of the soil remediation process and leads to very different wastes). Both the surfactant and the herbicide are completely degraded, even when single electrolysis is used; and only two intermediates are detected by HPLC in very low concentrations. Conversely, the efficiency of single sonolysis approach, for the oxidation of pollutant, is very low and just small changes in the herbicides and surfactant concentrations are observed during the tests carried out. Sono-electrolysis with diamond electrodes achieved higher degradation rates than those obtained by single sonolysis and/or single electrolysis with diamond anodes. A key role of sulfate is developed, when it is released after the electrochemical degradation of surfactant. The efficient catalytic effect observed which can be explained by the anodic formation of persulfate and the later, a sono-activation is attained to produce highly efficient sulfate radicals. The effect of irradiating US is more importantly observed in the pesticide than in the surfactant, in agreement with the well-known behavior of these radicals which are known to oxidize more efficiently aromatic compounds than aliphatic species. Copyright © 2016 Elsevier B.V. All rights reserved.

Ohmic contacts to semiconducting diamond

NASA Astrophysics Data System (ADS)

Zeidler, James R.; Taylor, M. J.; Zeisse, Carl R.; Hewett, C. A.; Delahoussaye, Paul R.

1990-10-01

Work was carried out to improve the electron beam evaporation system in order to achieve better deposited films. The basic system is an ion pumped vacuum chamber, with a three-hearth, single-gun e-beam evaporator. Four improvements were made to the system. The system was thoroughly cleaned and new ion pump elements, an e-gun beam adjust unit, and a more accurate crystal monitor were installed. The system now has a base pressure of 3 X 10(exp -9) Torr, and can easily deposit high-melting-temperature metals such as Ta with an accurately controlled thickness. Improved shadow masks were also fabricated for better alignment and control of corner contacts for electrical transport measurements. Appendices include: A Thermally Activated Solid State Reaction Process for Fabricating Ohmic Contacts to Semiconducting Diamond; Tantalum Ohmic Contacts to Diamond by a Solid State Reaction Process; Metallization of Semiconducting Diamond: Mo, Mo/Au, and Mo/Ni/Au; Specific Contact Resistance Measurements of Ohmic Contracts to Diamond; and Electrical Activation of Boron Implanted into Diamond.

Effects of the shape anisotropy and biasing field on the magnetization reversal process of the diamond-shaped NiFe nano films

NASA Astrophysics Data System (ADS)

Xu, Sichen; Yin, Jianfeng; Tang, Rujun; Zhang, Wenxu; Peng, Bin; Zhang, Wanli

2017-11-01

The effects of the planar shape anisotropy and biasing field on the magnetization reversal process (MRP) of the diamond-shaped NiFe nano films have been investigated by micromagnetic simulations. Results show that when the length to width ratio (LWR) of the diamond-shaped film is small, the MRP of the diamond-shaped films are sensitive to LWR. But when LWR is larger than 2, a stable domain switching mode is observed which nucleates from the center of the diamond and then expands to the edges. At a fixed LWR, the magnitude of the switching fields decrease with the increase of the biasing field, but the domain switching mode is not affected by the biasing field. Further analysis shows that demagnetization energy dominates over the MRP of the diamond-shaped films. The above LWR dependence of MRP can be well explained by a variation of the shape anisotropic factor with LWR.

Microstructure and mechanical properties of diamond films on titanium-aluminum-vanadium alloy

NASA Astrophysics Data System (ADS)

Catledge, Shane Aaron

The primary focus of this dissertation is the investigation of the processing-structure-property relationships of diamond films deposited on Ti-6Al-4V alloy by microwave plasma chemical vapor deposition (MPCVD). By depositing a well-adhered protective layer of diamond on an alloy component, its hardness, wear-resistance, performance, and overall lifetime could be significantly increased. However, due to the large thermal expansion mismatch between the diamond film and metal (and the corresponding residual stress induced in the film), film adhesion is typically unsatisfactory and often results in immediate delamination after processing. Therefore, it is a major goal of this research to improve adhesion of the diamond film to the alloy substrate. Through the use of innovative processing techniques involving MPCVD deposition conditions and methane (CH4), nitrogen (N2), and hydrogen (H2) chemistry, we have achieved diamond films which consistently adhere to the alloy substrate. In addition, we have discovered that, with the appropriate choice of deposition conditions, the film structure can be tailored to range from highly crystalline, well-faceted diamond to nanocrystalline diamond with extremely low surface roughness (as low as 27 nm). The relationship between processing and structure was studied using in-situ optical emission spectroscopy, micro-Raman spectroscopy, surface profilometry, glancing-angle x-ray diffraction, and scanning electron microscopy. We observe that when nitrogen is added to the H2/CH4 feedgas mixture, a carbon-nitrogen (CN) emission band arises and its relative abundance to the carbon dimer (C2) gas species is shown to have a pronounced influence on the diamond film structure. By appropriate choice of deposition chemistry and conditions, we can tailor the diamond film structure and its corresponding properties. The mechanical properties of interest in this thesis are those relating to the integrity of the film/substrate interface, as well as the hardness, wear resistance, residual stress, and elastic modulus of the film. The mechanical properties of the diamond coatings were characterized by indentation and wear testing instruments. Finally, we developed a model based on fundamental thermodynamic and optical principles for extracting the time dependence of film thickness and surface roughness using optical pyrometry for the case of an absorbing substrate. This model provides a convenient way to determine film thickness during growth in CVD systems as well as a reliable estimate of surface roughness.

Evidence of subduction and crust-mantle mixing from a single diamond

NASA Astrophysics Data System (ADS)

Schulze, Daniel J.; Harte, Ben; Valley, John W.; Channer, Dominic M. DeR.

2004-09-01

Cathodoluminescence (CL) imaging of polished sections of a diamond from the Guaniamo region of Venezuela suggests a history of the diamond involving two periods of growth separated by a period of resorption and possibly brittle deformation. In situ electron probe analysis of multiple eclogitic garnet inclusions reveals a correlation between garnet composition and location in the stone. An early-formed garnet in the diamond core has higher Ca/(Ca+Mg) and lower Mg/(Mg+Fe) values than later garnets associated with the second period of diamond growth. This variation conforms to an extensive trend of variation in the suite of eclogitic garnets extracted from Venezuelan diamonds. The diamond is zoned in carbon isotope composition (in situ secondary ion mass spectrometry, SIMS, data). The core compositions ( δ13C PDB), corresponding to the first stage of growth, average -17.7‰. The second period of growth is apparently in two sub-sets of CL zones with mean values of -13.0‰ and -7.9‰. Nitrogen contents of diamond are low (30-300 atomic ppm) and do not correlate with carbon isotope composition. Oxygen isotope ratios of the garnet inclusions are elevated substantially above those expected for "common mantle"; δ18O VSMOW of early garnet is approximately +10.5‰ and two late garnets average +8.8‰. The evolutionary trend of magnesium enrichment in garnet is unlikely to represent igneous fractionation. The stable isotope data are consistent with diamond formation in subducted meta-basic rocks that had interacted with sea water at low temperatures at or near the sea floor and contained a substantial biogenic carbon component. During or following subduction, diamonds continued to form in an evolving system that was progressively modified by interaction with mantle material.

Photothermal effects during nanodiamond synthesis from a carbon aerogel in a laser-heated diamond anvil cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crane, Matthew J.; Smith, Bennett E.; Meisenheimer, Peter B.

Nanodiamonds have emerged as promising materials for quantum computing, biolabeling, and sensing due to their ability to host color centers with remarkable photostability and long spin-coherence times at room temperature. Recently, a bottom-up, high-pressure, high-temperature (HPHT) approach was demonstrated for growing nanodiamonds with color centers from amorphous carbon precursors in a laser-heated diamond anvil cell (LH-DAC) that was supported by a near-hydrostatic noble gas pressure medium. However, a detailed understanding of the photothermal heating and its effect on diamond growth, including the phase conversion conditions and the temperature-dependence of color center formation, has not been reported. In this work, wemore » measure blackbody radiation during LH-DAC synthesis of nanodiamond from carbon aerogel to examine these temperature-dependent effects. Blackbody temperature measurements suggest that nanodiamond growth can occur at 16.3 GPa and 1800 K. We use Mie theory and analytical heat transport to develop a predictive photothermal heating model. This model demonstrates that melting the noble gas pressure medium during laser heating decreases the local thermal conductivity to drive a high spatial resolution of phase conversion to diamond. In conclusion, we observe a temperature-dependent formation of nitrogen vacancy centers and interpret this phenomenon in the context of HPHT carbon vacancy diffusion.« less

Photothermal effects during nanodiamond synthesis from a carbon aerogel in a laser-heated diamond anvil cell

DOE PAGES

Crane, Matthew J.; Smith, Bennett E.; Meisenheimer, Peter B.; ...

2018-05-17

Nanodiamonds have emerged as promising materials for quantum computing, biolabeling, and sensing due to their ability to host color centers with remarkable photostability and long spin-coherence times at room temperature. Recently, a bottom-up, high-pressure, high-temperature (HPHT) approach was demonstrated for growing nanodiamonds with color centers from amorphous carbon precursors in a laser-heated diamond anvil cell (LH-DAC) that was supported by a near-hydrostatic noble gas pressure medium. However, a detailed understanding of the photothermal heating and its effect on diamond growth, including the phase conversion conditions and the temperature-dependence of color center formation, has not been reported. In this work, wemore » measure blackbody radiation during LH-DAC synthesis of nanodiamond from carbon aerogel to examine these temperature-dependent effects. Blackbody temperature measurements suggest that nanodiamond growth can occur at 16.3 GPa and 1800 K. We use Mie theory and analytical heat transport to develop a predictive photothermal heating model. This model demonstrates that melting the noble gas pressure medium during laser heating decreases the local thermal conductivity to drive a high spatial resolution of phase conversion to diamond. In conclusion, we observe a temperature-dependent formation of nitrogen vacancy centers and interpret this phenomenon in the context of HPHT carbon vacancy diffusion.« less

Organophosphonate biofunctionalization of diamond electrodes.

PubMed

Caterino, R; Csiki, R; Wiesinger, M; Sachsenhauser, M; Stutzmann, M; Garrido, J A; Cattani-Scholz, A; Speranza, Giorgio; Janssens, S D; Haenen, K

2014-08-27

The modification of the diamond surface with organic molecules is a crucial aspect to be considered for any bioapplication of this material. There is great interest in broadening the range of linker molecules that can be covalently bound to the diamond surface. In the case of protein immobilization, the hydropathicity of the surface has a major influence on the protein conformation and, thus, on the functionality of proteins immobilized at surfaces. For electrochemical applications, particular attention has to be devoted to avoid that the charge transfer between the electrode and the redox center embedded in the protein is hindered by a thick insulating linker layer. This paper reports on the grafting of 6-phosphonohexanoic acid on OH-terminated diamond surfaces, serving as linkers to tether electroactive proteins onto diamond surfaces. X-ray photoelectron spectroscopy (XPS) confirms the formation of a stable layer on the surface. The charge transfer between electroactive molecules and the substrate is studied by electrochemical characterization of the redox activity of aminomethylferrocene and cytochrome c covalently bound to the substrate through this linker. Our work demonstrates that OH-terminated diamond functionalized with 6-phosphonohexanoic acid is a suitable platform to interface redox-proteins, which are fundamental building blocks for many bioelectronics applications.

Structural evolution of Ti destroyable interlayer in large-size diamond film deposition by DC arc plasma jet

NASA Astrophysics Data System (ADS)

Guo, Jianchao; Li, Chengming; Liu, Jinlong; Wei, Junjun; Chen, Liangxian; Hua, Chenyi; Yan, Xiongbo

2016-05-01

The addition of titanium (Ti) interlayer was verified to reduce the residual stress of diamond films by self-fracturing and facilitate the harvest of a crack-free free-standing diamond film prepared by direct current (DC) arc plasma jet. In this study, the evolution of the Ti interlayer between large-area diamond film and substrate was studied and modeled in detail. The evolution of the interlayer was found to be relevant to the distribution of the DC arc plasma, which can be divided into three areas (arc center, arc main, and arc edge). The formation rate of titanium carbide (TiC) in the arc main was faster than in the other two areas and resulted in the preferred generation of crack in the diamond film in the arc main during cooling. Sandwich structures were formed along with the growth of TiC until the complete transformation of the Ti interlayer. The interlayer released stress via self-fracture. Avoiding uneven fragile regions that formed locally in the interlayer and achieving cooperatively released stress are crucial for the preparation of large crack-free diamond films.

Nanocrystalline hexagonal diamond formed from glassy carbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shiell, Thomas. B.; McCulloch, Dougal G.; Bradby, Jodie E.

Carbon exhibits a large number of allotropes and its phase behaviour is still subject to signifcant uncertainty and intensive research. The hexagonal form of diamond, also known as lonsdaleite, was discovered in the Canyon Diablo meteorite where its formation was attributed to the extreme conditions experienced during the impact. However, it has recently been claimed that lonsdaleite does not exist as a well-defned material but is instead defective cubic diamond formed under high pressure and high temperature conditions. Here we report the synthesis of almost pure lonsdaleite in a diamond anvil cell at 100GPa and 400 C. The nanocrystalline materialmore » was recovered at ambient and analysed using difraction and high resolution electron microscopy. We propose that the transformation is the result of intense radial plastic fow under compression in the diamond anvil cell, which lowers the energy barrier by locking in favourable stackings of graphene sheets. This strain induced transformation of the graphitic planes of the precursor to hexagonal diamond is supported by frst principles calculations of transformation pathways and explains why the new phase is found in an annular region. Furthermore, our findings establish that high purity lonsdaleite is readily formed under strain and hence does not require meteoritic impacts.« less

Thermodynamic approach to the paradox of diamond formation with simultaneous graphite etching in the low pressure synthesis of diamond

NASA Astrophysics Data System (ADS)

Hwang, Nong M.; Yoon, Duk Y.

1996-03-01

In spite of the critical handicap from the thermodynamic point of view, the atomic hydrogen hypothesis is strongly supported by experimental observations of diamond deposition with simultaneous graphite etching. Thermodynamic analysis of the CH system showed that at ˜ 1500 K, carbon solubility in the gas phase is minimal and thus, the equilibrium fraction of solid carbon is maximal. Depending on whether gas phase nucleation takes place or not, the driving force is for deposition or for etching of solid carbon below ˜ 1500 K for the input gas of the typical mixture of 1% CH 499% H 2. The previous observation of etching of the graphite substrate is not expected unless solid carbon precipitated in the gas phase. By rigorous thermodynamic analysis of the previous experimental observations of diamond deposition with simultaneous graphite etching, we suggested that the previous implicit assumption that diamond deposits by an atomic unit should be the weakest point leading to the thermodynamic paradox. The experimental observations could be successfully explained without violating thermodynamics by assuming that the diamond phase had nucleated in the gas phase as fine clusters.

Nanocrystalline hexagonal diamond formed from glassy carbon

DOE PAGES

Shiell, Thomas. B.; McCulloch, Dougal G.; Bradby, Jodie E.; ...

2016-11-29

Carbon exhibits a large number of allotropes and its phase behaviour is still subject to signifcant uncertainty and intensive research. The hexagonal form of diamond, also known as lonsdaleite, was discovered in the Canyon Diablo meteorite where its formation was attributed to the extreme conditions experienced during the impact. However, it has recently been claimed that lonsdaleite does not exist as a well-defned material but is instead defective cubic diamond formed under high pressure and high temperature conditions. Here we report the synthesis of almost pure lonsdaleite in a diamond anvil cell at 100GPa and 400 C. The nanocrystalline materialmore » was recovered at ambient and analysed using difraction and high resolution electron microscopy. We propose that the transformation is the result of intense radial plastic fow under compression in the diamond anvil cell, which lowers the energy barrier by locking in favourable stackings of graphene sheets. This strain induced transformation of the graphitic planes of the precursor to hexagonal diamond is supported by frst principles calculations of transformation pathways and explains why the new phase is found in an annular region. Furthermore, our findings establish that high purity lonsdaleite is readily formed under strain and hence does not require meteoritic impacts.« less

A billion years of metasomatic alteration of the Kaapvaal SCLM encapsulated in fibrous diamonds

NASA Astrophysics Data System (ADS)

Weiss, Yaakov; Goldstein, Steven; Class, Cornelia; Winckler, Gisela

2017-04-01

Constraining the nature and timing of metasomatic events by C-O-H fluids in the sub-continental lithospheric mantle (SCLM) is an ongoing challenge in our understanding of the SCLM history. 'Fibrous' diamonds, which rapidly grow during such fluid-rock interaction, commonly encapsulate the C-O-H fluid metasomatic agents, which are trapped and encapsulated as μm-scale high-density fluid (HDF) inclusions and can be directly sampled. They thus offer a unique opportunity to investigate metasomatic events involving C-O-H fluids in the SCLM. We analyzed major and trace elements and the helium content and isotopic composition of the HDFs included in a set of diamonds from the DeBeers-Pool and Finsch kimberlites in the Kaapvaal craton, South Africa. Saline HDF micro-inclusions in 3 of the DeBeers diamonds and in 2 from Finsch have very similar major and trace element compositions, suggesting they formed in related metasomatic events. They are characterized by high alkalis (K, Rb and Cs), Ba and LREEs compared to Th, U, Nb and Ta, and by Ti, Zr, Hf and Y negative anomalies relative to REEs of similar compatibility. Their 3He/4He ratios vary between 3-4 Ra. Plotting the 3 DeBeers-Pool diamonds on an 4He/3He vs 238U/3He diagram defines an 'isochron' with an age of 96±45 Ma. This result represents the first radiometric age reported for fibrous diamonds and the C-O-H mantle fluids they carry. In addition, 1 diamond from DeBeers-Pool has silicic microinclusion compositions while 2 diamonds from Finsch carry carbonatitic HDFs. These diamonds display more radiogenic 3He/4He ratios between 0.07-0.6 Ra, which suggests formation during earlier and different metasomatic events. Using the measured U, Th, 4He and 3He content of these diamonds, and the equation for 4He production by U and Th, we calculate 3He/4He ratios as a function of time. Assuming that the HDFs initial R/Ra values varied between 3-11, representing common values for MORB, the SCLM and subducted components, the silicic and carbonatitic HDFs signify two older metasomatic events that took place in the Kaapvaal lithosphere at 350 and 850 Ma, respectively. Thus, our new data reveal 3 episodes of chemical changes in the Kaapvaal craton SCLM during the last 1 Ga, each by a different metasomatic agent. The youngest episodes indicate direct relationships between highly-saline fluid metasomatism, fibrous diamond formation and late-Mesozoic kimberlite eruptions, while the older silicic and carbonatitic metasomatic events may be related to the regional Namaqua-Natal Orogeny and Damara Orogeny at 1 Ga and 500 Ma, respectively.

Fundamental Discovery of New Phases and Direct Conversion of Carbon into Diamond and hBN into cBN and Properties

NASA Astrophysics Data System (ADS)

Narayan, Jagdish; Bhaumik, Anagh

2016-04-01

We review the discovery of new phases of carbon (Q-carbon) and BN (Q-BN) and address critical issues related to direct conversion of carbon into diamond and hBN into cBN at ambient temperatures and pressures in air without any need for catalyst and the presence of hydrogen. The Q-carbon and Q-BN are formed as a result of quenching from super undercooled state by using high-power nanosecond laser pulses. We discuss the equilibrium phase diagram ( P vs T) of carbon, and show that by rapid quenching, kinetics can shift thermodynamic graphite/diamond/liquid carbon triple point from 5000 K/12 GPa to super undercooled carbon at atmospheric pressure in air. Similarly, the hBN-cBN-Liquid triple point is shifted from 3500 K/9.5 GPa to as low as 2800 K and atmospheric pressure. It is shown that nanosecond laser heating of amorphous carbon and nanocrystalline BN on sapphire, glass, and polymer substrates can be confined to melt in a super undercooled state. By quenching this super undercooled state, we have created a new state of carbon (Q-carbon) and BN (Q-BN) from which nanocrystals, microcrystals, nanoneedles, microneedles, and thin films are formed depending upon the nucleation and growth times allowed and the presence of growth template. The large-area epitaxial diamond and cBN films are formed, when appropriate planar matching or lattice matching template is provided for growth from super undercooled liquid. The Q-phases have unique atomic structure and bonding characteristics as determined by high-resolution SEM and backscatter diffraction, HRTEM, STEM-Z, EELS, and Raman spectroscopy, and exhibit new and improved mechanical hardness, electrical conductivity, and chemical and physical properties, including room-temperature ferromagnetism and enhanced field emission. The Q-carbon exhibits robust bulk ferromagnetism with estimated Curie temperature of about 500 K and saturation magnetization value of 20 emu g-1. We have also deposited diamond on cBN by using a novel pulsed laser evaporation of carbon and obtained cBN/diamond composites, where cBN acts as template for diamond growth. Both diamond and cBN grown from super undercooled liquid can be alloyed with both p- and n-type dopants. This process allows carbon to diamond and hBN to cBN conversions and formation of useful nanostructures and microstructures at ambient temperatures in air at atmospheric pressure on practical and heat-sensitive substrates in a controlled way without need for any catalysts and hydrogen to stabilize sp3 bonding for diamond and cBN phases.

Diamond growth beneath Letlhakane established by Re-Os and Sm-Nd systematics of individual eclogitic sulphide, garnet and clinopyroxene inclusions

NASA Astrophysics Data System (ADS)

Gress, Michael U.; Pearson, D. Graham; Timmerman, Suzette; Chinn, Ingrid L.; Koornneef, Janne M.; Davies, Gareth R.

2017-04-01

The diamondiferous Letlhakane kimberlites are part of the Orapa kimberlite cluster (˜ 93.1 Ma) in north-eastern Botswana, located on the edge of the Zimbabwe Craton, close to the Proterozoic Magondi Mobile Belt. Here we report the first Re-Os ages of six individual eclogitic sulphide inclusions (3.0 to 35.7μg) from Letlhakane diamonds along with their rhenium, osmium, iridium and platinum concentrations, and carbon isotope, nitrogen content and N-aggregation data from the corresponding growth zones of the host diamonds. For the first time, Re-Os data will be compared to Sm-Nd ages of individual eclogitic silicate inclusions recovered from the same diamonds using a Triton Plus equipped with four 1013Ω amplifiers. The analysed inclusion set currently encompasses pairs of individual sulphides from two diamonds (LK040 sf4 & 5, LK113 sf1 & 2) and two sulphide inclusions from separate diamonds (LK048, LK362). Ongoing work will determine the Sm-Nd ages and element composition of multiple individual eclogitic garnets (LK113/LK362, n=4) and an eclogitic clinopyroxene (LK040) inclusion. TMA ages of the six sulphides range from 1.06 to 2.38 Ga (± 0.1 to 0.54 Ga) with Re and Os contents between 7 and 68 ppb and 0.03 and 0.3 ppb, respectively. The host diamond growth zones have low nitrogen abundances (21 to 43 ppm N) and high N-aggregation (53 to 90% IaB). Carbon isotope data suggests the involvement of crustal carbon (δ13C between -19.3 to -22.7 ± 0.2 per mill) during diamond precipitation. Cathodoluminescence imaging of central plates from LK040 and LK113 displays homogenous internal structure with no distinct zonation. The two sulphide inclusions from LK040 define an 'isochron' of 0.92 ± 0.23 Ga (2SD) with initial 187Os/188Os = 1.31 ± 0.24. Sulphides from LK113 have clear imposed diamond morphology and indicate diamond formation at 0.93 ± 0.36 Ga (2SD) with initial 187Os/188Os = 0.69 ± 0.44. The variation in the initial 187Os/188Os does not justify including these inclusions (or any from other diamonds) on the same isochron and implies an extremely heterogeneous diamond crystallisation environment that incorporated recycled Os. C1-normalized osmium, iridium and platinum (PGE) compositions from the analysed sulphide inclusions display enrichment in Ir (3.4 to 33) and Pt (2.3 to 28.1) in comparison to eclogitic xenolith data from Orapa that are depleted relative to chondrite. The Re-Os isochrons determined in this study are within error of previously reported ages from the adjacent (˜40km) Orapa diamond mine (1.0 to 2.9 Ga) based on sulphide inclusions and a multi-point 990 ± 50 Ma (2SD) isochron for composite (n=730) silicate inclusions. Together with additional new Sm-Nd isochron age determinations from individual silicate inclusions from Letlhakane (2.3 ± 0.02 (n = 3); 1.0 ± 0.14 (n = 4) and 0.25 ± 0.04 Ga (n = 3), all 2SE) these data suggest a phase of Mesoproterozoic diamond formation as well as Neoarchean/Paleoproterozoic and Mesozoic diamond growth, in punctuated events spanning >2.0 Ga.

Diamond brecciation and annealing accompanying major metasomatism in eclogite xenoliths from the Sask Craton, Canada

NASA Astrophysics Data System (ADS)

Czas, Janina; Stachel, Thomas; Pearson, D. Graham; Stern, Richard A.; Read, George H.

2018-05-01

We studied eclogite xenoliths (diamond-free n = 28; diamondiferous n = 22) from the Cretaceous Fort à la Corne Kimberlite Field in Western Canada for their major element, trace element and oxygen isotope compositions to assess their origin and metasomatic history, and possible relationships between metasomatism and diamond formation. All eclogites have major element and oxygen isotope compositions consistent with a derivation from different levels of subducted, seawater altered oceanic crust. While barren xenoliths are more likely to be of gabbroic origin, diamond-bearing samples commonly have signatures consistent with shallow basaltic protoliths. The mineral chemistry in bimineralic diamond-free eclogites spans a wide compositional range, yet it is typically homogenous within individual xenoliths. Temperatures calculated from Mg-Fe exchange between garnet and clinopyroxene range widely for these eclogites, from 740 to 1300 °C, indicating the presence of eclogite through most of the lithospheric mantle. Diamondiferous samples are restricted to high temperatures (1180-1390 °C), consistent with derivation from the zone of diamond stability. Compositionally, diamond-bearing eclogites span a broad range similar to their barren counterparts, but there is also heterogeneity in mineral chemistry on the intra-sample level and in particular garnets are characterised by strong internal chemical gradients. This intra-sample heterogeneity is interpreted as the result of intense melt metasomatism, which occurred in temporal proximity to host kimberlite magmatism, strongly affected major, trace and even oxygen isotope values and resulted in diamond brecciation and annealing.

Structures and Mechanical Properties of Natural and Synthetic Diamonds. Chapter 8

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1998-01-01

A revolution in diamond technology is in progress as the low-pressure process becomes an industrial reality. It will soon be possible to take advantage of the demanding properties of diamond to develop a myriad of new applications, particularly for self-lubricating, wear, and superhard coatings. The production of large diamond films or sheets at low cost, a distinct possibility in the not-too-distant future, may drastically change tribology technology, particularly solid lubricants and lubricating materials and systems. This chapter reviews the structures and properties of natural and synthetic diamond to gain a better understanding of the tribological properties of diamond and related materials to be described in the following chapters. Atomic and crystal structure, impurities, mechanical properties, and indentation hardness of diamond are described.

3-D X-ray tomography of diamondiferous mantle eclogite xenoliths, Siberia: A review

NASA Astrophysics Data System (ADS)

Howarth, Geoffrey H.; Sobolev, Nikolay V.; Pernet-Fisher, John F.; Ketcham, Richard A.; Maisano, Jessica A.; Pokhilenko, Lyudmila N.; Taylor, Dawn; Taylor, Lawrence A.

2015-04-01

Diamonds form over billions of years, hundreds of kilometers beneath the Earth's surface, and in combination with inclusions trapped within, provide important constraints on the evolution of the mantle over geological time. Diamonds are generally studied as individual crystals sourced from highly explosive kimberlite pipes, which entrain and subsequently disaggregate mantle fragments (xenoliths) en route to the surface. This has resulted in a general absence of robust textural descriptions of diamonds relative to their hosting mantle protolith. The textural associations of diamonds within their mantle host rocks are reviewed here on the basis of a compilation of X-ray tomographic data for 17 diamondiferous eclogite xenoliths from Siberian kimberlites. This review represents a comprehensive description of diamonds relative to their host silicates. The lack of such descriptions in previous studies is largely due to the rarity of these xenoliths, the difficulty in preparing petrographic thin sections containing diamonds, and their high-monetary value. High-resolution computed X-ray tomography (HRCXT) produces up to 1200 sequential 2-D slices through individual xenoliths, each of which represents a 'pseudo thin-section' with a resolution on the order of 5-20 μm. The improved resolution of X-ray imaging in recent studies allows for the identification of not only primary minerals, but metasomatic minerals assemblages, including: 'spongy' textured clinopyroxene, phlogopite/K-richterite, and hercynitic spinel, allowing for the delineation of distinct metasomatic pathways through the xenoliths and their relationship to diamonds. Diamonds are observed in three distinct textural settings, potentially representing several temporally distinct diamond growth events, these setting includes: (1) diamonds completely enclosed in garnet; (2) diamonds associated with highly embayed silicate grain boundaries; and (3) diamonds contained within distinct metasomatic 'plumbing-systems'. Diamonds observed completely enclosed in garnets suggest an early diamond-forming event prior to major re-crystallization and eclogite formation during subduction. The occurrence of diamond in association with embayed garnets suggests that diamond grew at the expense of the hosting silicate protolith. In addition, the spatial relationships of diamonds with metasomatic pathways, which are generally interpreted to result from late-stage proto-kimberlitic fluid percolation, indicate a period of diamond growth occurring close to, but prior to, the time of kimberlite emplacement. Furthermore, the paragenesis of sulfides within eclogite xenoliths are described using 3-D models for entire xenoliths volumes, providing important constraints of the timing of sulfide mobilization within the mantle. Three-D animations created using X-ray tomography data for ten of the xenoliths can be viewed at the following link: http://eps.utk.edu/faculty/taylor/tomography.php

Fabrication of diamond based sensors for use in extreme environments

DOE PAGES

Samudrala, Gopi K.; Moore, Samuel L.; Vohra, Yogesh K.

2015-04-23

Electrical and magnetic sensors can be lithographically fabricated on top of diamond substrates and encapsulated in a protective layer of chemical vapor deposited single crystalline diamond. This process when carried out on single crystal diamond anvils employed in high pressure research is termed as designer diamond anvil fabrication. These designer diamond anvils allow researchers to study electrical and magnetic properties of materials under extreme conditions without any possibility of damaging the sensing elements. We describe a novel method for the fabrication of designer diamond anvils with the use of maskless lithography and chemical vapor deposition in this paper. This methodmore » can be utilized to produce diamond based sensors which can function in extreme environments of high pressures, high and low temperatures, corrosive and high radiation conditions. Here, we demonstrate applicability of these diamonds under extreme environments by performing electrical resistance measurements during superconducting transition in rare earth doped iron-based compounds under high pressures to 12 GPa and low temperatures to 10 K.« less

Fabrication of diamond based sensors for use in extreme environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samudrala, Gopi K.; Moore, Samuel L.; Vohra, Yogesh K.

Electrical and magnetic sensors can be lithographically fabricated on top of diamond substrates and encapsulated in a protective layer of chemical vapor deposited single crystalline diamond. This process when carried out on single crystal diamond anvils employed in high pressure research is termed as designer diamond anvil fabrication. These designer diamond anvils allow researchers to study electrical and magnetic properties of materials under extreme conditions without any possibility of damaging the sensing elements. We describe a novel method for the fabrication of designer diamond anvils with the use of maskless lithography and chemical vapor deposition in this paper. This methodmore » can be utilized to produce diamond based sensors which can function in extreme environments of high pressures, high and low temperatures, corrosive and high radiation conditions. Here, we demonstrate applicability of these diamonds under extreme environments by performing electrical resistance measurements during superconducting transition in rare earth doped iron-based compounds under high pressures to 12 GPa and low temperatures to 10 K.« less

Characterization of N-doped polycrystalline diamond films deposited on microgrinding tools

NASA Astrophysics Data System (ADS)

Jackson, M. J.; Ahmed, W.

2005-10-01

Chemical vapor deposited diamond films have many industrial applications but are assuming increasing importance in the area of microengineering, most notably in the development of diamond coated microgrinding tools. For these applications the control of structure and morphology is of critical importance. The crystallite size, orientation, surface roughness, and the degree of sp 3 character have a profound effect on the tribological properties of the films deposited. In this article, we present experimental results on the effects of nitrogen doping on the surface morphology, crystallite size, and wear of microgrinding tools. The sp 3 character optimizes at 200 ppm nitrogen, and above this value the surface becomes much smoother and crystal sizes decrease considerably. Fracture-induced wear of the diamond grain is the most important mechanism of material removal from a microgrinding tool during the grinding process. Fracture occurs as a consequence of tensile stresses induced into diamond grains by grinding forces to which they are subjected. The relationship between the wear of diamond coated grinding tools, component grinding forces, and induced stresses in the model diamond grains is described in detail. A significant correlation was found between the maximum value of tensile stress induced in the diamond grain and the appropriate wheel-wear parameter (grinding ratio). It was concluded that the magnitude of tensile stresses induced in the diamond grain by grinding forces at the rake face is the best indicator of tool wear during the grinding process.

Multi-functional laser fabrication of diamond (Conference Presentation)

NASA Astrophysics Data System (ADS)

Salter, Patrick S.; Booth, Martin J.

2017-03-01

Ultrafast laser fabrication enables micro-structuring of diamond in 3D with a range of functionality. An ultrashort pulsed beam focused beneath the diamond surface induces structural modifications which are highly localised in three dimensions. At high pulse energy, the laser breaks down the diamond lattice at focus to form a graphitic phase. We demonstrate high resolution analysis of the structural changes revealing the graphitic phase to be formed of small clusters ( 100 nm in size) of amorphous sp2 bonded carbon accompanied by localised cracking of the diamond. When the laser focus is traced through the diamond, continuous graphitic wires are created which are electrically conductive. We have used such wires to fabricate large-area 3D radiation sensors which have been employed for the detection of high energy protons. Such graphitic wires have an associated stress field and a related localised modulation of the refractive index. We have recently written combinations of graphitic tracks in diamond to engineer stress fields to give a desired refractive index distribution and form an optical waveguide. Type III waveguides are demonstrated that allow guiding of both polarization states. We also show that by reducing the laser pulse energy, it is possible to avoid complete breakdown of the diamond lattice and simply introduce an ensemble of vacancies within the focal volume. This can be used to create single coherent NV centres in diamond isolated in 3D. All these processes are improved by processing at high numerical aperture (NA), for which adaptive optics aberration correction is essential.

Imaging the atomic structure and local chemistry of platelets in natural type Ia diamond

NASA Astrophysics Data System (ADS)

Olivier, E. J.; Neethling, J. H.; Kroon, R. E.; Naidoo, S. R.; Allen, C. S.; Sawada, H.; van Aken, P. A.; Kirkland, A. I.

2018-03-01

In the past decades, many efforts have been devoted to characterizing {001} platelet defects in type Ia diamond. It is known that N is concentrated at the defect core. However, an accurate description of the atomic structure of the defect and the role that N plays in it is still unknown. Here, by using aberration-corrected transmission electron microscopy and electron energy-loss spectroscopy we have determined the atomic arrangement within platelet defects in a natural type Ia diamond and matched it to a prevalent theoretical model. The platelet has an anisotropic atomic structure with a zigzag ordering of defect pairs along the defect line. The electron energy-loss near-edge fine structure of both carbon K- and nitrogen K-edges obtained from the platelet core is consistent with a trigonal bonding arrangement at interstitial sites. The experimental observations support an interstitial aggregate mode of formation for platelet defects in natural diamond.

Imaging the atomic structure and local chemistry of platelets in natural type Ia diamond.

PubMed

Olivier, E J; Neethling, J H; Kroon, R E; Naidoo, S R; Allen, C S; Sawada, H; van Aken, P A; Kirkland, A I

2018-03-01

In the past decades, many efforts have been devoted to characterizing {001} platelet defects in type Ia diamond. It is known that N is concentrated at the defect core. However, an accurate description of the atomic structure of the defect and the role that N plays in it is still unknown. Here, by using aberration-corrected transmission electron microscopy and electron energy-loss spectroscopy we have determined the atomic arrangement within platelet defects in a natural type Ia diamond and matched it to a prevalent theoretical model. The platelet has an anisotropic atomic structure with a zigzag ordering of defect pairs along the defect line. The electron energy-loss near-edge fine structure of both carbon K- and nitrogen K-edges obtained from the platelet core is consistent with a trigonal bonding arrangement at interstitial sites. The experimental observations support an interstitial aggregate mode of formation for platelet defects in natural diamond.

Diamond synthesis at atmospheric pressure by microwave capillary plasma chemical vapor deposition

NASA Astrophysics Data System (ADS)

Hemawan, Kadek W.; Gou, Huiyang; Hemley, Russell J.

2015-11-01

Polycrystalline diamond has been synthesized on silicon substrates at atmospheric pressure, using a microwave capillary plasma chemical vapor deposition technique. The CH4/Ar plasma was generated inside of quartz capillary tubes using 2.45 GHz microwave excitation without adding H2 into the deposition gas chemistry. Electronically excited species of CN, C2, Ar, N2, CH, Hβ, and Hα were observed in the emission spectra. Raman measurements of deposited material indicate the formation of well-crystallized diamond, as evidenced by the sharp T2g phonon at 1333 cm-1 peak relative to the Raman features of graphitic carbon. Field emission scanning electron microscopy images reveal that, depending on the growth conditions, the carbon microstructures of grown films exhibit "coral" and "cauliflower-like" morphologies or well-facetted diamond crystals with grain sizes ranging from 100 nm to 10 μm.

Charge transport properties of intrinsic layer in diamond vertical pin diode

NASA Astrophysics Data System (ADS)

Shimaoka, Takehiro; Kuwabara, Daisuke; Hara, Asuka; Makino, Toshiharu; Tanaka, Manobu; Koizumi, Satoshi

2017-05-01

Diamond is hoped to be utilized in ultimate power electronic devices exhibiting ultra-high blocking voltages. For practical device formation, it is important to characterize the electric properties to precisely simulate carrier transport and to practically design optimum device structures. In this study, we experimentally evaluated the charge transport properties of intrinsic layers in diamond vertical pin diodes using alpha-particle induced charge distribution measurements. The charge collection efficiencies were 98.1 ± 0.6% for a {111} pin diode and 96.9 ± 0.6% for a {100} pin diode, which means that almost all generated charges are collected accordingly equivalent to conventional Silicon pin photodiodes. Mobility-lifetime (μτ) products of holes were (2.2 ± 0.3) × 10-6 cm2/V for {111} and (1.8 ± 0.1) × 10-5 cm2/V for {100} diamond pin diodes.

Diamond synthesis at atmospheric pressure by microwave capillary plasma chemical vapor deposition

DOE PAGES

Gou, Huiyang; Hemley, Russell J.; Hemawan, Kadek W.

2015-11-02

Polycrystalline diamond has been successfully synthesized on silicon substrates at atmospheric pressure using a microwave capillary plasma chemical vapor deposition technique. The CH 4/Ar plasma was generated inside of quartz capillary tubes using 2.45 GHz microwave excitation without adding H2 into the deposition gas chemistry. Electronically excited species of CN, C 2, Ar, N 2, CH, H β and H α were observed in emission spectra. Raman measurements of deposited material indicate the formation of well-crystallized diamond, as evidenced by the sharp T 2g phonon at 1333 cm -1 peak relative to the Raman features of graphitic carbon. Furthermore, fieldmore » emission scanning electron microscopy (SEM) images reveal that, depending on the on growth conditions, the carbon microstructures of grown films exhibit “coral” and “cauliflower-like” morphologies or well-facetted diamond crystals with grain sizes ranging from 100 nm to 10 μm.« less

Origins of diamond-forming fluids: An isotopic and trace element study of diamonds and silicates from diamondiferous xenoliths

NASA Astrophysics Data System (ADS)

Laiginhas, Fernando; Pearson, D. Graham; McNeill, John; Gurney, John; Nowell, Geoff; Ottley, Chris

2010-05-01

While there is increasing understanding of the age of formation and nature of "gem" diamonds, significant debate revolves around the nature of the fluids/melts from which they form. Stable C and N isotopes have been shown to be highly variable and yet the role of subduction-related fluids remains strongly debated. Recent studies on fibrous diamonds have yielded new trace and major element data (e.g., Weiss et al., 2009) that, together with new radiogenic isotope data (Klein BenDavid et al., 2010) indicate such diamonds grow from fluids that comprise mixtures of hydrous silicic, hydrous saline and carbonatitic fluids, derived from different source components of asthenospheric and lithospheric origin. However, until now such data has been lacking from gem diamonds. Using a new laser-based technique (McNeill et al., 2009), we have analysed a suite of diamonds plus co-existing host silicates from several diamondiferous xenoliths (6 harzburgites, 1 eclogite) from the Finsch and Newlands kimberlites in order to try to understand the fluid compositions that produce gem diamonds and better understand their effects of their mantle wall rocks. Diamonds from the xenoliths show a wide variety of trace element enrichment levels. While the eclogitic diamond shows similar trace element systematics to some of the harzburgitic diamonds there are significant differences within the harzburgitic diamonds from different xenoliths, with those from Finsch being significantly enriched in Ba, Sr and Pb relative to other elements. Nd isotope data on the host silicates is variable and dominantly unradiogenic, indicative of long-term enrichment typically associated with the source of some diamond-forming fluids. We will present Sr isotopic data on host silicates and diamond fluids to constrain whether the "gem" diamonds require the complex sources of fluids that characterise the growth of fibrous diamonds. 1) Y. Weiss, R. Kessel, W.L. Griffin, I. Kiflawi, O. Klein-BenDavid, D.R. Bell, J.W. Harris and O. Navon (2009). A new model for the evolution of diamond-forming fluids: Evidence from microinclusion-bearing diamonds from Kankan, Guinea. Lithos 112, Supp. 2: 660-674. 2) O. Klein-BenDavid, D.G. Pearson, G.M. Nowell, C. Ottley, J.C.R. McNeill, P. Cartigny (2010). Mixed fluid sources involved in diamond growth constrained by Sr-Nd-Pb-C-N isotopes and trace elements. EPSL 289, 1-2: 123-133. 3) J. McNeill, D.G. Pearson, O. Klein-BenDavid, G.M. Nowell, C.J. Ottley and I. Chinn (2009). Quantitative analysis of trace element concentrations in some gem-quality diamonds. J. Phys.: Condens. Matter 21: 364207 (13pp).

A Solar-Blind UV Detector Based on Graphene-Microcrystalline Diamond Heterojunctions.

PubMed

Wei, Minsong; Yao, Kaiyuan; Liu, Yumeng; Yang, Chen; Zang, Xining; Lin, Liwei

2017-09-01

An ultraviolet detector is demonstrated through a whole-wafer, thin diamond film transfer process to realize the heterojunction between graphene and microcrystalline diamond (MCD). Conventional direct transfer processes fail to deposit graphene onto the top surface of the MCD film. However, it is found that the 2 µm thick MCD diamond film can be easily peeled off from the growth silicon substrate to expose its smooth backside for the graphene transfer process for high-quality graphene/MCD heterojunctions. A vertical graphene/MCD/metal structure is constructed as the photodiode device using graphene as the transparent top electrode for solar-blind ultraviolet sensing with high responsivity and gain factor. As such, this material system and device architecture could serve as the platform for next-generation optoelectronic systems. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oxidation and adduct formation of xenobiotics in a microfluidic electrochemical cell with boron doped diamond electrodes and an integrated passive gradient rotation mixer.

PubMed

van den Brink, Floris T G; Wigger, Tina; Ma, Liwei; Odijk, Mathieu; Olthuis, Wouter; Karst, Uwe; van den Berg, Albert

2016-10-05

Reactive xenobiotic metabolites and their adduct formation with biomolecules such as proteins are important to study as they can be detrimental to human health. Here, we present a microfluidic electrochemical cell with integrated micromixer to study phase I and phase II metabolism as well as protein adduct formation of xenobiotics in a purely instrumental approach. The newly developed microfluidic device enables both the generation of reactive metabolites through electrochemical oxidation and subsequent adduct formation with biomolecules in a chemical microreactor. This allows us to study the detoxification of reactive species with glutathione and to predict potential toxicity of xenobiotics as a result of protein modification. Efficient mixing in microfluidic systems is a slow process due to the typically laminar flow conditions in shallow channels. Therefore, a passive gradient rotation micromixer has been designed that is capable of mixing liquids efficiently in a 790 pL volume within tens of milliseconds. The mixing principle relies on turning the concentration gradient that is initially established by bringing together two streams of liquid, to take advantage of the short diffusion distances in the shallow microchannels of thin-layer flow cells. The mixer is located immediately downstream of the working electrode of an electrochemical cell with integrated boron doped diamond electrodes. In conjunction with mass spectrometry, the two microreactors integrated in a single device provide a powerful tool to study the metabolism and toxicity of xenobiotics, which was demonstrated by the investigation of the model compound 1-hydroxypyrene.

Tribology: Diamonds are forever - or are they?

NASA Astrophysics Data System (ADS)

Fineberg, Jay

2011-01-01

The friction and wear of materials is part of our everyday experience, and yet these processes are not well understood. The example of diamond highlights wear processes that result from bumping atoms, showing that the devil is indeed in the details.

The chemo-mechanical effect of cutting fluid on material removal in diamond scribing of silicon

NASA Astrophysics Data System (ADS)

Kumar, Arkadeep; Melkote, Shreyes N.

2017-07-01

The mechanical integrity of silicon wafers cut by diamond wire sawing depends on the damage (e.g., micro-cracks) caused by the cutting process. The damage type and extent depends on the material removal mode, i.e., ductile or brittle. This paper investigates the effect of cutting fluid on the mode of material removal in diamond scribing of single crystal silicon, which simulates the material removal process in diamond wire sawing of silicon wafers. We conducted scribing experiments with a diamond tipped indenter in the absence (dry) and in the presence of a water-based cutting fluid. We found that the cutting mode is more ductile when scribing in the presence of cutting fluid compared to dry scribing. We explain the experimental observations by the chemo-mechanical effect of the cutting fluid on silicon, which lowers its hardness and promotes ductile mode material removal.

Nano-crystalline diamond-coated titanium dental implants - a histomorphometric study in adult domestic pigs.

PubMed

Metzler, Philipp; von Wilmowsky, Cornelius; Stadlinger, Bernd; Zemann, Wolfgang; Schlegel, Karl Andreas; Rosiwal, Stephan; Rupprecht, Stephan

2013-09-01

Promising biomaterial characteristics of diamond-coatings in biomedicine have been described in the literature. However, there is a lack of knowledge about implant osseointegration of this surface modification compared to the currently used sandblasted acid-etched Ti-Al6-V4 implants. The aim of this study was to investigate the osseointegration of microwave plasma-chemical-vapour deposition (MWP-CVD) diamond-coated Ti-Al6-V4 dental implants after healing periods of 2 and 5 months. Twenty-four MWP-CVD diamond-coated and 24 un-coated dental titanium-alloy implants (Ankylos(®)) were placed in the frontal skull of eight adult domestic pigs. To evaluate the effects of the nano-structured surfaces on bone formation, a histomorphometric analysis was performed after 2 and 5 months of implant healing. Histomorphometry analysed the bone-to-implant contact (BIC). No significant difference in BIC for the diamond-coated implants in comparison to reference implants could be observed for both healing periods. Scanning electron microscopy revealed an adequate interface between the bone and the diamond surface. No delamination or particle-dissociation due to shearing forces could be detected. In this study, diamond-coated dental titanium-alloy implants and sandblasted acid-etched implants showed a comparable degree of osseointegration. Copyright © 2012 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Optical characterization of single-crystal diamond grown by DC arc plasma jet CVD

NASA Astrophysics Data System (ADS)

Hei, Li-fu; Zhao, Yun; Wei, Jun-jun; Liu, Jin-long; Li, Cheng-ming; Lü, Fan-xiu

2017-12-01

Optical centers of single-crystal diamond grown by DC arc plasma jet chemical vapor deposition (CVD) were examined using a low-temperature photoluminescence (PL) technique. The results show that most of the nitrogen-vacancy (NV) complexes are present as NV- centers, although some H2 and H3 centers and B-aggregates are also present in the single-crystal diamond because of nitrogen aggregation resulting from high N2 incorporation and the high mobility of vacancies under growth temperatures of 950-1000°C. Furthermore, emissions of radiation-induced defects were also detected at 389, 467.5, 550, and 588.6 nm in the PL spectra. The reason for the formation of these radiation-induced defects is not clear. Although a Ni-based alloy was used during the diamond growth, Ni-related emissions were not detected in the PL spectra. In addition, the silicon-vacancy (Si-V)-related emission line at 737 nm, which has been observed in the spectra of many previously reported microwave plasma chemical vapor deposition (MPCVD) synthetic diamonds, was absent in the PL spectra of the single-crystal diamond prepared in this work. The high density of NV- centers, along with the absence of Ni-related defects and Si-V centers, makes the single-crystal diamond grown by DC arc plasma jet CVD a promising material for applications in quantum computing.

Ultra-Smooth Nanostructured Diamond Films Deposited from He/H2/CH4/N2 Microwave Plasmas

PubMed Central

Konovalov, Valery V.; Melo, Andrew; Catledge, Shane A.; Chowdhury, Shafiul

2008-01-01

Addition of He to a high CH4 content (10.7 vol%) H2/CH4/N2 feedgas mixture for microwave plasma chemical vapor deposition produced hard (56–72 GPa), ultra-smooth nanostructured diamond films on Ti-6Al-4V alloy substrates. Upon increase in He content up to 71 vol%, root mean squared (RMS) surface roughness of the film decreased to 9–10 nm and average diamond grain size to 5–6 nm. Our studies show that increased nanocrystallinity with He addition in plasma is related to plasma dilution, enhanced fragmentation of carbon containing species, and enhanced formation of CN radical. PMID:16573106

Effect of the quantum zero-point atomic motion on the optical and electronic properties of diamond and trans-polyacetylene.

PubMed

Cannuccia, Elena; Marini, Andrea

2011-12-16

The quantum zero-point motion of the carbon atoms is shown to induce strong effects on the optical and electronic properties of diamond and trans-polyacetylene, a conjugated polymer. By using an ab initio approach, we interpret the subgap states experimentally observed in diamond in terms of entangled electron-phonon states. These states also appear in trans-polyacetylene causing the formation of strong structures in the band structure that even call into question the accuracy of the band theory. This imposes a critical revision of the results obtained for carbon-based nanostructures by assuming the atoms frozen in their equilibrium positions. © 2011 American Physical Society

Genesis of diamond inclusions: An integrated cathodoluminescence (CL) and Electron backscatter diffraction (EBSD) study on eclogitic and peridotitic inclusions and their diamond host.

NASA Astrophysics Data System (ADS)

van den Heuvel, Quint; Matveev, Sergei; Drury, Martyn; Gress, Michael; Chinn, Ingrid; Davies, Gareth

2017-04-01

Diamond inclusions are potentially fundamental to understanding the formation conditions of diamond and the volatile cycles in the deep mantle. In order to fully understand the implications of the compositional information recorded by inclusions it is vital to know whether the inclusions are proto-, syn-, or epigenetic and the extent to which they have equilibrated with diamond forming fluids. In previous studies, the widespread assumption was made that the majority of diamond inclusions are syngenetic, based upon observation of cubo-octahedral morphology imposed on the inclusions. Recent work has reported the crystallographic relationship between inclusions and the host diamond to be highly complex and the lack of crystallographic relationships between inclusions and diamonds has led some to question the significance of imposed cubo-octahedral morphology. This study presents an integrated EBSD and CL study of 9 diamonds containing 20 pyropes, 2 diopsides, 1 forsterite and 1 rutile from the Jwaneng and Letlhakane kimberlite clusters, Botswana. A new method was developed to analyze the crystallographic orientation of the host diamond and the inclusions with EBSD. Diamonds plates were sequentially polished to expose inclusions at different levels in the diamond. CL imaging at different depths was performed in order to produce a 3D view of diamond growth zones around the inclusions. Standard diamond polishing techniques proved too aggressive for silicate inclusions as they were damaged to such a degree that EBSD measurements on the inclusions were impossible. The inclusions were milled with a Ga+ focused ion beam (FIB) at a 12° angle to clean the surface for EBSD measurements. Of the 24 inclusions, 9 have an imposed cubo-octahedral morphology. Of these inclusions, 6 have faces orientated parallel to diamond growth zones and/or appear to have nucleated on a diamond growth surface, implying syngenesis. In contrast, other diamonds record resorption events such that inclusions now cut diamond growth zones. In most cases, the growth zonation around inclusions is not well defined due to CL haloes but some inclusions clearly disrupt diamond growth. Crystallographic orientations of diamond and the inclusions, determined using EBSD, revealed that each inclusion has a homogeneous orientation and record no compositional zonation. The diamonds also showed no angular deviations despite many having multiple growth and resorption zones; implying epitaxial growth of diamond. Crystallographic alignment between diamond and inclusions was not recorded for the principle planes and limited to 3 possible coincidences on minor planes from the 24 inclusions studied. The CL data show no evidence of syngenesis for these 3 inclusions. Analyses of two diamonds with inclusion clusters in different growth zones, 400 µm apart, revealed the same chemical composition and orientation, potentially implying they originated from an original larger inclusion. Combined EBSD and CL data suggest that there is no direct orientational correlation (epitaxial growth) between silicate inclusions and the host diamond, even when the mineral phases are of the same symmetry group. The presentation will provide a detailed evaluation of the genesis of individual inclusions.

Diamond deposition using a planar radio frequency inductively coupled plasma

NASA Astrophysics Data System (ADS)

Bozeman, S. P.; Tucker, D. A.; Stoner, B. R.; Glass, J. T.; Hooke, W. M.

1995-06-01

A planar radio frequency inductively coupled plasma has been used to deposit diamond onto scratched silicon. This plasma source has been developed recently for use in large area semiconductor processing and holds promise as a method for scale up of diamond growth reactors. Deposition occurs in an annulus which coincides with the area of most intense optical emission from the plasma. Well-faceted diamond particles are produced when the substrate is immersed in the plasma.

Morphological Transition in Diamond Thin-Films Induced by Boron in a Microwave Plasma Deposition Process.

PubMed

Baker, Paul A; Goodloe, David R; Vohra, Yogesh K

2017-11-14

The purpose of this study is to understand the basic mechanisms responsible for the synthesis of nanostructured diamond films in a microwave plasma chemical vapor deposition (MPCVD) process and to identify plasma chemistry suitable for controlling the morphology and electrical properties of deposited films. The nanostructured diamond films were synthesized by MPCVD on Ti-6Al-4V alloy substrates using H₂/CH₄/N₂ precursor gases and the plasma chemistry was monitored by the optical emission spectroscopy (OES). The synthesized thin-films were characterized by x -ray diffraction and scanning electron microscopy. The addition of B₂H₆ to the feedgas during MPCVD of diamond thin-films changes the crystal grain size from nanometer to micron scale. Nanostructured diamond films grown with H₂/CH₄/N₂ gases demonstrate a broad (111) Bragg x -ray diffraction peak (Full-Width at Half-Maximum (FWHM) = 0.93° 2θ), indicating a small grain size, whereas scans show a definite sharpening of the diamond (111) peak (FWHM = 0.30° 2θ) with the addition of boron. OES showed a decrease in CN (carbon-nitrogen) radical in the plasma with B₂H₆ addition to the gas mixture. Our study indicates that CN radical plays a critical role in the synthesis of nanostructured diamond films and suppression of CN radical by boron-addition in the plasma causes a morphological transition to microcrystalline diamond.

Plasma spraying method for forming diamond and diamond-like coatings

DOEpatents

Holcombe, C.E.; Seals, R.D.; Price, R.E.

1997-06-03

A method and composition is disclosed for the deposition of a thick layer of diamond or diamond-like material. The method includes high temperature processing wherein a selected composition including at least glassy carbon is heated in a direct current plasma arc device to a selected temperature above the softening point, in an inert atmosphere, and is propelled to quickly quenched on a selected substrate. The softened or molten composition crystallizes on the substrate to form a thick deposition layer comprising at least a diamond or diamond-like material. The selected composition includes at least glassy carbon as a primary constituent and may include at least one secondary constituent. Preferably, the secondary constituents are selected from the group consisting of at least diamond powder, boron carbide (B{sub 4}C) powder and mixtures thereof. 9 figs.

Volatile Composition and Odour-Activity Value of Thornless 'Black Diamond' and 'Marion' Blackberries

USDA-ARS?s Scientific Manuscript database

'Black Diamond' is a recently developed thornless blackberry cultivar with large fruit size, high yield, and good processed fruit quality that has rapidly become an industry standard. The flavour of 'Black Diamond' fruit is not the same as 'Marion', which is regarded by the industry as having the id...

Process for the formation of wear- and scuff-resistant carbon coatings

DOEpatents

Malaczynski, Gerard W.; Qiu, Xiaohong; Mantese, Joseph V.; Elmoursi, Alaa A.; Hamdi, Aboud H.; Wood, Blake P.; Walter, Kevin C.; Nastasi, Michael A.

1995-01-01

A process for forming an adherent diamond-like carbon coating on a workpiece of suitable material such as an aluminum alloy is disclosed. The workpiece is successively immersed in different plasma atmospheres and subjected to short duration, high voltage, negative electrical potential pulses or constant negative electrical potentials or the like so as to clean the surface of oxygen atoms, implant carbon atoms into the surface of the alloy to form carbide compounds while codepositing a carbonaceous layer on the surface, bombard and remove the carbonaceous layer, and to thereafter deposit a generally amorphous hydrogen-containing carbon layer on the surface of the article.

Tracking Crust-Mantle Recycling through Superdeep Diamonds and their Mineral Inclusions

NASA Astrophysics Data System (ADS)

Walter, Michael; Bulanova, Galina; Smith, Chris; Thomson, Andrew; Kohn, Simon; Burnham, Antony

2013-04-01

Sublithospheric, or 'superdeep' diamonds, originate in the deep upper mantle, transition zone, and at least as deep as the shallow lower mantle. When diamonds crystallize in the mantle from fluids or melts they occasionally entrap coexisting mineral phases. Because of their great physical resiliency, diamonds can potentially preserve information over long distance- and time-scales, revealing important information about the petrologic, tectonic and geodynamic environment in which the diamonds grew and were transported. Superdeep diamonds and their inclusions have proven especially powerful for probing processes related to subduction of slabs into the deep mantle [1-3]. In contrast to lithospheric diamonds that are effectively frozen-in geodynamically, mineral inclusions in superdeep diamonds often record hundreds of kilometers of uplift in the convecting mantle from their original depth of origin [3-5]. The phase equilibria of unmixing of original deep mantle phases such as Ca- and Mg-perovskite, NAL-phase, CF-phase, CAS-phase, and majorite provide a means to establish amounts of uplift. The few available age constraints indicate superdeep diamond growth from the Proterozoic to the Cretaceous, and further dating can potentially lead to constraining mantle upwelling rates [4]. Here we will provide several examples showing how superdeep diamonds and their inclusions record processes of subduction and slab foundering, and ultimately recycling of slab material from the transition zone and lower mantle into the shallow upper mantle. 1. Harte, B., Mineralogical Magazine, 2010. 74: p. 189-215. 2. Tappert, R., et al., Geology, 2005. 33: p. 565-568. 3. Walter, M.J., et al., Science, 2011. 333: p. 54-57. 4. Bulanova, G.P., et al., Contributions to Mineralogy and Petrology, 2010. 160: p. 489-510. 5. Harte, B. and N. Cayzer, Physics and Chemistry of Minerals, 2007.

Method and apparatus for diamond wire cutting of metal structures

DOEpatents

Parsells, Robert; Gettelfinger, Geoff; Perry, Erik; Rule, Keith

2005-04-19

A method and apparatus for diamond wire cutting of metal structures, such as nuclear reactor vessels, is provided. A diamond wire saw having a plurality of diamond beads with beveled or chamfered edges is provided for sawing into the walls of the metal structure. The diamond wire is guided by a plurality of support structures allowing for a multitude of different cuts. The diamond wire is cleaned and cooled by CO.sub.2 during the cutting process to prevent breakage of the wire and provide efficient cutting. Concrete can be provided within the metal structure to enhance cutting efficiency and reduce airborne contaminants. The invention can be remotely controlled to reduce exposure of workers to radioactivity and other hazards.

Redox Equilibria Involving Chromium Minerals in Aqueous Fluids in the Deep Earth - Implications for Diamond Formation

NASA Astrophysics Data System (ADS)

Huang, J.; Huang, F.; Hao, J.; Sverjensky, D. A.

2017-12-01

Diamonds are often associated with inclusions of garnet that are characteristically Cr-rich and Ca-poor, suggesting metasomatic reactions involving fluids [1]. To investigate these reactions, we developed a thermodynamic characterization of Cr-bearing minerals and integrated it with our database for the thermodynamic properties of aqueous Cr-species [2]. We retrieved thermodynamic properties of picrochromite (MgCr2O4), and knorringite (Mg3Cr2Si3O12) consistent with minerals in the Berman (1988) using calorimetric data and experimental phase equilibria involving the reactions: MgCr2O4 + SiO2 = Cr2O3 + MgSiO3 [2] and MgCr2O4 + 4MgSiO3 = Mg3Cr2Si3O12 + Mg2SiO4 [3], respectively.At high temperatures and pressures, neutral pH and FMQ, the predicted solubilities of eskolaite and knorringite equilibrium with Cr2+ in a pure water system are very low. However, we found that complexes of Cr2+ and Cl- could increase the solubilities of chromium minerals significantly. At 500°C and 0.2 - 1.0 GPa, we retrieved the CrCl(OH)0 neutral complex from experiments on the solubility of Cr2O3 in HCl solutions [4]. At 1,000°C and 4.0 GPa, we retrieved the properties of a CrCl3- complex from experiments on the solubility of Cr2O3 in KCl solutions [5]. The predicted solubility of a garnet containing 23 mole% of knorringite in equilibrium with CrCl3- in a peridotitic diamond-forming fluid is 22 millimolal (1,144 ppm). This result suggests that a redox reaction relating to diamond formation might involveMg3Al2Si3O12 + 0.5CO2(aq) + 2 CrCl3- + 2H+ = Mg3Cr2Si3O12 + 0.5C-Diamond + 2Al3+ + 6Cl-. In this way, high temperature and pressure fluids containing Cr(II)-complexes might promote the mobility of chromium and be involved in metasomatic reactions and diamond formation.[1]Boyd et al. (1993)[2] Hao et al. (submitted to Geochem. Persp. Letters)[3] Berman (1988)[4] Klemme et al. (2000)[5] Klemme et al. (2004)[6] Watenphul et al. (2014)[7] Klein-BenDavid et al. (2011)

Low water contents in diamond mineral inclusions: Proto-genetic origin in a dry cratonic lithosphere

NASA Astrophysics Data System (ADS)

Taylor, Lawrence A.; Logvinova, Alla M.; Howarth, Geoffrey H.; Liu, Yang; Peslier, Anne H.; Rossman, George R.; Guan, Yunbin; Chen, Yang; Sobolev, Nikolay V.

2016-01-01

The mantle is the major reservoir of Earth's water, hosted within Nominally Anhydrous Minerals (NAMs) (e.g., Bell and Rossman, 1992; Peslier et al., 2010; Peslier, 2010; Nestola and Smyth, 2015), in the form of hydrogen bonded to the silicate's structural oxygen. From whence cometh this water? Is the water in these minerals representative of the Earth's primitive upper mantle or did it come from melting events linked to crustal formation or to more recent metasomatic/re-fertilization events? During diamond formation, NAMs are encapsulated at hundreds of kilometers depth within the mantle, thereby possibly shielding and preserving their pristine water contents from re-equilibrating with fluids and melts percolating through the lithospheric mantle. Here we show that the NAMs included in diamonds from six locales on the Siberian Craton contain measurable and variable H2O concentrations from 2 to 34 parts per million by weight (ppmw) in olivine, 7 to 276 ppmw in clinopyroxene, and 11-17 ppmw in garnets. Our results suggest that if the inclusions were in equilibrium with the diamond-forming fluid, the water fugacity would have been unrealistically low. Instead, we consider the H2O contents of the inclusions, shielded by diamonds, as pristine representatives of the residual mantle prior to encapsulation, and indicative of a protogenetic origin for the inclusions. Hydrogen diffusion in the diamond does not appear to have modified these values significantly. The H2O contents of NAMs in mantle xenoliths may represent some later metasomatic event(s), and are not always representative of most of the continental lithospheric mantle. Results from the present study also support the conclusions of Peslier et al. (2010) and Novella et al. (2015) that the dry nature of the SCLM of a craton may provide stabilization of its thickened continental roots.

Deposition of diamond-like films by ECR microwave plasma

NASA Technical Reports Server (NTRS)

Shing, Yuh-Han (Inventor); Pool, Frederick S. (Inventor)

1995-01-01

Hard amorphous hydrogenated carbon, diamond-like films are deposited using an electron cyclotron resonance microwave plasma with a separate radio frequency power bias applied to a substrate stage. The electron cyclotron resonance microwave plasma yields low deposition pressure and creates ion species otherwise unavailable. A magnetic mirror configuration extracts special ion species from a plasma chamber. Different levels of the radio frequency power bias accelerate the ion species of the ECR plasma impinging on a substrate to form different diamond-like films. During the deposition process, a sample stage is maintained at an ambient temperature of less than 100.degree. C. No external heating is applied to the sample stage. The deposition process enables diamond-like films to be deposited on heat-sensitive substrates.

Synthesis of ultra-nano-carbon composite materials with extremely high conductivity by plasma post-treatment process of ultrananocrystalline diamond films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yeh, Chien-Jui; Leou, Keh-Chyang; Manoharan, Divinah

2015-08-24

Needle-like diamond grains encased in nano-graphitic layers are an ideal granular structure of diamond films to achieve high conductivity and superior electron field emission (EFE) properties. This paper describes the plasma post-treatment (ppt) of ultrananocrystalline diamond (UNCD) films at low substrate temperature to achieve such a unique granular structure. The CH{sub 4}/N{sub 2} plasma ppt-processed films exhibit high conductivity of σ = 1099 S/cm as well as excellent EFE properties with turn-on field of E{sub 0} = 2.48 V/μm (J{sub e} = 1.0 mA/cm{sup 2} at 6.5 V/μm). The ppt of UNCD film is simple and robust process that is especially useful for device applications.

Ion Beam Processing of Diamond

DTIC Science & Technology

1990-05-07

Diamond structure. We can make ohmic contacts to silicon . If we could tailor the structure from Si to Si. C,-, to diamond, we should be able to form a low...func- ricr injection. Refractory metals such as tantalum. tung- tion of contact spacing. Extrapolation of the data to zero sten , or titanium have also...layer of the diamond could be miade n-type gallium nitride. and silicon carbide.- Mater. Sci. Fng.. vol. 91, pp.77-104.1(998. with a five to six orders

Combination process of diamond machining and roll-to-roll UV-replication for thin film micro- and nanostructures

NASA Astrophysics Data System (ADS)

Väyrynen, J.; Mönkkönen, K.; Siitonen, S.

2016-09-01

Roll-to-roll (R2R) ultraviolet (UV) curable embossing replication process is a highly accurate and cost effective way to replicate large quantities of thin film polymer parts. These structures can be used for microfluidics, LED-optics, light guides, displays, cameras, diffusers, decorative, laser sensing and measuring devices. In the R2R UV-process, plastic thin film coated with UV-curable lacquer, passes through an imprinting embossing drum and is then hardened by an UV-lamp. One key element for mastering this process is the ability to manufacture a rotating drum containing micro- and nanostructures. Depending on the pattern shapes, the drum can be directly machined by diamond machining or it can be done through wafer level lithographical process. Due to the shrinkage of UV-curable lacquer, the R2R drum pattern process needs to be prototyped few times, in order to get the desired performance and shape from the R2R produced part. To speed up the prototyping and overall process we have developed a combination process where planar diamond machining patterns are being turned into a drum roller. Initially diamond machined patterns from a planar surface are replicated on a polymer sheet using UV-replication. Secondly, a nickel stamper shim is grown form the polymer sheet and at the end the stamper is turned into a roller and used in the R2R process. This process allows various micro milled, turned, grooved and ruled structures to be made at thin film products through the R2R process. In this paper, the process flow and examples of fabricating R2R embossed UVcurable thin film micro- and nanostructures from planar diamond machined patterns, is reported.

Selected Topics in CVD Diamond Research

NASA Astrophysics Data System (ADS)

Koizumi, Satoshi; Nebel, Christoph E.; Nesladek, Milos

2006-10-01

Since the discovery of Chemical Vapor Deposition (CVD) diamond growth in 1976, the steady scientific progress often resulted in surprising new discoveries and breakthroughs. This brought us to the idea to publish the special issue Selected Topics in CVD Diamond Research in physica status solidi (a), reflecting such advancements and interesting results at the leading edge of diamond research.The present issue summarizes this progress in the CVD diamond field by selecting contributions from several areas such as superconductivity, super-excitonic radiation, quantum computing, bio-functionalization, surface electronic properties, the nature of phosphorus doping, transport properties in high energy detectors, CVD growth and properties of nanocrystalline diamond. In all these directions CVD diamond appears to be very competitive in comparison with other semiconducting materials.As Editors of this special issue, we must admit that the selection is biased by our opinion. Nonetheless, we are sure that each contribution introduces new ideas and results which will improve the understanding of the current level of physics and chemistry of this attractive wide-bandgap semiconductor and which will help to bring it closer to applications.All submissions were invited based on the contributions of the authors to their specific research field. The Feature Articles have the format of topical reviews to give the reader a comprehensive summary. Partially, however, they are written in research paper style to report new results of ongoing research.We hope that this issue will attract the attention of a broad community of scientists and engineers, and that it will facilitate the utilization of diamond in electronic applications and technologies of the future.

Development of a templated approach to fabricate diamond patterns on various substrates.

PubMed

Shimoni, Olga; Cervenka, Jiri; Karle, Timothy J; Fox, Kate; Gibson, Brant C; Tomljenovic-Hanic, Snjezana; Greentree, Andrew D; Prawer, Steven

2014-06-11

We demonstrate a robust templated approach to pattern thin films of chemical vapor deposited nanocrystalline diamond grown from monodispersed nanodiamond (mdND) seeds. The method works on a range of substrates, and we herein demonstrate the method using silicon, aluminum nitride (AlN), and sapphire substrates. Patterns are defined using photo- and e-beam lithography, which are seeded with mdND colloids and subsequently introduced into microwave assisted chemical vapor deposition reactor to grow patterned nanocrystalline diamond films. In this study, we investigate various factors that affect the selective seeding of different substrates to create high quality diamond thin films, including mdND surface termination, zeta potential, surface treatment, and plasma cleaning. Although the electrostatic interaction between mdND colloids and substrates is the main process driving adherence, we found that chemical reaction (esterification) or hydrogen bonding can potentially dominate the seeding process. Leveraging the knowledge on these different interactions, we optimize fabrication protocols to eliminate unwanted diamond nucleation outside the patterned areas. Furthermore, we have achieved the deposition of patterned diamond films and arrays over a range of feature sizes. This study contributes to a comprehensive understanding of the mdND-substrate interaction that will enable the fabrication of integrated nanocrystalline diamond thin films for microelectronics, sensors, and tissue culturing applications.

Synthesis of SiV-diamond particulates via the microwave plasma chemical deposition of ultrananocrystalline diamond on soda-lime glass fibers

NASA Astrophysics Data System (ADS)

Kunuku, Srinivasu; Chen, Yen-Chun; Yeh, Chien-Jui; Chang, Wen-Hao; Manoharan, Divinah; Leou, Keh-Chyang; Lin, I.-Nan

2016-10-01

We report the synthesis of silicon-vacancy (SiV) incorporated spherical shaped ultrananocrystalline diamond (SiV-UNCD) particulates (size ∼1 μm) with bright luminescence at 738 nm. For this purpose, different granular structured polycrystalline diamond films and particulates were synthesized by using three different kinds of growth plasma conditions on the three types of substrate materials in the microwave plasma enhanced CVD process. The grain size dependent photoluminescence properties of nitrogen vacancy (NV) and SiV color centers have been investigated for different granular structured diamond samples. The luminescence of NV center and the associated phonon sidebands, which are usually observed in microcrystalline diamond and nanocrystalline diamond films, were effectively suppressed in UNCD films and UNCD particulates. Micron sized SiV-UNCD particulates with bright SiV emission has been attained by transfer of SiV-UNCD clusters on soda-lime glass fibers to inverted pyramidal cavities fabricated on Si substrates by the simple crushing of UNCD/soda-lime glass fibers in deionized water and ultrasonication. Such a plasma enhanced CVD process for synthesizing SiV-UNCD particulates with suppressed NV emission is simple and robust to attain the bright SiV-UNCD particulates to employ in practical applications.

Diamond- cBN alloy: A universal cutting material

DOE PAGES

Wang, Pei; He, Duanwei; Wang, Liping; ...

2015-09-08

Diamond and cubic boron nitride ( cBN) as conventional superhard materials have found widespread industrial applications, but both have inherent limitations. Diamond is not suitable for high-speed cutting of ferrous materials due to its poor chemical inertness, while cBN is only about half as hard as diamond. Because of their affinity in structural lattices and covalent bonding character, diamond and cBN could form alloys that can potentially fill the performance gap. However, the idea has never been demonstrated because samples obtained in the previous studies were too small to be tested for their practical performance. Here, we report the synthesismore » and characterization of transparent bulk diamond- cBN alloy compacts whose diameters (3 mm) are sufficiently large for them to be processed into cutting tools. The testing results show that the diamond- cBN alloy has superior chemical inertness over polycrystalline diamond and higher hardness than single crystal cBN. In conclusion, high-speed cutting tests on hardened steel and granite suggest that diamond- cBN alloy is indeed a universal cutting material.« less

Diamond-cBN alloy: A universal cutting material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Pei; High Pressure Science and Engineering Center and Department of Physics and Astronomy, University of Nevada Las Vegas, Las Vegas, Nevada 89154; He, Duanwei, E-mail: duanweihe@scu.edu.cn

Diamond and cubic boron nitride (cBN) as conventional superhard materials have found widespread industrial applications, but both have inherent limitations. Diamond is not suitable for high-speed cutting of ferrous materials due to its poor chemical inertness, while cBN is only about half as hard as diamond. Because of their affinity in structural lattices and covalent bonding character, diamond and cBN could form alloys that can potentially fill the performance gap. However, the idea has never been demonstrated because samples obtained in the previous studies were too small to be tested for their practical performance. Here, we report the synthesis andmore » characterization of transparent bulk diamond-cBN alloy compacts whose diameters (3 mm) are sufficiently large for them to be processed into cutting tools. The testing results show that the diamond-cBN alloy has superior chemical inertness over polycrystalline diamond and higher hardness than single crystal cBN. High-speed cutting tests on hardened steel and granite suggest that diamond-cBN alloy is indeed a universal cutting material.« less

Diamond- cBN alloy: A universal cutting material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Pei; He, Duanwei; Wang, Liping

Diamond and cubic boron nitride ( cBN) as conventional superhard materials have found widespread industrial applications, but both have inherent limitations. Diamond is not suitable for high-speed cutting of ferrous materials due to its poor chemical inertness, while cBN is only about half as hard as diamond. Because of their affinity in structural lattices and covalent bonding character, diamond and cBN could form alloys that can potentially fill the performance gap. However, the idea has never been demonstrated because samples obtained in the previous studies were too small to be tested for their practical performance. Here, we report the synthesismore » and characterization of transparent bulk diamond- cBN alloy compacts whose diameters (3 mm) are sufficiently large for them to be processed into cutting tools. The testing results show that the diamond- cBN alloy has superior chemical inertness over polycrystalline diamond and higher hardness than single crystal cBN. In conclusion, high-speed cutting tests on hardened steel and granite suggest that diamond- cBN alloy is indeed a universal cutting material.« less

Fabrication of Fe-Based Diamond Composites by Pressureless Infiltration

PubMed Central

Li, Meng; Sun, Youhong; Meng, Qingnan; Wu, Haidong; Gao, Ke; Liu, Baochang

2016-01-01

A metal-based matrix is usually used for the fabrication of diamond bits in order to achieve favorable properties and easy processing. In the effort to reduce the cost and to attain the desired bit properties, researchers have brought more attention to diamond composites. In this paper, Fe-based impregnated diamond composites for drill bits were fabricated by using a pressureless infiltration sintering method at 970 °C for 5 min. In addition, boron was introduced into Fe-based diamond composites. The influence of boron on the density, hardness, bending strength, grinding ratio, and microstructure was investigated. An Fe-based diamond composite with 1 wt % B has an optimal overall performance, the grinding ratio especially improving by 80%. After comparing with tungsten carbide (WC)-based diamond composites with and without 1 wt % B, results showed that the Fe-based diamond composite with 1 wt % B exhibits higher bending strength and wear resistance, being satisfactory to bit needs. PMID:28774124

Dated eclogitic diamond growth zones reveal variable recycling of crustal carbon through time

NASA Astrophysics Data System (ADS)

Timmerman, S.; Koornneef, J. M.; Chinn, I. L.; Davies, G. R.

2017-04-01

Monocrystalline diamonds commonly record complex internal structures reflecting episodic growth linked to changing carbon-bearing fluids in the mantle. Using diamonds to trace the evolution of the deep carbon cycle therefore requires dating of individual diamond growth zones. To this end Rb-Sr and Sm-Nd isotope data are presented from individual eclogitic silicate inclusions from the Orapa and Letlhakane diamond mines, Botswana. δ13 C values are reported from the host diamond growth zones. Heterogeneous 87Sr/86Sr ratios (0.7033-0.7097) suggest inclusion formation in multiple and distinct tectono-magmatic environments. Sm-Nd isochron ages were determined based on groups of inclusions with similar trace element chemistry, Sr isotope ratios, and nitrogen aggregation of the host diamond growth zone. Diamond growth events at 0.14 ± 0.09, 0.25 ± 0.04, 1.1 ± 0.09, 1.70 ± 0.34 and 2.33 ± 0.02 Ga can be directly related to regional tectono-magmatic events. Individual diamonds record episodic growth with age differences of up to 2 Ga. Dated diamond zones have variable δ13 C values (-5.0 to -33.6‰ vs PDB) and appear to imply changes in subducted material over time. The studied Botswanan diamonds are interpreted to have formed in different tectono-magmatic environments that involve mixing of carbon from three sources that represent: i) subducted biogenic sediments (lightest δ13 C, low 87Sr/86Sr); ii) subducted carbonate-rich sediments (heavy δ13 C, high 87Sr/86Sr) and iii) depleted upper mantle (heavy δ13 C, low 87Sr/86Sr). We infer that older diamonds from these two localities are more likely to have light δ13 C due to greater subduction of biogenic sediments that may be related to hotter and more reduced conditions in the Archaean before the Great Oxidation Event at 2.3 Ga. These findings imply a marked temporal change in the nature of subducted carbon beneath Botswana and warrant further study to establish if this is a global phenomenon.

Use of valence band Auger electron spectroscopy to study thin film growth: oxide and diamond-like carbon films

NASA Astrophysics Data System (ADS)

Steffen, H. J.

1994-12-01

It is demonstrated how Auger line shape analysis with factor analysis (FA), least-squares fitting and even simple peak height measurements may provide detailed information about the composition, different chemical states and also defect concentration or crystal order. Advantage is taken of the capability of Auger electron spectroscopy to give valence band structure information with high surface sensitivity and the special aspect of FA to identify and discriminate quantitatively unknown chemical species. Valence band spectra obtained from Ni, Fe, Cr and NiFe40Cr20 during oxygen exposure at room temperature reveal the oxidation process in the initial stage of the thin layer formation. Furthermore, the carbon chemical states that were formed during low energy C(+) and Ne(+) ion irradiation of graphite are delineated and the evolution of an amorphous network with sp3 bonds is disclosed. The analysis represents a unique method to quantify the fraction of sp3-hybridized carbon in diamond-like materials.

Technics study on high accuracy crush dressing and sharpening of diamond grinding wheel

NASA Astrophysics Data System (ADS)

Jia, Yunhai; Lu, Xuejun; Li, Jiangang; Zhu, Lixin; Song, Yingjie

2011-05-01

Mechanical grinding of artificial diamond grinding wheel was traditional wheel dressing process. The rotate speed and infeed depth of tool wheel were main technics parameters. The suitable technics parameters of metals-bonded diamond grinding wheel and resin-bonded diamond grinding wheel high accuracy crush dressing were obtained by a mount of experiment in super-hard material wheel dressing grind machine and by analysis of grinding force. In the same time, the effect of machine sharpening and sprinkle granule sharpening was contrasted. These analyses and lots of experiments had extent instruction significance to artificial diamond grinding wheel accuracy crush dressing.

Noble gases in diamonds - Occurrences of solarlike helium and neon

NASA Technical Reports Server (NTRS)

Honda, M.; Reynolds, J. H.; Roedder, E.; Epstein, S.

1987-01-01

Seventeen diamond samples from diverse locations were analyzed for the contents of He, Ar, Kr, and Xe, and of their isotopes, using a Reynolds (1956) type glass mass spectrometer. The results disclosed a large spread in the He-3/He-4 ratios, ranging from values below atmospheric to close to the solar ratio. In particular, solarlike He-3/He-4 ratios were seen for an Australian colorless diamond composite and an Arkansas diamond, which also displayed solarlike neon isotopic ratios. Wide variation was also observed in the He-4/Ar-40 ratios, suggesting a complex history for the source regions and the diamond crystallization processes.

High quality factor single-crystal diamond mechanical resonators

NASA Astrophysics Data System (ADS)

Ovartchaiyapong, P.; Pascal, L. M. A.; Myers, B. A.; Lauria, P.; Bleszynski Jayich, A. C.

2012-10-01

Single-crystal diamond is a promising material for microelectromechanical systems (MEMs) because of its low mechanical loss, compatibility with extreme environments, and built-in interface to high-quality spin centers. But its use has been limited by challenges in processing and growth. We demonstrate a wafer bonding-based technique to form diamond on insulator, from which we make single-crystal diamond micromechanical resonators with mechanical quality factors as high as 338 000 at room temperature. Variable temperature measurements down to 10 K reveal a nonmonotonic dependence of quality factor on temperature. These resonators enable integration of single-crystal diamond into MEMs technology for classical and quantum applications.

Plasma-assisted conversion of solid hydrocarbon to diamond

DOEpatents

Valone, Steven M.; Pattillo, Stevan G.; Trkula, Mitchell; Coates, Don M.; Shah, S. Ismat

1996-01-01

A process of preparing diamond, e.g., diamond fiber, by subjecting a hydrocarbon material, e.g., a hydrocarbon fiber, to a plasma treatment in a gaseous feedstream for a sufficient period of time to form diamond, e.g., a diamond fiber is disclosed. The method generally further involves pretreating the hydrocarbon material prior to treatment with the plasma by heating within an oxygen-containing atmosphere at temperatures sufficient to increase crosslinking within said hydrocarbon material, but at temperatures insufficient to melt or decompose said hydrocarbon material, followed by heating at temperatures sufficient to promote outgassing of said crosslinked hydrocarbon material, but at temperatures insufficient to convert said hydrocarbon material to carbon.

Low substrate temperature deposition of diamond coatings derived from glassy carbon

DOEpatents

Holcombe, C.E. Jr.; Seals, R.D.

1995-09-26

A process is disclosed for depositing a diamond coating on a substrate at temperatures less than about 550 C. A powder mixture of glassy carbon and diamond particles is passed through a high velocity oxy-flame apparatus whereupon the powders are heated prior to impingement at high velocity against the substrate. The powder mixture contains between 5 and 50 powder volume percent of the diamond particles, and preferably between 5 and 15 powder volume percent. The particles have a size from about 5 to about 100 micrometers, with the diamond particles being about 5 to about 30 micrometers. The flame of the apparatus provides a velocity of about 350 to about 1000 meters per second, with the result that upon impingement upon the substrate, the glassy carbon is phase transformed to diamond as coaxed by the diamond content of the powder mixture. 2 figs.

Low substrate temperature deposition of diamond coatings derived from glassy carbon

DOEpatents

Holcombe, Jr., Cressie E.; Seals, Roland D.

1995-01-01

A process for depositing a diamond coating on a substrate at temperatures less than about 550.degree. C. A powder mixture of glassy carbon and diamond particles is passed through a high velocity oxy-flame apparatus whereupon the powders are heated prior to impingement at high velocity against the substrate. The powder mixture contains between 5 and 50 powder volume percent of the diamond particles, and preferably between 5 and 15 powder volume percent. The particles have a size from about 5 to about 100 micrometers, with the diamond particles being about 5 to about 30 micrometers. The flame of the apparatus provides a velocity of about 350 to about 1000 meters per second, with the result that upon impingement upon the substrate, the glassy carbon is phase transformed to diamond as coaxed by the diamond content of the powder mixture.

Plasma spraying method for forming diamond and diamond-like coatings

DOEpatents

Holcombe, Cressie E.; Seals, Roland D.; Price, R. Eugene

1997-01-01

A method and composition for the deposition of a thick layer (10) of diamond or diamond-like material. The method includes high temperature processing wherein a selected composition (12) including at least glassy carbon is heated in a direct current plasma arc device to a selected temperature above the softening point, in an inert atmosphere, and is propelled to quickly quenched on a selected substrate (20). The softened or molten composition (18) crystallizes on the substrate (20) to form a thick deposition layer (10) comprising at least a diamond or diamond-like material. The selected composition (12) includes at least glassy carbon as a primary constituent (14) and may include at least one secondary constituent (16). Preferably, the secondary constituents (16) are selected from the group consisting of at least diamond powder, boron carbide (B.sub.4 C) powder and mixtures thereof.

Status and applications of diamond and diamond-like materials: An emerging technology

NASA Technical Reports Server (NTRS)

1990-01-01

Recent discoveries that make possible the growth of crystalline diamond by chemical vapor deposition offer the potential for a wide variety of new applications. This report takes a broad look at the state of the technology following from these discoveries in relation to other allied materials, such as high-pressure diamond and cubic boron nitride. Most of the potential defense, space, and commercial applications are related to diamond's hardness, but some utilize other aspects such as optical or electronic properties. The growth processes are reviewed, and techniques for characterizing the resulting materials' properties are discussed. Crystalline diamond is emphasized, but other diamond-like materials (silicon carbide, amorphous carbon containing hydrogen) are also examined. Scientific, technical, and economic problem areas that could impede the rapid exploitation of these materials are identified. Recommendations are presented covering broad areas of research and development.

Numerical Analysis of Incipient Separation on 53 Deg Swept Diamond Wing

NASA Technical Reports Server (NTRS)

Frink, Neal T.

2015-01-01

A systematic analysis of incipient separation and subsequent vortex formation from moderately swept blunt leading edges is presented for a 53 deg swept diamond wing. This work contributes to a collective body of knowledge generated within the NATO/STO AVT-183 Task Group titled 'Reliable Prediction of Separated Flow Onset and Progression for Air and Sea Vehicles'. The objective is to extract insights from the experimentally measured and numerically computed flow fields that might enable turbulence experts to further improve their models for predicting swept blunt leading-edge flow separation. Details of vortex formation are inferred from numerical solutions after establishing a good correlation of the global flow field and surface pressure distributions between wind tunnel measurements and computed flow solutions. From this, significant and sometimes surprising insights into the nature of incipient separation and part-span vortex formation are derived from the wealth of information available in the computational solutions.

Process for making diamonds

NASA Technical Reports Server (NTRS)

Rasquin, J. R.; Estes, M. F. (Inventor)

1973-01-01

A description is given of a device and process for making industrial diamonds. The device is composed of an exponential horn tapering from a large end to a small end, with a copper plate against the large end. A magnetic hammer abuts the copper plate. The copper plate and magnetic hammer function together to create a shock wave at the large end of the horn. As the wave propagates to the small end, the extreme pressure and temperature caused by the wave transforms the graphite, present in an anvil pocket at the small end, into diamonds.

Microstructural evolution of diamond films from CH{sub 4}/H{sub 2}/N{sub 2} plasma and their enhanced electrical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sankaran, K. J.; Tai, N. H., E-mail: nhtai@mx.nthu.edu.tw; Lin, I. N., E-mail: inanlin@mail.tku.edu.tw

2015-02-21

The influence of N{sub 2} concentration in CH{sub 4}/H{sub 2}/N{sub 2} plasma on microstructural evolution and electrical properties of diamond films is systematically investigated. While the diamond films grown in CH{sub 4}/H{sub 2} plasma contain large diamond grains, for the diamond films grown using CH{sub 4}/H{sub 2}/(4%)N{sub 2} plasma, the microstructure drastically changed, resulting in ultra-nanosized diamond grains with Fd3m structure and a{sub 0} = 0.356 nm, along with the formation of n-diamond (n-D), a metastable form of diamond with space group Fm3m and a{sub 0} = 0.356 nm, and i-carbon (i-C) clusters, the bcc structured carbon with a{sub 0} = 0.432 nm. In addition, these films contain widemore » grain boundaries containing amorphous carbon (a-C). The electron field emission (EFE) studies show the best EFE behavior for 4% N{sub 2} films among the CH{sub 4}/H{sub 2}/N{sub 2} grown diamond films. They possess the lowest turn-on field value of 14.3 V/μm and the highest EFE current density value of 0.37 mA/cm{sup 2} at an applied field of 25.4 V/μm. The optical emission spectroscopy studies confirm that CN species are the major criterion to judge the changes in the microstructure of the films. It seems that the grain boundaries can provide electron conduction networks to transport efficiently the electrons to emission sites for field emission, as long as they have sufficient thickness. Whether the matrix nano-sized grains are 3C-diamond, n-D or i-C is immaterial.« less

Microdiamonds from the European Variscan Orogenic Belt

NASA Astrophysics Data System (ADS)

Kotkova, J.; Jakubova, P.; Whitehouse, M.; Fedortchouk, Y.

2014-12-01

Diamond, along with coesite, has been discovered recently in the continental crustal rocks of the European Variscan orogenic belt, namely the Bohemian Massif (BM). In addition to the garnet-phengite gneiss in Germany, western BM, microdiamond occurs in major rock forming minerals - garnet, kyanite - and in zircon in ultrahigh-pressure rocks overprinted under high-pressure granulite facies conditions (c. 16-20 kbar, c. 1000°C) in the northern and eastern BM. Well-preserved 10-30 μm-sized microdiamonds from northern BM exhibit diverse morphologies (SEM data) depending upon the host rock type. Octahedral diamond occurs in felsic garnet-kyanite-feldspar-quartz rock (metasediment), whereas intermediate garnet-clinopyroxene-feldspar-quartz rock contains a cubo-octahedral variety. Diamond morphology can be thus controlled by solid impurities available in the medium of crystallization (K- vs. Ca-bearing fluids or melts), as shown by experiments. Pointed-bottom negatively oriented trigonal etch pits on the octahedral diamond faces developed due to diamond resorption at CO2-dominated environment (less than 50 wt % of H2O, experimental data), possibly by action of a residual fluid. SIMS determined δ13C values range from -22 to -21 ‰ for the felsic rock and from - 26 to - 33 for the intermediate one, corresponding to the typical range of organic carbon δ13C and inconsistent with a significant mantle carbon (δ13C ~ - 5 ‰) input. Diamond-bearing domains in zircon, also analysed by SIMS, yielded a Variscan U-Pb age of c. 340 Ma. The present stage of knowledge allows us to conclude that (i) metamorphic diamonds in the BM occur in lithologies of metasedimentary character, and their carbon source was organic; (ii) crustal-derived CO2-rich fluids with impurities played an important role in diamond formation and dissolution; (iii) diamonds formed during the Variscan orogenic cycle and (iv) diamonds are best preserved in the external domain of the Variscan orogenic belt.

Trace element analyses of fluid-bearing diamonds from Jwaneng, Botswana

NASA Astrophysics Data System (ADS)

Schrauder, Marcus; Koeberl, Christian; Navon, Oded

1996-12-01

Fibrous diamonds from Botswana contain abundant micro-inclusions, which represent syngenetic mantle fluids under high pressure. The major element composition of the fluids within individual diamonds was found to be uniform, but a significant compositional variation exists between different diamond specimens. The composition of the fluids varies between a carbonatitic and a hydrous endmember. To constrain the composition of fluids in the mantle, the trace element contents of thirteen micro-inclusion-bearing fibrous diamonds from Botswana was studied using neutron activation analysis. The concentrations of incompatible elements (including K, Na, Br, Rb, Sr, Zr, Cs, Ba, Hf, Ta, Th, U, and the LREEs) in the fluids are higher than those of mantle-derived rocks and melt inclusions. The compatible elements (e.g., Cr, Co, Ni) have abundances that are similar to those of the primitive mantle. The concentrations of most trace elements decrease by a factor of two from the carbonate-rich fluids to the hydrous fluids. Several models may explain the observed elemental variations. Minerals in equilibrium with the fluid were most likely enriched in incompatible elements, which does not agree with derivation of the fluids by partial melting of common peridotites or eclogites. Fractional crystallization of a kimberlite-like magma at depth may yield carbonatitic fluids with low mg numbers (atomic ratio [Mg/(Mg+Fe)]) and high trace element contents. Fractionation of carbonates and additional phases (e.g., rutile, apatite, zircon) may, in general, explain the concentrations of incompatible elements in the fluids, which preferably partition into these phases. Alternatively, mixing of fluids with compositions similar to those of the two endmembers may explain the observed variation of the elemental contents. The fluids in fibrous diamonds might have equilibrated with mineral inclusions in eclogitic diamonds, while peridotitic diamonds do not show evidence of interaction with these fluids. The chemical composition of the fluids in fibrous diamonds indicates that, at p, T conditions that are characteristic for diamond formation, carbonatitic and hydrous fluids are efficient carriers of incompatible elements.

The Magnetic Properties Of Aggregate Polycrystalline Diamond: Implications For Carbonado Petrogenesis

NASA Technical Reports Server (NTRS)

Kleteschka, Gunther; Taylor, Patrick T.; Wasilewski, Peter J.; Hill, Hugh G. M.

2000-01-01

Carbonados are a type of diamond, which are made up of many aggregrates of small crystalline diamonds or microdiamonds. The term "carbonado" comes from the Portuguese word carbonated. They are only found in sedimentary deposits in the Central African Republic (CAR) and the Bahia Province of Brazil. They were once the source of the world's supply of industrial diamonds. Their origin is uncertain but several mutually exclusive hypotheses have been proposed. This theories are: (1) extraterrestrial, that is they formed from the dust cloud of original solar nebulae; (2) produced by the high temperatures and pressures of the Earth's mantle; (3) or as the result of an extra-terrestrial impact into a carbon rich layer of sediment. Our study was done to further the understanding of their origin. We measured the magnetic properties on some twenty samples from the CAR. An earlier study was done on whole samples of carbonados and the "common" or kimberlitic diamond. Our work differed in that we started at the surface and subsequently removed the surface layers (by days of acid immersion) into the interior; measuring the magnetic properties at each interval. This procedure permits us to monitor the distribution of magnetic substances within the samples. Our results showed that the magnetic carriers are distributed on the surface including the open pores and that the carbonado interior is essentially non-magnetic. This result suggests that the initial formation environment was deficient in magnetic particles. Such a situation could indicate that their formation was the result of an extra-terrestrial body impacting carbon-rich sediment. Obviously, more work will be required on isotopic and chemical analyses before a more detailed ori-in can be determined.

PREFACE: Science's gem: diamond science 2009 Science's gem: diamond science 2009

NASA Astrophysics Data System (ADS)

Mainwood, Alison; Newton, Mark E.; Stoneham, Marshall

2009-09-01

Natural diamond has been valued for its appearance and mechanical properties for at least two thousand years. As a gem stone diamond is unsurpassed. However, scientific work, especially in the last 20 years, has demonstrated that diamond has numerous surprising properties and many unique ones. Some of the extreme properties have been known for many years, but the true scale of diamond's other highly desirable features is still only coming to light as control in the synthesis of diamond, and hence material perfection, improves. The ultimate prize for man-made diamond is surely not in the synthesis of gem stones, but in delivering technological solutions enabled by diamond to the challenges facing our society today. If the special properties are to be exploited to their full potential, at least four crucial factors must be considered. First, there must be sufficient scientific understanding of diamond to make applications effective, efficient and economical. Secondly, the means of fabrication and control of properties have to be achieved so that diamond's role can be optimised. Thirdly, it is not enough that its properties are superior to existing materials: they must be so much better that it is worth initiating new technologies to exploit them. Finally, any substantial applications will have to address the society's major needs worldwide. The clear technology drivers for the 21st century come from the biomedical technologies, the demand for energy subject to global constraints, and the information technologies, where perhaps diamond will provide the major enabling technology [1]. The papers in this volume concern the solid state physics of diamond, and primarily concern the first two factors: understanding, and control of properties. They address many of the outstanding basic problems, such as the identification of existing defects, which affect the material's properties, both desirable and less so. Regarding future substantial applications, one paper discusses diamond's exceptional properties for quantum information processing [2], a topic on which there have been many recent papers, and where a diamond colour centre single photon source is already commercially available. Biomedical applications of diamond are recognised, partly tribological and partly electrochemical, but lie outside the present group of papers. Processing and controlling diamond surfaces and interfaces with other materials in their environment are critical steps en route to exploitation. Boron-doped diamond has already found application in electro-analysis and in the bulk oxidation of dissolved species in solution [3]. Energy-related applications—ranging from high-power electronics [3] to a potential first wall of fusion reactors [4]—are further exciting potential applications. Even small and ugly diamonds have value. Their mechanical properties [5] dominate, with significant niche applications such as thermal sinks. The major applications for diamond to date exploit only a fraction of diamond's special properties: visual for status diamonds, and mechanical for working diamonds. Diamond physics reaches well beyond the usual laboratory, to the geological diamond formation processes in the Earth's mantle. Characterization of natural gem diamonds [6, 7] is one part of the detective story that allows us to understand the conditions under which they formed. It was only half a century ago that the scientific and technological challenges of diamond synthesis were met systematically. Today, most of the recent research on diamond has concentrated on synthetics, whether created using high pressure, high temperature (HPHT) techniques or chemical vapour deposition (CVD). The HPHT synthesis of diamond has advanced dramatically [8, 9] to the extent that dislocation birefringence [10] can be largely eliminated. In silicon technology, the elimination of dislocations was a major step in microelectronics. Now, even diamond can be synthesised containing virtually no dislocations. The understanding of the critical processes that are involved in CVD diamond growth are becoming clearer. Two papers in this issue model it on a microscopic scale [11, 12], and a further two explore the practical techniques [13, 14] in order to lead to improvement in deposition techniques. Diamond is emerging as an engineering material [3] with its cost no longer regarded as prohibitive even for some large-scale uses, such as the fusion reactor first wall. It is striking how few useful dopants can be put into diamond in a controlled way. The studies reported here, whether theory or experiment, concentrate on phosphorus [14] as the donor, and demonstrate that boron (although deep in semiconductor terms,) can act as the acceptor [3] in practical devices. Other impurities, with deeper levels, such as nitrogen [15], with the muon as an honorary hydrogen [16], are studied in depth. Here, many of the characterization techniques developed over several decades have been brought to bear, to attempt to quantify impurities and defects and ultimately assist in improving the crystal quality [17, 18, 15]. However, further, more novel techniques such as reflection anisotropy spectroscopy [19] and luminescence lifetime mapping [20] have been introduced to diamond in this issue, and one can see how such techniques might play a crucial role in areas such as systems for quantum information processing. The presence and migration of radiation damage defects [21, 22], vacancies and interstitials, and vacancy clusters can dramatically influence the exploitable properties of diamond [23, 24]. It is now apparent that charge traps not only impact on electrical properties, but also on the colour of diamond and that thermo-chromic and photo-chromic effects are more common than previously thought [25, 23]. Combinations, like the negatively charged nitrogen-vacancy centre, have proved impressive in quantum information studies [26]. But diamond has yet to benefit from the sort of dopant engineering that has helped silicon to become ubiquitous. It is becoming clear that because of the deep ionisation energies of the dopants that can be incorporated into diamond, conventional semiconductor physics can only be applied at high temperatures; rather different technologies have to be exploited to ensure that diamond's potential for devices is fulfilled. There are technical improvements which need to be made: the elimination of defects that trap carriers, cause de-coherence, affect the colour or strength, or have other serious effects in the relevant application, and the development of robust ohmic contacts [27]. The material developments of the last 50 years include silicon becoming the semiconductor of choice, many new and better-developed polymers, the transformation of communications by silica-based optical fibres, and the emergence of synthetic diamond. Could diamond's special virtues yield major new opportunities? Its optical properties are exceptional, usually in desirable ways (high refractive indices can create indirect problems). The mechanical properties are truly outstanding, again usually in desirable ways (adhesion can be challenging). The thermal properties are similarly exceptional, with a thermal conductivity that exceeds copper. Diamond withstands aggressive environments, including extremes of pH. Its carrier mobility can be phenomenal, and electron emission can be excellent. Moreover, diamond can be compatible with silicon electronics, even if the involvement of a second material is inconvenient. Here the problems start. Even limited developments could be significant. For instance, the ability to control the populations of the various N, B, P and vacancy centres would open up potentially unique optoelectronic and spintronic opportunities. Control of diamond's properties is difficult, but this is where basic research can help (using all the techniques explored in this issue, and more). It is barely practical to create n-type diamond, but unipolar devices, exploiting excellent quality boron doped p-type material, can be designed [3]. Electrical contacts can be tricky to fabricate, but progress is being made here [3, 27]. Diamond is perceived as unacceptably expensive, but for a high-quality device for an exceptional environment, this is not a problem. Carbon-based electronic materials are strikingly diverse. They include diamond, graphite, nanotubes and buckyball structures, amorphous carbons, and nanodiamond. Add hydrogen and one has a range of diamond-like carbons and the wealth of organics. Such carbon-based materials include small molecules and polymers: impressive insulators, semiconducting and conducting polymers, switchable forms, superconducting and magnetic forms, and some with the highest electrical conductivities of any material. Diamond-like carbons can have controllable mechanical properties from the viscoelastic to the highly rigid. Photochemistry brings opportunities for novel processing methods. Even water-based processing may sometimes be possible (alas, not for diamond), and additional tools like self-organisation of organic molecules on surfaces have been demonstrated. The best carbons have impressive, sometimes supreme, performances, including the mobility and optical properties of diamond, spin-conserving transport in carbon nanotubes, and electron emission. For almost all measures of performance, there is some carbon-based material that performs better than silicon. Might hybrid carbon-based materials be more successful even than silicon [28]? Should we think less about 'diamond' and more about the integration of diamond as one component of carbon electronics? Device fabrication needs lithography optics and resists, and processing at the anticipated smaller scales may well exploit new electronic excitation methods. Alternative dielectrics and interconnect materials introduce new compatibility issues, and there are further varied constraints from displays, spintronic components, electron emitters or transparent conductors. Could the many carbon-based materials with interesting functional properties lead to a new class of alternative systems? This collection of papers was brought together to celebrate 60 years of conferences sponsored by the De Beers Group of companies on the science and technology of diamond. The transformation of diamond science and technology over those 60 years can be seen in varied ways. First, there has been a series of books stimulated by the conferences [29-31] complementing numerous other more recent texts on diamond (e.g. [32]). These show a striking evolution from the early pioneering studies of tribology, radiation damage, and thermal and optical properties to a wider range of electronic properties, spectroscopies, and characterization from the macroscopic to nanoscopic scales, as well as the now almost universal dialogue between experiment and theory. Secondly, new experimental and theoretical techniques have emerged, many of which are featured in the papers in this issue. Thirdly, there is a range of new technologies only made possible because of the catalytic role of the conferences. These include the spectroscopies that distinguish natural from synthetic or treated diamonds in a way that earns customer confidence. There are also new customer products, like speaker domes, where success has depended on the understanding of mechanical properties at a level not commonly available. Potentially big applications, like the fusion reactor's first wall, will follow on from early radiation damage studies. Fourthly, the young scientists who have been supported over the years have now made their way in many fields, not just diamond research, but certainly including technologies that use diamond. The sponsorship of science in this field has benefited both those supported and those who provide that support. Finally, we see serious thoughts about what might be the big new technologies of the 21st century, since these will need a fundamental understanding of materials properties and their control. There has been exceptional progress in this area, in specimen sizes, quality, and performance. These massive improvements in materials availability create opportunities for the major technological applications in the energy, environment, health and information technologies that will surely drive the big industrial expansions over the next decades. References [1] Stoneham A M 2007 Thinking about diamond (ed P Bergonzo, R Gat, R B Jackman and C E Nebel) MRS Proc. 956 1-10 [2] Stoneham A M 2008 Future Perspectives for Diamond for Physics and Applications of CVD Diamond ed S Koizumi, M Nesladek and C E Nebel (New York: Wiley-VCH) [3] Balmer R S et al 2009 J. Phys.: Condens. Matter 21 364221 [4] Stoneham A M, Matthews J R and Ford I J 2004 J. Phys.: Condens. Matter 16 S2597 [5] Liang Q, Yan C, Meng Y, Lai J, Krasnicki S, Mao H and Hemley R J 2009 J. Phys.: Condens. Matter 21 364215 [6] Stachel T and Harris J W 2009 J. Phys.: Condens. Matter 21 364206 [7] McNeill J, Pearson D G, Klein-BenDavid O, Nowell G M, Ottley C J and Chinn I 2009 J. Phys.: Condens. Matter 21 364207 [8] Martineau P M, Gaukroger M P, Guy K B, Lawson S C, Twitchen D J, Friel I, Hansen J O, Summerton G C, Addison T P G and Burns R 2009 J. Phys.: Condens. Matter 21 364205 [9] Burns R C et al 2009 J. Phys.: Condens. Matter 21 364224 [10] Pinto H and Jones R 2009 J. Phys.: Condens. Matter 21 364220 [11] May P W, Allan N L, Ashfold M N R, Richley J C and Mankelevich Yu A 2009 J. Phys.: Condens. Matter 21 364203 [12] Butler J E, Mankelevich Yu A, Cheesman A, Ma J and Ashfold N R 2009 J. Phys.: Condens. Matter 21 364201 [13] Silva F, Hassouni K, Bonnin X and Gicquel A 2009 J. Phys.: Condens. Matter 21 364202 [14] Haenen K, Lazea A, Barjon J, D'Haen J, Habka N, Teraji T, Koizumi S and Mortet V 2009 J. Phys.: Condens. Matter 21 364204 [15] Felton S, Cann B L, Edmonds A M, Liggins S, Cruddace R J, Newton M E, Fisher D and Baker J M 2009 J. Phys.: Condens. Matter 21 364212 [16] Etmimi K M, Goss J P, Briddon P R and Gseia E M 2009 J. Phys.: Condens. Matter 21 364211 [17] Moore M 2009 J. Phys.: Condens. Matter 21 364217 [18] Maki J M, Tuomisto F, Kelly C J, Fisher D and Martineau P M 2009 J. Phys.: Condens. Matter 21 364216 [19] Schwitters M, Martin D S, Unsworth P, Farrell T, Butler J E and Weightman P 2009 J. Phys.: Condens. Matter 21 364218 [20] Liaugaudas G, Collins A T, Suhling K, Davies G and Heintzmann R 2009 J. Phys.: Condens. Matter 21 364210 [21] Collins A T and Kiflawi I 2009 J. Phys.: Condens. Matter 21 364209 [22] Steeds J W, Sullivan W, Wotherspoon A and Hayes J M 2009 J. Phys.: Condens. Matter 21 364219 [23] Fisher D, Sibley S J and Kelly C J 2009 J. Phys.: Condens. Matter 21 364213 [24] Bangert U, Barnes R, Gass M H, Bleloch A L, and Godfrey I S 2009 J. Phys.: Condens. Matter 21 364208 [25] Khan R U A, Martineau P M, Cann B L, Newton M E and Twitchen D J 2009 J. Phys.: Condens. Matter 21 364214 [26] Stoneham A M, Harker A H and Morley G W 2009 J. Phys.: Condens. Matter 21 364222 [27] Evans D A, Roberts O R, Williams G T, Vearey-Roberts A R, Bain F, Evans S, Langstaff D and Twitchen D J 2009 J. Phys.: Condens. Matter 21 364223 [28] Stoneham A M 2004 Nat. Mater. 3 3 [29] Berman R (ed) 1965 Physical Properties of Diamond (Oxford: Clarendon) [30] Field J E (ed) 1979 The Properties of Diamond (London: Academic) [31] Field J E (ed) 1992 The Properties of Natural and Synthetic Diamond (London: Academic) [32] Sussmann R S (ed) 2009 CVD Diamond for Electronic Devices and Sensors (Wiley Series in Materials for Electronic and Optoelectronic Applications) (New York: Wiley)

DEVELOPMENT OF A SCALABLE, LOW-COST, ULTRANANOCRYSTALLINE DIAMOND ELECTROCHEMICAL PROCESS FOR THE DESTRUCTION OF CONTAMINANTS OF EMERGING CONCERN (CECS) - PHASE II

EPA Science Inventory

This Small Business Innovation Research (SBIR) Phase II project will employ the large scale; highly reliable boron-doped ultrananocrystalline diamond (BD-UNCD®) electrodes developed during Phase I project to build and test Electrochemical Anodic Oxidation process (EAOP)...

Metal-induced rapid transformation of diamond into single and multilayer graphene on wafer scale

DOE PAGES

Berman, Diana; Deshmukh, Sanket; Narayanan, Badri; ...

2016-07-04

The degradation of intrinsic properties of graphene during the transfer process constitutes a major challenge in graphene device fabrication, stimulating the need for direct growth of graphene on dielectric substrates. Previous attempts of metal-induced transformation of diamond and silicon carbide into graphene suffers from metal contamination and inability to scale graphene growth over large area. Here in this article, we introduce a direct approach to transform polycrystalline diamond into high-quality graphene layers on wafer scale (4 inch in diameter) using a rapid thermal annealing process facilitated by a nickel, Ni thin film catalyst on top. We show that the processmore » can be tuned to grow single or multilayer graphene with good electronic properties. Molecular dynamics simulations elucidate the mechanism of graphene growth on polycrystalline diamond. Additionally, we demonstrate the lateral growth of free-standing graphene over micron-sized pre-fabricated holes, opening exciting opportunities for future graphene/diamond-based electronics.« less

Metal-induced rapid transformation of diamond into single and multilayer graphene on wafer scale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berman, Diana; Deshmukh, Sanket; Narayanan, Badri

The degradation of intrinsic properties of graphene during the transfer process constitutes a major challenge in graphene device fabrication, stimulating the need for direct growth of graphene on dielectric substrates. Previous attempts of metal-induced transformation of diamond and silicon carbide into graphene suffers from metal contamination and inability to scale graphene growth over large area. Here in this article, we introduce a direct approach to transform polycrystalline diamond into high-quality graphene layers on wafer scale (4 inch in diameter) using a rapid thermal annealing process facilitated by a nickel, Ni thin film catalyst on top. We show that the processmore » can be tuned to grow single or multilayer graphene with good electronic properties. Molecular dynamics simulations elucidate the mechanism of graphene growth on polycrystalline diamond. Additionally, we demonstrate the lateral growth of free-standing graphene over micron-sized pre-fabricated holes, opening exciting opportunities for future graphene/diamond-based electronics.« less

A mantle origin for Paleoarchean peridotitic diamonds from the Panda kimberlite, Slave Craton: Evidence from 13C-, 15N- and 33,34S-stable isotope systematics

NASA Astrophysics Data System (ADS)

Cartigny, Pierre; Farquhar, James; Thomassot, Emilie; Harris, Jeffrey W.; Wing, Bozwell; Masterson, Andy; McKeegan, Kevin; Stachel, Thomas

2009-11-01

In order to address diamond formation and origin in the lithospheric mantle underlying the Central Slave Craton, we report N- and C-stable isotopic compositions and N-contents and aggregation states for 85 diamonds of known paragenesis (73 peridotitic, 8 eclogitic and 4 from lower mantle) from the Panda kimberlite (Ekati Mine, Lac de Gras Area, Canada). For 12 peridotitic and two eclogitic sulfide inclusion-bearing diamonds from this sample set, we also report multiple-sulfur isotope ratios. The 73 peridotitic diamonds have a mean δ13C-value of - 5.2‰ and range from - 6.9 to - 3.0‰, with one extreme value at - 14.1‰. The associated δ15N-values range from - 17.0 to + 8.5‰ with a mean value of - 4.0‰. N-contents range from 0 to 1280 ppm. The 8 eclogitic diamonds have δ13C-values ranging from - 11.2 to - 4.4‰ with one extreme value at - 19.4‰. Their δ15N ranges from - 2.1 to + 7.9‰ and N-contents fall between 0 and 3452 ppm. Four diamonds with an inferred lower mantle origin are all Type II (i.e. nitrogen-free) and have a narrow range of δ13C values, between - 4.5 and - 3.5‰. The δ34S of the 14 analyzed peridotitic and eclogitic sulfide inclusions ranges from - 3.5 to +5.7‰. None of them provide evidence for anomalous δ33S-values; observed variations in δ33S are from +0.19 to - 0.33‰, i.e. within the 2 sigma uncertainties of mantle sulfur ( δ33S = 0‰). At Panda, the N contents and the δ13C of sulfide-bearing peridotitic diamonds show narrower ranges than silicate-bearing peridotitic diamonds. This evidence supports the earlier suggestion established from eclogitic diamonds from the Kaapvaal that sulfide-(±silicate) bearing diamonds sample a more restricted portion of sublithospheric mantle than silicate-(no sulfide) bearing diamonds. Our findings at Panda suggest that sulfide-bearing diamonds should be considered as a specific diamond population on a global-scale. Based on our study of δ34S, Δ 33S, δ15N and δ13C, we find no evidence for subduction-related isotopic signatures in the mantle sampled by Panda diamonds.

Implications of diamond-turned versus diamond-ground mold fabrication techniques on precision-molded optics

NASA Astrophysics Data System (ADS)

Mertus, Lou; Symmons, Alan

2012-10-01

In recent years, the trend within the molded optics community has been an overall advancement in the capability to diamond grind molds using a variety of grinding techniques. Improvements in grinding equipment, materials and tooling have enabled higher quality ceramic and carbide molds and thereby lenses. Diamond turned molds from ductile metals are still used prevalently throughout the molding industry. Each technology presents a unique set of advantages and disadvantages whether used for precision injection molding of plastic optics or precision glass molding. This paper reviews the manufacturing techniques for each approach and applicable molding process. The advantages and disadvantages of each are compared and analyzed. The subtle differences that exist in optics molded from each technique and the impact they have on the performance in various applications is reviewed. Differences stemming from tooling material properties, material-specific minor defects, as well as cutting and grinding process-induced artifacts are described in detail as well as their influence on the roughness, waviness, and form errors present on the molded surface. A comparison with results between similar surfaces for both diamond grinding and diamond turning is presented.

Alluvial diamond resource potential and production capacity assessment of Guinea

USGS Publications Warehouse

Chirico, Peter G.; Malpeli, Katherine C.; Van Bockstael, Mark; Diaby, Mamadou; Cissé, Kabinet; Diallo, Thierno Amadou; Sano, Mahmoud

2012-01-01

In May of 2000, a meeting was convened in Kimberley, South Africa, by representatives of the diamond industry and leaders of African governments to develop a certification process intended to assure that export shipments of rough diamonds were free of conflict concerns. Outcomes of the meeting were formally supported later in December of 2000 by the United Nations in a resolution adopted by the General Assembly. By 2002, the Kimberley Process Certification Scheme (KPCS) was ratified and signed by diamond-producing and diamond-importing countries. The goal of this study was to estimate the alluvial diamond resource endowment and the current production capacity of the alluvial diamond mining sector of Guinea. A modified volume and grade methodology was used to estimate the remaining diamond reserves within Guinea's diamondiferous regions, while the diamond-production capacity of these zones was estimated by inputting the number of artisanal miners, the number of days artisans work per year, and the average grade of the deposits into a formulaic expression. Guinea's resource potential was estimated to be approximately 40 million carats, while the production capacity was estimated to lie within a range of 480,000 to 720,000 carats per year. While preliminary results have been produced by integrating historical documents, five fieldwork campaigns, and remote sensing and GIS analysis, significant data gaps remain. The artisanal mining sector is dynamic and is affected by a variety of internal and external factors. Estimates of the number of artisans and deposit variables, such as grade, vary from site to site and from zone to zone. This report has been developed on the basis of the most detailed information available at this time. However, continued fieldwork and evaluation of artisanally mined deposits would increase the accuracy of the results.

Periodic metallo-dielectric structure in diamond.

PubMed

Shimizu, M; Shimotsuma, Y; Sakakura, M; Yuasa, T; Homma, H; Minowa, Y; Tanaka, K; Miura, K; Hirao, K

2009-01-05

Intense ultrashort light pulses induce three dimensional localized phase transformation of diamond. Photoinduced amorphous structures have electrical conducting properties of a maximum of 64 S/m based on a localized transition from sp(3) to sp(2) in diamond. The laser parameters of fluence and scanning speed affect the resultant electrical conductivities due to recrystallization and multi-filamentation phenomena. We demonstrate that the laser-processed diamond with the periodic cylinder arrays have the characteristic transmission properties in terahertz region, which are good agreement with theoretical calculations. The fabricated periodic structures act as metallo-dielectric photonic crystal.

Superhard nanocomposite of dense polymorphs of boron nitride: Noncarbon material has reached diamond hardness

NASA Astrophysics Data System (ADS)

Dubrovinskaia, Natalia; Solozhenko, Vladimir L.; Miyajima, Nobuyoshi; Dmitriev, Vladimir; Kurakevych, Oleksandr O.; Dubrovinsky, Leonid

2007-03-01

The authors report a synthesis of unique superhard aggregated boron nitride nanocomposites (ABNNCs) showing the enhancement of hardness up to 100% in comparison with single crystal c-BN. Such a great hardness increase is due to the combination of the Hall-Petch and the quantum confinement effects. The decrease of the grain size down to 14nm and the simultaneous formation of the two dense BN phases with hexagonal and cubic structures within the grains at nano- and subnanolevel result in enormous mechanical property enhancement with maximum hardness of 85(5)GPa. Thus, ABNNC is the first non-carbon-based bulk material with the value of hard-ness approaching that of single crystal and polycrystalline diamond and aggregated diamond nanorods. ABNNC also has an unusually high fracture toughness for superhard materials (K1C=15MPam0.5) and wear resistance (WH=11; compare, for industrial polycrystalline diamond, WH=3-4), in combination with high thermal stability (above 1600K in air), making it an exceptional superabrasive.

A superhard, quenchable carbon polymorph formed by the room-temperature compression of graphite (Invited)

NASA Astrophysics Data System (ADS)

Wang, Y.; Kiefer, B.; Lee, K. K.

2010-12-01

As one of the revolutionary inventions of the 20th century, synthetic diamond has had a large impact on industry and on scientific research. However, the necessities of high pressures, high temperatures and a metal catalyst during the manufacturing of synthetic diamond make it energy consuming thus limits its availability and use. Here, we report on the synthesis of a superhard non-diamond material resulting from the compression of graphite above ~20 GPa at room temperature without the utilization of metal catalysts. The final product includes a nano-sized phase of carbon that is recoverable at ambient conditions. Furthermore, the ring cracks left on the diamond anvils suggest that the hardness of this post-graphite phase is at least comparable to that of diamond. We use high-resolution synchrotron x-ray diffraction and micro-Raman spectroscopy to monitor the structural transformation in graphite under high pressure and room temperature and find the transition to be sluggish. The possible crystal structure of the new, quenchable phase will be discussed and the time-dependent formation of this superhard post-graphite carbon will be addressed and compared to first-principle predictions.

Profiling of Current Transients in Capacitor Type Diamond Sensors.

PubMed

Gaubas, Eugenijus; Ceponis, Tomas; Meskauskaite, Dovile; Kazuchits, Nikolai

2015-06-08

The operational characteristics of capacitor-type detectors based on HPHT and CVD diamond have been investigated using perpendicular and parallel injection of carrier domain regimes. Simulations of the drift-diffusion current transients have been implemented by using dynamic models based on Shockley-Ramo's theorem, under injection of localized surface domains and of bulk charge carriers. The bipolar drift-diffusion regimes have been analyzed for the photo-induced bulk domain (packet) of excess carriers. The surface charge formation and polarization effects dependent on detector biasing voltage have been revealed. The screening effects ascribed to surface charge and to dynamics of extraction of the injected bulk excess carrier domain have been separated and explained. The parameters of drift mobility of the electrons μ(e) = 4000 cm2/Vs and holes μ(h) = 3800 cm2/Vs have been evaluated for CVD diamond using the perpendicular profiling of currents. The coefficient of carrier ambipolar diffusion D(a) = 97 cm2/s and the carrier recombination lifetime τ(R,CVD) ≌ 110 ns in CVD diamond were extracted by combining analysis of the transients of the sensor current and the microwave probed photoconductivity. The carrier trapping with inherent lifetime τR,HPHT ≌ 2 ns prevails in HPHT diamond.

Self-Organization of Amorphous Carbon Nanocapsules into Diamond Nanocrystals Driven by Self-Nanoscopic Excessive Pressure under Moderate Electron Irradiation without External Heating.

PubMed

Wang, Chengbing; Ling, San; Yang, Jin; Rao, Dewei; Guo, Zhiguang

2018-01-01

Phase transformation between carbon allotropes usually requires high pressures and high temperatures. Thus, the development of low-temperature phase transition approaches between carbon allotropes is highly desired. Herein, novel amorphous carbon nanocapsules are successfully synthesized by pulsed plasma glow discharge. These nanocapsules are comprised of highly strained carbon clusters encapsulated in a fullerene-like carbon matrix, with the formers serving as nucleation sites. These nucleation sites favored the formation of a diamond unit cell driven by the self-nanoscopic local excessive pressure, thereby significantly decreasing the temperature required for its transformation into a diamond nanocrystal. Under moderate electron beam irradiation (10-20 A cm -2 ) without external heating, self-organization of the energetic carbon clusters into diamond nanocrystals is achieved, whereas the surrounding fullerene-like carbon matrix remains nearly unchanged. Molecular dynamics simulations demonstrate that the defective rings as the active sites dominate the phase transition of amorphous carbon to diamond nanocrystal. The findings may open a promising route to realize phase transformation between carbon allotropes at a lower temperature. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DNA-controlled assembly of a NaTl lattice structure from gold nanoparticles and protein nanoparticles

NASA Astrophysics Data System (ADS)

Cigler, Petr; Lytton-Jean, Abigail K. R.; Anderson, Daniel G.; Finn, M. G.; Park, Sung Yong

2010-11-01

The formation of diamond structures from tailorable building blocks is an important goal in colloidal crystallization because the non-compact diamond lattice is an essential component of photonic crystals for the visible-light range. However, designing nanoparticle systems that self-assemble into non-compact structures has proved difficult. Although several methods have been proposed, single-component nanoparticle assembly of a diamond structure has not been reported. Binary systems, in which at least one component is arranged in a diamond lattice, provide alternatives, but control of interparticle interactions is critical to this approach. DNA has been used for this purpose in a number of systems. Here we show the creation of a non-compact lattice by DNA-programmed crystallization using surface-modified Qβ phage capsid particles and gold nanoparticles, engineered to have similar effective radii. When combined with the proper connecting oligonucleotides, these components form NaTl-type colloidal crystalline structures containing interpenetrating organic and inorganic diamond lattices, as determined by small-angle X-ray scattering. DNA control of assembly is therefore shown to be compatible with particles possessing very different properties, as long as they are amenable to surface modification.

Diamonds: Exploration, mines and marketing

NASA Astrophysics Data System (ADS)

Read, George H.; Janse, A. J. A. (Bram)

2009-11-01

The beauty, value and mystique of exceptional quality diamonds such as the 603 carat Lesotho Promise, recovered from the Letseng Mine in 2006, help to drive a multi-billion dollar diamond exploration, mining and marketing industry that operates in some 45 countries across the globe. Five countries, Botswana, Russia, Canada, South Africa and Angola account for 83% by value and 65% by weight of annual diamond production, which is mainly produced by four major companies, De Beers, Alrosa, Rio Tinto and BHP Billiton (BHPB), which together account for 78% by value and 72% by weight of annual diamond production for 2007. During the last twelve years 16 new diamond mines commenced production and 4 re-opened. In addition, 11 projects are in advanced evaluation and may begin operations within the next five years. Exploration for diamondiferous kimberlites was still energetic up to the last quarter of 2008 with most work carried out in Canada, Angola, Democratic Republic of the Congo (DRC) and Botswana. Many kimberlites were discovered but no new economic deposits were outlined as a result of this work, except for the discovery and possible development of the Bunder project by Rio Tinto in India. Exploration methods have benefitted greatly from improved techniques of high resolution geophysical aerial surveying, new research into the geochemistry of indicator minerals and further insights into the formation of diamonds and the relation to tectonic/structural events in the crust and mantle. Recent trends in diamond marketing indicate that prices for rough diamonds and polished goods were still rising up to the last quarter of 2008 and subsequently abruptly sank in line with the worldwide financial crisis. Most analysts predict that prices will rise again in the long term as the gap between supply and demand will widen because no new economic diamond discoveries have been made recently. The disparity between high rough and polished prices and low share prices of publicly traded diamond companies may be due to investors losing patience with the slow pace or absence of new promising discoveries and switching into shares of base metals and fertilizers for agriculture (potash and phosphates).

Identifying the Source of Gem Diamonds: Requirements for a Certification System

NASA Astrophysics Data System (ADS)

Shigley, J. E.

2002-05-01

Recent civil conflicts in several countries, in which profits from the sales of gem diamonds have supported the rival factions, have forced the jewelry industry to confront the need to certify the geographic sources of gem diamonds. The goals of this program are to prohibit the sale of so-called "conflict diamonds", and to prevent the loss of consumer confidence. Efforts to identify unique characteristics of gem diamonds have been hampered so far by the absence of chemical or physical features that are diagnostic of particular sources, and the lack of a representative collection of diamonds from major producing areas that would be required for a rigorous scientific study. The jewelry industry has therefore adopted plans to track gem diamonds from the mine through the manufacturing process to the consumer. Practical requirements for implementation of such a certification system will be summarized. Any proposed solutions for determining the sources of gem diamonds by some analytical technique, or for following diamonds from the mine, must take into account the annual production of several tens of millions of carats of rough diamonds, which are transformed during manufacturing into several hundreds of millions of polished gemstones (with an average weight of only about 0.03 carat, or 0.006 gram).

Hot Deformation Behavior and Processing Maps of Diamond/Cu Composites

NASA Astrophysics Data System (ADS)

Zhang, Hongdi; Liu, Yue; Zhang, Fan; Zhang, Di; Zhu, Hanxing; Fan, Tongxiang

2018-03-01

The hot deformation behaviors of 50 vol pct uncoated and Cr-coated diamond/Cu composites were investigated using hot isothermal compression tests under the temperature and strain rate ranging from 1073 K to 1273 K (800 °C to 1000 °C) and from 0.001 to 5 s-1, respectively. Dynamic recrystallization was determined to be the primary restoration mechanism during deformation. The Cr3C2 coating enhanced the interfacial bonding and resulted in a larger flow stress for the Cr-coated diamond/Cu composites. Moreover, the enhanced interfacial affinity led to a higher activation energy for the Cr-coated diamond/Cu composites (238 kJ/mol) than for their uncoated counterparts (205 kJ/mol). The strain-rate-dependent constitutive equations of the diamond/Cu composites were derived based on the Arrhenius model, and a high correlation (R = 0.99) was observed between the calculated flow stresses and experimental data. With the help of processing maps, hot extrusions were realized at 1123 K/0.01 s-1 and 1153 K/0.01 s-1 (850 °C/0.01 s-1 and 880 °C/0.01 s-1) for the uncoated and coated diamond/Cu composites, respectively. The combination of interface optimization and hot extrusion led to increases of the density and thermal conductivity, thereby providing a promising route for the fabrication of diamond/Cu composites.

Hot Deformation Behavior and Processing Maps of Diamond/Cu Composites

NASA Astrophysics Data System (ADS)

Zhang, Hongdi; Liu, Yue; Zhang, Fan; Zhang, Di; Zhu, Hanxing; Fan, Tongxiang

2018-06-01

The hot deformation behaviors of 50 vol pct uncoated and Cr-coated diamond/Cu composites were investigated using hot isothermal compression tests under the temperature and strain rate ranging from 1073 K to 1273 K (800 °C to 1000 °C) and from 0.001 to 5 s-1, respectively. Dynamic recrystallization was determined to be the primary restoration mechanism during deformation. The Cr3C2 coating enhanced the interfacial bonding and resulted in a larger flow stress for the Cr-coated diamond/Cu composites. Moreover, the enhanced interfacial affinity led to a higher activation energy for the Cr-coated diamond/Cu composites (238 kJ/mol) than for their uncoated counterparts (205 kJ/mol). The strain-rate-dependent constitutive equations of the diamond/Cu composites were derived based on the Arrhenius model, and a high correlation ( R = 0.99) was observed between the calculated flow stresses and experimental data. With the help of processing maps, hot extrusions were realized at 1123 K/0.01 s-1 and 1153 K/0.01 s-1 (850 °C/0.01 s-1 and 880 °C/0.01 s-1) for the uncoated and coated diamond/Cu composites, respectively. The combination of interface optimization and hot extrusion led to increases of the density and thermal conductivity, thereby providing a promising route for the fabrication of diamond/Cu composites.

Electrochemical Behavior of Biomedical Titanium Alloys Coated with Diamond Carbon in Hanks' Solution

NASA Astrophysics Data System (ADS)

Gnanavel, S.; Ponnusamy, S.; Mohan, L.; Radhika, R.; Muthamizhchelvan, C.; Ramasubramanian, K.

2018-03-01

Biomedical implants in the knee and hip are frequent failures because of corrosion and stress on the joints. To solve this important problem, metal implants can be coated with diamond carbon, and this coating plays a critical role in providing an increased resistance to implants toward corrosion. In this study, we have employed diamond carbon coating over Ti-6Al-4V and Ti-13Nb-13Zr alloys using hot filament chemical vapor deposition method which is well-established coating process that significantly improves the resistance toward corrosion, wears and hardness. The diamond carbon-coated Ti-13Nb-13Zr alloy showed an increased microhardness in the range of 850 HV. Electrochemical impedance spectroscopy and polarization studies in SBF solution (simulated body fluid solution) were carried out to understand the in vitro behavior of uncoated as well as coated titanium alloys. The experimental results showed that the corrosion resistance of Ti-13Nb-13Zr alloy is relatively higher when compared with diamond carbon-coated Ti-6Al-4V alloys due to the presence of β phase in the Ti-13Nb-13Zr alloy. Electrochemical impedance results showed that the diamond carbon-coated alloys behave as an ideal capacitor in the body fluid solution. Moreover, the stability in mechanical properties during the corrosion process was maintained for diamond carbon-coated titanium alloys.

Boosting surface charge-transfer doping efficiency and robustness of diamond with WO3 and ReO3

NASA Astrophysics Data System (ADS)

Tordjman, Moshe; Weinfeld, Kamira; Kalish, Rafi

2017-09-01

An advanced charge-transfer yield is demonstrated by employing single monolayers of transition-metal oxides—tungsten trioxide (WO3) and rhenium trioxide (ReO3)—deposited on the hydrogenated diamond surface, resulting in improved p-type sheet conductivity and thermal stability. Surface conductivities, as determined by Hall effect measurements as a function of temperature for WO3, yield a record sheet hole carrier concentration value of up to 2.52 × 1014 cm-2 at room temperature for only a few monolayers of coverage. Transfer doping with ReO3 exhibits a consistent narrow sheet carrier concentration value of around 3 × 1013 cm-2, exhibiting a thermal stability of up to 450 °C. This enhanced conductivity and temperature robustness exceed those reported for previously exposed surface electron acceptor materials used so far on a diamond surface. X-ray photoelectron spectroscopy measurements of the C1s core level shift as a function of WO3 and ReO3 layer thicknesses are used to determine the respective increase in surface band bending of the accumulation layers, leading to a different sub-surface two-dimensional hole gas formation efficiency in both cases. This substantial difference in charge-exchange efficiency is unexpected since both surface acceptors have very close work functions. Consequently, these results lead us to consider additional factors influencing the transfer doping mechanism. Transfer doping with WO3 reveals the highest yet reported transfer doping efficiency per minimal surface acceptor coverage. This improved surface conductivity performance and thermal stability will promote the realization of 2D diamond-based electronic devices facing process fabrication challenges.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahnood, Arman, E-mail: arman.ahnood@unimelb.edu.au; Ganesan, Kumaravelu; Stacey, Alastair

Beyond conventional electrically-driven neuronal stimulation methods, there is a growing interest in optically-driven approaches. In recent years, nitrogen-doped ultrananocrystalline diamond (N-UNCD) has emerged as a strong material candidate for use in electrically-driven stimulation electrodes. This work investigates the electrochemical activity of N-UNCD in response to pulsed illumination, to assess its potential for use as an optically-driven stimulation electrode. Whilst N-UNCD in the as-grown state exhibits a weak photoresponse, the oxygen plasma treated film exhibits two orders of magnitude enhancement in its sub-bandgap open circuit photovoltage response. The enhancement is attributed to the formation of a dense network of oxygen-terminated diamondmore » nanocrystals at the N-UNCD surface. Electrically connected to the N-UNCD bulk via sub-surface graphitic grain boundaries, these diamond nanocrystals introduce a semiconducting barrier between the sub-surface graphitic semimetal and the electrolyte solution, leading to a photovoltage under irradiation with wavelengths of λ = 450 nm and shorter. Within the safe optical exposure limit of 2 mW mm{sup −2}, charge injection capacity of 0.01 mC cm{sup −2} is achieved using a 15 × 15 μm electrode, meeting the requirements for extracellular and intercellular stimulation. The nanoscale nature of processes presented here along with the diamond's biocompatibility and biostability open an avenue for the use of oxygen treated N-UNCD as optically driven stimulating electrodes.« less

Studies on synthesis of diamond at high pressure and temperature

NASA Astrophysics Data System (ADS)

Kailath, Ansu J.

Diamond is an essential material of modern industry and probably the most versatile abrasive available today. It also has many other industrial applications attributable to its unique mechanical, optical, thermal and electrical properties. Its usage has grown to the extent that there is hardly a production process in modern industry in which industrial diamond does not play a part. Bulk diamond production today is a major industry. Diamonds can be produced in its thermodynamically stable regions either by direct static conversion, or shock-wave conversion. The pressures and temperatures required for direct static conversion are very high. In the catalyst-solvent method, the material used establishes a reaction path with lower activation energy than for direct transformation. This helps in a quicker transformation under more benign conditions. Hence, catalyst-solvent synthesis is readily accomplished and is now a viable and successful industrial process. Diamonds produced by shock wave are very small (approximately 60mu). Therefore this diamond is limited to applications such as polishing compounds only. The quality, quantity, size and morphology of the crystals synthesized by catalyst-solvent process depend on different conditions employed for synthesis. These details, because of commercial reasons are not disclosed in published literature. Hence, systematic studies have been planned to investigate the effect of various growth parameters on the synthesized crystals. During the growth of synthetic diamond crystals, some catalyst-solvent is retained into the crystals in some form and behaves like an impurity. Several physico-mechanical properties of the crystals are found to depend on the total quantity and distribution of these inclusions. Thus, detailed investigation of the crystallization medium and inclusions in synthesized diamonds was also undertaken in the present work. The work incorporated in this thesis has been divided into seven chapters. The first chapter is a general introduction incorporating the information regarding diamond together with a brief history of diamond synthesis. It also includes the details of the high pressure synthesis of diamond, the uses of diamond grits, the advantages of the synthetic diamond grit over natural grit and an outline to elucidate the reasons which prompted to undertake the present work. The details of the technique used in the present studies for synthesis of diamond grits by high-pressure high-temperature process are included in chapter II. The hydraulic press used for synthesis, the details of the reactant materials, stacking of the high pressure cell and the details of synthesis run have been described together with the separation procedure to isolate diamond grits from the frozen slug. Different analytical and characterization techniques used in the present studies for the analysis and characterization of the reactant materials, synthesized diamonds and the crystallization medium have been illustrated in chapter III. The effect of different synthesizing parameters on synthesized diamond crystals were studied. This study includes: (a) dependence of yield of diamond on temperature and pressure, (b) dependence of crystal size on cook length, (c) effect of variation of the relative amounts of carbonaceous material and catalyst on synthesis, (d) morphological variation and (e) effect of pressure pulse on synthesized crystals. Various observations made during this study and the results obtained have been compiled in chapter IV. The synthesized diamond crystals were characterized by X-ray Powder Diffraction (XRD), Raman Spectroscopy, Scanning Electron Microscopy (SEM) and Optical Microscopy. The results obtained have been compiled in chapter V. In addition to these, the results obtained from the Infrared Spectra and the Electron Paramagnetic Spectra have also been included. Studies of crystallization medium and inclusions in the synthesized diamonds were carried out. This include: (a) X-ray diffraction study of the phase composition of crystallization medium and inclusions in synthesized diamonds, (b) metallographic examination of the initial catalyst-solvent and the frozen slug after synthesis, (c) temperature dependence of the magnetic susceptibility of the initial catalyst-solvent and the frozen catalyst-solvent after synthesis, (d) scanning electron microscopic examination of the inclusion on the mechanically polished cross-sections of the synthesized crystals, (e) EDAX analysis of these observed inclusions and the frozen catalyst-solvent matrix after growth, (f) temperature dependence of the magnetic susceptibility of the synthesized crystals and (g) the Mossbauer spectroscopic analysis of the synthesized crystals. Different observations and the results obtained from these studies have been compiled and presented in chapter VI. Chapter VII illustrates the various conclusions drawn from the present studies.

Micro-optical fabrication by ultraprecision diamond machining and precision molding

NASA Astrophysics Data System (ADS)

Li, Hui; Li, Likai; Naples, Neil J.; Roblee, Jeffrey W.; Yi, Allen Y.

2017-06-01

Ultraprecision diamond machining and high volume molding for affordable high precision high performance optical elements are becoming a viable process in optical industry for low cost high quality microoptical component manufacturing. In this process, first high precision microoptical molds are fabricated using ultraprecision single point diamond machining followed by high volume production methods such as compression or injection molding. In the last two decades, there have been steady improvements in ultraprecision machine design and performance, particularly with the introduction of both slow tool and fast tool servo. Today optical molds, including freeform surfaces and microlens arrays, are routinely diamond machined to final finish without post machining polishing. For consumers, compression molding or injection molding provide efficient and high quality optics at extremely low cost. In this paper, first ultraprecision machine design and machining processes such as slow tool and fast too servo are described then both compression molding and injection molding of polymer optics are discussed. To implement precision optical manufacturing by molding, numerical modeling can be included in the future as a critical part of the manufacturing process to ensure high product quality.

'The Diamond': a structure for simulation debrief.

PubMed

Jaye, Peter; Thomas, Libby; Reedy, Gabriel

2015-06-01

Despite debriefing being found to be the most important element in providing effective learning in simulation-based medical education reviews, there are only a few examples in the literature to help guide a debriefer. The diamond debriefing method is based on the technique of description, analysis and application, along with aspects of the advocacy-inquiry approach and of debriefing with good judgement. It is specifically designed to allow an exploration of the non-technical aspects of a simulated scenario. The debrief diamond, a structured visual reminder of the debrief process, was developed through teaching simulation debriefing to hundreds of faculty members over several years. The diamond shape visually represents the idealised process of a debrief: opening out a facilitated discussion about the scenario, before bringing the learning back into sharp focus with specific learning points. Debriefing is the most important element in providing effective learning in simulation-based medical education reviews The Diamond is a two-sided prompt sheet: the first contains the scaffolding, with a series of specifically constructed questions for each phase of the debrief; the second lays out the theory behind the questions and the process. The Diamond encourages a standardised approach to high-quality debriefing on non-technical skills. Feedback from learners and from debriefing faculty members has indicated that the Diamond is useful and valuable as a debriefing tool, benefiting both participants and faculty members. It can be used by junior and senior faculty members debriefing in pairs, allowing the junior faculty member to conduct the description phase, while the more experienced faculty member leads the later and more challenging phases. The Diamond gives an easy but pedagogically sound structure to follow and specific prompts to use in the moment. © 2015 The Authors. The Clinical Teacher published by Association for the Study of Medical Education and John Wiley & Sons Ltd.

Diamond surface functionalization with biomimicry - Amine surface tether and thiol moiety for electrochemical sensors

NASA Astrophysics Data System (ADS)

Sund, James B.; Causey, Corey P.; Wolter, Scott D.; Parker, Charles B.; Stoner, Brian R.; Toone, Eric J.; Glass, Jeffrey T.

2014-05-01

The surface of conducting diamond was functionalized with a terminal thiol group that is capable of binding and detecting nitrogen-oxygen species. The functionalization process employed multiple steps starting with doped diamond films grown by plasma enhanced chemical vapor deposition followed by hydrogen termination and photochemical attachment of a chemically protected amine alkene. The surface tether was deprotected to reveal the amine functionality, which enabled the tether to be extended with surface chemistry to add a terminal thiol moiety for electrochemical sensing applications. Each step of the process was validated using X-ray photoelectron spectroscopy analysis.

ONR Far East Scientific Information Bulletin. Volume 14, Number 1. HEISEI, Achieving Universal Peace

DTIC Science & Technology

1989-03-01

grounding gated for basic and central meanings, traced in the Western classics and Indo-European for subsequent etymological development, comparative...controlled properties at reasonable costs. diamond films, processing conditions for Diamond for industrial applications the fabrication of diamond films... applications such as diamondlike films, are beginning to reach heat sinks will also become economically the industrial marketplace. The precise

Trapezoidal diffraction grating beam splitters in single crystal diamond

NASA Astrophysics Data System (ADS)

Kiss, Marcell; Graziosi, Teodoro; Quack, Niels

2018-02-01

Single Crystal Diamond has been recognized as a prime material for optical components in high power applications due to low absorption and high thermal conductivity. However, diamond microstructuring remains challenging. Here, we report on the fabrication and characterization of optical diffraction gratings exhibiting a symmetric trapezoidal profile etched into a single crystal diamond substrate. The optimized grating geometry diffracts the transmitted optical power into precisely defined proportions, performing as an effective beam splitter. We fabricate our gratings in commercially available single crystal CVD diamond plates (2.6mm x 2.6mm x 0.3mm). Using a sputter deposited hard mask and patterning by contact lithography, the diamond is etched in an inductively coupled oxygen plasma with zero platen power. The etch process effectively reveals the characteristic {111} diamond crystal planes, creating a precisely defined angled (54.7°) profile. SEM and AFM measurements of the fabricated gratings evidence the trapezoidal shape with a pitch of 3.82μm, depth of 170 nm and duty cycle of 35.5%. Optical characterization is performed in transmission using a 650nm laser source perpendicular to the sample. The recorded transmitted optical power as function of detector rotation angle shows a distribution of 21.1% in the 0th order and 23.6% in each +/-1st order (16.1% reflected, 16.6% in higher orders). To our knowledge, this is the first demonstration of diffraction gratings with trapezoidal profile in single crystal diamond. The fabrication process will enable beam splitter gratings of custom defined optical power distribution profiles, while antireflection coatings can increase the efficiency.

Study on electroplating technology of diamond tools for machining hard and brittle materials

NASA Astrophysics Data System (ADS)

Cui, Ying; Chen, Jian Hua; Sun, Li Peng; Wang, Yue

2016-10-01

With the development of the high speed cutting, the ultra-precision machining and ultrasonic vibration technique in processing hard and brittle material , the requirement of cutting tools is becoming higher and higher. As electroplated diamond tools have distinct advantages, such as high adaptability, high durability, long service life and good dimensional stability, the cutting tools are effective and extensive used in grinding hard and brittle materials. In this paper, the coating structure of electroplating diamond tool is described. The electroplating process flow is presented, and the influence of pretreatment on the machining quality is analyzed. Through the experimental research and summary, the reasonable formula of the electrolyte, the electroplating technologic parameters and the suitable sanding method were determined. Meanwhile, the drilling experiment on glass-ceramic shows that the electroplating process can effectively improve the cutting performance of diamond tools. It has laid a good foundation for further improving the quality and efficiency of the machining of hard and brittle materials.

Endo-Fullerene and Doped Diamond Nanocrystallite Based Models of Qubits for Solid-State Quantum Computers

NASA Technical Reports Server (NTRS)

Park, Seongjun; Srivastava, Deepak; Cho, Kyeongjae; Biegel, Bryan (Technical Monitor)

2001-01-01

Models of encapsulated 1/2 nuclear spin H-1 and P-31 atoms in fullerene and diamond nanocrystallite, respectively, are proposed and examined with ab-initio local density functional method for possible applications as single quantum bits (qubits) in solid-state quantum computers. A H-1 atom encapsulated in a fully deuterated fullerene, C(sub 20)D(sub 20), forms the first model system and ab-initio calculation shows that H-1 atom is stable in atomic state at the center of the fullerene with a barrier of about 1 eV to escape. A P-31 atom positioned at the center of a diamond nanocrystallite is the second model system, and 3 1P atom is found to be stable at the substitutional site relative to interstitial sites by 15 eV, Vacancy formation energy is 6 eV in diamond so that substitutional P-31 atom will be stable against diffusion during the formation mechanisms within the nanocrystallite. The coupling between the nuclear spin and weakly bound (valance) donor electron coupling in both systems is found to be suitable for single qubit applications, where as the spatial distributions of (valance) donor electron wave functions are found to be preferentially spread along certain lattice directions facilitating two or more qubit applications. The feasibility of the fabrication pathways for both model solid-state qubit systems within practical quantum computers is discussed with in the context of our proposed solid-state qubits.

Diamond-like nanoparticles influence on flavonoids transport: molecular modelling

NASA Astrophysics Data System (ADS)

Plastun, Inna L.; Agandeeva, Ksenia E.; Bokarev, Andrey N.; Zenkin, Nikita S.

2017-03-01

Intermolecular interaction of diamond-like nanoparticles and flavonoids is investigated by numerical simulation. Using molecular modelling by the density functional theory method, we analyze hydrogen bonds formation and their influence on IR - spectra and structure of molecular complex which is formed due to interaction between flavonoids and nanodiamonds surrounded with carboxylic groups. Enriched adamantane (1,3,5,7 - adamantanetetracarboxylic acid) is used as an example of diamond-like nanoparticles. Intermolecular forces and structure of hydrogen bonds are investigated. IR - spectra and structure parameters of quercetin - adamantanetetracarboxylic acid molecular complex are obtained by numerical simulation using the Gaussian software complex. Received data coincide well with experimental results. Intermolecular interactions and hydrogen bonding structure in the obtained molecular complex are examined. Possibilities of flavonoids interaction with DNA at the molecular level are also considered.

Multienergy gold ion implantation for enhancing the field electron emission characteristics of heterogranular structured diamond films grown on Au-coated Si substrates

NASA Astrophysics Data System (ADS)

Sankaran, K. J.; Manoharan, D.; Sundaravel, B.; Lin, I. N.

2016-09-01

Multienergy Au-ion implantation enhanced the electrical conductivity of heterogranular structured diamond films grown on Au-coated Si substrates to a high level of 5076.0 (Ω cm)-1 and improved the field electron emission (FEE) characteristics of the films to low turn-on field of 1.6 V/μm, high current density of 5.4 mA/cm2 (@ 2.65 V/μm), and high lifetime stability of 1825 min. The catalytic induction of nanographitic phases in the films due to Au-ion implantation and the formation of diamond-to-Si eutectic interface layer due to Au-coating on Si together encouraged the efficient conducting channels for electron transport, thereby improved the FEE characteristics of the films.

An all-diamond X-ray position and flux monitor using nitrogen-incorporated ultra-nanocrystalline diamond contacts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zou, Mengnan; Gaowei, Mengjia; Zhou, Tianyi

Diamond X-ray detectors with conducting nitrogen-incorporated ultra-nanocrystalline diamond (N-UNCD) films as electrodes were fabricated to measure X-ray beam flux and position. Structural characterization and functionality tests were performed for these devices. The N-UNCD films grown on unseeded diamond substrates were compared with N-UNCD films grown on a seeded silicon substrate. The feasibility of the N-UNCD films acting as electrodes for X-ray detectors was confirmed by the stable performance in a monochromatic X-ray beam. The fabrication process is able to change the surface status which may influence the signal uniformity under low bias, but this effect can be neglected under fullmore » collection bias.« less

Laser-induced multi-energy processing in diamond growth

NASA Astrophysics Data System (ADS)

Xie, Zhiqiang

Laser-induced multi-energy processing (MEP) introduces resonant vibrational excitations of precursor molecules to conventional chemical vapor deposition methods for material synthesis. In this study, efforts were extended to explore the capability of resonant vibrational excitations for promotion of energy efficiency in chemical reactions, for enhancement of diamond deposition, and for control of chemical reactions. The research project mainly focused on resonant vibrational excitations of precursor molecules using lasers in combustion flame deposition of diamond, which led to: 1) promotion of chemical reactions; 2) enhancement of diamond growth with higher growth rate and better crystallizations; 3) steering of chemical reactions which lead to preferential growth of {100}-oriented diamond films and crystals; and 4) mode-selective excitations of precursor molecules toward bond-selective control of chemical reactions. Diamond films and crystals were deposited in open air by combustion flame deposition through resonant vibrational excitations of precursor molecules, including ethylene (C2H4) and propylene (C3H 6). A kilowatt wavelength-tunable CO2 laser with spectral range from 9.2 to 10.9 microm was tuned to match vibrational modes of the precursor molecules. Resonant vibrational excitations of these molecules were achieved with high energy efficiency as compared with excitations using a common CO2 laser (fixed wavelength at 10.591microm). With resonant vibrational excitations, the diamond growth rate was increased; diamond quality was promoted; diamond crystals with lengths up to 5 mm were deposited in open air; preferential growth of {100}-oriented diamond films and single crystals was achieved; mode-selective excitations of precursor molecules were investigated toward control of chemical reactions. Optical emission spectroscopy (OES), mass spectrometry (MS), and molecular dynamic simulations were conducted to obtain an in-depth understanding of the resonant vibrational excitations. Species concentrations in flames without and with laser excitations under different wavelengths were investigated both experimentally and theoretically. Detection of C2, CH, and OH radicals, as well as CxHy species and their oxides (CxH yO) (x=1, 2; y=0˜5) using OES and MS, together with reaction pathway simulations, were used to explain the effect of vibrational excitations of precursor molecules on chemical reactions and on diamond depositions.

SERS activity of Ag decorated nanodiamond and nano-β-SiC, diamond-like-carbon and thermally annealed diamond thin film surfaces.

PubMed

Kuntumalla, Mohan Kumar; Srikanth, Vadali Venkata Satya Siva; Ravulapalli, Satyavathi; Gangadharini, Upender; Ojha, Harish; Desai, Narayana Rao; Bansal, Chandrahas

2015-09-07

In the recent past surface enhanced Raman scattering (SERS) based bio-sensing has gained prominence owing to the simplicity and efficiency of the SERS technique. Dedicated and continuous research efforts have been made to develop SERS substrates that are not only stable, durable and reproducible but also facilitate real-time bio-sensing. In this context diamond, β-SiC and diamond-like-carbon (DLC) and other related thin films have been promoted as excellent candidates for bio-technological applications including real time bio-sensing. In this work, SERS activities of nanodiamond, nano-β-SiC, DLC, thermally annealed diamond thin film surfaces were examined. DLC and thermally annealed diamond thin films were found to show SERS activity without any metal nanostructures on their surfaces. The observed SERS activities of the considered surfaces are explained in terms of the electromagnetic enhancement mechanism and charge transfer resonance process.

Diamond photonics platform enabled by femtosecond laser writing

PubMed Central

Sotillo, Belén; Bharadwaj, Vibhav; Hadden, J. P.; Sakakura, Masaaki; Chiappini, Andrea; Fernandez, Toney Teddy; Longhi, Stefano; Jedrkiewicz, Ottavia; Shimotsuma, Yasuhiko; Criante, Luigino; Osellame, Roberto; Galzerano, Gianluca; Ferrari, Maurizio; Miura, Kiyotaka; Ramponi, Roberta; Barclay, Paul E.; Eaton, Shane Michael

2016-01-01

Diamond is a promising platform for sensing and quantum processing owing to the remarkable properties of the nitrogen-vacancy (NV) impurity. The electrons of the NV center, largely localized at the vacancy site, combine to form a spin triplet, which can be polarized with 532 nm laser light, even at room temperature. The NV’s states are isolated from environmental perturbations making their spin coherence comparable to trapped ions. An important breakthrough would be in connecting, using waveguides, multiple diamond NVs together optically. However, still lacking is an efficient photonic fabrication method for diamond akin to the photolithographic methods that have revolutionized silicon photonics. Here, we report the first demonstration of three dimensional buried optical waveguides in diamond, inscribed by focused femtosecond high repetition rate laser pulses. Within the waveguides, high quality NV properties are observed, making them promising for integrated magnetometer or quantum information systems on a diamond chip. PMID:27748428

Comparison of Finite Element Modeling and Experimental Pressure Distribution in a Diamond Anvil Cell

NASA Astrophysics Data System (ADS)

Kondrat'yev, Andreiy I.; Murphy, Michael J.; Weir, Samuel T.; Vohra, Yogesh K.

2002-10-01

Ultra high pressures can be obtained in a Diamond Anvil Cell (DAC) device by optimizing the geometrical shape of diamond anvil and by use of high strength gasket materials. Radial pressure distribution in a diamond-coated rhenium gasket was measured by the micro-collimated X-ray diffraction techniques at NSLS, Brookhaven National Laboratory up to peak pressure of 220 GPa. The process of DAC compression was described by finite element analysis using NIKE-2D software. The mechanical properties of the diamond-coated gasket material were modeled and radial pressure distribution obtained was in good agreement with the experimental data. The calculated shear stress in diamond in the axial direction was shown to depend strongly on the yield strength of the gasket material and may limit the ultimate pressure that can be obtained with the use of high strength gasket materials. Supported by the National Science Foundation (NSF) Grant No. DMR-0203779.

New Stability Field of Jeffbenite (ex-"TAPP"): Possibility of Super-Deep Origin

NASA Astrophysics Data System (ADS)

Anzolini, C.; Drewitt, J.; Lord, O. T.; Walter, M. J.; Nestola, F.

2016-12-01

Jeffbenite is a new tetragonal phase with garnet-like stoichiometry (Nestola et al., 2016) previously referred to as TAPP (Tetragonal Almandine-Pyrope Phase), which is found exclusively in nature as inclusions in super-deep diamonds and may provide key information about their depth of formation. Nevertheless, whether jeffbenite forms as a primary phase in the transition zone (TZ) or in the lower mantle (LM), or is the product of retrogression from high-pressure mantle phases is still controversial. At present two possibilities are proposed for its formation: 1) entrapment as a primary mineral by diamond in the upper mantle at pressures up to 13 GPa (Armstrong & Walter, 2012); 2) retrograde formation from a bridgmanite or a majoritic garnet below 13 GPa (Armstrong & Walter, 2012; Brenker et al., 2002; Harte & Hudson, 2013). The only previously experimentally determined stability field for jeffbenite is that of Armstrong & Walter (2012), which provides a maximum pressure for jeffbenite stability of 13 GPa ( 390 km) at 1700 K. This suggested that jeffbenite is a sub-lithospheric mineral, but ruled out direct incorporation of jeffbenite into diamond at the TZ-LM boundary. These results were obtained on a Ti-rich jeffbenite, which is usually found as part of composite inclusions, and not on a Ti-free jeffbenite, which occurs as single-phase inclusions in diamonds. We therefore performed new laser heated diamond-anvil cell experiments from 5 to 30 GPa on a Ti-free jeffbenite, in order to determine the role that TiO2 plays in its stability field and to determine if jeffbenite can be directly incorporated into diamond in the TZ or LM. Our preliminary results indicate that the absence of TiO2 extends the stability field of jeffbenite to higher pressures than previously determined. This work was supported by Fondazione CaRiPaRo, NERC Grant NE/M000419/1 to MJW, NERC Fellowship Grant NE/J018945/1 to OTL and ERC-2012-StG 307322 to FN. Armstrong, L.S. & Walter, M.J. (2012) Eur J Mineral, 24:587-597. Brenker, F.E., Stachel, T., Harris, J.W. (2002) Earth Planet Sci Lett, 198:1-9. Harte & Hudson (2013) Proceedings of 10th International Kimberlite Conference, 235-253. Nestola, F., Burnham, A.D., Peruzzo, L., Tauro, L., Alvaro, M., Walter, M.J., Gunter, M., Anzolini, C., Kohn, S.C. (2016) Mineral Mag, DOI: 10.1180/minmag.2016.080.059

Patterning of nanocrystalline diamond films for diamond microstructures useful in MEMS and other devices

DOEpatents

Gruen, Dieter M [Downers Grove, IL; Busmann, Hans-Gerd [Bremen, DE; Meyer, Eva-Maria [Bremen, DE; Auciello, Orlando [Bolingbrook, IL; Krauss, Alan R [late of Naperville, IL; Krauss, Julie R [Naperville, IL

2004-11-02

MEMS structure and a method of fabricating them from ultrananocrystalline diamond films having average grain sizes of less than about 10 nm and feature resolution of less than about one micron . The MEMS structures are made by contacting carbon dimer species with an oxide substrate forming a carbide layer on the surface onto which ultrananocrystalline diamond having average grain sizes of less than about 10 nm is deposited. Thereafter, microfabrication process are used to form a structure of predetermined shape having a feature resolution of less than about one micron.

ONR (Office of Naval Research) Far East Scientific Information Bulletin. Volume 14, Number 1, January-March 1989

DTIC Science & Technology

1989-03-01

central meanings, traced in the Western classics and Indo-European for subsequent etymological development, comparative linguistics, Dr. Thieme has and...properties at reasonable costs. diamond films, processing conditions for Diamond for industrial applications the fabrication of diamond films, applica- is... applications such as diamondlike films, are beginning to reach heat sinks will also become economically the industrial marketplace. The precise feasible

The induction of nanographitic phase on Fe coated diamond films for the enhancement in electron field emission properties

NASA Astrophysics Data System (ADS)

Panda, Kalpataru; Sundaravel, B.; Panigrahi, B. K.; Chen, H.-C.; Huang, P.-C.; Shih, W.-C.; Lo, S.-C.; Lin, L.-J.; Lee, C.-Y.; Lin, I.-N.

2013-03-01

A thin layer of iron coating and subsequent post-annealing (Fe-coating/post-annealing) is seen to significantly enhance the electron field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films. The best EFE properties, with a turn on field (E0) of 1.98 V/μm and current density (Je) of 705 μA/cm2 at 7.5 V/μm, are obtained for the films, which were Fe-coated/post-annealed at 900 °C in H2 atmosphere. The mechanism behind the enhanced EFE properties of Fe coated/post-annealed UNCD films are explained by the microstructural analysis which shows formation of nanographitic phase surrounding the Fe (or Fe3C) nanoparticles. The role of the nanographitic phase in improving the emission sites of Fe coated/post-annealed UNCD films is clearly revealed by the current imaging tunneling spectroscopy (CITS) images. The CITS images clearly show significant increase in emission sites in Fe-coated/post-annealed UNCD films than the as-deposited one. Enhanced emission sites are mostly seen around the boundaries of the Fe (or Fe3C) nanoparticles which were formed due to the Fe-coating/post-annealing processes. Moreover, the Fe-coating/post-annealing processes enhance the EFE properties of UNCD films more than that on the microcrystalline diamond films. The authentic factor, resulting in such a phenomenon, is attributed to the unique granular structure of the UNCD films. The nano-sized and uniformly distributed grains of UNCD films, resulted in markedly smaller and densely populated Fe-clusters, which, in turn, induced more finer and higher populated nano-graphite clusters.

Electrochemical mineralization and detoxification of naphthenic acids on boron-doped diamond anodes.

PubMed

Diban, Nazely; Urtiaga, Ane

2018-01-05

Electrochemical oxidation (ELOX) with boron-doped diamond (BDD) anodes was successfully applied to degrade a model aqueous solution of a mixture of commercial naphthenic acids (NAs). The model mixture was prepared resembling the NA and salt composition of oil sands process-affected water (OSPW) as described in the literature. The initial concentration of NAs between 70 and 120 mg/L did not influence the electrooxidation kinetics. However, increasing the applied current density from 20 to 100 A/m 2 and the initial chloride concentration from 15 to 70 and 150 mg/L accelerated the rate of NA degradation. At higher chloride concentration, the formation of indirect oxidative species could contribute to the faster oxidation of NAs. Complete chemical oxygen demand removal at an initial NA concentration of 120 mg/L, 70 mg/L of chloride and applied 50 A/m 2 of current density was achieved, and 85% mineralization, defined as the decrease of the total organic carbon (TOC) content, was attained. Moreover, after 6 h of treatment and independently on the experimental conditions, the formation of more toxic species, i.e. perchlorate and organochlorinated compounds, was not detected. Finally, the use of ELOX with BDD anodes produced a 7 to 11-fold reduction of toxicity (IC 50 towards Vibrio fischeri) after 2 h of treatment.

Equilibrium, chemical kinetic, and transport limitations to diamond growth

NASA Astrophysics Data System (ADS)

Evans, Edward Anthony

Because of their extreme properties, diamond films have found some industrial applications, i.e., heat sinks and tool coatings. However, to increase their economic attractiveness, the growth rate must be increased, the deposition temperature must be lowered, and single crystal films must be achieved. We have studied two types of chemical vapor deposition systems, hot-filament and microwave assisted, in order to understand the factors limiting diamond growth rate. From simultaneous microbalance growth rate measurements and mass spectrometer measurements, changes in growth rate are correlated with changes in gas phase composition. Measured reaction orders support the proposal that diamond growth occurs through a single-carbon-atom species, e.g., CHsb3. When a two-carbon atom source gas is used, it is likely that the dissociation to two, single-carbon atom species occurs on the substrate surface (dissociative adsorption). Furthermore, a shift to zero-order suggests that the diamond growth is a surface-site limited process at higher hydrocarbon concentrations. The diamond growth rate maximum with pressure is explained by transport limitations of species within the reaction zone. The reported diamond growth rates in the hot-filament reactor are several times higher than those reported by other research groups. These higher growth rates result from surrounding the substrate with the filament. We have used the measured growth rates, filament temperatures, and thermocouple measurements to calculate activation energies for diamond growth. When the filament temperature is used for the calculation, an activation energy of 73 kcal per mole is obtained; however, based on estimated substrate temperatures, an activation energy of 18 kcal per mole is determined. A dimensional analysis approach was developed to select the most important gas phase reactions occurring during diamond CVD. Steady-state analysis of these reactions and the application of mass transport equations lead to the conclusion that diamond growth, in current hot-filament and microwave assisted CVD processes, is occurring in a partial equilibrium environment in which diffusion of atomic hydrogen controls the overall diamond growth rate. The initial stages of diamond growth on non-diamond substrates correspond to carburization, nucleation and growth. When polycrystalline or single crystal diamond is used as a substrate, the carburization and nucleation stages are not observed and growth begins immediately. The nucleation rate depends sensitively on the radiative heat transfer to the substrate. Adding ozone to the hot-filament CVD charge increases the production of carbon monoxide and carbon dioxide; this increase is observed with or without the filament being activated. A consistent effect on the diamond growth rate was not observed when ozone was added to the hot-filament reactor.

Electrochemical Oxidation of Resorcinol in Aqueous Medium Using Boron-Doped Diamond Anode: Reaction Kinetics and Process Optimization with Response Surface Methodology

PubMed Central

Körbahti, Bahadır K.; Demirbüken, Pelin

2017-01-01

Electrochemical oxidation of resorcinol in aqueous medium using boron-doped diamond anode (BDD) was investigated in a batch electrochemical reactor in the presence of Na2SO4 supporting electrolyte. The effect of process parameters such as resorcinol concentration (100–500 g/L), current density (2–10 mA/cm2), Na2SO4 concentration (0–20 g/L), and reaction temperature (25–45°C) was analyzed on electrochemical oxidation using response surface methodology (RSM). The optimum operating conditions were determined as 300 mg/L resorcinol concentration, 8 mA/cm2 current density, 12 g/L Na2SO4 concentration, and 34°C reaction temperature. One hundred percent of resorcinol removal and 89% COD removal were obtained in 120 min reaction time at response surface optimized conditions. These results confirmed that the electrochemical mineralization of resorcinol was successfully accomplished using BDD anode depending on the process conditions, however the formation of intermediates and by-products were further oxidized at much lower rate. The reaction kinetics were evaluated at optimum conditions and the reaction order of electrochemical oxidation of resorcinol in aqueous medium using BDD anode was determined as 1 based on COD concentration with the activation energy of 5.32 kJ/mol that was supported a diffusion-controlled reaction. PMID:29082225

Oxidation of carbon monoxide, hydrogen peroxide and water at a boron doped diamond electrode: the competition for hydroxyl radicals.

PubMed

Kisacik, Izzet; Stefanova, Ana; Ernst, Siegfried; Baltruschat, Helmut

2013-04-07

Boron doped diamond (BDD) electrodes have an extremely high over-voltage for oxygen evolution from water, which favours its use in oxidation processes of other compounds at high potentials. We used a rotating ring disc (RRDE) assembly and differential electrochemical mass spectrometry (DEMS) in order to monitor the consumption or the production of species in the course of the electrode processes. By intercepting the intermediate of the electrochemical water oxidation with chemical reactions we demonstrate clearly, albeit indirectly, that in the water oxidation process at BDD above 2.5 V the first step is the formation of ˙OH radicals. The electro-oxidation of CO to CO2 at BDD electrodes proceeds only via a first attack by ˙OH radicals followed by a further electron transfer to the electrode. At potentials below the onset of oxygen evolution from water, H2O2 is oxidised by a direct electron transfer to the BDD electrode, while at higher potentials, two different reactions paths compete for the ˙OH radicals formed in the first electron transfer from water: one, where these ˙OH radicals react with each other followed by further electron transfers leading to O2 on the one hand and one, where ˙OH radicals react with other species like H2O2 or CO with subsequent electron transfers on the other hand.

Radiation Halos, a Rare Microstructure in Diamonds From the Central African Republic

NASA Astrophysics Data System (ADS)

Vicenzi, E. P.; Heaney, P. J.; Snyder, K.; Armstrong, L.

2002-05-01

The geochemical characterization of bulk diamonds and associated inclusions as a tool for determining provenance carries significant inherent limitations. Isotopic and trace element signatures are imparted within the mantle during diamond growth; hence, discriminating crystals from a particular region on the Earth's surface on this basis is difficult at best, and impossible (using current technologies) in many cases. In contrast, rare diamond characteristics may provide a partial solution for recognizing stones from a limited number of localities. Here we discuss an analysis of radiation halos in alluvially deposited polycrystalline diamonds (carbonados) from the Central African Republic (CAR). Large amounts of implanted Xe and Kr, as well as isotopic ratios of those elements consistent with fission, in carbonado strongly suggest that diamond crystallization took place in the presence of significant quantities of uranium [1]. Such ionizing radiation ultimately results in the loss of periodicity of the diamond structure. Crystallographically damaged areas produce fewer photons in cathodoluminescence microscopy, and therefore, the metamict regions resulting from point source radiation in diamond can be visualized on the scale of ~1-25 micrometers [2]. Because intermediate daughter products in the decay chain release alpha particles at differing energies, a ``bull's eye'' pattern is produced in 2-D by the point source radiation. Radiation haloes have been previously observed in carbonados and are thought to result from U deposition associated with fluids following diamond formation [3,4]. We have made a series of measurements of the apparent diameter of the largest circle within a damage halo. By comparing the statistical distribution of this dimension to the distribution expected for a series of circles resulting from random sectioning of mono-sized spheres, one can estimate whether the radiation resulted from one or more fluid pulses widely separated in time. Preliminary data are consistent with a single pulse of uranium deposition in CAR carbonado. [1] Ozima et al. 1991, Nature 351 : 472. [2] Mendelssohn et al. 1979, Diamond Research:35. [3] Milledge et al. 1998, 7th Intl. Kimberlite Conf: 589. [4] Magee 2001, Ph.D. ANU 247p.

The sources and time-integrated evolution of diamond-forming fluids - Trace elements and isotopic evidence

NASA Astrophysics Data System (ADS)

Klein-BenDavid, Ofra; Pearson, D. Graham; Nowell, Geoff M.; Ottley, Chris; McNeill, John C. R.; Logvinova, Alla; Sobolev, Nikolay V.

2014-01-01

Sub-micrometer inclusions in fibrous diamond growth zones carry high-density fluids (HDF) from which the host diamonds have precipitated. The chemistry of these fluids is our best opportunity of characterizing the diamond-forming environment. The major and trace element patterns of diamond-forming fluids vary widely. Such elemental signatures can be easily modified by a variety of mantle processes whereas radiogenic isotopes give a clear fingerprint of the time-integrated evolution of the fluid source region. Thus, the combination of elemental and isotope data is a powerful tool in constraining the origin of fluids from which diamonds precipitate. Here we present combined trace element composition (34 diamonds) and Sr isotopic data (23 diamonds) for fluid-rich diamonds from six worldwide locations. The Nd and Pb isotopic composition of two of the diamonds were also obtained. Several of the samples were analyzed in at least 2 locations to investigate variations in the fluid during diamond growth. The data was acquired using an off-line laser sampling technique followed by solution ICPMS and TIMS analysis. The Sr isotopic compositions of diamond fluids from the different suites range between convecting mantle values for Udachnaya (87Sr/86Sr363 = 0.70300 ± 16 to 0.70361 ± 4), to highly enriched values, up to 87Sr/86Sr = 0.72330 ± 3, for a diamond from Congo. No isochronous relationships were observed in any of the suites. The lowest Nd isotopic composition recorded so far in a diamond is from Congo (εNd71 = -40.4), which also contains the most radiogenic Sr isotopic composition. In contrast, a less enriched but still rather unradiogenic Nd isotope composition (εNd540 = -11) was obtained for a diamond from Snap Lake, which has moderately radiogenic Sr isotopic enrichment (87Sr/86Sr540 = 0.70821 ± 1). The Pb isotopic system measured in one diamond indicates a complex evolution for the fluid source, with extreme 207Pb/204Pb ratio (15.810 ± 3) and moderate, kimberlite-like 206Pb/204Pb and 208Pb/204Pb ratios. A multi-stage evolution of the diamond-forming fluids source can be constrained from our new isotopic data, indicating an Achaean enrichment event resulting in elevated U/Pb, Rb/Sr ratios and enrichment in LREEs. This source underwent a more recent fractionation, in the last 500 Myr that may have been related to the diamond-forming event. There is a strong correspondence between fluids with relatively unradiogenic Sr isotopes and relatively low (La, Nd, Sm)/(Nb, Zr) and (Ba, Th)/(Nb) ratios. Sr isotopic enrichment is accompanied by an increase in these ratios. The least trace element enriched and most isotopically depleted fluids are from the high-Mg carbonatitic suite. Thus, HDFs could be derived from asthenospheric mantle as low degree melts that interact to varying degrees with an ancient, metasomatized, rutile- and phlogopite bearing, sub continental lithosphere mantle. The internal heterogeneity in the Sr isotopic ratios within a single diamond suite and even within single diamonds may indicate fluid-mixing processes. Such mixing may occur during migration through preferred mantle veins and may be affected by the small-scale geochemical variability within them.

Free-standing nanomechanical and nanophotonic structures in single-crystal diamond

NASA Astrophysics Data System (ADS)

Burek, Michael John

Realizing complex three-dimensional structures in a range of material systems is critical to a variety of emerging nanotechnologies. This is particularly true of nanomechanical and nanophotonic systems, both relying on free-standing small-scale components. In the case of nanomechanics, necessary mechanical degrees of freedom require physically isolated structures, such as suspended beams, cantilevers, and membranes. For nanophotonics, elements like waveguides and photonic crystal cavities rely on light confinement provided by total internal reflection or distributed Bragg reflection, both of which require refractive index contrast between the device and surrounding medium (often air). Such suspended nanostructures are typically fabricated in a heterolayer structure, comprising of device (top) and sacrificial (middle) layers supported by a substrate (bottom), using standard surface nanomachining techniques. A selective, isotropic etch is then used to remove the sacrificial layer, resulting in free-standing devices. While high-quality, crystalline, thin film heterolayer structures are readily available for silicon (as silicon-on-insulator (SOI)) or III-V semiconductors (i.e. GaAs/AlGaAs), there remains an extensive list of materials with attractive electro-optic, piezoelectric, quantum optical, and other properties for which high quality single-crystal thin film heterolayer structures are not available. These include complex metal oxides like lithium niobate (LiNbO3), silicon-based compounds such as silicon carbide (SiC), III-V nitrides including gallium nitride (GaN), and inert single-crystals such as diamond. Diamond is especially attractive for a variety of nanoscale technologies due to its exceptional physical and chemical properties, including high mechanical hardness, stiffness, and thermal conductivity. Optically, it is transparent over a wide wavelength range (from 220 nm to the far infrared), has a high refractive index (n ~ 2.4), and is host to a vast inventory of luminescent defect centers (many with direct optical access to highly coherent electron and nuclear spins). Diamond has many potential applications ranging from radio frequency nanoelectromechanical systems (RF-NEMS), to all-optical signal processing and quantum optics. Despite the commercial availability of wafer-scale nanocrystalline diamond thin films on foreign substrates (namely SiO2), this diamond-on-insulator (DOI) platform typically exhibits inferior material properties due to friction, scattering, and absorption losses at grain boundaries, significant surface roughness, and large interfacial stresses. In the absence of suitable heteroepitaxial diamond growth, substantial research and development efforts have focused on novel processing techniques to yield nanoscale single-crystal diamond mechanical and optical elements. In this thesis, we demonstrate a scalable 'angled-etching' nanofabrication method for realizing nanomechanical systems and nanophotonic networks starting from bulk single-crystal diamond substrates. Angled-etching employs anisotropic oxygen-based plasma etching at an oblique angle to the substrate surface, resulting in suspended optical structures with triangular cross-sections. Using this approach, we first realize single-crystal diamond nanomechanical resonant structures. These nanoscale diamond resonators exhibit high mechanical quality-factors (approaching Q ~ 105) with mechanical resonances up to 10 MHz. Next, we demonstrate engineered nanophotonic structures, specifically racetrack resonators and photonic crystal cavities, in bulk single-crystal diamond. Our devices feature large optical Q-factors, in excess of 10 5, and operate over a wide wavelength range, spanning visible and telecom. These newly developed high-Q diamond optical nanocavities open the door for a wealth of applications, ranging from nonlinear optics and chemical sensing, to quantum information processing and cavity optomechanics. Beyond isolated nanophotonic devices, we also developed free-standing angled-etched diamond waveguides which efficiently route photons between optical nanocavities, realizing true on-chip diamond nanophotonic networks. A high efficiency fiber-optical interface with aforementioned on-chip diamond nanophotonic networks, achieving > 90% power coupling, is also demonstrated. Lastly, we demonstrate a cavity-optomechanical system in single-crystal diamond, which builds upon previously realized diamond nanobeam photonic crystal cavities fabricated by angled-etching. Specifically, we demonstrate diamond optomechanical crystals (OMCs), where the engineered co-localization of photons and phonons in a quasi-periodic diamond nanostructure leads to coupling of an optical cavity field to a mechanical mode via the radiation pressure of light. In contrast to other material systems, diamond OMCs possess large intracavity photon capacity and sufficient optomechanical coupling rates to exceed a cooperativity of ~ 1 at room temperature and realize large amplitude optomechanical self-oscillations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robert Radtke

The manufacture of thermally stable diamond (TSP) cutters for drill bits used in petroleum drilling requires the brazing of two dissimilar materials--TSP diamond and tungsten carbide. The ENDURUS{trademark} thermally stable diamond cutter developed by Technology International, Inc. exhibits (1) high attachment (shear) strength, exceeding 345 MPa (50,000 psi), (2) TSP diamond impact strength increased by 36%, (3) prevents TSP fracture when drilling hard rock, and (4) maintains a sharp edge when drilling hard and abrasive rock. A novel microwave brazing (MWB) method for joining dissimilar materials has been developed. A conventional braze filler metal is combined with microwave heating whichmore » minimizes thermal residual stress between materials with dissimilar coefficients of thermal expansion. The process results in preferential heating of the lower thermal expansion diamond material, thus providing the ability to match the thermal expansion of the dissimilar material pair. Methods for brazing with both conventional and exothermic braze filler metals have been developed. Finite element modeling (FEM) assisted in the fabrication of TSP cutters controllable thermal residual stress and high shear attachment strength. Further, a unique cutter design for absorbing shock, the densification of otherwise porous TSP diamond for increased mechanical strength, and diamond ion implantation for increased diamond fracture resistance resulted in successful drill bit tests.« less

19 CFR 163.2 - Persons required to maintain records.

Code of Federal Regulations, 2014 CFR

2014-04-01

... rough diamonds must retain a copy of the Kimberley Process Certificate accompanying each shipment for a... exports from the United States any rough diamonds and does not keep records in this time frame may be...

Measurements and Studies of Secondary Electron Emission of Diamond Amplified Photocathode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu,Q.

2008-10-01

The Diamond Amplified Photocathode (DAP) is a novel approach to generating electrons. By following the primary electron beam, which is generated by traditional electron sources, with an amplifier, the electron beam available to the eventual application is increased by 1 to 2 orders of magnitude in current. Diamond has a very wide band gap of 5.47eV which allows for a good negative electron affinity with simple hydrogenation, diamond can hold more than 2000MV/m field before breakdown. Diamond also provides the best rigidity among all materials. These two characters offer the capability of applying high voltage across very thin diamond filmmore » to achieve high SEY and desired emission phase. The diamond amplifier also is capable of handling a large heat load by conduction and sub-nanosecond pulse input. The preparation of the diamond amplifier includes thinning and polishing, cleaning with acid etching, metallization, and hydrogenation. The best mechanical polishing available can provide high purity single crystal diamond films with no less than 100 {micro}m thickness and <15 nm Ra surface roughness. The ideal thickness for 700MHz beam is {approx}30 {micro}m, which requires further thinning with RIE or laser ablation. RIE can achieve atomic layer removal precision and roughness eventually, but the time consumption for this procedure is very significant. Laser ablation proved that with <266nm ps laser beam, the ablation process on the diamond can easily achieve removing a few microns per hour from the surface and <100nm roughness. For amplifier application, laser ablation is an adequate and efficient process to make ultra thin diamond wafers following mechanical polishing. Hydrogenation will terminate the diamond surface with monolayer of hydrogen, and form NEA so that secondary electrons in the conduction band can escape into the vacuum. The method is using hydrogen cracker to strike hydrogen atoms onto the bare diamond surface to form H-C bonds. Two independent experiments were carried out to determine the transport of the electrons within the diamond and their emission at the surface. In transmission mode measurements, the diamond amplifier was coated with metal on both sides, so results simply depend only on the electron transport within the diamond. The SEY for this mode provides one secondary electron per 20eV energy, which gives the gain of more than 200 for 4.7keV (effective energy) primary electrons under 2MV/m. Laser detrapping can help the signal maintain the gain with lops pulse and duty cycle of 1.67 x 10{sup -7}. In emission mode measurements, in which the diamond is prepared as in the actual application, the SEY is {approx}20 for 700eV (effective energy) primary electrons under 1.21MV/m. The electric field applied and the primary electron energy is limited by the experiment setup, but the results show good trend toward large gain under high field. Thermal emittance of the diamond secondary emission is critical for the beam application. A careful design is setup to measure with very fine precision and accuracy of 0.01eV.« less

Scratch-Resistant Lenses

NASA Technical Reports Server (NTRS)

1996-01-01

Lewis Research Center developed a process for achieving diamond- hard coatings for aerospace systems. The technique involves coating the material with a film of diamond-like carbon (DLC) using direct ion deposition. An ion generator creates a stream of ions from a hydrocarbon gas source; the carbon ions impinge directly on the target substrate and 'grow' into a thin DLC film. In 1988, Air Products and Chemicals, Inc. received a license to the NASA patent. Diamonex, an Air Products spinoff company, further developed the NASA process to create the DiamondHard technology used on the Bausch & Lomb Ray- Ban Survivors sunglasses. The sunglasses are scratch-resistant and shed water more easily, thus reducing spotting.

Vertically aligned diamond-graphite hybrid nanorod arrays with superior field electron emission properties

NASA Astrophysics Data System (ADS)

Ramaneti, R.; Sankaran, K. J.; Korneychuk, S.; Yeh, C. J.; Degutis, G.; Leou, K. C.; Verbeeck, J.; Van Bael, M. K.; Lin, I. N.; Haenen, K.

2017-06-01

A "patterned-seeding technique" in combination with a "nanodiamond masked reactive ion etching process" is demonstrated for fabricating vertically aligned diamond-graphite hybrid (DGH) nanorod arrays. The DGH nanorod arrays possess superior field electron emission (FEE) behavior with a low turn-on field, long lifetime stability, and large field enhancement factor. Such an enhanced FEE is attributed to the nanocomposite nature of the DGH nanorods, which contain sp2-graphitic phases in the boundaries of nano-sized diamond grains. The simplicity in the nanorod fabrication process renders the DGH nanorods of greater potential for the applications as cathodes in field emission displays and microplasma display devices.

Effect of magnetic and electric coupling fields on micro- and nano- structure of carbon films in the CVD diamond process and their electron field emission property

NASA Astrophysics Data System (ADS)

Wang, Yijia; Li, Jiaxin; Hu, Naixiu; Jiang, Yunlu; Wei, Qiuping; Yu, Zhiming; Long, Hangyu; Zhu, Hekang; Xie, Youneng; Ma, Li; Lin, Cheng-Te; Su, Weitao

2018-03-01

In this paper, both electric field and magnetic field were used to assist the hot filament chemical vapor deposition (HFCVD) and we systematically investigated the effects of which on the (1) phase composition, (2) grain size, (3) thickness and (4) preferred orientation of diamond films through SEM, Raman and XRD. The application of magnetic field in electric field, so called ‘the magnetic and electric coupling fields’, enhanced the graphitization and refinement of diamond crystals, slowed down the decrease of film thickness along with the increase of bias current, and suppressed diamond (100) orientation. During the deposition process, the electric field provided additional energy to HFCVD system and generated large number of energetic particles which might annihilate at the substrate and lose kinetic energy, while the Lorentz force, provided by magnetic field, could constrict charged particles (including electrons) to do spiral movement, which prolonged their moving path and life, thus the system energy increased. With the graphitization of diamond films intensified, the preferred orientation of diamond films completely evolved from (110) to (100), until the orientation and diamond phase disappeared, which can be attributed to (I) the distribution and concentration ratio of carbon precursors (C2H2 and CH3) and (II) graphitization sequence of diamond crystal facets. Since the electron field emission property of carbon film is sensitive to the phase composition, thickness and preferred orientation, nano- carbon cones, prepared by the negative bias current of 20 mA and magnetic field strength of 80 Gauss, exhibited the lowest turn-on field of 6.1 V -1 μm-1.

Effect of cutting temperature on hardness of SiC and diamond in the nano-cutting process of monocrystalline silicon

NASA Astrophysics Data System (ADS)

Wang, Jiachun; Li, Yuntao; Liu, Xiaoxuan; Lv, Maoqiang

2016-10-01

In the process of cutting silicon by natural diamond tools, groove wear happens on the flank face of cutting tool frequently.Scholars believe that one of the wear reasons is mechanical scratching effect by hard particles like SiC. To reveal the mechanical scratching mechanism, it is essential to study changes in the mechanical properties of hard particles and diamond, especially the effect of cutting temperature on hardness of diamond and hard particles. Molecular dynamics (MD) model that contact-zone temperature between tool and workpiece was calculated by dividing zone while nano-cutting monocrystalline silicon was established, cutting temperature values in different regions were computed as the simulation was carried out.On this basis, the models of molecular dynamics simulation of SiC and diamond were established separately with setting the initial temperature to room temperature. The laws of length change of C-C bond and Si-C bond varing with increase of simulation temperature were studied. And drawing on predecessors' research on theoretical calculation of hardness of covalent crystals and the relationship between crystal valence electron density and bond length, the curves that the hardness of diamond and SiC varing with bond length were obtained. The effect of temperature on the hardness was calculated. Results show that, local cutting temperature can reach 1300K.The rise in cutting temperature leaded to a decrease in the diamond local atomic clusters hardness,SiC local atomic clusters hardness increased. As the cutting temperature was more than 1100K,diamond began to soften, the local clusters hardness was less than that of SiC.

Evolution of diamond resorption in a silicic aqueous fluid at 1-3 GPa: Application to kimberlite emplacement and mantle metasomatism

NASA Astrophysics Data System (ADS)

Zhang, Zhihai; Fedortchouk, Yana; Hanley, Jacob J.

2015-06-01

Natural diamonds grow and partially dissolve during mantle metasomatism and undergo further resorption during the ascent to the Earth's surface in kimberlite magmas. This study uses atomic force microscopy (AFM) for quantitative characterization of diamond resorption morphology in order to provide robust constraints of the composition of kimberlitic and mantle metasomatic fluids. We performed experiments in a piston-cylinder apparatus at pressures (P) of 1-3 GPa and temperatures (T) of 1150-1400 °C to examine the impact of P, T, and silica content of an aqueous fluid on diamond dissolution. Petrographic observation and microthermometry of synthetic fluid inclusions trapped in olivine at the run conditions provide constraints on the composition and density of the fluid reacting with the diamond. Our results confirm an inverse relationship between P and T on diamond dissolution kinetics. A P increase of 1 GPa suppresses diamond oxidation rates by the same value as a T decrease by 50 °C, while the transformation rate of diamond crystal morphology from octahedron to tetrahexahedron increases with both P and T. All dissolved diamonds develop glossy surfaces, ditrigonal {111} faces, sheaf striations, and negative trigons, while circular pits only occur in aqueous fluids with low silica content (≤ 4.2 mol/kg) at 1 GPa. We identify five distinct morphological groups of trigons: two types of point-bottomed (p/b) (trumpet- and V-shaped) and three types of flat-bottomed (f/b) (trumpet-shaped, trapezoid-shaped and rounded). AFM measurements of trigons from two successive runs showed three stages of their evolution. Etch pits nucleate at defects as trumpet p/b trigons with the vertical dissolution rate (Vd) faster than the dissolution rates at the surface free of defects; they further develop by growth of the bottoms in (111) plane to create trumpet-shaped f/b trigons accompanied by decrease in Vd; and finally form trapezoid-shaped f/b trigon with constant wall angles. The diameter of f/b trigons developed in the aqueous fluids depends on the diamond weight loss and dissolution kinetics, and does not correlate with their depth. Integration of our AFM data with the theoretical model for trigon formation suggests that the change from point- to flat-bottomed trigons depends on the defect sizes and dissolution conditions. Application of our results to the diamonds from Ekati diamond Mine, Canada, suggests that variations in diamond rounding in different pipes implies variable depth of fluid exsolution; presence of circular pits on diamonds indicates predominantly aqueous fluid during the latest stages of kimberlite emplacement; and comparison to the mantle-derived morphologies on Ekati diamonds implies the importance of CO2-rich fluids and/or carbonate melts during mantle metasomatism. The constrained effect of P on diamond dissolution kinetics indicates that appreciable diamond weight loss can only happen at P < 1 GPa and therefore the conditions at the latest stages of kimberlite emplacement are very important for assessments of diamond preservation in a kimberlite pipe.

Partitioning experiments in the laser-heated diamond anvil cell: volatile content in the Earth's core.

PubMed

Jephcoat, Andrew P; Bouhifd, M Ali; Porcelli, Don

2008-11-28

The present state of the Earth evolved from energetic events that were determined early in the history of the Solar System. A key process in reconciling this state and the observable mantle composition with models of the original formation relies on understanding the planetary processing that has taken place over the past 4.5Ga. Planetary size plays a key role and ultimately determines the pressure and temperature conditions at which the materials of the early solar nebular segregated. We summarize recent developments with the laser-heated diamond anvil cell that have made possible extension of the conventional pressure limit for partitioning experiments as well as the study of volatile trace elements. In particular, we discuss liquid-liquid, metal-silicate (M-Sil) partitioning results for several elements in a synthetic chondritic mixture, spanning a wide range of atomic number-helium to iodine. We examine the role of the core as a possible host of both siderophile and trace elements and the implications that early segregation processes at deep magma ocean conditions have for current mantle signatures, both compositional and isotopic. The results provide some of the first experimental evidence that the core is the obvious replacement for the long-sought, deep mantle reservoir. If so, they also indicate the need to understand the detailed nature and scale of core-mantle exchange processes, from atomic to macroscopic, throughout the age of the Earth to the present day.

Profiling of Current Transients in Capacitor Type Diamond Sensors

PubMed Central

Gaubas, Eugenijus; Ceponis, Tomas; Meskauskaite, Dovile; Kazuchits, Nikolai

2015-01-01

The operational characteristics of capacitor-type detectors based on HPHT and CVD diamond have been investigated using perpendicular and parallel injection of carrier domain regimes. Simulations of the drift-diffusion current transients have been implemented by using dynamic models based on Shockley-Ramo’s theorem, under injection of localized surface domains and of bulk charge carriers. The bipolar drift-diffusion regimes have been analyzed for the photo-induced bulk domain (packet) of excess carriers. The surface charge formation and polarization effects dependent on detector biasing voltage have been revealed. The screening effects ascribed to surface charge and to dynamics of extraction of the injected bulk excess carrier domain have been separated and explained. The parameters of drift mobility of the electrons μe = 4000 cm2/Vs and holes μh = 3800 cm2/Vs have been evaluated for CVD diamond using the perpendicular profiling of currents. The coefficient of carrier ambipolar diffusion Da = 97 cm2/s and the carrier recombination lifetime τR,CVD ≌ 110 ns in CVD diamond were extracted by combining analysis of the transients of the sensor current and the microwave probed photoconductivity. The carrier trapping with inherent lifetime τR,HPHT ≌ 2 ns prevails in HPHT diamond. PMID:26061200

Study of process of trueing diamond grinding wheels on metal bonds by method of free abrasive after processing of leucosapphire blanks

NASA Astrophysics Data System (ADS)

Fedonin, O. N.; Handozhko, A. V.; Fedukov, A. G.

2018-03-01

The problem of mechanical processing, in particular, grinding products from leucosapphire, is considered. The main problem with this treatment is the need to adjust the diamond tool. One of the methods of tool trueing using loose abrasive technique is considered. The results of a study on restoring the tool cutting ability, its shape and profile after straightening are given.

Large-area low-temperature ultrananocrystaline diamond (UNCD) films and integration with CMOS devices for monolithically integrated diamond MEMD/NEMS-CMOS systems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sumant, A.V.; Auciello, O.; Yuan, H.-C

2009-05-01

Because of exceptional mechanical, chemical, and tribological properties, diamond has a great potential to be used as a material for the development of high-performance MEMS and NEMS such as resonators and switches compatible with harsh environments, which involve mechanical motion and intermittent contact. Integration of such MEMS/NEMS devices with complementary metal oxide semiconductor (CMOS) microelectronics will provide a unique platform for CMOS-driven commercial MEMS/NEMS. The main hurdle to achieve diamond-CMOS integration is the relatively high substrate temperatures (600-800 C) required for depositing conventional diamond thin films, which are well above the CMOS operating thermal budget (400 C). Additionally, a materialsmore » integration strategy has to be developed to enable diamond-CMOS integration. Ultrananocrystalline diamond (UNCD), a novel material developed in thin film form at Argonne, is currently the only microwave plasma chemical vapor deposition (MPCVD) grown diamond film that can be grown at 400 C, and still retain exceptional mechanical, chemical, and tribological properties comparable to that of single crystal diamond. We have developed a process based on MPCVD to synthesize UNCD films on up to 200 mm in diameter CMOS wafers, which will open new avenues for the fabrication of monolithically integrated CMOS-driven MEMS/NEMS based on UNCD. UNCD films were grown successfully on individual Si-based CMOS chips and on 200 mm CMOS wafers at 400 C in a MPCVD system, using Ar-rich/CH4 gas mixture. The CMOS devices on the wafers were characterized before and after UNCD deposition. All devices were performing to specifications with very small degradation after UNCD deposition and processing. A threshold voltage degradation in the range of 0.08-0.44V and transconductance degradation in the range of 1.5-9% were observed.« less

Controlled in situ boron doping of diamond thin films using solution phase

NASA Astrophysics Data System (ADS)

Roy, M.; Dua, A. K.; Nuwad, J.; Girija, K. G.; Tyagi, A. K.; Kulshreshtha, S. K.

2006-12-01

Controlled boron doping of diamond film using nontoxic reagents is a challenge in itself. During the present study, attempts have been made to dope diamond films in situ with boron from a solution of boric acid (H3BO3) in methanol (CH3OH) using a specially designed bubbler that ensured continuous and controlled flow of vapors of boron precursors during deposition. The samples are thoroughly characterized using a host of techniques comprising of x-ray photoelectron spectroscopy, Raman, x-ray diffraction, and current-voltage measurements (I-V). Cross-sectional micro-Raman spectroscopy has been used to obtain depth profile of boron in diamond films. Boron concentration ([B]) in the films is found to vary linearly on a semilog scale with molarity (M) of H3BO3 in CH3OH. Lattice constant of our samples is smaller than the reported American society for testing and materials (ASTM) values due to oxygen incorporation and it increases with [B] in the diamond samples. Heavily boron doped samples exhibit Fano deformation of the Raman line shape and negative and/zero activation barrier in temperature dependent I-V measurements that indicate the formation of metallic phase in the samples. The present study illustrates the feasibility of safe and controlled boron doping of diamond films using a solution of H3BO3 in CH3OH over a significant range of [B] from semiconductor to metallic regime but with a little adverse effect due to unintentional but unavoidable incorporation of oxygen.

Quantitative analysis of trace element concentrations in some gem-quality diamonds

NASA Astrophysics Data System (ADS)

McNeill, J.; Pearson, D. G.; Klein-Ben David, O.; Nowell, G. M.; Ottley, C. J.; Chinn, I.

2009-09-01

The geochemical signature of diamond-forming fluids can be used to unravel diamond-forming processes and is of potential use in the detection of so-called 'conflict' diamonds. While fluid-rich fibrous diamonds can be analyzed by a variety of techniques, very few data have been published for fluid-poor, gem-quality diamonds because of their very low impurity levels. Here we present a new ICPMS-based (ICPMS: inductively coupled plasma mass spectrometry) method for the analysis of trace element concentrations within fluid-poor, gem-quality diamonds. The method employs a closed-system laser ablation cell. Diamonds are ablated and the products trapped for later pre-concentration into solutions that are analyzed by sector-field ICPMS. We show that our limits of quantification for a wide range of elements are at the sub-pg to low pg level. The method is applied to a suite of 10 diamonds from the Cullinan Mine (previously known as Premier), South Africa, along with other diamonds from Siberia (Mir and Udachnaya) and Venezuela. The concentrations of a wide range of elements for all the samples (expressed by weight in the solid) are very low, with rare earth elements along with Y, Nb, Cs ranging from 0.01 to 2 ppb. Large ion lithophile elements (LILE) such as Rb and Ba vary from 1 to 30 ppb. Ti ranges from ppb levels up to 2 ppm. From the combined, currently small data set we observe two kinds of diamond-forming fluids within gem diamonds. One group has enrichments in LILE over Nb, whereas a second group has normalized LILE abundances more similar to those of Nb. These two groups bear some similarity to different groups of fluid-rich diamonds, providing some supporting evidence of a link between the parental fluids for both fluid-inclusion-rich and gem diamonds.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hemawan, Kadek W.; Gou, Huiyang; Hemley, Russell J.

Polycrystalline diamond has been synthesized on silicon substrates at atmospheric pressure, using a microwave capillary plasma chemical vapor deposition technique. The CH4/Ar plasma was generated inside of quartz capillary tubes using 2.45 GHz microwave excitation without adding H2 into the deposition gas chemistry. Electronically excited species of CN, C2, Ar, N2, CH, Hβ, and Hα were observed in the emission spectra. Raman measurements of deposited material indicate the formation of well-crystallized diamond, as evidenced by the sharp T2g phonon at 1333 cm-1 peak relative to the Raman features of graphitic carbon. Field emission scanning electron microscopy images reveal that, dependingmore » on the growth conditions, the carbon microstructures of grown films exhibit “coral” and “cauliflower-like” morphologies or well-facetted diamond crystals with grain sizes ranging from 100 nm to 10 μm.« less

Synthesis of flat sticky hydrophobic carbon diamond-like films using atmospheric pressure Ar/CH4 dielectric barrier discharge

NASA Astrophysics Data System (ADS)

Rincón, R.; Hendaoui, A.; de Matos, J.; Chaker, M.

2016-06-01

An Ar/CH4 atmospheric pressure dielectric barrier discharge (AP-DBD) was used to synthesize sticky hydrophobic diamond-like carbon (DLC) films on glass surface. The film is formed with plasma treatment duration shorter than 30 s, and water contact angles larger than 90° together with contact angle hysteresis larger than 10° can be achieved. According to Fourier transform infrared spectroscopy and atomic force microscopy analysis, hydrocarbon functional groups are created on the glass substrate, producing coatings with low surface energy (˜35 mJ m-2) with no modification of the surface roughness. To infer the plasma processes leading to the formation of low energy DLC surfaces, optical emission spectroscopy was used. From the results, a direct relationship between the CH species present in the plasma and the carbon concentration in the hydrophobic layer was found, which suggests that the CH species are the precursors of DLC film growth. Additionally, the plasma gas temperature was measured to be below 350 K which highlights the suitability of using AP-DBD to treat thermo-sensitive surfaces.

Boron doped diamond sensor for sensitive determination of metronidazole: Mechanistic and analytical study by cyclic voltammetry and square wave voltammetry.

PubMed

Ammar, Hafedh Belhadj; Brahim, Mabrouk Ben; Abdelhédi, Ridha; Samet, Youssef

2016-02-01

The performance of boron-doped diamond (BDD) electrode for the detection of metronidazole (MTZ) as the most important drug of the group of 5-nitroimidazole was proven using cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques. A comparison study between BDD, glassy carbon and silver electrodes on the electrochemical response was carried out. The process is pH-dependent. In neutral and alkaline media, one irreversible reduction peak related to the hydroxylamine derivative formation was registered, involving a total of four electrons. In acidic medium, a prepeak appears probably related to the adsorption affinity of hydroxylamine at the electrode surface. The BDD electrode showed higher sensitivity and reproducibility analytical response, compared with the other electrodes. The higher reduction peak current was registered at pH11. Under optimal conditions, a linear analytical curve was obtained for the MTZ concentration in the range of 0.2-4.2μmolL(-1), with a detection limit of 0.065μmolL(-1). Copyright © 2015 Elsevier B.V. All rights reserved.

Optimization of Deep Drilling Performance - Development and Benchmark Testing of Advanced Diamond Product Drill Bits & HP/HT Fluids to Significantly Improve Rates of Penetration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alan Black; Arnis Judzis

2005-09-30

This document details the progress to date on the OPTIMIZATION OF DEEP DRILLING PERFORMANCE--DEVELOPMENT AND BENCHMARK TESTING OF ADVANCED DIAMOND PRODUCT DRILL BITS AND HP/HT FLUIDS TO SIGNIFICANTLY IMPROVE RATES OF PENETRATION contract for the year starting October 2004 through September 2005. The industry cost shared program aims to benchmark drilling rates of penetration in selected simulated deep formations and to significantly improve ROP through a team development of aggressive diamond product drill bit--fluid system technologies. Overall the objectives are as follows: Phase 1--Benchmark ''best in class'' diamond and other product drilling bits and fluids and develop concepts for amore » next level of deep drilling performance; Phase 2--Develop advanced smart bit-fluid prototypes and test at large scale; and Phase 3--Field trial smart bit--fluid concepts, modify as necessary and commercialize products. As of report date, TerraTek has concluded all Phase 1 testing and is planning Phase 2 development.« less

Diamonds from the Machado River alluvial deposit, Rondônia, Brazil, derived from both lithospheric and sublithospheric mantle

NASA Astrophysics Data System (ADS)

Burnham, A. D.; Bulanova, G. P.; Smith, C. B.; Whitehead, S. C.; Kohn, S. C.; Gobbo, L.; Walter, M. J.

2016-11-01

Diamonds from the Machado River alluvial deposit have been characterised on the basis of external morphology, internal textures, carbon isotopic composition, nitrogen concentration and aggregation state and mineral inclusion chemistry. Variations in morphology and features of abrasion suggest some diamonds have been derived directly from local kimberlites, whereas others have been through extensive sedimentary recycling. On the basis of mineral inclusion compositions, both lithospheric and sublithospheric diamonds are present at the deposit. The lithospheric diamonds have clear layer-by-layer octahedral and/or cuboid internal growth zonation, contain measurable nitrogen and indicate a heterogeneous lithospheric mantle beneath the region. The sublithospheric diamonds show a lack of regular sharp zonation, do not contain detectable nitrogen, are isotopically heavy (δ13CPDB predominantly - 0.7 to - 5.5) and contain inclusions of ferropericlase, former bridgmanite, majoritic garnet and former CaSiO3-perovskite. This suggests source lithologies that are Mg- and Ca-rich, probably including carbonates and serpentinites, subducted to lower mantle depths. The studied suite of sublithospheric diamonds has many similarities to the alluvial diamonds from Kankan, Guinea, but has more extreme variations in mineral inclusion chemistry. Of all superdeep diamond suites yet discovered, Machado River represents an end-member in terms of either the compositional range of materials being subducted to Transition Zone and lower mantle or the process by which materials are transferred from the subducted slab to the diamond-forming region.

Effect of Polishing on the Friction Behaviors and Cutting Performance of Boron-Doped Diamond Films on WC-Co Inserts

NASA Astrophysics Data System (ADS)

Wang, Liang; Shen, Bin; Sun, Fanghong; Zhang, Zhiming

2014-04-01

Boron doped (B-doped) diamond films are deposited onto WC-Co inserts by HFCVD with the mixture of acetone, trimethyl borate (C3H9BO3) and H2. The as-deposited B-doped diamond films are characterized with scanning electron microscope (SEM), X-ray diffraction (XRD) spectroscopy, Raman spectroscopy, 3D surface topography based on white-light interferometry and Rockwell hardness tester. The effects of mechanical polishing on the friction behavior and cutting performance of B-doped diamond are evaluated by ball-on-plate type reciprocating tribometer and turning of aluminum alloy 7075 materials, respectively. For comparison, the same tests are also conducted for the bare WC-Co inserts with smooth surface. Friction tests suggest that the unpolished and polished B-doped diamond films possess relatively low fluctuation of friction coefficient than as-received bare WC-Co samples. The average stable friction coefficient for B-doped diamond films decreases apparently after mechanical polishing. The values for WC-Co sample, unpolished and polished B-doped diamond films are approximately 0.38, 0.25 and 0.11, respectively. The cutting results demonstrate that the low friction coefficient and high adhesive strength of B-doped diamond films play an essential role in the cutting performance enhancement of the WC-Co inserts. However, the mechanical polishing process may lower the adhesive strength of B-doped diamond films. Consequently, the polished B-doped diamond coated inserts show premature wear in the machining of adhesive aluminum alloy materials.

Focused-ion-beam overlay-patterning of three-dimensional diamond structures for advanced single-photon properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Qianqing; Liu, Dongqi; Liu, Gangqin

2014-07-28

Sources of single photons are of fundamental importance in many applications as to provide quantum states for quantum communication and quantum information processing. Color centers in diamond are prominent candidates to generate and manipulate quantum states of light, even at room temperature. However, the efficiency of photon collection of the color centers in bulk diamond is greatly reduced by refraction at the diamond/air interface. To address this issue, diamond structuring has been investigated by various methods. Among them, focused-ion-beam (FIB) direct patterning has been recognized as the most favorable technique. But it has been noted that diamond tends to presentmore » significant challenges in FIB milling, e.g., the susceptibility of forming charging related artifacts and topographical features. In this work, periodically-positioned-rings and overlay patterning with stagger-superimposed-rings were proposed to alleviate some problems encountered in FIB milling of diamond, for improved surface morphology and shape control. Cross-scale network and uniform nanostructure arrays have been achieved in single crystalline diamond substrates. High quality diamond solid immersion lens and nanopillars were sculptured with a nitrogen-vacancy center buried at the desired position. Compared with the film counterpart, an enhancement of about ten folds in single photon collection efficiency was achieved with greatly improved signal to noise ratio. All these results indicate that FIB milling through over-lay patterning could be an effective approach to fabricate diamond structures, potentially for quantum information studies.« less

Biomineralized diamond-like carbon films with incorporated titanium dioxide nanoparticles improved bioactivity properties and reduced biofilm formation.

PubMed

Lopes, F S; Oliveira, J R; Milani, J; Oliveira, L D; Machado, J P B; Trava-Airoldi, V J; Lobo, A O; Marciano, F R

2017-12-01

Recently, the development of coatings to protect biomedical alloys from oxidation, passivation and to reduce the ability for a bacterial biofilm to form after implantation has emerged. Diamond-like carbon films are commonly used for implanted medical due to their physical and chemical characteristics, showing good interactions with the biological environment. However, these properties can be significantly improved when titanium dioxide nanoparticles are included, especially to enhance the bactericidal properties of the films. So far, the deposition of hydroxyapatite on the film surface has been studied in order to improve biocompatibility and bioactive behavior. Herein, we developed a new route to obtain a homogeneous and crystalline apatite coating on diamond-like carbon films grown on 304 biomedical stainless steel and evaluated its antibacterial effect. For this purpose, films containing two different concentrations of titanium dioxide (0.1 and 0.3g/L) were obtained by chemical vapor deposition. To obtain the apatite layer, the samples were soaked in simulated body fluid solution for up to 21days. The antibacterial activity of the films was evaluated by bacterial eradication tests using Staphylococcus aureus biofilm. Scanning electron microscopy, X-ray diffraction, Raman scattering spectroscopy, and goniometry showed that homogeneous, crystalline, and hydrophilic apatite films were formed independently of the titanium dioxide concentration. Interestingly, the diamond-like films containing titanium dioxide and hydroxyapatite reduced the biofilm formation compared to controls. A synergism between hydroxyapatite and titanium dioxide that provided an antimicrobial effect against opportunistic pathogens was clearly observed. Copyright © 2017 Elsevier B.V. All rights reserved.

Diamond thin film temperature and heat-flux sensors

NASA Technical Reports Server (NTRS)

Aslam, M.; Yang, G. S.; Masood, A.; Fredricks, R.

1995-01-01

Diamond film temperature and heat-flux sensors are developed using a technology compatible with silicon integrated circuit processing. The technology involves diamond nucleation, patterning, doping, and metallization. Multi-sensor test chips were designed and fabricated to study the thermistor behavior. The minimum feature size (device width) for 1st and 2nd generation chips are 160 and 5 micron, respectively. The p-type diamond thermistors on the 1st generation test chip show temperature and response time ranges of 80-1270 K and 0.29-25 microseconds, respectively. An array of diamond thermistors, acting as heat flux sensors, was successfully fabricated on an oxidized Si rod with a diameter of 1 cm. Some problems were encountered in the patterning of the Pt/Ti ohmic contacts on the rod, due mainly to the surface roughness of the diamond film. The use of thermistors with a minimum width of 5 micron (to improve the spatial resolution of measurement) resulted in lithographic problems related to surface roughness of diamond films. We improved the mean surface roughness from 124 nm to 30 nm by using an ultra high nucleation density of 10(exp 11)/sq cm. To deposit thermistors with such small dimensions on a curved surface, a new 3-D diamond patterning technique is currently under development. This involves writing a diamond seed pattern directly on the curved surface by a computer-controlled nozzle.

Visible sub-band gap photoelectron emission from nitrogen doped and undoped polycrystalline diamond films

NASA Astrophysics Data System (ADS)

Elfimchev, S.; Chandran, M.; Akhvlediani, R.; Hoffman, A.

2017-07-01

In this study the origin of visible sub-band gap photoelectron emission (PEE) from polycrystalline diamond films is investigated. The PEE yields as a function of temperature were studied in the wavelengths range of 360-520 nm. Based on the comparison of electron emission yields from diamond films deposited on silicon and molybdenum substrates, with different thicknesses and nitrogen doping levels, we suggested that photoelectrons are generated from nitrogen related centers in diamond. Our results show that diamond film thickness and substrate material have no significant influence on the PEE yield. We found that nanocrystalline diamond films have low electron emission yields, compared to microcrystalline diamond, due to the presence of high amount of defects in the former, which trap excited electrons before escaping into the vacuum. However, the low PEE yield of nanocrystalline diamond films was found to increase with temperature. The phenomenon was explained by the trap assisted photon enhanced thermionic emission (ta-PETE) model. According to the ta-PETE model, photoelectrons are trapped by shallow traps, followed by thermal excitation at elevated temperatures and escape into the vacuum. Activation energies of trap levels were estimated for undoped nanocrystalline, undoped microcrystalline and N-doped diamond films using the Richardson-Dushman equation, which gives 0.13, 0.39 and 0.04 eV, respectively. Such low activation energy of trap levels makes the ta-PETE process very effective at elevated temperatures.

Functionally gradient hard carbon composites for improved adhesion and wear

NASA Astrophysics Data System (ADS)

Narayan, Roger Jagdish

A new approach is proposed for fabricating biomedical devices that last longer and are more biocompatible than those presently available. In this approach, a bulk material is chosen that has desirable mechanical properties (low modulus, high strength, high ductility and high fatigue strength). This material is coated with corrosion-resistant, wear-resistant, hard, and biocompatible hard carbon films. One of the many forms of carbon, tetrahedral amorphous carbon, consists mainly of sp3-bonded atoms. Tetrahedral amorphous carbon possesses properties close to diamond in terms of hardness, atomic smoothness, and inertness. Tetrahedral amorphous carbon and diamond films usually contain large amounts of compressive and sometimes tensile stresses; adhesive failure from these stresses has limited widespread use of these materials. This research involves processing, characterization and modeling of functionally gradient tetrahedral amorphous carbon and diamond composite films on metals (cobalt-chromium and titanium alloys) and polymers (polymethylmethacrylate and polyethylene) used in biomedical applications. Multilayer discontinuous thin films of titanium carbide, titanium nitride, aluminum nitride, and tungsten carbide have been developed to control stresses and graphitization in diamond films. A morphology of randomly interconnected micron sized diamond crystallites provides increased toughness and stress reduction. Internal stresses in tetrahedral amorphous carbon were reduced via incorporation of carbide forming elements (silicon and titanium) and noncarbide forming elements (copper, platinum, and silver). These materials were produced using a novel target design during pulsed laser deposition. These alloying atoms reduce hardness and sp3-bonded carbon content, but increase adhesion and wear resistance. Silver and platinum provide the films with antimicrobial properties, and silicon provides bioactivity and aids bone formation. Bilayer coatings were created that couple the adherence, biocompatibility, erosion resistance, and long term release of functional elements from hard carbon coatings with bioactive properties of nanocrystalline hydroxyapatite and short term drug release properties of resorbable poly (D,L) lactide-based materials. Finally, these hard carbon coatings have a variety of non-medical applications, including use in microelectronics packaging, sensors, flat panel displays, photodiodes, cutting tools, optical switches, and wear-resistant magnetic disks.

Investigation of DBS electro-oxidation reaction in the aqueous-organic solution of LiClO4.

PubMed

Darlewski, Witold; Popiel, Stanisław; Nalepa, Tomasz; Gromotowicz, Waldemar; Szewczyk, Rafał; Stankiewicz, Romuald

2010-03-15

A process of dibutyl sulphide (DBS) electro-oxidation using electrolysis and cyclic voltamperometry was investigated in water-methanol solution using different electrodes (platinum, boron doped diamond, graphite and glassy carbon). Obtained results indicate that the DBS electro-oxidation process is irreversible in voltamperometric conditions. It was shown that during DBS electrolytic oxidation on Pt, at the low anode potential (1.8 V), DBS was oxidized to sulphoxide and sulphone. Electrolysis at higher potential (up to 3.0 V) resulted in complete DBS oxidation and formation of various products, including: butyric acid, sulphuric acid, butanesulphinic acid, butanesulphonic acid, identified using gas chromatography (GC-AED) and mass spectrometry (GC-MS) methods. (c) 2009 Elsevier B.V. All rights reserved.

High-temperature Superconductivity in Diamond Films - from Fundamentals to Device Applications

DTIC Science & Technology

2014-12-20

film is later removed by acid boiling in nitric acid. The laser cutting process is completely based on CNC machine language. Therefore arbitrary...designed Hall bar shapes and converted them in CNC language. Fig 6. Laser Cutter (Alpha) to create holes in the diamond plates (Oxford Lasers). [5...diamond density is not uniform throughout the plate as it appears lighter on the right side. This could be caused by the plasma being of different

Phase Retrieval System for Assessing Diamond Turning and Optical Surface Defects

NASA Technical Reports Server (NTRS)

Dean, Bruce; Maldonado, Alex; Bolcar, Matthew

2011-01-01

An optical design is presented for a measurement system used to assess the impact of surface errors originating from diamond turning artifacts. Diamond turning artifacts are common by-products of optical surface shaping using the diamond turning process (a diamond-tipped cutting tool used in a lathe configuration). Assessing and evaluating the errors imparted by diamond turning (including other surface errors attributed to optical manufacturing techniques) can be problematic and generally requires the use of an optical interferometer. Commercial interferometers can be expensive when compared to the simple optical setup developed here, which is used in combination with an image-based sensing technique (phase retrieval). Phase retrieval is a general term used in optics to describe the estimation of optical imperfections or aberrations. This turnkey system uses only image-based data and has minimal hardware requirements. The system is straightforward to set up, easy to align, and can provide nanometer accuracy on the measurement of optical surface defects.

Vacuum encapsulated, high temperature diamond amplified cathode capsule and method for making same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rao, Triveni; Walsh, Josh; Gangone, Elizabeth

2015-12-29

A vacuum encapsulated, hermetically sealed cathode capsule for generating an electron beam of secondary electrons, which generally includes a cathode element having a primary emission surface adapted to emit primary electrons, an annular insulating spacer, a diamond window element comprising a diamond material and having a secondary emission surface adapted to emit secondary electrons in response to primary electrons impinging on the diamond window element, a first high-temperature solder weld disposed between the diamond window element and the annular insulating spacer and a second high-temperature solder weld disposed between the annular insulating spacer and the cathode element. The cathode capsulemore » is formed by a high temperature weld process under vacuum such that the first solder weld forms a hermetical seal between the diamond window element and the annular insulating spacer and the second solder weld forms a hermetical seal between the annular spacer and the cathode element whereby a vacuum encapsulated chamber is formed within the capsule.« less

Tribological performance of polycrystalline tantalum-carbide-incorporated diamond films on silicon substrates

NASA Astrophysics Data System (ADS)

Ullah, Mahtab; Rana, Anwar Manzoor; Ahmed, E.; Malik, Abdul Sattar; Shah, Z. A.; Ahmad, Naseeb; Mehtab, Ujala; Raza, Rizwan

2018-05-01

Polycrystalline tantalum-carbide-incorporated diamond coatings have been made on unpolished side of Si (100) wafer by hot filament chemical vapor deposition process. Morphology of the coatings has been found to vary from (111) triangular-facetted to predominantly (111) square-faceted by increasing the concentration of tantalum carbide. The results have been compared to those of a diamond reference coating with no tantalum content. An increase in roughness has been observed with the increase of tantalum carbide (TaC) due to change in morphology of the diamond films. It is noticed that roughness of the coatings increases as grains become more square-faceted. It is found that diamond coatings involving tantalum carbide are not as resistant as diamond films with no TaC content and the coefficient of friction for such coatings with microcrystalline grains can be manipulated to 0·33 under high vacuum of 10-7 Torr. Such a low friction coefficient value enhances tribological behavior of unpolished Si substrates and can possibly be used in sliding applications.

Vacuum encapsulated hermetically sealed diamond amplified cathode capsule and method for making same

DOEpatents

Rao, Triveni; Walsh, John; Gangone, Elizabeth

2014-12-30

A vacuum encapsulated, hermetically sealed cathode capsule for generating an electron beam of secondary electrons, which generally includes a cathode element having a primary emission surface adapted to emit primary electrons, an annular insulating spacer, a diamond window element comprising a diamond material and having a secondary emission surface adapted to emit secondary electrons in response to primary electrons impinging on the diamond window element, a first cold-weld ring disposed between the cathode element and the annular insulating spacer and a second cold-weld ring disposed between the annular insulating spacer and the diamond window element. The cathode capsule is formed by a vacuum cold-weld process such that the first cold-weld ring forms a hermetical seal between the cathode element and the annular insulating spacer and the second cold-weld ring forms a hermetical seal between the annular spacer and the diamond window element whereby a vacuum encapsulated chamber is formed within the capsule.

Fabrication of an infrared Shack-Hartmann sensor by combining high-speed single-point diamond milling and precision compression molding processes.

PubMed

Zhang, Lin; Zhou, Wenchen; Naples, Neil J; Yi, Allen Y

2018-05-01

A novel fabrication method by combining high-speed single-point diamond milling and precision compression molding processes for fabrication of discontinuous freeform microlens arrays was proposed. Compared with slow tool servo diamond broaching, high-speed single-point diamond milling was selected for its flexibility in the fabrication of true 3D optical surfaces with discontinuous features. The advantage of single-point diamond milling is that the surface features can be constructed sequentially by spacing the axes of a virtual spindle at arbitrary positions based on the combination of rotational and translational motions of both the high-speed spindle and linear slides. By employing this method, each micro-lenslet was regarded as a microstructure cell by passing the axis of the virtual spindle through the vertex of each cell. An optimization arithmetic based on minimum-area fabrication was introduced to the machining process to further increase the machining efficiency. After the mold insert was machined, it was employed to replicate the microlens array onto chalcogenide glass. In the ensuing optical measurement, the self-built Shack-Hartmann wavefront sensor was proven to be accurate in detecting an infrared wavefront by both experiments and numerical simulation. The combined results showed that precision compression molding of chalcogenide glasses could be an economic and precision optical fabrication technology for high-volume production of infrared optics.

Fabrication of High Thermal Conductivity NARloy-Z-Diamond Composite Combustion Chamber Liner for Advanced Rocket Engines

NASA Technical Reports Server (NTRS)

Bhat, Biliyar N.; Greene, Sandra E.; Singh, Jogender

2016-01-01

NARloy-Z alloy (Cu-3 percent, Ag-0.5 percent, Zr) is a state of the art alloy currently used for fabricating rocket engine combustion chamber liners. Research conducted at NASA-MSFC and Penn State – Applied Research Laboratory has shown that thermal conductivity of NARloy-Z can be increased significantly by adding diamonds to form a composite (NARloy-Z-D). NARloy-Z-D is also lighter than NARloy-Z. These attributes make this advanced composite material an ideal candidate for fabricating combustion chamber liner for an advanced rocket engine. Increased thermal conductivity will directly translate into increased turbopump power and increased chamber pressure for improved thrust and specific impulse. This paper describes the process development for fabricating a subscale high thermal conductivity NARloy-Z-D combustion chamber liner using Field Assisted Sintering Technology (FAST). The FAST process uses a mixture of NARloy-Z and diamond powders which is sintered under pressure at elevated temperatures. Several challenges were encountered, i.e., segregation of diamonds, machining the super hard NARloy-Z-D composite, net shape fabrication and nondestructive examination. The paper describes how these challenges were addressed. Diamonds coated with copper (CuD) appear to give the best results. A near net shape subscale combustion chamber liner is being fabricated by diffusion bonding cylindrical rings of NARloy-Z-CuD using the FAST process.

Volatile composition of microinclusions in diamonds from the Panda kimberlite, Canada: Implications for chemical and isotopic heterogeneity in the mantle

NASA Astrophysics Data System (ADS)

Burgess, Ray; Cartigny, Pierre; Harrison, Darrell; Hobson, Emily; Harris, Jeff

2009-03-01

In order to better investigate the compositions and the origins of fluids associated with diamond growth, we have carried-out combined noble gas (He and Ar), C and N isotope, K, Ca and halogen (Cl, Br, I) determinations on fragments of individual microinclusion-bearing diamonds from the Panda kimberlite, North West Territories, Canada. The fluid concentrations of halogens and noble gases in Panda diamonds are enriched by several orders of magnitude over typical upper mantle abundances. However, noble gas, C and N isotopic ratios ( 3He/ 4He = 4-6 Ra, 40Ar/ 36Ar = 20,000-30,000, δ 13C = -4.5‰ to -6.9‰ and δ 15N = -1.2‰ to -8.8‰) are within the worldwide range determined for fibrous diamonds and similar to the mid ocean ridge basalt (MORB) source value. The high 36Ar content of the diamonds (>1 × 10 -9 cm 3/g) is at least an order of magnitude higher than any previously reported mantle sample and enables the 36Ar content of the subcontinental lithospheric mantle to be estimated at ˜0.6 × 10 -12 cm 3/g, again similar to estimates for the MORB source. Three fluid types distinguished on the basis of Ca-K-Cl compositions are consistent with carbonatitic, silicic and saline end-members identified in previous studies of diamonds from worldwide sources. These fluid end-members also have distinct halogen ratios (Br/Cl and I/Cl). The role of subducted seawater-derived halogens, originally invoked to explain some of the halogen ratio variations in diamonds, is not considered an essential component in the formation of the fluids. In contrast, it is considered that large halogen fractionation of a primitive mantle ratio occurs during fluid-melt partitioning in forming silicic fluids, and during separation of an immiscible saline fluid.

IR-stimulated visible fluorescence in pink and brown diamond.

PubMed

Byrne, K S; Chapman, J G; Luiten, A N

2014-03-19

Irradiation of natural pink and brown diamond by middle-ultraviolet light (photon energy ϵ ≥ 4.1 eV ) is seen to induce anomalous fluorescence phenomena at N3 defect centres (structure N3-V). When diamonds primed in this fashion are subsequently exposed to infrared light (even with a delay of many hours), a transient burst of blue N3 fluorescence is observed. The dependence of this IR-triggered fluorescence on pump wavelength and intensity suggest that this fluorescence phenomena is intrinsically related to pink diamond photochromism. An energy transfer process between N3 defects and other defect species can account for both the UV-induced fluorescence intensity changes, and the apparent optical upconversion of IR light. From this standpoint, we consider the implications of this N3 fluorescence behaviour for the current understanding of pink diamond photochromism kinetics.

A Novel Porous Diamond - Titanium Biomaterial: Structure, Microstructure, Physico-Mechanical Properties and Biocompatibility.

PubMed

Guimarães, Zulmira A S; Damatta, Renato A; Guimarães, Renan S; Filgueira, Marcello

2017-01-01

With the aim of introducing permanent prostheses with main properties equivalent to cortical human bone, Ti-diamond composites were processed through powder metallurgy. Grade 1 titanium and mixtures of Ti powder with 2%, 5% and 10 wt% diamond were compacted at 100MPa, and then sintered at 1250°C/2hr/10-6mbar. Sintered samples were studied in the point of view of their microstructures, structures, yield strength and elastic modulus. The results showed that the best addition of diamonds was 2 wt%, which led to a uniform porosity, yield strength of 370MPa and elastic modulus of 13.9 GPa. Samples of Ti and Ti-2% diamond were subjected to in vitro cytotoxicity test, using cultures of VERO cells, and it resulted in a biocompatible and nontoxic composite material.

Diffusion of helium, hydrogen and deuterium in diamond: Experiment, theory and geochemical applications

NASA Astrophysics Data System (ADS)

Cherniak, D. J.; Watson, E. B.; Meunier, V.; Kharche, N.

2018-07-01

Diffusivities of helium, deuterium and hydrogen have been characterized in diamond. Polished CVD diamond was implanted with either 3He, 2H, or 1H. Implanted samples were sealed under vacuum in silica glass capsules, and annealed in 1-atm furnaces. 3He, 2H and 1H distributions were measured with Nuclear Reaction Analysis. We obtain these Arrhenius relations: DHe = 4.00 × 10-15 exp(-138 ± 14 kJ mol-1/RT) m2 s-1. D2H = 1.02 × 10-4 exp(-262 ± 17 kJ mol-1/RT) m2 s-1. D1H = 2.60 × 10-4 exp(-267 ± 15 kJ mol-1/RT) m2 s-1. Diffusivities of 1H and 2H agree within experimental uncertainties, indicating little diffusive mass fractionation of hydrogen in diamond. To complement the experimental measurements, we performed calculations using a first-principles quantum mechanical description of diffusion in diamond within the Density Functional Theory (DFT). Differences in 1H and 2H diffusivities from calculations are found to be ∼4.5%, reflected in differences in the pre-exponential factor. This small difference in diffusivities, despite the large relative mass difference between these isotopes, is due to the fact that the atomistic process involved in the transition along the diffusion pathway is dictated by local changes to the diamond structures rather than to vibrations involving 1H/2H. This finding is consistent with the experimental results given experimental uncertainties. In contrast, calculations for helium diffusion in diamond indicate a difference of 15% between diffusivities of 3He and 4He. Calculations of diffusion distances for hydrogen using our data yield a distance of 50 μm in diamond in 300,000 years at 500 °C and ∼30 min at 1400 °C. Diffusion distances for He in diamond are shorter than for H at all temperatures above ∼350 °C, but differences increase dramatically with temperature because of the higher activation energy for H diffusion. For example, a 50 μm diffusion distance for He would be attained in ∼40 Myr at 500 °C and 400 yr at 1400 °C. For comparison, a 50 μm diffusion distance for N in diamond would require nearly 1 billion years at 1400 °C. The experimental data indicate that diamonds equilibrate with ambient H and He in the mantle on timescales brief relative to most geological processes and events. However, He diffusion in diamond is slower than in any other mineral measured to date, including other kimberlite-hosted minerals. Under some circumstances, diamond may provide information about mantle He not recoverable from other minerals. One possibility is diamonds entrained in kimberlites. Since the ascent of kimberlite from the mantle to near-surface is very rapid, entrained diamonds may retain most or all of the H and He acquired in mantle environments. Calculations using reasonable ascent rates and T-t paths indicate that He diffusive loss from kimberlite-hosted diamonds is negligible for grains of 1.0-0.2 mm radius, with fractional losses <0.15% for all ascent rates considered. If the host kimberlite magma is effectively quenched in the near-surface (or is erupted), diamonds should contain a faithful record of [He] and He isotopes from the mantle source region. Preservation of H in kimberlite-hosted diamonds is less clear-cut, with model outcomes depending critically upon rates of ascent and cooling.

A unique patterned diamond stamp for a periodically hierarchical nanoarray structure.

PubMed

Wang, Yi; Shen, Yanting; Xu, Weiqing; Xu, Shuping; Li, Hongdong

2016-09-23

A diamond stamp with a hierarchical pattern was designed for the direct preparation of a periodic nanoarray structure, which was prepared by the reactive ion etching technique with a hierarchical ultrathin alumina membrane (HUTAM) as a mask. The optimal etching conditions for fabricating the diamond stamp were discussed in order to realize a vertical nanopore structure, avoiding structural damage from lateral etching. By using this diamond stamp, a polymer film with the desired hierarchical nanorod array structure can be obtained easily via the simple stamping process, which greatly simplifies the processing procedure. More importantly, the stamp is reusable because of its super-hardness, which ensures the reproducibility of the nanorod array pattern. Another merit is that the smooth surface of the etched diamond can avoid the use of a release agent. Our results prove that this hard stamp can be used for quick preparation of an elaborate periodic nanoarray structure. This study is significant in that it solves the problems of high cost and easy damage of stamps in nanoimprint lithography, and it might inspire more sophisticated applications of such an ordered structure in nanoplasmonics, biochemical sensing and nanophotonic devices.

Fabrication of High Thermal Conductivity NARloy-Z-Diamond Composite Combustion Chamber Liner for Advanced Rocket Engines

NASA Technical Reports Server (NTRS)

Bhat, Biliyar N.; Greene, Sandra E.; Singh, Jogender

2016-01-01

This paper describes the process development for fabricating a high thermal conductivity NARloy-Z-Diamond composite (NARloy-Z-D) combustion chamber liner for application in advanced rocket engines. The fabrication process is challenging and this paper presents some details of these challenges and approaches used to address them. Prior research conducted at NASA-MSFC and Penn State had shown that NARloy-Z-40%D composite material has significantly higher thermal conductivity than the state of the art NARloy-Z alloy. Furthermore, NARloy-Z-40 %D is much lighter than NARloy-Z. These attributes help to improve the performance of the advanced rocket engines. Increased thermal conductivity will directly translate into increased turbopump power, increased chamber pressure for improved thrust and specific impulse. Early work on NARloy-Z-D composites used the Field Assisted Sintering Technology (FAST, Ref. 1, 2) for fabricating discs. NARloy-Z-D composites containing 10, 20 and 40vol% of high thermal conductivity diamond powder were investigated. Thermal conductivity (TC) data. TC increased with increasing diamond content and showed 50% improvement over pure copper at 40vol% diamond. This composition was selected for fabricating the combustion chamber liner using the FAST technique.

Mechanism-Based FE Simulation of Tool Wear in Diamond Drilling of SiCp/Al Composites.

PubMed

Xiang, Junfeng; Pang, Siqin; Xie, Lijing; Gao, Feinong; Hu, Xin; Yi, Jie; Hu, Fang

2018-02-07

The aim of this work is to analyze the micro mechanisms underlying the wear of macroscale tools during diamond machining of SiC p /Al6063 composites and to develop the mechanism-based diamond wear model in relation to the dominant wear behaviors. During drilling, high volume fraction SiC p /Al6063 composites containing Cu, the dominant wear mechanisms of diamond tool involve thermodynamically activated physicochemical wear due to diamond-graphite transformation catalyzed by Cu in air atmosphere and mechanically driven abrasive wear due to high-frequency scrape of hard SiC reinforcement on tool surface. An analytical diamond wear model, coupling Usui abrasive wear model and Arrhenius extended graphitization wear model was proposed and implemented through a user-defined subroutine for tool wear estimates. Tool wear estimate in diamond drilling of SiC p /Al6063 composites was achieved by incorporating the combined abrasive-chemical tool wear subroutine into the coupled thermomechanical FE model of 3D drilling. The developed drilling FE model for reproducing diamond tool wear was validated for feasibility and reliability by comparing numerically simulated tool wear morphology and experimentally observed results after drilling a hole using brazed polycrystalline diamond (PCD) and chemical vapor deposition (CVD) diamond coated tools. A fairly good agreement of experimental and simulated results in cutting forces, chip and tool wear morphologies demonstrates that the developed 3D drilling FE model, combined with a subroutine for diamond tool wear estimate can provide a more accurate analysis not only in cutting forces and chip shape but also in tool wear behavior during drilling SiC p /Al6063 composites. Once validated and calibrated, the developed diamond tool wear model in conjunction with other machining FE models can be easily extended to the investigation of tool wear evolution with various diamond tool geometries and other machining processes in cutting different workpiece materials.

Mechanism-Based FE Simulation of Tool Wear in Diamond Drilling of SiCp/Al Composites

PubMed Central

Xiang, Junfeng; Pang, Siqin; Xie, Lijing; Gao, Feinong; Hu, Xin; Yi, Jie; Hu, Fang

2018-01-01

The aim of this work is to analyze the micro mechanisms underlying the wear of macroscale tools during diamond machining of SiCp/Al6063 composites and to develop the mechanism-based diamond wear model in relation to the dominant wear behaviors. During drilling, high volume fraction SiCp/Al6063 composites containing Cu, the dominant wear mechanisms of diamond tool involve thermodynamically activated physicochemical wear due to diamond-graphite transformation catalyzed by Cu in air atmosphere and mechanically driven abrasive wear due to high-frequency scrape of hard SiC reinforcement on tool surface. An analytical diamond wear model, coupling Usui abrasive wear model and Arrhenius extended graphitization wear model was proposed and implemented through a user-defined subroutine for tool wear estimates. Tool wear estimate in diamond drilling of SiCp/Al6063 composites was achieved by incorporating the combined abrasive-chemical tool wear subroutine into the coupled thermomechanical FE model of 3D drilling. The developed drilling FE model for reproducing diamond tool wear was validated for feasibility and reliability by comparing numerically simulated tool wear morphology and experimentally observed results after drilling a hole using brazed polycrystalline diamond (PCD) and chemical vapor deposition (CVD) diamond coated tools. A fairly good agreement of experimental and simulated results in cutting forces, chip and tool wear morphologies demonstrates that the developed 3D drilling FE model, combined with a subroutine for diamond tool wear estimate can provide a more accurate analysis not only in cutting forces and chip shape but also in tool wear behavior during drilling SiCp/Al6063 composites. Once validated and calibrated, the developed diamond tool wear model in conjunction with other machining FE models can be easily extended to the investigation of tool wear evolution with various diamond tool geometries and other machining processes in cutting different workpiece materials. PMID:29414839

Influence of Interfacial Carbide Layer Characteristics on Thermal Properties of Copper-Diamond Composites (Postprint)

DTIC Science & Technology

2014-04-01

wettability of diamond is not an issue. Moreover, the solid-state processing can, in principle , be carried out at relatively low temperatures even for non...capacity. q was mea- sured using Archimedes ’ method, and D was measured with laser flash technique per ASTM E1461. The speci- mens for D measurement... principle , attainable by changing the interfacial Cr3C2 layer characteristics. In an earlier study [3], for a given diamond particle size and volume

Diamond turning of Si and Ge single crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blake, P.; Scattergood, R.O.

Single-point diamond turning studies have been completed on Si and Ge crystals. A new process model was developed for diamond turning which is based on a critical depth of cut for plastic flow-to-brittle fracture transitions. This concept, when combined with the actual machining geometry for single-point turning, predicts that {open_quotes}ductile{close_quotes} machining is a combined action of plasticity and fracture. Interrupted cutting experiments also provide a meant to directly measure the critical depth parameter for given machining conditions.

Multi-Energy Processing for Novel Coating Technologies

DTIC Science & Technology

2014-12-18

tungsten carbide (WC) substrate (BS-6S, Basic Carbide Corp.) with a dimension of 25.4 x 25.4 x 1.6 mm^ and a cobalt composition of 6% was placed on a...as dopant sources. (a) No NH3 + No laser (b) NH3 added, No laser (c) 10.591 ^m Figure 4.4 SEM micrographs of the diamond films deposited using...typed 37 diamond. Nitrogen was widely used as n-typed dopant . Nitrogen-containing additives in CVD diamond growth led to severe deterioration of the

Improvement of diamond-like carbon electrochemical corrosion resistance by addition of nanocrystalline diamond.

PubMed

Marciano, F R; Almeida, E C; Bonetti, L F; Corat, E J; Trava-Airoldi, V J

2010-02-15

Nanocrystalline diamond (NCD) particles were incorporated into diamond-like carbon (DLC) films in order to investigate NCD-DLC electrochemical corrosion resistance. The films were grown over 304 stainless steel using plasma-enhanced chemical vapor deposition. NCD particles were incorporated into DLC during the deposition process. The investigation of NCD-DLC electrochemical corrosion behavior was performed using potentiodynamic polarization against NaCl. NCD-DLC films presented more negative corrosion potential and lower anodic and cathodic current densities. The electrochemical analysis indicated that NCD-DLC films present superior impedance and polarization resistance compared to the pure DLC, which indicate that they are promising corrosion protective coatings in aggressive solutions. Copyright 2009 Elsevier Inc. All rights reserved.

Diamond like carbon nanocomposites with embedded metallic nanoparticles

NASA Astrophysics Data System (ADS)

Tamulevičius, Sigitas; Meškinis, Šarūnas; Tamulevičius, Tomas; Rubahn, Horst-Günter

2018-02-01

In this work we present an overview on structure formation, optical and electrical properties of diamond like carbon (DLC) based metal nanocomposites deposited by reactive magnetron sputtering and treated by plasma and laser ablation methods. The influence of deposition mode and other technological conditions on the properties of the nanosized filler, matrix components and composition were studied systematically in relation to the final properties of the nanocomposites. Applications of the nanocomposites in the development of novel biosensors combining resonance response of wave guiding structures in DLC based nanocomposites as well as plasmonic effects are also presented.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gou, Huiyang; Hemley, Russell J.; Hemawan, Kadek W.

Polycrystalline diamond has been successfully synthesized on silicon substrates at atmospheric pressure using a microwave capillary plasma chemical vapor deposition technique. The CH 4/Ar plasma was generated inside of quartz capillary tubes using 2.45 GHz microwave excitation without adding H2 into the deposition gas chemistry. Electronically excited species of CN, C 2, Ar, N 2, CH, H β and H α were observed in emission spectra. Raman measurements of deposited material indicate the formation of well-crystallized diamond, as evidenced by the sharp T 2g phonon at 1333 cm -1 peak relative to the Raman features of graphitic carbon. Furthermore, fieldmore » emission scanning electron microscopy (SEM) images reveal that, depending on the on growth conditions, the carbon microstructures of grown films exhibit “coral” and “cauliflower-like” morphologies or well-facetted diamond crystals with grain sizes ranging from 100 nm to 10 μm.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hemawan, Kadek W.; Gou, Huiyang; Hemley, Russell J.

Polycrystalline diamond has been synthesized on silicon substrates at atmospheric pressure, using a microwave capillary plasma chemical vapor deposition technique. The CH{sub 4}/Ar plasma was generated inside of quartz capillary tubes using 2.45 GHz microwave excitation without adding H{sub 2} into the deposition gas chemistry. Electronically excited species of CN, C{sub 2}, Ar, N{sub 2}, CH, H{sub β}, and H{sub α} were observed in the emission spectra. Raman measurements of deposited material indicate the formation of well-crystallized diamond, as evidenced by the sharp T{sub 2g} phonon at 1333 cm{sup −1} peak relative to the Raman features of graphitic carbon. Field emission scanningmore » electron microscopy images reveal that, depending on the growth conditions, the carbon microstructures of grown films exhibit “coral” and “cauliflower-like” morphologies or well-facetted diamond crystals with grain sizes ranging from 100 nm to 10 μm.« less

Formation of diamond nanoparticle thin films by electrophoretic deposition

NASA Astrophysics Data System (ADS)

Goto, Yosuke; Ohishi, Fujio; Tanaka, Kuniaki; Usui, Hiroaki

2016-03-01

Thin films of diamond nanoparticles were prepared by electrophoretic deposition (EPD) using 0.5 wt % dispersions in water, ethanol, and 2-propanol. The film growth rate increased with increasing voltage applied to the electrodes. However, an excessive increase in voltage caused the degradation of film morphology. The optimum voltage was 4 V with an electrode separation of 5 mm. The film growth rate was higher in organic solvents than in water. The deposited film had a smooth surface with an average surface roughness comparable to the size of primary particles of the source material. It is notable that the EPD films had a considerably higher physical stability than spin-coated and cast films. The stability was further improved by thermally annealing the films. IR analysis revealed that the diamond nanoparticles have carboxy and amino groups on their surfaces. It is considered that the stability of the EPD films originate from a chemical reaction between these functional groups.

Microstructural Characterisation and Wear Behaviour of Diamond Composite Materials

PubMed Central

Boland, James N.; Li, Xing S.

2010-01-01

Since the initial research leading to the production of diamond composite materials, there have been several important developments leading to significant improvements in the properties of these superhard composite materials. Apart from the fact that diamonds, whether originating from natural resources or synthesised commercially, are the hardest and most wear-resistant materials commonly available, there are other mechanical properties that limit their industrial application. These include the low fracture toughness and low impact strength of diamond. By incorporating a range of binder phases into the sintering production process of these composites, these critically important properties have been radically improved. These new composites can withstand much higher operating temperatures without markedly reducing their strength and wear resistance. Further innovative steps are now being made to improve the properties of diamond composites by reducing grain and particle sizes into the nano range. This review will cover recent developments in diamond composite materials with special emphasis on microstructural characterisation. The results of such studies should assist in the design of new, innovative diamond tools as well as leading to radical improvements in the productivity of cutting, drilling and sawing operations in the exploration, mining, civil construction and manufacturing industries.

Chirped circular dielectric gratings for near-unity collection efficiency from quantum emitters in bulk diamond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Jiabao; Liapis, Andreas C.; Chen, Edward H.

Effcient collection of fluorescence from nitrogen vacancy (NV) centers in diamond underlies the spin-dependent optical read-out that is necessary for quantum information processing and enhanced sensing applications. The optical collection effciency from NVs within diamond substrates is limited primarily due to the high refractive index of diamond and the non-directional dipole emission. Here we introduce a light collection strategy based on chirped, circular dielectric gratings that can be fabricated on a bulk diamond substrate to redirect an emitter’s far-field radiation pattern. Using a genetic optimization algorithm, these grating designs achieve 98.9% collection effciency for the NV zero-phonon emission line, collectedmore » from the back surface of the diamond with an objective of aperture 0.9. Across the broadband emission spectrum of the NV (600-800 nm), the chirped grating achieves 82.2% collection e ciency into a numerical aperture of 1.42, corresponding to an oil immersion objective again on the back side of the diamond. Our proposed bulk-dielectric grating structures are applicable to other optically active solid state quantum emitters in high index host materials.« less

Chirped circular dielectric gratings for near-unity collection efficiency from quantum emitters in bulk diamond

DOE PAGES

Zheng, Jiabao; Liapis, Andreas C.; Chen, Edward H.; ...

2017-12-13

Effcient collection of fluorescence from nitrogen vacancy (NV) centers in diamond underlies the spin-dependent optical read-out that is necessary for quantum information processing and enhanced sensing applications. The optical collection effciency from NVs within diamond substrates is limited primarily due to the high refractive index of diamond and the non-directional dipole emission. Here we introduce a light collection strategy based on chirped, circular dielectric gratings that can be fabricated on a bulk diamond substrate to redirect an emitter’s far-field radiation pattern. Using a genetic optimization algorithm, these grating designs achieve 98.9% collection effciency for the NV zero-phonon emission line, collectedmore » from the back surface of the diamond with an objective of aperture 0.9. Across the broadband emission spectrum of the NV (600-800 nm), the chirped grating achieves 82.2% collection e ciency into a numerical aperture of 1.42, corresponding to an oil immersion objective again on the back side of the diamond. Our proposed bulk-dielectric grating structures are applicable to other optically active solid state quantum emitters in high index host materials.« less

Feedback‐amplified electrochemical dual‐plate boron‐doped diamond microtrench detector for flow injection analysis

PubMed Central

Lewis, Grace E. M.; Gross, Andrew J.; Kasprzyk‐Hordern, Barbara; Lubben, Anneke T.

2015-01-01

An electrochemical flow cell with a boron‐doped diamond dual‐plate microtrench electrode has been developed and demonstrated for hydroquinone flow injection electroanalysis in phosphate buffer pH 7. Using the electrochemical generator‐collector feedback detector improves the sensitivity by one order of magnitude (when compared to a single working electrode detector). The diffusion process is switched from an analyte consuming “external” process to an analyte regenerating “internal” process with benefits in selectivity and sensitivity. PMID:25735831

Carbonate Mineral Assemblages as Inclusions in Yakutian Diamonds: TEM Verifications

NASA Astrophysics Data System (ADS)

Logvinova, A. M.; Wirth, R.; Sobolev, N. V.; Taylor, L. A.

2014-12-01

Carbonate mineral inclusions are quite rare in diamonds from the upper mantle, but are evidence for a carbonate abundance in the mantle. It is believed that such carbonatitic inclusions originated from high-density fluids (HDFs) that were enclosed in diamond during its growth. Using TEM and EPMA, several kinds of carbonate inclusions have been identified in Yakutian diamonds : aragonite, dolomite, magnesite, Ba-, Sr-, and Fe-rich carbonates. Most of them are represented by multi-phase inclusions of various chemically distinct carbonates, rich in Ca, Mg, and K and associated with minor amounts of silicate, oxide, saline, and volatile phases. Volatiles, leaving some porosity, played a significant role in the diamond growth. A single crystal of aragonite (60μm) is herein reported for the first time. This inclusion is located in the center of a diamond from the Komsomolskaya pipe. Careful CL imaging reveals the total absence of cracks around the aragonite inclusion - i.e., closed system. This inclusion has been identified by X-ray diffraction and microprobe analysis. At temperatures above 1000 0C, aragonite is only stable at high pressures of 5-6 GPa. Inside this aragonite, we observed nanocrystalline inclusions of titanite, Ni-rich sulfide, magnetite, water-bearing Mg-silicate, and fluid bubbles. Dolomite is common in carbonate multi-phase inclusions in diamonds from the Internatsionalnaya, Yubileinaya, and Udachnaya kimberlite pipes. Alluvial diamonds of the northeastern Siberian Platform are divided into two groups based on the composition of HDFs: 1) Mg-rich multi-phase inclusions (60% magnesite + dolomite + Fe-spinel + Ti-silicate + fluid bubbles); and 2) Ca-rich multi-phase inclusions (Ca,Ba-, Ca,Sr-, Ca,Fe-carbonates + Ti-silicate + Ba-apatite + fluid bubbles). High-density fluids also contain K. Volatiles in the fluid bubbles are represented by water, Cl, F, S, CO2, CH4, and heavy hydrocarbons. Origin of the second group of HDFs may be related to the non-silicate carbonatitic melt. We consider the primary hydrous, Сa-rich and Mg-poor carbonate melts as having formed in subducted oceanic crust. Variations of carbonate-inclusion compositions among diamonds indicate the variability in the source media during the formation of diamond and may be the result of metasomatic interaction with host rocks.

Diamond growth from oxidized carbon sources beneath the Northern Slave Craton, Canada: A δ 13C-N study of eclogite-hosted diamonds from the Jericho kimberlite

NASA Astrophysics Data System (ADS)

Smart, Katie A.; Chacko, Thomas; Stachel, Thomas; Muehlenbachs, Karlis; Stern, Richard A.; Heaman, Larry M.

2011-10-01

Diamonds from high- and low-MgO groups of eclogite xenoliths from the Jericho kimberlite, Slave Craton, Canada were analyzed for carbon isotope compositions and nitrogen contents. Diamonds extracted from the two groups show remarkably different nitrogen abundances and δ 13C values. While diamonds from high-MgO eclogites have low nitrogen contents (5-82 ppm) and extremely low δ 13C values clustering at ˜-40‰, diamonds from the low-MgO eclogites have high nitrogen contents (>1200 ppm) and δ 13C values from -3.5‰ to -5.3‰. Coupled cathodoluminescence (CL) imaging and SIMS analysis of the Jericho diamonds provides insight into diamond growth processes. Diamonds from the high-MgO eclogites display little CL structure and generally have constant δ 13C values and nitrogen contents. Some of these diamonds have secondary rims with increasing δ 13C values from -40‰ to ˜-34‰, which suggests secondary diamond growth occurred from an oxidized growth medium. The extreme negative δ 13C values of the high-MgO eclogite diamonds cannot be produced by Rayleigh isotopic fractionation of average mantle-derived carbon (-5‰) or carbon derived from typical organic matter (˜-25‰). However, excursions in δ 13C values to -60‰ are known in the organic sedimentary record at ca. 2.7 and 2.0 Ga, such that diamonds from the high-MgO eclogites could have formed from similar organic matter brought into the Slave lithospheric mantle by subduction. SIMS analyses of a diamond from a low-MgO eclogite show an outer core with systematic rimwards increases in δ 13C values coupled with decreases in nitrogen contents, and a rim with pronounced alternating growth zones. The coupled δ 13C-nitrogen data suggest that the diamond precipitated during fractional crystallization from an oxidized fluid/melt from which nitrogen was progressively depleted during growth. Model calculations of the co-variation of δ 13C-N yielded a partition coefficient ( KN) value of 5, indicating that nitrogen is strongly compatible in diamond relative to the growth medium. δ 13C values of diamond cores (-4‰) dictate the growth medium had higher δ 13C values than primary mantle-derived carbon. Therefore, possible carbon sources for the low-MgO eclogite diamonds include oxidized mantle-derived (e.g. protokimberlite or carbonatite) fluids/melts that underwent some fractionation during migration or, devolatilized subducted carbonates.

Accelerated aggregation of donor nitrogen in diamond containing NV centers

NASA Astrophysics Data System (ADS)

Lobanov, Sergey; Vins, Victor; Yelisseev, Alexander; Afonin, Dmitry; Blinkov, Alexander; Maximov, Yuriy

2010-05-01

The aggregation of donor nitrogen (C centers) into nitrogen pairs (A centers) is considered to be a second-order chemical reaction and the kinetics of this reaction can be written as follows: Kt = 1-- -1- Ct C0 where K is the aggregation rate constant that depends exponentially on temperature and activation energy K = Aexp (- Ea-kT ) and C0 and CT are C center concentrations before and after the aggregation. The activation energy Ea in natural diamonds is equal to 5±0.3 eV. However, it was shown by Vins (2004) that Ea varied in synthetic diamonds depending on Ni concentration from 3 to 6 eV; and in synthetic diamonds containing cobalt the activation energy exceeded 4 eV. The aggregation rate of C centers also increased dramatically in diamonds irradiated with high-energy electrons (Collins, 1980). An HPHT diamond single crystal grown in the Fe-Co-C system using the TGG method was studied. The initial C center concentration determined from the intensity of the 1130 cm-1 IR absorption band was equal to 118 ppm. In order to determine the influence of NV centers on the activation energy of aggregation, the crystal was at first irradiated with high-energy electrons (3MeV, 2×1018cm-2) and annealed in a quartz ampoule in vacuum (8000C, 2 hrs). This led to the formation of over 5 ppm of NV centers. After that the sample was annealed at high temperatures in the argon flow (15300C, 30 minutes). The IR absorption spectra revealed an

High growth rate homoepitaxial diamond film deposition at high temperatures by microwave plasma-assisted chemical vapor deposition

NASA Technical Reports Server (NTRS)

Vohra, Yogesh K. (Inventor); McCauley, Thomas S. (Inventor)

1997-01-01

The deposition of high quality diamond films at high linear growth rates and substrate temperatures for microwave-plasma chemical vapor deposition is disclosed. The linear growth rate achieved for this process is generally greater than 50 .mu.m/hr for high quality films, as compared to rates of less than 5 .mu.m/hr generally reported for MPCVD processes.

Surface functionalization of thin-film diamond for highly stable and selective biological interfaces

PubMed Central

Stavis, Courtney; Clare, Tami Lasseter; Butler, James E.; Radadia, Adarsh D.; Carr, Rogan; Zeng, Hongjun; King, William P.; Carlisle, John A.; Aksimentiev, Aleksei; Bashir, Rashid; Hamers, Robert J.

2011-01-01

Carbon is an extremely versatile family of materials with a wide range of mechanical, optical, and mechanical properties, but many similarities in surface chemistry. As one of the most chemically stable materials known, carbon provides an outstanding platform for the development of highly tunable molecular and biomolecular interfaces. Photochemical grafting of alkenes has emerged as an attractive method for functionalizing surfaces of diamond, but many aspects of the surface chemistry and impact on biological recognition processes remain unexplored. Here we report investigations of the interaction of functionalized diamond surfaces with proteins and biological cells using X-ray photoelectron spectroscopy (XPS), atomic force microscopy, and fluorescence methods. XPS data show that functionalization of diamond with short ethylene glycol oligomers reduces the nonspecific binding of fibrinogen below the detection limit of XPS, estimated as > 97% reduction over H-terminated diamond. Measurements of different forms of diamond with different roughness are used to explore the influence of roughness on nonspecific binding onto H-terminated and ethylene glycol (EG)-terminated surfaces. Finally, we use XPS to characterize the chemical stability of Escherichia coli K12 antibodies on the surfaces of diamond and amine-functionalized glass. Our results show that antibody-modified diamond surfaces exhibit increased stability in XPS and that this is accompanied by retention of biological activity in cell-capture measurements. Our results demonstrate that surface chemistry on diamond and other carbon-based materials provides an excellent platform for biomolecular interfaces with high stability and high selectivity. PMID:20884854

Diamond deposition by chemical vapor transport with hydrogen in a closed system

NASA Astrophysics Data System (ADS)

Piekarczyk, W.; Messier, R.; Roy, R.; Engdahl, C.

1990-11-01

The carbon-hydrogen chemical vapor transport system was examined in accordance with a four-stage transport model. A result of this examination is that graphite co-deposition could be avoided when diamond is deposited from gas solutions undersaturated with regard to diamond. Actual deposition experiments showed that this unusual requirement can be fulfilled but only for the condition that the transport distance between the carbon source and the substrate surface is short. In such a case diamond can be deposited equally from supersaturated as well as from undersaturated gas solutions. On the basis of thermodynamic considerations, a possible explanation of this unusual phenomenon is given. It is shown that there is a possibility of deposition of diamond from both supersaturated and undersaturated gas solutions but only on the condition that they are in a non-equilibrium state generally called the activated state. A model of the diamond deposition process consisting of two steps is proposed. In the first step diamond and graphite are deposited simultaneously. The most important carbon deposition reaction is C 2H 2(g)+2H(g) = C(diamond+graphite) +CH 4(g). The amount of co-deposited graphite is not a direct function of the saturation state of the gas phase. In the second step graphite is etched according to the most probable reaction C(graphite)+4H(g) = CH 4(g). Atomic hydrogen in a concentration exceeding equilibrium is necessary not only to etch graphite, but also to precipitate diamond and graphite.

Magnetic properties of point defects in proton irradiated diamond

NASA Astrophysics Data System (ADS)

Makgato, T. N.; Sideras-Haddad, E.; Ramos, M. A.; García-Hernández, M.; Climent-Font, A.; Zucchiatti, A.; Muñoz-Martin, A.; Shrivastava, S.; Erasmus, R.

2016-09-01

We investigate the magnetic properties of ultra-pure type-IIa diamond following irradiation with proton beams of ≈1-2 MeV energy. SQUID magnetometry indicate the formation of Curie type paramagnetism according to the Curie law. Raman and Photoluminescence spectroscopy measurements show that the primary structural features created by proton irradiation are the centers: GR1, ND1, TR12 and 3H. The Stopping and Range of Ions in Matter (SRIM) Monte Carlo simulations together with SQUID observations show a strong correlation between vacancy production, proton fluence and the paramagnetic factor. At an average surface vacancy spacing of ≈1-1.6 nm and bulk (peak) vacancy spacing of ≈0.3-0.5 nm Curie paramagnetism is induced by formation of ND1 centres with an effective magnetic moment μeff~(0.1-0.2)μB. No evidence of long range magnetic ordering is observed in the temperature range 4.2-300 K.

Carbon solids in oxygen-deficient explosives (LA-UR-13-21151)

NASA Astrophysics Data System (ADS)

Peery, Travis

2013-06-01

The phase behavior of excess carbon in oxygen-deficient explosives has a significant effect on detonation properties and product equations of state. Mixtures of fuel oil in ammonium nitrate (ANFO) above a stoichiometric ratio demonstrate that even small amounts of graphite, on the order of 5% by mole fraction, can substantially alter the Chapman-Jouget (CJ) state properties, a central ingredient in modeling the products equation of state. Similar effects can be seen for Composition B, which borders the carbon phase boundary between graphite and diamond. Nano-diamond formation adds complexity to the product modeling because of surface adsorption effects. I will discuss these carbon phase issues in our equation of state modeling of detonation products, including our statistical mechanics description of carbon clustering and surface chemistry to properly treat solid carbon formation. This work is supported by the Advanced Simulation and Computing Program, under the NNSA.

Synthesis of ultrasmooth nanostructured diamond films by microwave plasma chemical vapor deposition using a He/H(2)/CH(4)/N(2) gas mixture.

PubMed

Chowdhury, S; Hillman, Damon A; Catledge, Shane A; Konovalov, Valery V; Vohra, Yogesh K

2006-10-01

Ultrasmooth nanostructured diamond (USND) films were synthesized on Ti-6Al-4V medical grade substrates by adding helium in H(2)/CH(4)/N(2) plasma and changing the N(2)/CH(4) gas flow from 0 to 0.6. We were able to deposit diamond films as smooth as 6 nm (root-mean-square), as measured by an atomic force microscopy (AFM) scan area of 2 μm(2). Grain size was 4-5 nm at 71% He in (H(2) + He) and N(2)/CH(4) gas flow ratio of 0.4 without deteriorating the hardness (~50-60 GPa). The characterization of the films was performed with AFM, scanning electron microscopy, x-ray diffraction (XRD), Raman spectroscopy, and nanoindentation techniques. XRD and Raman results showed the nanocrystalline nature of the diamond films. The plasma species during deposition were monitored by optical emission spectroscopy. With increasing N(2)/CH(4) feedgas ratio (CH(4) was fixed) in He/H(2)/CH(4)/N(2) plasma, a substantial increase of CN radical (normalized by Balmer H(α) line) was observed along with a drop in surface roughness up to a critical N(2)/CH(4) ratio of 0.4. The CN radical concentration in the plasma was thus correlated to the formation of ultrasmooth nanostructured diamond films.

Proceedings of the Seventh Applied Diamond Conference/Third Frontier Carbon Technology Joint Conference (ADC/FCT 2003)

NASA Technical Reports Server (NTRS)

Murakawa, M. (Editor); Miyoshi, K. (Editor); Koga, Y. (Editor); Schaefer, L. (Editor); Tzeng, Y. (Editor)

2003-01-01

These are the Proceedings of the Seventh Applied Diamond Conference/Third Frontier Carbon Technology Joint Conference held at Epochal Tsukuba International Conference Center from August 18 to 21, 2003. The diamond CVD process was first reported by Dr. Spitsyn in 1981 and Prof. S. Iijima reported his discovery of carbon nanotubes in 1991. In the past years, both diamond-related materials and novel carbon materials have attracted considerable interest by the scientific, technological, and industrial community. Many practical and commercial products of diamond materials are reported in these proceedings. A broad variety of applications of carbon nanotubes and novel carbons have also been explored and demonstrated. Having more than 175 invited and contributing papers by authors from over 18 countries for presentations at ADC/FCT 2003 clearly demonstrates that these materials, due to the combination of their superior properties, are both scientifically amazing and economically significant.

Colloidal crystals with diamond symmetry at optical lengthscales

NASA Astrophysics Data System (ADS)

Wang, Yifan; Jenkins, Ian C.; McGinley, James T.; Sinno, Talid; Crocker, John C.

2017-02-01

Future optical materials promise to do for photonics what semiconductors did for electronics, but the challenge has long been in creating the structure they require--a regular, three-dimensional array of transparent microspheres arranged like the atoms in a diamond crystal. Here we demonstrate a simple approach for spontaneously growing double-diamond (or B32) crystals that contain a suitable diamond structure, using DNA to direct the self-assembly process. While diamond symmetry crystals have been grown from much smaller nanoparticles, none of those previous methods suffice for the larger particles needed for photonic applications, whose size must be comparable to the wavelength of visible light. Intriguingly, the crystals we observe do not readily form in previously validated simulations; nor have they been predicted theoretically. This finding suggests that other unexpected microstructures may be accessible using this approach and bodes well for future efforts to inexpensively mass-produce metamaterials for an array of photonic applications.

Surface Modification of Boron-Doped Diamond with Microcrystalline Copper Phthalocyanine: Oxygen Reduction Catalysis.

PubMed

Gan, Patrick; Foord, John S; Compton, Richard G

2015-10-01

Surface modification of boron-doped diamond (BDD) with copper phthalocyanine was achieved using a simple and convenient dropcast deposition, giving rise to a microcrystalline structure. Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution. A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD. Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide. The lack of a further conversion of the peroxide was attributed to its rapid diffusion away from the triple phase boundary at which the reaction is expected to exclusively occur.

Diamond and diamondlike carbon as wear-resistant, self-lubricating coatings for silicon nitride

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1995-01-01

Recent work on the friction and wear properties of as-deposited fine-grain diamond, polished coarse-grain diamond, and as-deposited diamondlike carbon (DLC) films in humid air at a relative humidity of approximately 40 percent and in dry nitrogen is reviewed. Two types of chemical vapor deposition (CVD) processes are used to deposit diamond films on silicon nitride (Si3N4) substrates: microwave-plasma and hot-filament. Ion beams are used to deposit DLC films of Si3N4 substrates. The diamond and DLC films in sliding contact with hemispherical bare Si3N4 pins have low steady-state coefficients of friction (less than 0.2) and low wear rates (less than 10(exp -7) mm(exp 2)/N-m), and thus, can be used effectively as wear-resistant, self-lubricating coatings for Si3N4 in the aforementioned two environments.

Proceedings of the Sixth Applied Diamond Conference/Second Frontier Carbon Technology Joint Conference (ADC/FCT 2001)

NASA Technical Reports Server (NTRS)

Tzeng, Y. (Editor); Miyoshi, K. (Editor); Yoshikawa, M. (Editor); Murakawa, M. (Editor); Koga, Y. (Editor); Kobashi, K. (Editor); Amaratunga, G. A. J. (Editor)

2001-01-01

These are the Proceedings of the Sixth Applied Diamond Conference/Second Frontier Carbon Technology Joint Conference hosted by Auburn University from August 6 to 10, 2001. The diamond CVD process was first reported by Dr. Spitsyn in 1981 and Prof. S. Iijima reported his discovery of carbon nanotubes in 1991. In the past years, both diamond-related materials and novel carbon materials have attracted considerable interest by the scientific, technological, and industrial community. Many practical and commercial products of diamond materials are reported in these proceedings. A broad variety of applications of carbon nanotubes and novel carbons have also been explored and demonstrated. Having more than 200 invited and contributing papers by authors from over 20 countries for presentations at ADC/FCT 2001 clearly demonstrates that these materials, due to the combination of their superior properties, are both scientifically amazing and economically significant.

Isotopic Characterization of Diamond Growth in Fluids

NASA Astrophysics Data System (ADS)

Bureau, Hélène; Remusat, Laurent; Esteve, Imène; Pinti, Daniele; Cartigny, Pierre

2017-04-01

Trapping inclusions in diamonds has been used as a diagnostic to constrain diamond growth media (e.g. Navon et al., 1994; Weiss et al., 2015) in the Earth's upper mantle. Experimental works now generate inclusion-bearing diamonds from seeds in mixtures of carbonates, graphite, and silicates in the presence of excess of pure water or saline fluids (H2O-NaCl) and investigate in more details the conditions of natural diamond growth (Bureau et al., 2012; 2016). Experiments were carried at conditions compatible with the Earth's geotherm between 6-7 GPa (1300-1675°C) in multi-anvil presses at the Bayerisches Geoinstitut, Bayreuth from a few hours two a few days. Results show that within the timescale of the experiments diamond growth occurs on seeds if water and alkali-bearing carbonates are present. We show that water promotes fast diamond growth, which is favorable to the formation of inclusions. Thin sections of a few diamond seeds containing exposed inclusions were prepared using a Focus Ion Beam (about 2 to 5 µm thickness). These sections were deposited on silicon wafers and gold coated for micron-scale determination of the delta 13C isotopic compositions using the NanoSIMS 50 installed at the Muséum National d'Histoire Naturelle, Paris. Carbon isotope measurement with NanoSIMS were calibrated against a natural Ia and a synthetic IIa diamond used for diamond anvil cells, whose compositions were determined by gas-source mass spectrometry at IPGP at 3.6±0.1‰ and -20.9±0.1‰, respectively (Pinti et al., 2016). All the starting materials used for the experiments were also characterized for their delta 13C by the same technique at GEOTOP, Montréal. The isotopic composition of the new diamond grown areas were measured close to the inclusions. They exhibit a different isotopic signature than that of the starting seeds (starting diamond composition: -29.6 to -30.4±1.4‰). The new diamond signatures are falling into the range of signatures of the starting carbonates used for the experiments (- 4.8±0.1 to -16.2±0.1‰) when they are far away from the composition of the starting graphite (-26.4±0.1‰). This shows that the carbon source for diamond growth must be the carbonates present either as CO32- ions dissolved in the melt or as carbon dioxide species CO2 in the aqueous fluid and that diamond growth occurred from carbonate reduction rather that from graphite dissolved in the melt. We suggest that the presence of small discrete or isolated volumes of water-carbonate-rich fluids are necessary to grow inclusion-bearing peridotitic, eclogitic, fibrous, cloudy and coated diamonds, and may also be involved in the growth of ultrahigh pressure metamorphic diamonds. Bureau, H., Langenhorst, F., Auzende, A.-L., Frost, D.J., Estève, I., Siebert, J., (2012). Geochimica et Cosmochimica Acta, 77, 202-214. H. Bureau, D.J. Frost, N. Bolfan-Casanova, C. Leroy, I. Esteve, P. Cordier (2016) Lithos 265, 4-15. D.L. Pinti, A. Ishida, N. Takahata, Y. Sano, H. Bureau, P. Cartigny (2016) Geochemical Journal 50/4, E7-E12. DOI: 10.2343/geochemj.2.0427 Navon, O., Hutcheon, I.D., Rossman, G.R., Wasserburg, G.J., 1988. Nature 335, 784-789. Weiss, Y.; McNeill, J.; Pearson, D. Graham; et al. 2015 Nature 524 : 339-344.

Low temperature growth of diamond films on optical fibers using Linear Antenna CVD system

NASA Astrophysics Data System (ADS)

Ficek, M.; Drijkoningen, S.; Karczewski, J.; Bogdanowicz, R.; Haenen, K.

2016-01-01

It is not trivial to achieve a good quality diamond-coated fibre interface due to a large difference in the properties and composition of the diamond films (or use coating even) and the optical fibre material, i.e. fused silica. One of the biggest problems is the high temperature during the deposition which influences the optical fibre or optical fibre sensor structure (e.g. long-period gratings (LPG)). The greatest advantage of a linear antenna microwave plasma enhanced chemical vapor deposition system (LA MW CVD) is the fact that it allows to grow the diamond layers at low temperature (below 300°C) [1]. High quality nanocrystalline diamond (NCD) thin films with thicknesses ranging from 70 nm to 150 nm, were deposited on silicon, glass and optical fibre substrates [2]. Substrates pretreatment by dip-coating and spin coating process with a dispersion consisting of detonation nanodiamond (DND) in dimethyl sulfoxide (DMSO) with polyvinyl alcohol (PVA) has been applied. During the deposition process the continuous mode of operation of the LA MW CVD system was used, which produces a continuous wave at a maximum power of 1.9 kW (in each antenna). Diamond films on optical fibres were obtained at temperatures below 350°C, providing a clear improvement of results compared to our earlier work [3]. The samples were characterized by scanning electron microscopy (SEM) imaging to investigate the morphology of the nanocrystalline diamond films. The film growth rate, film thickness, and optical properties in the VIS-NIR range, i.e. refractive index and extinction coefficient will be discussed based on measurements on reference quartz plates by using spectroscopic ellipsometry (SE).

Electron-Beam Irradiation Effect on Thermal and Mechanical Properties of Nylon-6 Nanocomposite Fibers Infused with Diamond and Diamond Coated Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Imam, Muhammad A.; Jeelani, Shaik; Rangari, Vijaya K.; Gome, Michelle G.; Moura, Esperidiana. A. B.

2016-02-01

Nylon-6 is an engineering plastic with excellent properties and processability, which are essential in several industrial applications. The addition of filler such as diamond (DN) and diamond coated carbon nanotubes (CNTs) to form molded composites may increase the range of Nylon-6 applications due to the resulting increase in strength. The effects of electron-beam irradiation on these thermoplastic nanocomposites are either increase in the cross-linking or causes chain scission. In this study, DN-coated CNTs were synthesized using the sonochemical technique in the presence of cationic surfactant cetyltrimethyl ammonium bromide (CTAB). The DN-coated CNTs nanoparticles and diamond nanoparticles were then introduced into Nylon-6 polymer through a melt extrusion process to form nanocomposite fibers. They were further tested for their mechanical (Tensile) and thermal properties (thermogravimetric analysis (TGA), differential scanning calorimetry (DSC)). These composites were further exposed to the electron-beam (160kGy, 132kGy and 99kGy) irradiation using a 1.5MeV electron-beam accelerator, at room temperature, in the presence of air and tested for their thermal and mechanical properties. The best ultimate tensile strength was found to be 690MPa and 864MPa irradiated at 132 for DN/CNTs/Nylon-6 and Diamond/Nylon-6 nanocomposite fiber as compared to 346MPa and 321MPa for DN/CNTs/Nylon-6 and Diamond/Nylon-6 nanocomposite fiber without irradiation. The neat Nylon-6 tensile strength was 240MPa. These results are consistent with the activation energy calculated from TGA graphs. DSC analysis result shows that the slight increase in glass transition temperature (Tg) and decrease in melting temperature (Tm) which was expected from high electron-beam radiation dose.

Adhesive bonding and brazing of nanocrystalline diamond foil onto different substrate materials

NASA Astrophysics Data System (ADS)

Lodes, Matthias A.; Sailer, Stefan; Rosiwal, Stefan M.; Singer, Robert F.

2013-10-01

Diamond coatings are used in heavily stressed industrial applications to reduce friction and wear. Hot-filament chemical vapour deposition (HFCVD) is the favourable coating method, as it allows a coating of large surface areas with high homogeneity. Due to the high temperatures occurring in this CVD-process, the selection of substrate materials is limited. With the desire to coat light materials, steels and polymers a new approach has been developed. First, by using temperature-stable templates in the HFCVD and stripping off the diamond layer afterwards, a flexible, up to 150 μm thick and free standing nanocrystalline diamond foil (NCDF) can be produced. Afterwards, these NCDF can be applied on technical components through bonding and brazing, allowing any material as substrate. This two-step process offers the possibility to join a diamond layer on any desired surface. With a modified scratch test and Rockwell indentation testing the adhesion strength of NCDF on aluminium and steel is analysed. The results show that sufficient adhesion strength is reached both on steel and aluminium. The thermal stress in the substrates is very low and if failure occurs, cracks grow undercritically. Adhesion strength is even higher for the brazed samples, but here crack growth is critical, delaminating the diamond layer to some extent. In comparison to a sample directly coated with diamond, using a high-temperature CVD interlayer, the brazed as well as the adhesively bonded samples show very good performance, proving their competitiveness. A high support of the bonding layer could be identified as crucial, though in some cases a lower stiffness of the latter might be acceptable considering the possibility to completely avoid thermal stresses which occur during joining at higher temperatures.

The P-T conditions of garnet inclusion formation in diamond: thermal expansion of synthetic end-member pyrope

NASA Astrophysics Data System (ADS)

Milani, Sula; Mazzucchelli, Matteo; Nestola, Fabrizio; Alvaro, Matteo; Angel, Ross J.; Geiger, Charles A.; Domeneghetti, Chiara

2013-04-01

Pyrope, Mg3Al2Si3O12, due to the abundance of garnet in Earths's upper mantle, has been studied many times. A number of different investigations have measured its physical and thermodynamic properties at high temperature or pressure and, even more recently, under simultaneous high P-T conditions (e.g. Zou et al., 2012). This abstract reports thermal expansion results on pyrope, as part of a much wider project on the determination of the physical properties of garnet, in order to obtain geobarometric information on the formation conditions of its inclusion in diamond. Our experimental approach is based on the elastic method (e.g. Izraeli et al., 1999; Howell et al., 2010; Nestola et al., 2011; Howell et al., 2012), which takes into account the thermoelastic properties of both diamond and any tiny solid phase inclusion within it. The method requires accurate and precise knowledge of thermal expansion and compressibility behavior in order to calculate precisely the pressure and temperature formation conditions of the diamond-inclusion pair. Thus, in order to do this, we measured the thermal expansion of an end-member synthetic single crystal of pyrope up to 1100 K at 52 different temperatures. This was done by measuring the ao unit-cell edge with high precision and accuracy under heating and cooling conditions. This allows excellent experimental reproducibility, which is also checked by monitoring any diffraction peak broadening over the entire range of temperatures. Fitting the temperature-volume data to the thermal expansion equation of Berman (1988), we obtained a room temperature volume-thermal expansion coefficient equal to 2.72(2)×10-5K-1. Using the same pyrope crystal, in situ high-pressure measurements are now in progress in order to determine its isothermal bulk modulus. The use of our results, along with the dK/dT data of Zou et al ( 2012), we plan to calculate the pressure of formation of diamonds containing pyrope-rich garnet inclusions. References Berman, R.G. (1988) J. Petrol., 29, 445-522. Zou Y., Irifune T., Greaux S., Whitaker M.L., Ohfuji H., Shinmei T., Higo Y., Baosheng L. (2012) Abstract n° MR43C-2333, AGU FALL MEETING 2012. Howell, D., Wood, I.G., Dobson, D.P., Jones, A.P., Nasdala, L., Harris, J.W. (2010) Contrib. Mineral. Petrol., 160, 705-717. Howell, D., Wood, I.G., Nestola, F., Nimis, P., Nasdala, L. (2012) Eur. J. Mineral., ,. Izraeli, E.S., Harris, J.W., Navon, O. (1999) Earth Planet Sci. Lett., 173, 351-360. Nestola, F., Nimis, P., Ziberna, L., Longo, M., Marzoli, A., Harris, J.W., Manghnani, M.H., Fedortchouk, Y. (2011) Earth Plan. Sc. Lett., 305, 249-255.

Laboratory Investigations for the Role of Flushing Media in Diamond Drilling of Marble

NASA Astrophysics Data System (ADS)

Bhatnagar, A.; Khandelwal, Manoj; Rao, K. U. M.

2011-05-01

Marble is used as a natural stone for decorative purposes from ages. Marble is a crystalline rock, composed predominantly of calcite, dolomite or serpentine. The presence of impurities imparts decorative pattern and colors. The diamond-based operations are extensively used in the mining and processing of marble. Marble is mined out in the form of blocks of cuboids shape and has to undergo extensive processing to make it suitable for the end users. The processing operation includes slabbing, sizing, polishing, etc. Diamond drilling is also commonly used for the exploration of different mineral deposits throughout the world. In this paper an attempt has been made to enhance the performance of diamond drilling on marble rocks by adding polyethylene-oxide (PEO) in the flushing water. The effect of PEO added with the drilling water was studied by varying different machine parameters and flushing media concentration in the laboratory. The responses were rate of penetration and torque at bit-rock interface. Different physico-mechanical properties of marble were also determined. It was found that flushing water added with PEO can substantially enhance the penetration rates and reduce the torque developed at the bit-rock interface as compared to plain flushing water.

Pulsed Electrodeposition of Ni with Uniform Co-Deposition of Micron Sized Diamond Particles on Copper Substrate

NASA Astrophysics Data System (ADS)

Kumar, Prashant; Mahato, Neelima

Nanocrystalline nickel was deposited on annealed copper substrate of unit surface area (1 cm2) via pulsed electrodeposition technique using potentiostat (model 263A, Princeton Applied Research, USA) from Watts bath containing nickel sulfate, nickel chloride ,boric acid and sodium citrate. Diamond particles of three different dimensions, viz., 1, 3, and 6 micron were added separately (5 g/L) to the watts bath and co-deposited along with nanocrystalline nickel. The temperature was kept constant at 55 °C. The solution was ultrasonicated for 45-60 minutes prior to deposition to disperse the diamond particles uniformly in the bath. Depositions were carried out at different current densities, viz., 50, 100,150 and 200 mA/ cm2 for different durations, i.e.7, 14 and 21 minutes and best results are optimized for 200mA/cm2 so it is used for all process here .Scanning electron micrographs (SEM) show uniform deposition of microstructure of micron diamond on the surface of copper embedded in the nickel matrix. Elemental mapping confirmed uniform deposition of nickel and diamond with almost no cracks or pits. Mechanical properties of the sample such as, Vicker's hardness increased abruptly after the electrodeposition. Improved microstructural and mechanical properties were found in the case of electrodeposited surfaces containing followed by 3 and 6 micron diamond. The properties were also found better than those processed via stirring the solution during deposition.

Processing parameter optimization for the laser dressing of bronze-bonded diamond wheels

NASA Astrophysics Data System (ADS)

Deng, H.; Chen, G. Y.; Zhou, C.; Li, S. C.; Zhang, M. J.

2014-01-01

In this paper, a pulsed fiber-laser dressing method for bronze-bonded diamond wheels was studied systematically and comprehensively. The mechanisms for the laser dressing of bronze-bonded diamond wheels were theoretically analyzed, and the key processing parameters that determine the results of laser dressing, including the laser power density, pulse overlap ratio, ablation track line overlap ratio, and number of scanning cycles, were proposed for the first time. Further, the effects of these four key parameters on the oxidation-damaged layer of the material surface, the material removal efficiency, the material surface roughness, and the average protrusion height of the diamond grains were explored and summarized through pulsed laser ablation experiments. Under the current experimental conditions, the ideal values of the laser power density, pulse overlap ratio, ablation track line overlap ratio, and number of scanning cycles were determined to be 4.2 × 107 W/cm2, 30%, 30%, and 16, respectively. Pulsed laser dressing experiments were conducted on bronze-bonded diamond wheels using the optimized processing parameters; next, both the normal and tangential grinding forces produced by the dressed grinding wheel were measured while grinding alumina ceramic materials. The results revealed that the normal and tangential grinding forces produced by the laser-dressed grinding wheel during grinding were smaller than those of grinding wheels dressed using the conventional mechanical method, indicating that the pulsed laser dressing technology provides irreplaceable advantages relative to the conventional mechanical dressing method.

Quenchable compressed graphite synthesized from neutron-irradiated highly oriented pyrolytic graphite in high pressure treatment at 1500 °C

NASA Astrophysics Data System (ADS)

Niwase, Keisuke; Terasawa, Mititaka; Honda, Shin-ichi; Niibe, Masahito; Hisakuni, Tomohiko; Iwata, Tadao; Higo, Yuji; Hirai, Takeshi; Shinmei, Toru; Ohfuji, Hiroaki; Irifune, Tetsuo

2018-04-01

The super hard material of "compressed graphite" (CG) has been reported to be formed under compression of graphite at room temperature. However, it returns to graphite under decompression. Neutron-irradiated graphite, on the other hand, is a unique material for the synthesis of a new carbon phase, as reported by the formation of an amorphous diamond by shock compression. Here, we investigate the change of structure of highly oriented pyrolytic graphite (HOPG) irradiated with neutrons to a fluence of 1.4 × 1024 n/m2 under static pressure. The neutron-irradiated HOPG sample was compressed to 15 GPa at room temperature and then the temperature was increased up to 1500 °C. X-ray diffraction, high-resolution transmission electron microscopy on the recovered sample clearly showed the formation of a significant amount of quenchable-CG with ordinary graphite. Formation of hexagonal and cubic diamonds was also confirmed. The effect of irradiation-induced defects on the synthesis of quenchable-CG under high pressure and high temperature treatment was discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dumpala, Ravikumar; Nano Functional Materials Technology Centre, Department of Physics, Indian Institute of Technology Madras, Chennai 600036; Kumar, N.

Tribo-layer formation and frictional characteristics of the SiC ball were studied with the sliding test against nanocrystalline diamond coating under atmospheric test conditions. Unsteady friction coefficients in the range of 0.04 to 0.1 were observed during the tribo-test. Friction and wear characteristics were found to be influenced by the formation of cohesive tribo-layer (thickness ∼ 1.3 μm) in the wear track of nanocrystalline diamond coating. Hardness of the tribo-layer was measured using nanoindentation technique and low hardness of ∼ 1.2 GPa was observed. The presence of silicon and oxygen in the tribo-layer was noticed by the energy dispersive spectroscopy mappingmore » and the chemical states of the silicon were analyzed using X-ray photoelectron spectroscopy. Large amount of oxygen content in the tribo-layer indicated tribo-oxidation wear mechanism. - Highlights: • Sliding wear and friction characteristics of SiC were studied against NCD coating. • Silicon oxide tribo-layer formation was observed in the NCD coating wear track. • Low hardness 1.2 GPa of tribo-layer was measured using nanoindentation technique. • Chemical states of silicon were analyzed using X-ray photoelectron spectroscopy.« less

Nitrogen-doped diamond electrode shows high performance for electrochemical reduction of nitrobenzene.

PubMed

Zhang, Qing; Liu, Yanming; Chen, Shuo; Quan, Xie; Yu, Hongtao

2014-01-30

Effective electrode materials are critical to electrochemical reduction, which is a promising method to pre-treat anti-oxidative and bio-refractory wastewater. Herein, nitrogen-doped diamond (NDD) electrodes that possess superior electrocatalytic properties for reduction were fabricated by microwave-plasma-enhanced chemical vapor deposition technology. Nitrobenzene (NB) was chosen as the probe compound to investigate the material's electro-reduction activity. The effects of potential, electrolyte concentration and pH on NB reduction and aniline (AN) formation efficiencies were studied. NDD exhibited high electrocatalytic activity and selectivity for reduction of NB to AN. The NB removal efficiency and AN formation efficiency were 96.5% and 88.4% under optimal conditions, respectively; these values were 1.13 and 3.38 times higher than those of graphite electrodes. Coulombic efficiencies for NB removal and AN formation were 27.7% and 26.1%, respectively; these values were 4.70 and 16.6 times higher than those of graphite electrodes under identical conditions. LC-MS analysis revealed that the dominant reduction pathway on the NDD electrode was NB to phenylhydroxylamine (PHA) to AN. Copyright © 2013 Elsevier B.V. All rights reserved.

Modeling and analysis of the chip formation and transient cutting force during elliptical vibration cutting process

NASA Astrophysics Data System (ADS)

Lin, Jieqiong; Guan, Liang; Lu, Mingming; Han, Jinguo; Kan, Yudi

2017-12-01

In traditional diamond cutting, the cutting force is usually large and it will affect tool life and machining quality. Elliptical vibration cutting (EVC) as one of the ultra-precision machining technologies has a lot of advantages, such as reduces cutting force, extend tool life and so on. It's difficult to predict the transient cutting force of EVC due to its unique elliptical motion trajectory. Study on chip formation will helpfully to predict cutting force. The geometric feature of chip has important effects on cutting force, however, few scholars have studied the chip formation. In order to investigate the time-varying cutting force of EVC, the geometric feature model of chip is established based on analysis of chip formation, and the effects of cutting parameters on the geometric feature of chip are analyzed. To predict transient force quickly and effectively, the geometric feature of chip is introduced into the cutting force model. The calculated results show that the error between the predicted cutting force in this paper and that in the literature is less than 2%, which proves its feasibility.

Influence of non-adherent yeast cells on electrical characteristics of diamond-based field-effect transistors

NASA Astrophysics Data System (ADS)

Procházka, Václav; Cifra, Michal; Kulha, Pavel; Ižák, Tibor; Rezek, Bohuslav; Kromka, Alexander

2017-02-01

Diamond thin films provide unique features as substrates for cell cultures and as bio-electronic sensors. Here we employ solution-gated field effect transistors (SGFET) based on nanocrystalline diamond thin films with H-terminated surface which exhibits the sub-surface p-type conductive channel. We study an influence of yeast cells (Saccharomyces cerevisiae) on electrical characteristics of the diamond SGFETs. Two different cell culture solutions (sucrose and yeast peptone dextrose-YPD) are used, with and without the cells. We have found that transfer characteristics of the SGFETs exhibit a negative shift of the gate voltage by -26 mV and -42 mV for sucrose and YPD with cells in comparison to blank solutions without the cells. This effect is attributed to a local pH change in close vicinity of the H-terminated diamond surface due to metabolic processes of the yeast cells. The pH sensitivity of the diamond-based SGFETs, the role of cell and protein adhesion on the gate surface and the role of negative surface charge of yeast cells on the SGFETs electrical characteristics are discussed as well.

Fabrication of a nanometer thick nitrogen delta doped layer at the sub-surface region of (100) diamond

NASA Astrophysics Data System (ADS)

Chandran, Maneesh; Michaelson, Shaul; Saguy, Cecile; Hoffman, Alon

2016-11-01

In this letter, we report on the proof of a concept of an innovative delta doping technique to fabricate an ensemble of nitrogen vacancy centers at shallow depths in (100) diamond. A nitrogen delta doped layer with a concentration of ˜1.8 × 1020 cm-3 and a thickness of a few nanometers was produced using this method. Nitrogen delta doping was realized by producing a stable nitrogen terminated (N-terminated) diamond surface using the RF nitridation process and subsequently depositing a thin layer of diamond on the N-terminated diamond surface. The concentration of nitrogen on the N-terminated diamond surface and its stability upon exposure to chemical vapor deposition conditions are determined by x-ray photoelectron spectroscopy analysis. The SIMS profile exhibits a positive concentration gradient of 1.9 nm/decade and a negative gradient of 4.2 nm/decade. The proposed method offers a finer control on the thickness of the delta doped layer than the currently used ion implantation and delta doping techniques.

Iron-carbonate interaction at Earth's core-mantle boundary

NASA Astrophysics Data System (ADS)

Dorfman, S. M.; Badro, J.; Nabiei, F.; Prakapenka, V.; Gillet, P.

2015-12-01

Carbon storage and flux in the deep Earth are moderated by oxygen fugacity and interactions with iron-bearing phases. The amount of carbon stored in Earth's mantle versus the core depends on carbon-iron chemistry at the core-mantle boundary. Oxidized carbonates subducted from Earth's surface to the lowermost mantle may encounter reduced Fe0 metal from disproportionation of Fe2+ in lower mantle silicates or mixing with the core. To understand the fate of carbonates in the lowermost mantle, we have performed experiments on sandwiches of single-crystal (Ca0.6Mg0.4)CO3 dolomite and Fe foil in the laser-heated diamond anvil cell at lower mantle conditions of 49-110 GPa and 1800-2500 K. Syntheses were conducted with in situ synchrotron X-ray diffraction to identify phase assemblages. After quench to ambient conditions, samples were sectioned with a focused Ga+ ion beam for composition analysis with transmission electron microscopy. At the centers of the heated spots, iron melted and reacted completely with the carbonate to form magnesiowüstite, iron carbide, diamond, magnesium-rich carbonate and calcium carbonate. In samples heated at 49 and 64 GPa, the two carbonates exhibit a eutectoid texture. In the sample heated at 110 GPa, the carbonates form rounded ~150-nm-diameter grains with a higher modal proportion of interspersed diamonds. The presence of reduced iron in the deep lower mantle and core-mantle boundary region will promote the formation of diamonds in carbonate-bearing subducted slabs. The complete reaction of metallic iron to oxides and carbides in the presence of mantle carbonate supports the formation of these phases at the Earth's core-mantle boundary and in ultra-low velocity zones.

Chloride-bearing liquids and partial melting of mantle eclogites: experimental study and application to the diamond-forming processes.

NASA Astrophysics Data System (ADS)

Safonov, Oleg

2010-05-01

Recent studies prove that the partial melting in some eclogite xenoliths in kimberlites is closely related to formation of diamonds in these rocks at 4-6 GPa and 1150-12500C [e.g. 1, 2]. Along with specific mineral assemblages, the products of the eclogite partial melting commonly include relics of potassium-rich silicic melts (45-65 wt. % of SiO2, 4-14 wt. % of K2O and K2O/Na2O > 1.0) [1, 2]. Available experimental data, however, demonstrate that such melts can not be produced by 'dry' or hydrous melting of a common eclogite. It implies that partial melting and conjugate diamond formation in mantle eclogites was triggered by infiltration of potassic fluids/melts. Assemblages of Cl-bearing phases and carbonates in eclogite xenoliths [1], and eclogitic diamonds [3-6] suggest that these agents were chloride-carbonate-H2O melts or/and chloride-H2O-CO2 fluids. In order to characterize interaction of both types of liquids with eclogites and their minerals, experiments in the eclogite-related systems with participation of CaCO3-Na2CO3-KCl-H2O or H2O-CO2-KCl are reviewed. Melting relations in the system eclogite-CaCO3-Na2CO3-KCl-H2O follow the general scheme proposed earlier for chloride-carbonate-silicate systems [7]. Below 12000C, Grt, Cpx and phlogopite (Phl) coexist with LCC only. Formation of Phl and Ca-rich Grt after Cpx indicate active reactions of Cpx with LCC accompanied by CO2 degassing and depletion of the clinopyroxene in jadeite. Subsequent dissolution of silicates in LCC at >1200OC results in formation of potassic silica-undersaturated carbonate and Cl-bearing melt (LCS) (37-40 wt. % of SiO2, 10-12 wt. % of K2O, ~3.5 wt. % of Cl) immiscible with the LCC. Compositional feature of this melt is very comparable to those of low-Mg carbonate-silicate melt inclusions in diamonds [6]. However, it is not relevant to the melt relics preserved in the partially molten eclogite xenoliths. Melting of eclogites with participation of the H2O-CO2-KCl fluid at 5 GPa at 1200-13000C [8] produces CO2-depleted aluminosilicate melts with up to 46 wt. % of SiO2, 9-10 wt. % of K2O, 2-5 wt. % of Cl, whose SiO2 and K2O contents resemble the silica-poor varieties of melt relics in the eclogite xenoliths [1, 2]. Presence of KCl in the fluid intensifies melting, that is related both to high Cl content in the melt and its enrichment in K2O via K-Na exchange reactions with the immiscible chloride melt. The ratio K2O/Cl in the melts increases with the increase of the KCl content in the system and reaches 2.5-3.5 in the melts coexisting with immiscible chloride liquids. No additional crystalline phases, except Grt, Cpx, and Phl, were observed in the above experiments. However, experiments in the model system jadeite-diopside-KCl(±H2O) at 4-5 GPa shows, that KCl liquids provoke formation of ultrapotassic Cl-bearing silica-rich (i.e. 63-65 wt. % of SiO2) melt, which is able to produce sanidine and Al-celadonite-phlogopite mica, which are observed in partially molten eclogites [2]. Dissolution of pyrope in KCl-rich liquids results in formation of spinel and olivine, which are also common products of garnet breakdown within the zones of partial melting in eclogite xenoliths [1, 2]. Thus, the reviewed experiments imply that the KCl-bearing liquids could serve as triggers for formation of the wide varieties of K-rich aluminosilicate and carbonate-silicate melts during the eclogite melting in the mantle. Nevertheless, compositional variability of the produced melts, as well as formation of some crystalline phases (sanidine, mica, spinel, olivine) during this process could be a result of highly localized action of these liquids. The study is supported by the RFBR (10-05-00040), Russian President Grant (MD-130.2008.5) and Russian Science Support Foundation. References: [1] Misra et al. (2004) Contrib. Mineral. Petrol., V. 146, P. 696-714; [2] Shatsky et al. (2008) Lithos, 105, 289-300; [3] Izraeli et al. (2001) Earth Planet. Sci. Lett., 5807, 1-10; [3] Zedgenizov et al. (2007) Doklady Earth Sci., 415, 961-964; [5] Tomlinson et al. (2006), Earth Planet. Sci. Lett., 250, 581-585; [6] Weiss et al. (2009), Lithos, 112S, 660-674; [7] Safonov et al. (2009), Lithos, 112S, 260-273; [8] Butvina et al. (2009), Doklady Earth Sci., 427A, 956-960.

I12: the Joint Engineering, Environment and Processing (JEEP) beamline at Diamond Light Source.

PubMed

Drakopoulos, Michael; Connolley, Thomas; Reinhard, Christina; Atwood, Robert; Magdysyuk, Oxana; Vo, Nghia; Hart, Michael; Connor, Leigh; Humphreys, Bob; Howell, George; Davies, Steve; Hill, Tim; Wilkin, Guy; Pedersen, Ulrik; Foster, Andrew; De Maio, Nicoletta; Basham, Mark; Yuan, Fajin; Wanelik, Kaz

2015-05-01

I12 is the Joint Engineering, Environmental and Processing (JEEP) beamline, constructed during Phase II of the Diamond Light Source. I12 is located on a short (5 m) straight section of the Diamond storage ring and uses a 4.2 T superconducting wiggler to provide polychromatic and monochromatic X-rays in the energy range 50-150 keV. The beam energy enables good penetration through large or dense samples, combined with a large beam size (1 mrad horizontally × 0.3 mrad vertically). The beam characteristics permit the study of materials and processes inside environmental chambers without unacceptable attenuation of the beam and without the need to use sample sizes which are atypically small for the process under study. X-ray techniques available to users are radiography, tomography, energy-dispersive diffraction, monochromatic and white-beam two-dimensional diffraction/scattering and small-angle X-ray scattering. Since commencing operations in November 2009, I12 has established a broad user community in materials science and processing, chemical processing, biomedical engineering, civil engineering, environmental science, palaeontology and physics.

I12: the Joint Engineering, Environment and Processing (JEEP) beamline at Diamond Light Source

PubMed Central

Drakopoulos, Michael; Connolley, Thomas; Reinhard, Christina; Atwood, Robert; Magdysyuk, Oxana; Vo, Nghia; Hart, Michael; Connor, Leigh; Humphreys, Bob; Howell, George; Davies, Steve; Hill, Tim; Wilkin, Guy; Pedersen, Ulrik; Foster, Andrew; De Maio, Nicoletta; Basham, Mark; Yuan, Fajin; Wanelik, Kaz

2015-01-01

I12 is the Joint Engineering, Environmental and Processing (JEEP) beamline, constructed during Phase II of the Diamond Light Source. I12 is located on a short (5 m) straight section of the Diamond storage ring and uses a 4.2 T superconducting wiggler to provide polychromatic and monochromatic X-rays in the energy range 50–150 keV. The beam energy enables good penetration through large or dense samples, combined with a large beam size (1 mrad horizontally × 0.3 mrad vertically). The beam characteristics permit the study of materials and processes inside environmental chambers without unacceptable attenuation of the beam and without the need to use sample sizes which are atypically small for the process under study. X-ray techniques available to users are radiography, tomography, energy-dispersive diffraction, monochromatic and white-beam two-dimensional diffraction/scattering and small-angle X-ray scattering. Since commencing operations in November 2009, I12 has established a broad user community in materials science and processing, chemical processing, biomedical engineering, civil engineering, environmental science, palaeontology and physics. PMID:25931103

Lasers in Synthesis, Characterization and Processing of Diamond, International Center, Tashkent, Uzbekistan, 6-9 October 1997

DTIC Science & Technology

1997-01-01

Chemistry Division, Code 6174 Materiaux Leninsky prospekt, 53 Gas/Surface Dinamics Section et des Hautes Pressions Moscow 117924, Russia Washington, D.C...reactor for diamond CVD. Strengths and limitations of this and the various alternative H atom detection methods will be summarised, before

Evaluation of beam halo from beam-gas scattering at the KEK Accelerator Test Facility

NASA Astrophysics Data System (ADS)

Yang, R.; Naito, T.; Bai, S.; Aryshev, A.; Kubo, K.; Okugi, T.; Terunuma, N.; Zhou, D.; Faus-Golfe, A.; Kubytskyi, V.; Liu, S.; Wallon, S.; Bambade, P.

2018-05-01

In circular colliders, as well as in damping rings and synchrotron radiation light sources, beam halo is one of the critical issues limiting the performance as well as potentially causing component damage and activation. It is imperative to clearly understand the mechanisms that lead to halo formation and to test the available theoretical models. Elastic beam-gas scattering can drive particles to large oscillation amplitudes and be a potential source of beam halo. In this paper, numerical estimation and Monte Carlo simulations of this process at the ATF of KEK are presented. Experimental measurements of beam halo in the ATF2 beam line using a diamond sensor detector are also described, which clearly demonstrate the influence of the beam-gas scattering process on the transverse halo distribution.

Numerical and Theoretical Considerations for the Design of the AVT-183 Diamond-Wing Experimental Investigations

NASA Technical Reports Server (NTRS)

Boelens, Okko J.; Luckring, James M.; Breitsamter, Christian; Hovelmann, Andreas; Knoth, Florian; Malloy, Donald J.; Deck, Sebatien

2015-01-01

A diamond-wing configuration has been developed to isolate and study blunt-leading edge vortex separation with both computations and experiments. The wing has been designed so that the results are relevant to a more complex Uninhabited Combat Air Vehicle concept known as SACCON. The numerical and theoretical development process for this diamond wing is presented, including a view toward planned wind tunnel experiments. This work was conducted under the NATO Science and Technology Organization, Applied Vehicle Technology panel. All information is in the public domain.

Nanodiamonds: The ways forward

NASA Astrophysics Data System (ADS)

Tamburri, Emanuela; Orlanducci, Silvia; Reina, Giacomo; Lavecchia, Teresa; Angjellari, Mariglen; Rossi, Marco; Terranova, Maria Letizia

2015-06-01

We present here a short overview of the main classes of methods used to generate diamond nanostructures. The described methodologies, namely the CVD techniques, the explosive reactions, the laser-induced processes and the plasma treatments, offer the feasibility to produce nanosized diamonds in forms of powders or films, to modulate size, shape and structure of individual nanograins or of nanodiamond aggregates, to build complex architectures. A proper design and a subsequent controlled production of diamond structures at the nanoscale are strict requirements for the transition from fundamental material research to real-world applications.

Survival of carbon grains in shocks

NASA Technical Reports Server (NTRS)

Seab, C. Gregory

1990-01-01

Supernova shocks play a significant part in the life of an interstellar grain. In a typical 10 to the 9th power year lifetime, a grain will be hit by an average of 10 shocks of 100 km s(sup -1) or greater velocity, and even more shocks of lower velocity. Evaluation of the results of this frequent shock processing is complicated by a number of uncertainties, but seems to give about 10 percent destruction of silicate grains and about half that for graphite grains. Because of the frequency of shocking, the mineralogy and sizes of the grain population is predominately determined by shock processing effects, and not by the initial grain nucleation and growth environment. One consequence of the significant role played by interstellar shocks is that a certain fraction (up to 5 percent) of the carbon should be transformed into the diamond phase. Diamond transformation is observed in the laboratory at threshold shock pressures easily obtainable in grain-grain collisions in supernova shocks. Yields for transforming graphite, amorphous carbon, glassy carbon, and other nearly pure carbon solids into diamond are quite high. Impurities up to at least the 10 percent level (for oxygen) are tolerated in the process. The typical size diamond expected from shock transformation agrees well with the observed sizes in the Lewis et al. findings in meteoritic material. Isotropic anomalies already contained in the grain are likely to be retained through the conversion process, while others may be implanted by the shock if the grain is close to the supernova. The meteoritic diamonds are likely to be the results of transformation of carbon grains in grain-grain collisions in supernova shock waves.

Atomic structure and potential energy of β-Si3N4/diamond interface in the process of detachment: A first-principles study

NASA Astrophysics Data System (ADS)

Chen, Naichao; Chen, Yingchao; Ai, Jun; Li, Cheng; He, Ping; Ren, Jianxing; Zhu, Quanjun

2018-03-01

Peeling is regarded as a main technique barrier for the application of coating. Many factors affects the peeling of coating. Among them, the interfacial properties between coating and substrate plays a vital role. In this work, the β-Si3N4/diamond interface is conducted as the sample to study the changes in atomic structure and potential energy in the process of detachment by the first-principles calculations. The β-Si3N4/diamond (2 × 2) crystal unit is used as the calculated model. The detachment is simulated by moving up β-Si3N4 far from diamond by the 0.1 Å of each step. The results show that in the beginning of detachment, the bonds in the interface keep a constant length, rather than extension like spring. When the distance between β-Si3N4 and diamond reaches a certain distance, the interfacial bonds would suddenly break, and the elongated β-Si3N4 resumes its original statues indicating that the interface between two surfaces may exist a threshold value to control the peeling. When the external force is less than this threshold value, the peeling of coating would not occur. However, once the external force is greater than this one, the peeling would immediately present. The interface presents the brittle failure in the process of detachment, which is in good agreement with the experimental observation. Meanwhile, the different physical properties between van der Waals and quantum effects lead to the transient status in the process of detachment, where although the interfacial bonds are broken, the adhesive strength is still strong due to its low negative adsorption energy.

Electrochemical incineration of diclofenac in neutral aqueous medium by anodic oxidation using Pt and boron-doped diamond anodes.

PubMed

Brillas, Enric; Garcia-Segura, Sergi; Skoumal, Marcel; Arias, Conchita

2010-04-01

The degradation of diclofenac, a common non-steroidal anti-inflammatory drug, in aqueous medium has been studied by anodic oxidation (AO) using an undivided cell with a Pt or boron-doped diamond (BDD) anode. Operating without pH regulation, AO with Pt acidifies the solution with precipitation of its protonated form, whereas using BDD, the solution becomes alkaline and only attains partial mineralization. Total incineration of low contents of the drug is feasible by AO with BDD in a neutral buffer medium of pH 6.5. Comparative treatment with Pt gives poor decontamination. The diclofenac decay always follows a pseudo first-order reaction. The increase in current for AO with BDD accelerates the degradative process, but decreases its efficiency. 2-Hydroxyphenylacetic acid, 2,5-dihydroxyphenylacetic acid, 2,6-dichloroaniline and 2,6-dichlorohydroquinone have been identified as aromatic intermediates. For AO with Pt, high amounts of malic, succinic, tartaric and oxalic acids are accumulated in the bulk and the N-derivatives produced are rapidly destroyed with loss of NH4+. When BDD is employed, some carboxylic acids are also accumulated in small extent, with a larger persistence of oxalic and oxamic acids. The process involves the formation of different N-derivatives that slowly release NH4+ and NO3(-) ions. Chloride ion is lost in all cases. 2010 Elsevier Ltd. All rights reserved.

Electrochemical disinfection using boron-doped diamond electrode--the synergetic effects of in situ ozone and free chlorine generation.

PubMed

Rajab, Mohamad; Heim, Carolin; Letzel, Thomas; Drewes, Jörg E; Helmreich, Brigitte

2015-02-01

This work investigated the capability of using a boron-doped diamond (BDD) electrode for bacterial disinfection in different water matrices containing varying amounts of chloride. The feed water containing Pseudomonas aeruginosa was electrochemically treated while applying different electrode conditions. Depending on the applied current density and the exposure time, inactivation between 4- and 8-log of the targeted microorganisms could be achieved. The disinfection efficiency was driven by the generation of free chlorine as a function of chloride concentration in the water. A synergetic effect of generating both free chlorine and ozone in situ during the disinfection process resulted in an effective bactericidal impact. The formation of the undesired by-products chlorate and perchlorate depended on the water matrix, the applied current density and the desired target disinfection level. In case of synthetic water with a low chloride concentration (20 mg L(-1)) and an applied current density of 167 mA cm(-2), a 6-log inactivation of Pseudomonas aeruginosa could be achieved after 5 min of exposure. The overall energy consumption ranged between 0.3 and 0.6 kW h m(-3) depending on the applied current density and water chemistry. Electrochemical water disinfection represents a suitable and efficient process for producing pathogen-free water without the use of any chemicals. Copyright © 2014 Elsevier Ltd. All rights reserved.

Diamond grinding wheels production study with the use of the finite element method.

PubMed

Kundrák, J; Fedorovich, V; Markopoulos, A P; Pyzhov, I; Kryukova, N

2016-11-01

Research results on 3D modeling of the diamond grain and its bearing layer when sintering diamond grinding wheels are provided in this paper. The influence of the main characteristics of the wheel materials and the wheel production process, namely the quantity of metallic phase within diamond grain, coefficient of thermal expansion of the metallic phase, the modulus of elasticity of bond material and sintering temperature, on the internal stresses arising in grains is investigated. The results indicate that the stresses in the grains are higher in the areas around the metallic phase. Additionally, sintering temperature has the greatest impact on the stresses of the grain-metallic phase-bond system regardless of the type of the bond. Furthermore, by employing factorial design for the carried out finite element model, a mathematical model that reflects the impact of these factors on the deflected mode of the diamond grain-metallic phase-bond material system is obtained. The results of the analysis allow for the identification of optimal conditions for the efficient production of improved diamond grinding wheels. More specifically, the smallest stresses are observed when using the metal bond with modulus of elasticity 204 GPa, the quantity of metallic phase in diamond grain of not higher than 7% and coefficient of thermal expansion of 1.32 × 10 -5  1/K or lower. The results obtained from the proposed 3D model can lead to the increase in the diamond grains utilization and improve the overall efficiency of diamond grinding.

Investigation of the shape transferability of nanoscale multi-tip diamond tools in the diamond turning of nanostructures

NASA Astrophysics Data System (ADS)

Luo, Xichun; Tong, Zhen; Liang, Yingchun

2014-12-01

In this article, the shape transferability of using nanoscale multi-tip diamond tools in the diamond turning for scale-up manufacturing of nanostructures has been demonstrated. Atomistic multi-tip diamond tool models were built with different tool geometries in terms of the difference in the tip cross-sectional shape, tip angle, and the feature of tool tip configuration, to determine their effect on the applied forces and the machined nano-groove geometries. The quality of machined nanostructures was characterized by the thickness of the deformed layers and the dimensional accuracy achieved. Simulation results show that diamond turning using nanoscale multi-tip tools offers tremendous shape transferability in machining nanostructures. Both periodic and non-periodic nano-grooves with different cross-sectional shapes can be successfully fabricated using the multi-tip tools. A hypothesis of minimum designed ratio of tool tip distance to tip base width (L/Wf) of the nanoscale multi-tip diamond tool for the high precision machining of nanostructures was proposed based on the analytical study of the quality of the nanostructures fabricated using different types of the multi-tip tools. Nanometric cutting trials using nanoscale multi-tip diamond tools (different in L/Wf) fabricated by focused ion beam (FIB) were then conducted to verify the hypothesis. The investigations done in this work imply the potential of using the nanoscale multi-tip diamond tool for the deterministic fabrication of period and non-periodic nanostructures, which opens up the feasibility of using the process as a versatile manufacturing technique in nanotechnology.

Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings

PubMed Central

Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

2016-01-01

Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings. PMID:26924136

Development of a diamond waveguide sensor for sensitive protein analysis using IR quantum cascade lasers

NASA Astrophysics Data System (ADS)

Piron, P.; Vargas Catalan, E.; Haas, J.; Österlund, L.; Nikolajeff, F.; Andersson, P. O.; Bergström, J.; Mizaikoff, B.; Karlsson, M.

2018-02-01

Microfabricated diamond waveguides, between 5 and 20 μm thick, manufactured by chemical vapor deposition of diamond, followed by standard lithographic techniques and inductively coupled plasma etching of diamond, are used as bio-chemical sensors in the mid infrared domain: 5-11 μm. Infrared light, emitted from a broadly tunable quantum cascade laser with a wavelength resolution smaller than 20 nm, is coupled through the diamond waveguides for attenuated total reflection spectroscopy. The expected advantages of these waveguides are a high sensitivity due to the high number of internal reflections along the propagation direction, a high transmittance in the mid-IR domain, the bio-compatibility of diamond and the possibility of functionalizing the surface layer. The sensor will be used for analyzing different forms of proteins such as α-synuclein which is relevant in understanding the mechanism behind Parkinson's disease. The fabrication process of the waveguide, its characteristics and several geometries are introduced. The optical setup of the biosensor is described and our first measurements on two analytes to demonstrate the principle of the sensing method will be presented. Future use of this sensor includes the functionalization of the diamond waveguide sensor surface to be able to fish out alpha-synuclein from cerebrospinal fluid.

Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings.

PubMed

Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

2016-02-29

Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings.

Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings

NASA Astrophysics Data System (ADS)

Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

2016-02-01

Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings.

Surprising synthesis of nanodiamond from single-walled carbon nanotubes by the spark plasma sintering process

NASA Astrophysics Data System (ADS)

Mirzaei, Ali; Ham, Heon; Na, Han Gil; Kwon, Yong Jung; Kang, Sung Yong; Choi, Myung Sik; Bang, Jae Hoon; Park, No-Hyung; Kang, Inpil; Kim, Hyoun Woo

2016-10-01

Nanodiamond (ND) was successfully synthesized using single-walled carbon nanotubes (SWCNTs) as a pure solid carbon source by means of a spark plasma sintering process. Raman spectra and X-ray diffraction patterns revealed the generation of the cubic diamond phase by means of the SPS process. Lattice-resolved TEM images confirmed that diamond nanoparticles with a diameter of about ˜10 nm existed in the products. The NDs were generated mainly through the gas-phase nucleation of carbon atoms evaporated from the SWCNTs. [Figure not available: see fulltext.

UAS measurements of ice fog and diamond dust in the Arctic at the DOE ARM mobile facility of Oliktok Point, Alaska

NASA Astrophysics Data System (ADS)

Schmitt, C. G.; Stuefer, M.; Heymsfield, A.

2013-12-01

We report on our planned airborne studies of ice fog and diamond dust at the DOE Atmospheric Radiation Measurement (ARM) mobile facility at Oliktok Point, Alaska. Measurements are proposed with a newly developed small version of a Video-Ice Particle Sampler (VIPS) as well as ice crystal replicators; the instruments will be flown aboard a hexacopter type unmanned aerial system (UAS). The UAS will operate at favorable low wind situations within an altitude range of approximate 3000 feet from the surface. Ice fog and diamond dust have been observed up to 50% of all winter days at selected locations in the Arctic. Strong surface-based temperature inversions form during the Arctic winter months from November to May as an effect of the low solar energy received at the surface. The cold and very stable boundary layer inhibits vertical aerosol exchange processes with the free atmosphere, which leads to continuous formation and accumulation of atmospheric ice crystals. Vertical changes in particle numbers, type, and size distribution will provide a wealth of new information about the properties and variability of low level Arctic ice aerosol. Additional continuous ground based cloud particle measurements will allow evaluation of temporal changes of the ice crystals. A goal of the study is to evaluate regional anthropogenic and natural effects on ice fog microphysics. Oliktok Point is located along the typical short-range trajectories of industrial pollutants (~30 miles northwest of the Prudhoe Bay Oilfields). Differences in ice particle microphysics and nuclei characteristics will allow evaluation of regional anthropogenic effects.

Self-assembling hybrid diamond-biological quantum devices

NASA Astrophysics Data System (ADS)

Albrecht, A.; Koplovitz, G.; Retzker, A.; Jelezko, F.; Yochelis, S.; Porath, D.; Nevo, Y.; Shoseyov, O.; Paltiel, Y.; Plenio, M. B.

2014-09-01

The realization of scalable arrangements of nitrogen vacancy (NV) centers in diamond remains a key challenge on the way towards efficient quantum information processing, quantum simulation and quantum sensing applications. Although technologies based on implanting NV-centers in bulk diamond crystals or hybrid device approaches have been developed, they are limited by the achievable spatial resolution and by the intricate technological complexities involved in achieving scalability. We propose and demonstrate a novel approach for creating an arrangement of NV-centers, based on the self-assembling capabilities of biological systems and their beneficial nanometer spatial resolution. Here, a self-assembled protein structure serves as a structural scaffold for surface functionalized nanodiamonds, in this way allowing for the controlled creation of NV-structures on the nanoscale and providing a new avenue towards bridging the bio-nano interface. One-, two- as well as three-dimensional structures are within the scope of biological structural assembling techniques. We realized experimentally the formation of regular structures by interconnecting nanodiamonds using biological protein scaffolds. Based on the achievable NV-center distances of 11 nm, we evaluate the expected dipolar coupling interaction with neighboring NV-centers as well as the expected decoherence time. Moreover, by exploiting these couplings, we provide a detailed theoretical analysis on the viability of multiqubit quantum operations, suggest the possibility of individual addressing based on the random distribution of the NV intrinsic symmetry axes and address the challenges posed by decoherence and imperfect couplings. We then demonstrate in the last part that our scheme allows for the high-fidelity creation of entanglement, cluster states and quantum simulation applications.

Interlayer utilization (including metal borides) for subsequent deposition of NSD films via microwave plasma CVD on 316 and 440C stainless steels

NASA Astrophysics Data System (ADS)

Ballinger, Jared

Diamond thin films have promising applications in numerous fields due to the extreme properties of diamonds in conjunction with the surface enhancement of thin films. Biomedical applications are numerous including temporary implants and various dental and surgical instruments. The unique combination of properties offered by nanostructured diamond films that make it such an attractive surface coating include extreme hardness, low obtainable surface roughness, excellent thermal conductivity, and chemical inertness. Regrettably, numerous problems exist when attempting to coat stainless steel with diamond generating a readily delaminated film: outward diffusion of iron to the surface, inward diffusion of carbon limiting necessary surface carbon precursor, and the mismatch between the coefficients of thermal expansion yielding substantial residual stress. While some exotic methods have been attempted to overcome these hindrances, the most common approach is the use of an intermediate layer between the stainless steel substrate and the diamond thin film. In this research, both 316 stainless steel disks and 440C stainless steel ball bearings were tested with interlayers including discrete coatings and graded, diffusion-based surface enhancements. Titanium nitride and thermochemical diffusion boride interlayers were both examined for their effectiveness at allowing for the growth of continuous and adherent diamond films. Titanium nitride interlayers were deposited by cathodic arc vacuum deposition on 440C bearings. Lower temperature diamond processing resulted in improved surface coverage after cooling, but ultimately, both continuity and adhesion of the nanostructured diamond films were unacceptable. The ability to grow quality diamond films on TiN interlayers is in agreement with previous work on iron and low alloy steel substrates, and the similarly seen inadequate adhesion strength is partially a consequence of the lacking establishment of an interfacial carbide phase. Surface boriding was implemented using the novel method of microwave plasma CVD with a mixture of hydrogen and diborane gases. On 440C bearings, dual phase boride layers of Fe2B and FeB were formed which supported adhered nanostructured diamond films. Continuity of the films was not seamless with limited regions remaining uncoated potentially corresponding to delamination of the film as evidenced by the presence of tubular structures presumably composed of sp2 bonded carbon. Surface boriding of 316 stainless steel discs was conducted at various powers and pressures to achieve temperatures ranging from 550-800 °C. The substrate boriding temperature was found to substantially influence the resultant interlayer by altering the metal boride(s) present. The lowest temperatures produced an interlayer where CrB was the single detected phase, higher temperatures yielded the presence of only Fe2B, and a combination of the two phases resulted from an intermediate boriding temperature. Compared with the more common, commercialized boriding methods, this a profound result given the problems posed by the FeB phase in addition to other advantages offered by CVD processes and microwave generated plasmas in general. Indentation testing of the boride layers revealed excellent adhesion strength for all borided interlayers, and above all, no evidence of cracking was observed for a sole Fe2B phase. As with boriding of 440C bearings, subsequent diamond deposition was achieved on these interlayers with substantially improved adhesion strength relative to diamond coated TiN interlayers. Both XRD and Raman spectroscopy confirmed a nanostructured diamond film with interfacial chromium carbides responsible for enhanced adhesion strength. Interlayers consisting solely of Fe2B have displayed an ability to support fully continuous nanostructured diamond films, yet additional study is required for consistent reproduction. This is in good agreement with initial work on pack borided high alloy steels to promote diamond film surface modification. The future direction for continued research of nanostructured diamond coatings on microwave plasma CVD borided stainless steel should further investigate the adhesion of both borided interlayers and subsequent NSD films in addition to short, interrupted diamond depositions to study the interlayer/diamond film interface.

Conductive diamond electrochemical oxidation of caffeine-intensified biologically treated urban wastewater.

PubMed

Martín de Vidales, María J; Millán, María; Sáez, Cristina; Pérez, José F; Rodrigo, Manuel A; Cañizares, Pablo

2015-10-01

In this work, the usefulness of Conductive Diamond Electrochemical Oxidation (CDEO) to degrade caffeine in real urban wastewater matrixes was assessed. The oxidation of actual wastewater intensified with caffeine (from 1 to 100 mg L(-1)) was studied, paying particular attention to the influence of the initial load of caffeine and the differences observed during the treatment of caffeine in synthetic wastewater. The results showed that CDEO is a technology that is capable of efficiently degrading this compound even at very low concentrations and that it can even be completely depleted. Profiles of the ionic species of S (SO4(2-)), N (NH4(+), NO3(-)) and Cl (ClO(-), ClO3(-) and ClO4(-)) were monitored and explained for plausible oxidation mechanisms. It was observed that the efficiency achieved is higher in the treatment of real wastewater than in the oxidation of synthetic wastewater because of the contribution of electrogenerated oxidant species such as hypochlorite. The formation of chlorate and perchlorate during electrochemical processes was observed, and a combined strategy to prevent this important drawback was successfully tested based on the application of low current densities with the simultaneous dosing of hydrogen peroxide. Copyright © 2015 Elsevier Ltd. All rights reserved.

Theoretical model of dynamic spin polarization of nuclei coupled to paramagnetic point defects in diamond and silicon carbide

NASA Astrophysics Data System (ADS)

Ivády, Viktor; Szász, Krisztián; Falk, Abram L.; Klimov, Paul V.; Christle, David J.; Janzén, Erik; Abrikosov, Igor A.; Awschalom, David D.; Gali, Adam

2015-09-01

Dynamic nuclear spin polarization (DNP) mediated by paramagnetic point defects in semiconductors is a key resource for both initializing nuclear quantum memories and producing nuclear hyperpolarization. DNP is therefore an important process in the field of quantum-information processing, sensitivity-enhanced nuclear magnetic resonance, and nuclear-spin-based spintronics. DNP based on optical pumping of point defects has been demonstrated by using the electron spin of nitrogen-vacancy (NV) center in diamond, and more recently, by using divacancy and related defect spins in hexagonal silicon carbide (SiC). Here, we describe a general model for these optical DNP processes that allows the effects of many microscopic processes to be integrated. Applying this theory, we gain a deeper insight into dynamic nuclear spin polarization and the physics of diamond and SiC defects. Our results are in good agreement with experimental observations and provide a detailed and unified understanding. In particular, our findings show that the defect electron spin coherence times and excited state lifetimes are crucial factors in the entire DNP process.

Concepts for diamond exploration in "on/off craton" areas—British Columbia, Canada

NASA Astrophysics Data System (ADS)

Simandl, George J.

2004-09-01

The tectonic setting of British Columbia (BC) differs from classic diamond-bearing intracratonic regions such as the Northwest Territories and South Africa. Nevertheless, several diamond occurrences have been reported in BC. It is also known that parts of the province are underlain by Proterozoic and possibly Archean basement. Because the continents of today are composites of fragments of ancient continents, it is possible that some of the regions underlain by old crystalline basement in eastern British Columbia were associated with a deep crustal keel. The keel may have predated the break-up of the early Neoproterozoic supercontinent called Rodinia and was preserved possibly until the Triassic. Some of these old continental fragments may have been displaced relative to their position of origin and dissociated from their keel, or the keel may have since been destroyed. Such fragments represent favourable exploration grounds in terms of the "Diamondiferous Mantle Root" model (DMR model) if they were intersected by kimberlites or lamproites prior to displacement or destruction of their underlying deep keel. Therefore, extrapolation of fragments of the diamond-bearing Precambrian basement from the Northwest Territories or Alberta to BC provides a sufficient reason for initiating reconnaissance indicator mineral surveys. The "Eclogite Subduction Zone" model (ES model) predicts formation of diamonds at lower pressure (i.e., depth) than required by the DMR model in convergent tectonic settings. Although not proven, this model is supported by thermal modeling of cold subduction zones and recent discoveries of diamonds in areas characterized by convergent tectonic settings. If the ES model is correct, then the parts of BC with a geological history similar to today's "cold" subduction zones, such as Honshu (Japan), or to continental collision zones, such as Kokchetav massif (Kazakhstan) and the Dabie-Sulu Terrane (east central China), may be diamondiferous. The terranes where geological evidences suggest an ultrahigh pressure (UHP) metamorphic event followed by rapid tectonic exhumation (which could have prevented complete resorption of diamonds on their journey to the surface) are worth investigating. If UHP rocks were intercepted at depth by syn- or post-subduction diamond elevators, such as kimberlites, lamproites, lamprophyres, nephelinites or other alkali volcanic rocks of deep-seated origin, the diamond potential of the area would be even higher.

Investigation of diamond deposition by chemical vapor transport with hydrogen

NASA Astrophysics Data System (ADS)

Piekarczyk, Wladyslaw; Messier, Russell F.; Roy, Rustum; Engdahl, Chris

1990-12-01

The carbon-hydrogen chemical vapor transport system was examined in accordance with a four-stage transport model. A result of this examination is that graphite co-deposition could be avoided when diamond is deposited from gas solutions under-saturated with respect to diamond. Actual deposition experiments showed that this unusual requirement can be fulfilled but only for the condition that the transport distance between the carbon source and the substrate surface is short. In such a case diamond can be deposited equally from super-saturated as well as from under-saturated gas solutions. On the basis of thermodynamic considerations a possible explanation of this unusual phenomenon is given. It is shown that there is a possibility of deposition of diamond from both super-saturated as well as under-saturated gas solutions but only on the condition that they are in a non-equilibrium state generally called the activated state. A model of the diamond deposition process consisting of two steps is proposed. In the first step diamond and graphite are deposited simultaneously. The most important carbon deposition reaction is C2H2(g) + 2 H(g) C(diamond graphite) + CH(g). The amount of co-deposited graphite is not a direct function of the saturation state of the gas phase. In the second step graphite is etched according to the most probable reaction C(graphite) + 4 H(g) CH4(g). Atomic hydrogen in a super-equilibrium concentration is necessary not only to etch graphite but also to precipitate and graphite. 1.

Stress engineering of high-quality single crystal diamond by heteroepitaxial lateral overgrowth

DOE PAGES

Tang, Y. -H.; Golding, B.

2016-02-02

Here, we describe a method for lateral overgrowth of low-stress single crystal diamond by chemical vapor deposition (CVD). The process is initiated by deposition of a thin (550 nm) (001) diamond layer on Ir-buffered a-plane sapphire. The diamond is partially masked by periodic thermally evaporated Au stripes using photolithography. Lateral overgrowth of the Au occurs with extremely effective filtering of threading dislocations. Thermal stress resulting from mismatch of the low thermal expansion diamond and the sapphire substrate is largely accommodated by the ductile Au layer. The stress state of the diamond is investigated by Raman spectroscopy for two thicknesses: atmore » 10 μm where the film has just overgrown the Au mask and at 180 μm where the film thickness greatly exceeds the scale of the masking. For the 10-μm film, the Raman linewidth shows spatial oscillations with the period of the Au stripes with a factor of 2 to 3 reduction relative to the unmasked region. In a 180-μm thick diamond film, the overall surface stress was extremely low, 0.00 ± 0.16 GPa, obtained from the Raman shift averaged over the 7.5mm diameter of the crystal at its surface. We conclude that the metal mask protects the overgrown diamond layer from substrate-induced thermal stress and cracking. Lastly, it is also responsible for low internal stress by reducing dislocation density by several orders of magnitude.« less

Laser-Assisted Field Evaporation and Three-Dimensional Atom-by-Atom Mapping of Diamond Isotopic Homojunctions.

PubMed

Mukherjee, Samik; Watanabe, Hideyuki; Isheim, Dieter; Seidman, David N; Moutanabbir, Oussama

2016-02-10

It addition to its high evaporation field, diamond is also known for its limited photoabsorption, strong covalent bonding, and wide bandgap. These characteristics have been thought for long to also complicate the field evaporation of diamond and make its control hardly achievable on the atomistic-level. Herein, we demonstrate that the unique behavior of nanoscale diamond and its interaction with pulsed laser lead to a controlled field evaporation thus enabling three-dimensional atom-by-atom mapping of diamond (12)C/(13)C homojunctions. We also show that one key element in this process is to operate the pulsed laser at high energy without letting the dc bias increase out of bounds for diamond nanotip to withstand. Herein, the role of the dc bias in evaporation of diamond is essentially to generate free charge carriers within the nanotip via impact ionization. The mobile free charges screen the internal electric field, eventually creating a hole rich surface where the pulsed laser is effectively absorbed leading to an increase in the nanotip surface temperature. The effect of this temperature on the uncertainty in the time-of-flight of an ion, the diffusion of atoms on the surface of the nanotip, is also discussed. In addition to paving the way toward a precise manipulation of isotopes in diamond-based nanoscale and quantum structures, this result also elucidates some of the basic properties of dielectric nanostructures under high electric field.

Large-scale fabrication of micro-lens array by novel end-fly-cutting-servo diamond machining.

PubMed

Zhu, Zhiwei; To, Suet; Zhang, Shaojian

2015-08-10

Fast/slow tool servo (FTS/STS) diamond turning is a very promising technique for the generation of micro-lens array (MLA). However, it is still a challenge to process MLA in large scale due to certain inherent limitations of this technique. In the present study, a novel ultra-precision diamond cutting method, as the end-fly-cutting-servo (EFCS) system, is adopted and investigated for large-scale generation of MLA. After a detailed discussion of the characteristic advantages for processing MLA, the optimal toolpath generation strategy for the EFCS is developed with consideration of the geometry and installation pose of the diamond tool. A typical aspheric MLA over a large area is experimentally fabricated, and the resulting form accuracy, surface micro-topography and machining efficiency are critically investigated. The result indicates that the MLA with homogeneous quality over the whole area is obtained. Besides, high machining efficiency, extremely small volume of control points for the toolpath, and optimal usage of system dynamics of the machine tool during the whole cutting can be simultaneously achieved.

Capacitively coupled RF diamond-like-carbon reactor

DOEpatents

Devlin, David James; Coates, Don Mayo; Archuleta, Thomas Arthur; Barbero, Robert Steven

2000-01-01

A process of coating a non-conductive fiber with diamond-like carbon, including passing a non-conductive fiber between a pair of parallel metal grids within a reaction chamber, introducing a hydrocarbon gas into the reaction chamber, forming a plasma within the reaction chamber for a sufficient period of time whereby diamond-like carbon is formed upon the non-conductive fiber, is provided together with a reactor chamber for deposition of diamond-like carbon upon a non-conductive fiber, including a vacuum chamber, a cathode assembly including a pair of electrically isolated opposingly parallel metal grids spaced apart at a distance of less than about 1 centimeter, an anode, a means of introducing a hydrocarbon gas into said vacuum chamber, and a means of generating a plasma within said vacuum chamber.

Impact of the Diamond Light Source on research in Earth and environmental sciences: current work and future perspectives

PubMed Central

Burke, Ian T.; Mosselmans, J. Frederick W.; Shaw, Samuel; Peacock, Caroline L.; Benning, Liane G.; Coker, Victoria S.

2015-01-01

Diamond Light Source Ltd celebrated its 10th anniversary as a company in December 2012 and has now accepted user experiments for over 5 years. This paper describes the current facilities available at Diamond and future developments that enhance its capacities with respect to the Earth and environmental sciences. A review of relevant research conducted at Diamond thus far is provided. This highlights how synchrotron-based studies have brought about important advances in our understanding of the fundamental parameters controlling highly complex mineral–fluid–microbe interface reactions in the natural environment. This new knowledge not only enhances our understanding of global biogeochemical processes, but also provides the opportunity for interventions to be designed for environmental remediation and beneficial use. PMID:25624516

Fabrication of planarised conductively patterned diamond for bio-applications.

PubMed

Tong, Wei; Fox, Kate; Ganesan, Kumaravelu; Turnley, Ann M; Shimoni, Olga; Tran, Phong A; Lohrmann, Alexander; McFarlane, Thomas; Ahnood, Arman; Garrett, David J; Meffin, Hamish; O'Brien-Simpson, Neil M; Reynolds, Eric C; Prawer, Steven

2014-10-01

The development of smooth, featureless surfaces for biomedical microelectronics is a challenging feat. Other than the traditional electronic materials like silicon, few microelectronic circuits can be produced with conductive features without compromising the surface topography and/or biocompatibility. Diamond is fast becoming a highly sought after biomaterial for electrical stimulation, however, its inherent surface roughness introduced by the growth process limits its applications in electronic circuitry. In this study, we introduce a fabrication method for developing conductive features in an insulating diamond substrate whilst maintaining a planar topography. Using a combination of microwave plasma enhanced chemical vapour deposition, inductively coupled plasma reactive ion etching, secondary diamond growth and silicon wet-etching, we have produced a patterned substrate in which the surface roughness at the interface between the conducting and insulating diamond is approximately 3 nm. We also show that the patterned smooth topography is capable of neuronal cell adhesion and growth whilst restricting bacterial adhesion. Copyright © 2014 Elsevier B.V. All rights reserved.

Dedicated multichannel readout ASIC coupled with single crystal diamond for dosimeter application

NASA Astrophysics Data System (ADS)

Fabbri, A.; Falco, M. D.; De Notaristefani, F.; Galasso, M.; Marinelli, M.; Orsolini Cencelli, V.; Tortora, L.; Verona, C.; Verona Rinati, G.

2013-02-01

This paper reports on the tests of a low-noise, multi-channel readout integrated circuit used as a readout electronic front-end for a diamond multi-pixel dosimeter. The system is developed for dose distribution measurement in radiotherapy applications. The first 10-channel prototype chip was designed and fabricated in a 0.18 um CMOS process. Every channel includes a charge integrator with a 10 pF capacitor and a double slope A/D converter. The diamond multi-pixel detector, based on CVD synthetic single crystal diamond Schottky diodes, is made by a 3 × 3 sensor matrix. The overall device has been tested under irradiation with 6 MeV radio therapeutic photon beams at the Policlinico ``Tor Vergata'' (PTV) hospital. Measurements show a 20 fA RMS leakage current from the front-end input stage and a negligible dark current from the diamond detector, a stable temporal response and a good linear behaviour as a function of both dose and dose rate. These characteristics were common to each tested channel.

Surface Modification of Boron-Doped Diamond with Microcrystalline Copper Phthalocyanine: Oxygen Reduction Catalysis

PubMed Central

Gan, Patrick; Foord, John S; Compton, Richard G

2015-01-01

Surface modification of boron-doped diamond (BDD) with copper phthalocyanine was achieved using a simple and convenient dropcast deposition, giving rise to a microcrystalline structure. Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution. A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD. Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide. The lack of a further conversion of the peroxide was attributed to its rapid diffusion away from the triple phase boundary at which the reaction is expected to exclusively occur. PMID:26491640

Surface structure of micro-diamond from ultrahigh-pressure felsic granulite, Bohemian Massif: AFM study of growth and resorption phenomena

NASA Astrophysics Data System (ADS)

Kotková, J.; Klapetek, P.

2012-04-01

Morphology, associated phases and retrogression phenomena of in-situ microdiamonds formed at extreme pressures in ultrahigh-pressure metamorphic terranes represent excellent tools to study character of diamond-forming media at great depths. Well-preserved microdiamonds discovered recently along with coesite in ultrahigh-pressure granulites of the north Bohemian crystalline basement, European Variscan belt (Kotková et al., 2011), provide unique material for such investigations. The diamonds are enclosed in major granulite phases, i.e. garnet both in felsic and intermediate lithologies and in kyanite in the felsic sample, as well as in zircon. Transmitted and reflected light microscopy of the felsic granulite sample, with peak mineral assemblage garnet, kyanite, feldspar and quartz, revealed presence of numerous, 5-20 μm-sized, perfectly preserved diamond crystals enclosed in kyanite grains. In contrast, diamonds within garnet are rare, can reach up to 30 μm in size, and graphite rims as well as polycrystalline graphite aggregates possibly representing complete diamond retrogression are common. We applied atomic force microscopy to study in-situ crystal morphology and surface microtopographic features, representing clues to the conditions and mechanisms of crystal formation as well as diamond resorption and retrogression. Both diamond enclosed in garnet and in kyanite of the felsic granulite occur exclusively as single crystals. The crystals have octahedral crystal shapes with straight but rounded edges and rounded corners. Concentric triangular terraces delimiting a flat triangular table on crystal scale and small micron-sized negatively oriented downward-pointing trigons developed on the octahedron crystal faces. Higher magnification reveals presence of discontinuous elongate hillocks oriented parallel to the octahedron face edge with positively oriented trigons. We suggest that the large-scale triangular terraces represent growth features. In contrast, the rounding of crystal edges and corners and development of negative trigons reflect diamond resorption. According to experimental works, such features are attributed to high temperature resorption, i.e. oxidation above ~ 950°C due to interaction with CO2 and/or H2O-bearing fluids (or fluid-bearing melts). Our results are consistent with presence of supercritical C-O-H fluid in the rocks in subduction zones documented from other ultrahigh-pressure metamorphic terranes, the resorption morphology corresponding rather to the interaction with water-rich than CO2-rich fluids. Kotková J., ÓBrien P., Ziemann M. (2011): Diamond and coesite discovered in Saxony-type granulite: Solution to the Variscan garnet peridotite enigma. Geology, 39, 7, 667-670.

Ultrabasic-basic change over primary inclusions in lower-mantle diamonds: Mineralogical and experimental evidence for crucial role of stishovite paradox

NASA Astrophysics Data System (ADS)

Litvin, Yuriy; Spivak, Anna

2017-04-01

Melting relations of the lower-mantle magmatic system MgO - FeO - CaO - SiO2 are characterized by peritectic reaction of bridgmanite (Mg,Fe)SiO3 and melt with formation of Fe-rich phases of periclase-wustite solid solutions (MgO•FeO)ss and stishovite SiO2. The reaction proceeds also in melts-solutions of lower-mantle diamond-parental system MgO - FeO - CaO - SiO2 - (Mg-Fe-Ca-Na-carbonate) - C. Xenoliths of lower mantle rocks were never found among the deep mantle derived materials. Estimation of lower-mantle mineralogy as ferropericlase+ bridgmanite+ Ca-perovskite association is inferred from high-pressure subsolidus experiments with ultrabasic pyrolite composition (Akaogi, 2007). The paradoxical in situ paragenesis of stishovite and ferropericlase as primary inclusions in lower-mantle diamonds (Kaminsky, 2012) takes its explanation from the bridgmanite peritectic reaction (effect of "stishovite paradox") (Litvin et al., 2014). Based on the data for inclusions, physico-chemical study on syngenesis of diamonds and primary inclusions has experimentally revealed the ferropericlase-bridgmanite-Ca-perovskite-stishovite-magnesiowustite-(Mg-Fe-Ca-Na-carbonate)-carbon compositions of the lower-mantle diamond-forming system .(Litvin et al., 2016). The generalized diagram of diamong-forming media characterizes the variable compositions of growths melts for diamonds and paragenetic phases and their genetic relationships with lower mantle matter, and it is the reason for genetic classifying primary inclusions. Fractional ultrabasic-basic evolution and continuous paragenetic transition from ultrabasic bridgmanite-ferropericlase to basic stishovite-magnesiowustite assemblages in the of lower-mantle diamond-parental melts-solutions are providing by the physico-chemical mechanism of stishovite paradox. References Akaogi M. (2007). Phase transformations of minerals in the transition zone and upper part of the lower mantle. In Advances in High-Pressure Mineralogy (Ohtani E., ed.). Geol. Soc. Am. Spec. Paper 421, 1-13. Kaminsky F.V. (2012). Mineralogy of the lower mantle: a review of "supper-deep" mineral inclusions in diamonds. Earth Sci. Rev. 110, 127-147. Litvin Yu.A., Spivak A.V., Solopova N.A., Dubrovinsky L.S. (2014). On origin of lower-mantle diamonds and their primary inclusions. Phys. Earth Planet. Inter. 228, 176-185. Litvin Yu.A., Spivak A.V., Dubrovinsky L.S. (2016). Magmatic evolution of the material of the Earth's lower mantle: stishovite paradox and origin of superdeep diamonds (experiments at 24-26 GPa). Geochemistry Internat. 54(11, 936-947.)

Controlled surface chemistry of diamond/β-SiC composite films for preferential protein adsorption.

PubMed

Wang, Tao; Handschuh-Wang, Stephan; Yang, Yang; Zhuang, Hao; Schlemper, Christoph; Wesner, Daniel; Schönherr, Holger; Zhang, Wenjun; Jiang, Xin

2014-02-04

Diamond and SiC both process extraordinary biocompatible, electronic, and chemical properties. A combination of diamond and SiC may lead to highly stable materials, e.g., for implants or biosensors with excellent sensing properties. Here we report on the controllable surface chemistry of diamond/β-SiC composite films and its effect on protein adsorption. For systematic and high-throughput investigations, novel diamond/β-SiC composite films with gradient composition have been synthesized using the hot filament chemical vapor deposition (HFCVD) technique. As revealed by scanning electron microscopy (SEM), the diamond/β-SiC ratio of the composite films shows a continuous change from pure diamond to β-SiC over a length of ∼ 10 mm on the surface. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) was employed to unveil the surface termination of chemically oxidized and hydrogen treated surfaces. The surface chemistry of the composite films was found to depend on diamond/β-SiC ratio and the surface treatment. As observed by confocal fluorescence microscopy, albumin and fibrinogen were preferentially adsorbed from buffer: after surface oxidation, the proteins preferred to adsorb on diamond rather than on β-SiC, resulting in an increasing amount of proteins adsorbed to the gradient surfaces with increasing diamond/β-SiC ratio. By contrast, for hydrogen-treated surfaces, the proteins preferentially adsorbed on β-SiC, leading to a decreasing amount of albumin adsorbed on the gradient surfaces with increasing diamond/β-SiC ratio. The mechanism of preferential protein adsorption is discussed by considering the hydrogen bonding of the water self-association network to OH-terminated surfaces and the change of the polar surface energy component, which was determined according to the van Oss method. These results suggest that the diamond/β-SiC gradient film can be a promising material for biomedical applications which require good biocompatibility and selective adsorption of proteins and cells to direct cell migration.

Bright nanowire single photon source based on SiV centers in diamond

DOE PAGES

Marseglia, L.; Saha, K.; Ajoy, A.; ...

2018-01-01

The practical implementation of quantum technologies such as quantum commu- nication and quantum cryptography relies on the development of indistinguishable, robust, and bright single photon sources that works at room temperature. The silicon- vacancy (SiV -) center in diamond has emerged as a possible candidate for a single photon source with all these characteristics. Unfortunately, due to the high refraction index mismatch between diamond and air, color centers in diamond show low photon out-coupling. This drawback can be overcome by fabrication of photonic structures that improve the in-coupling of excitation laser to the diamond defect as well as the out-couplingmore » emission from the color centers. An additional shortcoming is due to the random localization of native defects in the diamond sample. Here we demonstrate deterministic implantation of Si ions with high conversion effciency to single SiV -, targeted to fabricated nanowires. The co-localization of single SiV - defects with the nanostructures yields a ten times higher light coupling effciency as compared to single SiV - in the bulk. This result, with its intrinsic scalability, enables a new class of devices for integrated photonics and quantum information processing.« less

Deformation of a laser beam in the fabrication of graphite microstructures inside a volume of diamond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kononenko, T V; Zavedeev, E V

2016-03-31

We report a theoretical and experimental study of the energy profile deformation along the laser beam axis during the fabrication of graphite microstructures inside a diamond crystal. The numerical simulation shows that the use of a focusing lens with a numerical aperture NA < 0.1 at a focusing depth of up to 2 mm makes it possible to avoid a noticeable change in the energy profile of the beam due to the spherical aberration that occurs in the case of refraction of the focused laser beam at the air – diamond interface. The calculation results are confirmed by experimental datamore » on the distribution of the laser intensity along the beam axis in front of its focal plane, derived from observations of graphitisation wave propagation in diamond. The effect of radiation self-focusing on laser-induced graphitisation of diamond is analysed. It is shown that if the wavefront distortion due to self-focusing can be neglected at a minimum pulse energy required for the optical breakdown of diamond, then an increase in the beam distortion with increasing pulse energy has no effect on the graphitisation process. (interaction of laser radiation with matter)« less

Scanning Tunneling Microscopy Studies of Diamond Films and Optoelectronic Materials

NASA Technical Reports Server (NTRS)

Perez, Jose M.

1996-01-01

We present a summary of the research, citations of publications resulting from the research and abstracts of such publications. We have made no inventions in the performance of the work in this project. The main goals of the project were to set up a Chemical Vapor Deposition (CVD) diamond growth system attached to an UltraHigh Vacuum (UHV) atomic resolution Scanning Tunneling Microscopy (STM) system and carry out experiments aimed at studying the properties and growth of diamond films using atomic resolution UHV STM. We successfully achieved these goals. We observed, for the first time, the atomic structure of the surface of CVD grown epitaxial diamond (100) films using UHV STM. We studied the effects of atomic hydrogen on the CVD diamond growth process. We studied the electronic properties of the diamond (100) (2x1) surface, and the effect of alkali metal adsorbates such as Cs on the work function of this surface using UHV STM spectroscopy techniques. We also studied, using STM, new electronic materials such as carbon nanotubes and gold nanostructures. This work resulted in four publications in refereed scientific journals and five publications in refereed conference proceedings.

Diamond nanoparticles as a support for Pt and PtRu catalysts for direct methanol fuel cells.

PubMed

La-Torre-Riveros, Lyda; Guzman-Blas, Rolando; Méndez-Torres, Adrián E; Prelas, Mark; Tryk, Donald A; Cabrera, Carlos R

2012-02-01

Diamond in nanoparticle form is a promising material that can be used as a robust and chemically stable catalyst support in fuel cells. It has been studied and characterized physically and electrochemically, in its thin film and powder forms, as reported in the literature. In the present work, the electrochemical properties of undoped and boron-doped diamond nanoparticle electrodes, fabricated using the ink-paste method, were investigated. Methanol oxidation experiments were carried out in both half-cell and full fuel cell modes. Platinum and ruthenium nanoparticles were chemically deposited on undoped and boron doped diamond nanoparticles through the use of NaBH(4) as reducing agent and sodium dodecyl benzene sulfonate (SDBS) as a surfactant. Before and after the reduction process, samples were characterized by electron microscopy and spectroscopic techniques. The ink-paste method was also used to prepare the membrane electrode assembly with Pt and Pt-Ru modified undoped and boron-doped diamond nanoparticle catalytic systems, to perform the electrochemical experiments in a direct methanol fuel cell system. The results obtained demonstrate that diamond supported catalyst nanomaterials are promising for methanol fuel cells.

Diamond exploration and regional prospectivity of Western Australia

NASA Astrophysics Data System (ADS)

Hutchison, Mark T.

2018-06-01

Pre-1.6 Ga rocks comprise around 45% of the onshore area of Western Australia (WA), constituting the West Australian Craton (WAC) (including the Archean Yilgarn and Pilbara Cratons) and the western part of the North Australian Craton (NAC). These areas provide the conditions suitable for diamond formation at depth, and numerous diamondiferous lamproite and kimberlite fields are known. As emplacement ages span close to 2500 Ma, there are significant opportunities for diamond-affinity rocks being present near-surface in much of the State, including amongst Phanerozoic rocks. WA's size, terrain, infrastructure and climate, mean that many areas remain underexplored. However, continuous diamond exploration since the 1970s has resulted in abundant data. In order to advance future exploration, a comprehensive database of results of diamond exploration sampling (Geological Survey of Western Australia 2018) has been assessed. The Yilgarn and Pilbara Cratons have spinel indicators almost exclusively dominated by chromite (>90% of grains), whereas (Mg,Fe,Ti)-bearing Al-chromites account for more of the indicator spinels in the NAC, up to 50% of grains at the Northern Territory (NT) border. Increasing dominance of Al in chromites is interpreted as a sign of weathering or a shallower source than Al-depleted Mg-chromites. Garnet compositions across the State also correlate with geological subdivisions, with lherzolitic garnets showing more prospective compositions (Ca-depleted) in WAC samples compared to the NAC. WAC samples also show a much broader scatter into strongly diamond-prospective G10 and G10D compositions. Ilmenites from the NAC show Mg-enriched compositions (consistent with kimberlites), over and above those present in NT data. However, ilmenites from the WAC again show the most diamond-prospective trends. Numerous indicator mineral concentrations throughout the State have unknown sources. Due in part to the presence of diamondiferous lamproites, it is cautioned that some accepted indicator mineral criteria do not apply in parts of WA. For example Ca-depleted garnets, Mg-depleted ilmenites and Cr-depleted and Al-absent clinopyroxenes are all sometimes associated with strongly diamondiferous localities. Quantitative prospectivity analysis has also been carried out based on the extent and results of sampling, age of surface rocks relative to ages of diamond-prospective rocks, and the underlying mantle structure. Results show that locations within the NAC and with proximity to WA's diamond mines score well. However, results point to parts of the WAC being more prospective, consistent with mineral chemical data. Most notable are the Hamersley Basin, Eastern Goldfields Superterrane and the Goodin Inlier of the Yilgarn Craton. Despite prolific diamond exploration, WA is considerably underexplored and the ageing Argyle mine and recent closure of operations at Ellendale warrant a re-evaluation of diamond potential. Results of mineral chemistry and prospectivity analysis make a compelling case for renewed exploration.

Optimization of chemical vapor deposition diamond films growth on steel: correlation between mechanical properties, structure, and composition.

PubMed

Laikhtman, A; Rapoport, L; Perfilyev, V; Moshkovich, A; Akhvlediani, R; Hoffman, A

2011-09-01

In the present work we perform optimization of mechanical and crystalline properties of CVD microcrystalline diamond films grown on steel substrates. A chromium-nitride (Cr-N) interlayer had been previously proposed to serve as a buffer for carbon and iron inter-diffusion and as a matching layer for the widely differing expansion coefficients of diamond and steel. However, adhesion and wear as well as crystalline perfection of diamond films are strongly affected by conditions of both Cr-N interlayer preparation and CVD diamond deposition. In this work we assess the effects of two parameters. The first one is the temperature of the Cr-N interlayer preparation: temperatures in the range of 500 degrees C-800 degrees C were used. The second one is diamond film thickness in the 0.5 microm-2 microm range monitored through variation of the deposition time from approximately 30 min to 2 hours. The mechanical properties of so deposited diamond films were investigated. For this purpose, scratch tests were performed at different indentation loads. The friction coefficient and wear loss were assessed. The mechanical and tribological properties were related to structure, composition, and crystalline perfection of diamond films which were extensively analyzed using different microscopic and spectroscopic techniques. It was found that relatively thick diamond film deposited on the Cr-N interlayer prepared at the temperature similar to that of the CVD process has the best mechanical and adhesion strength. This film was stable without visible cracks around the wear track during all scratch tests with different indentation loads. In other cases, cracking and delamination of the films took place at low to moderate indentation loads.

Polymer Treatment by Plasma Immersion Ion Implantation of Nitrogen for Formation of Diamond-Like Carbon Film

NASA Astrophysics Data System (ADS)

Tan, Ing Hwie; Ueda, Mario; Kostov, Konstantin; Nascente, Pedro Augusto P.; Demarquette, Nicole Raymonde

2004-09-01

Nitrogen ions were implanted by plasma immersion in Kapton, Mylar and polypropylene, with the objective of forming a diamond-like carbon layer on these polymers. The Raman spectrum of the implanted polypropylene showed typical Diamond-Like Carbon (DLC) graphite (G) and disorder (D) peaks, with an sp3/sp2 hybridization ratio of approximately 0.4 to 0.6. The XPS analysis of the three implanted polymers also showed peaks of C-C and N-C bonds in the sp3 configuration, with hybridization ratios in the same range as the Raman result. The implanted polymers were exposed to oxygen plasma to test the resistance of the polymers to oxygen degradation. Mass loss rate results, however, showed that the DLC layer formed is not sufficiently robust for this application. Nevertheless, the layer formed can be suitable for other applications such as in gas barriers in beverage containers. Further study of implantation conditions may improve the quality of the DLC layer.

Enhanced field electron emission from aligned diamond-like carbon nanorod arrays prepared by reactive ion beam etching

NASA Astrophysics Data System (ADS)

Zhao, Yong; Qin, Shi-Qiao; Zhang, Xue-Ao; Chang, Sheng-Li; Li, Hui-Hui; Yuan, Ji-Ren

2016-05-01

Homogeneous diamond-like carbon (DLC) films were deposited on Si supports by a pulsed filtered cathodic vacuum arc deposition system. Using DLC films masked by Ni nanoparticles as precursors, highly aligned diamond-like carbon nanorod (DLCNR) arrays were fabricated by the etching of inductively coupled radio frequency oxygen plasma. The as-prepared DLCNR arrays exhibit excellent field emission properties with a low turn-on field of 2.005 V μm-1 and a threshold field of 4.312 V μm-1, respectively. Raman spectroscopy and x-ray photoelectron spectroscopy were employed to determine the chemical bonding structural change of DLC films before and after etching. It is confirmed that DLC films have good connection with Si supports via the formation of the SiC phase, and larger conductive sp2 domains are formed in the as-etched DLC films, which play essential roles in the enhanced field emission properties for DLCNR arrays.

OPTIMIZATION OF DEEP DRILLING PERFORMANCE--DEVELOPMENT AND BENCHMARK TESTING OF ADVANCED DIAMOND PRODUCT DRILL BITS & HP/HT FLUIDS TO SIGNIFICANTLY IMPROVE RATES OF PENETRATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alan Black; Arnis Judzis

2004-10-01

The industry cost shared program aims to benchmark drilling rates of penetration in selected simulated deep formations and to significantly improve ROP through a team development of aggressive diamond product drill bit--fluid system technologies. Overall the objectives are as follows: Phase 1--Benchmark ''best in class'' diamond and other product drilling bits and fluids and develop concepts for a next level of deep drilling performance; Phase 2--Develop advanced smart bit-fluid prototypes and test at large scale; and Phase 3--Field trial smart bit-fluid concepts, modify as necessary and commercialize products. As of report date, TerraTek has concluded all major preparations for themore » high pressure drilling campaign. Baker Hughes encountered difficulties in providing additional pumping capacity before TerraTek's scheduled relocation to another facility, thus the program was delayed further to accommodate the full testing program.« less

Diamond deposition in a hot-filament reactor using different hydrocarbon precursor gases

NASA Astrophysics Data System (ADS)

May, P. W.; Everitt, N. M.; Trevor, C. G.; Ashfold, M. N. R.; Rosser, K. N.

1993-07-01

A hot-filament reactor was used to deposit polycrystalline diamond films upon single-crystal Si substrates using hydrocarbon/H 2 gas mixtures. We studied the effect upon the deposition process and resulting film properties by varying the hydrocarbon gas from C 1H x to C 4H x alkanes. This was done maintaining a constant carbon-to-hydrogen ratio, but using a substantially lower-than- normal filament temperature (1500°C) in order to highlight differences in activation barriers and in the chemistry of the diamond-forming step. It was found that with increasing hydrocarbon chain length the deposition rate decreased, from a value of about 0.4 μm h -1 for methane/H 2 mixtures to less than 0.07 μm h -1 for butane/H 2. This was accompanied by an increase in the relative proportion of amorphous carbon to diamond present in the films. After one hour deposition the diamond grain size remained constant at about 20 nm, irrespective of the precursor gas. The measured Knoop hardness of the films also decreased when using process gases other than methane. We also studied the effect of changing the bond order in C 2H x precursor gases (ethane, ethene, ethyne) but found that this had no effect on either the deposition rate or the film quality.

Laser spectroscopy of highly doped NV- centers in diamond

NASA Astrophysics Data System (ADS)

Subedi, Shova D.; Fedorov, Vladimir V.; Peppers, Jeremy; Martyshkin, Dmitry V.; Mirov, Sergey B.; Shao, Linbo; Loncar, Marko

2018-02-01

In this paper, prospects of using diamond with NV- centers as a gain medium have been studied. Spectroscopic characterization of NV- centers in diamond as well as absorption saturation and pump-probe experiments have been carried out. Absorption and emission cross-sections were estimated to be 2.8 × 10-17 cm2 and 4.3 × 10-17 cm2 at the maximum of absorption and emission bands, respectively. It was observed from emission spectra under pulse excitation that some NV- are photoionized to NV0 centers with ZPL at 575 nm. Room temperature luminescence lifetime of NV- centers was measured to be 12ns, which is close to the previously reported lifetime in bulk diamond ( 13ns). Saturated transmission was only about 11% of calculated values even at energy fluence much higher than the saturation flux. Two excited state absorptions (ESAs) with different relaxation times ("fast-decay" and "slow-decay with relaxation times of 500 ns and several tens of microseconds, respectively) were revealed in transmission decay kinetics at 632 nm. Kinetics of transmission at 670 nm was dominated by "slow-decay" ESA process. Kinetics of dk/k0 in shorter wavelength were strongly dominated by "fast-decay" ESA process. These results definitively indicate that stimulated emission of NV- centers is suppressed by photoionization and ESAs and the possibility of diamond lasers based on NV- centers is low.

Exploring the plasma chemistry in microwave chemical vapor deposition of diamond from C/H/O gas mixtures.

PubMed

Kelly, Mark W; Richley, James C; Western, Colin M; Ashfold, Michael N R; Mankelevich, Yuri A

2012-09-27

Microwave (MW)-activated CH(4)/CO(2)/H(2) gas mixtures operating under conditions relevant to diamond chemical vapor deposition (i.e., X(C/Σ) = X(elem)(C)/(X(elem)(C) + X(elem)(O)) ≈ 0.5, H(2) mole fraction = 0.3, pressure, p = 150 Torr, and input power, P = 1 kW) have been explored in detail by a combination of spatially resolved absorption measurements (of CH, C(2)(a), and OH radicals and H(n = 2) atoms) within the hot plasma region and companion 2-dimensional modeling of the plasma. CO and H(2) are identified as the dominant species in the plasma core. The lower thermal conductivity of such a mixture (cf. the H(2)-rich plasmas used in most diamond chemical vapor deposition) accounts for the finding that CH(4)/CO(2)/H(2) plasmas can yield similar maximal gas temperatures and diamond growth rates at lower input powers than traditional CH(4)/H(2) plasmas. The plasma chemistry and composition is seen to switch upon changing from oxygen-rich (X(C/Σ) < 0.5) to carbon-rich (X(C/Σ) > 0.5) source gas mixtures and, by comparing CH(4)/CO(2)/H(2) (X(C/Σ) = 0.5) and CO/H(2) plasmas, to be sensitive to the choice of source gas (by virtue of the different prevailing gas activation mechanisms), in contrast to C/H process gas mixtures. CH(3) radicals are identified as the most abundant C(1)H(x) [x = 0-3] species near the growing diamond surface within the process window for successful diamond growth (X(C/Σ) ≈ 0.5-0.54) identified by Bachmann et al. (Diamond Relat. Mater.1991, 1, 1). This, and the findings of similar maximal gas temperatures (T(gas) ~2800-3000 K) and H atom mole fractions (X(H)~5-10%) to those found in MW-activated C/H plasmas, points to the prevalence of similar CH(3) radical based diamond growth mechanisms in both C/H and C/H/O plasmas.

Synthesis of sea urchin-like carbon nanotubes on nano-diamond powder.

PubMed

Hwang, E J; Lee, S K; Jeong, M G; Lee, Y B; Lim, D S

2012-07-01

Carbon nanotubes (CNTs) have unique atomic structure and properties, such as a high aspect ratio and high mechanical, electrical and thermal properties. On the other hand, the agglomeration and entanglement of CNTs restrict their applications. Sea urchin-like multiwalled carbon nanotubes, which have a small aspect ratio, can minimize the problem of dispersion. The high hardness, thermal conductivity and chemical inertness of the nano-diamond powder make it suitable for a wide range of applications in the mechanical and electronic fields. CNTs were synthesized on nano-diamond powder by thermal CVD to fabricate a filler with suitable mechanical properties and chemical stability. This paper reports the growth of CNTs with a sea urchin-like structure on the surface of the nano-diamond powder. Nano-diamond powders were dispersed in an attritional milling system using zirconia beads in ethanol. After the milling process, 3-aminopropyltrimethoxysilane (APS) was added as a linker. Silanization was performed between the nano-diamond particles and the metal catalyst. Iron chloride was used as a catalyst for the fabrication of the CNTs. After drying, catalyst-attached nano-diamond powders could be achieved. The growth of the carbon nanotubes was carried out by CVD. The CNT morphology was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The mean diameter and length of the CNTs were 201 nm and 3.25 microm, respectively.

The diamondiferous xenoliths from kimberlites of Yakutia: a key for the diamonds origin

NASA Astrophysics Data System (ADS)

Spetsius, Zdislav V.; Kovalchuck, Oleg E.

2010-05-01

More than 400 diamondiferous xenoliths have been discovered in the kimberlite pipes of Yakutia. Diamond-bearing specimens are encountered among ultramafic xenoliths predominantly dunite harzburgites and in all types of eclogitic rocks: bimineral eclogites, kyanite and corundum eclogites and also in garnet-websterites. The diamonds in xenoliths are found mainly as separate crystals but in some xenoliths the amount of diamonds may be as high as 1000. The distribution of crystals in the specimens is irregular and does not coincide with the specimen surfaces. The sizes of the crystals vary from fraction of millimeter to 10 millimeters. The diamonds from xenoliths are correlated with the diamonds from kimberlites by their morphology and physical properties. Mineral inclusions are rare in the xenolith diamonds. Careful examination of more than 300 diamonds from about 100 xenoliths shows that 40% of macrodiamonds (size > 1mm) contain some visible inclusions. In most cases these are a little tiny opaque grain. Microprobe data suggest that overwhelming majority of them are sulfides. Silicate inclusions of garnet, clinopyroxene and very seldom rutile or others are rare. The diamonds in some specimens have sulfide rims around them. A number of facts show that in the process of diamonds growth the sulfide melt was present together with the silicate melt. The mechanism of diamond growth should be discussed in a complex sulfide-silicate system enriched in fluids. The diamondiferous eclogites do not stand out of the general series of mantle eclogites from kimberlite pipes either by specific properties and minerals composition, or major and trace elements distribution between coexisting garnets and clinopyroxenes. Intensive partial melting is characteristic feature for most of the specimens. To some extent this is a typomorphic sign of diamondiferous eclogites. A selective enrichment pattern REE is observed in some xenolith minerals (high content of LREE in clinopyroxene and enhanced HREE in garnet). In proposed topic will be summarized data on diamondiferous xenoliths from the Udachnaya, Nyurbinskaya and other pipes of Yakutia. These results comprise in the whole about 300 samples and include data on major and trace element chemistry of xenolith minerals with attention to the morphology and distribution of diamonds in separate xenoliths. Special attention will be given to variation of physical properties of diamonds that were measured in 500 diamonds recovered from new parcel of 30 xenoliths. These properties include total content of nitrogen, co-variations in B1 and B2 defects and hydrogen. It should be pointed that there exist a rather strong correlation between morphology and some physical properties of diamonds. Special remarks will be given to the evidence of possible metasomatic origin of diamonds in some xenoliths.

Pretreatment process for forming a smooth surface diamond film on a carbon-coated substrate

DOEpatents

Feng, Zhu; Brewer, Marilee; Brown, Ian; Komvopoulos, Kyriakos

1994-01-01

A process is disclosed for the pretreatment of a carbon-coated substrate to provide a uniform high density of nucleation sites thereon for the subsequent deposition of a continuous diamond film without the application of a bias voltage to the substrate. The process comprises exposing the carbon-coated substrate, in a microwave plasma enhanced chemical vapor deposition system, to a mixture of hydrogen-methane gases, having a methane gas concentration of at least about 4% (as measured by partial pressure), while maintaining the substrate at a pressure of about 10 to about 30 Torr during the pretreatment.

Microstructure Analyses of NA-Nanodiamond Particles

DTIC Science & Technology

2016-08-01

approximately 5 to 6 nm in diameter, similar to those obtained by distilled water purification . The energy dispersive analyzer from these perfectly well...NOTES 14. ABSTRACT The purification process of detonation diamond nanoparticles was perfectly accomplished using nitric acid at high...pressure nitric acid, whereas the previous detonation diamond nanoparticle was washed with distilled water and purified by oxidation

Nondual Psychotherapy and Second Stage Sexual Addictions Recovery: Transforming "Master of the Universe" Narcissism into Nondual Being

ERIC Educational Resources Information Center

Nixon, Gary; Theriault, Brian

2012-01-01

This article describes the process of working through the "dry drunk" second stage of sexual addiction recovery through transforming the narcissistic "Master of the Universe" personality into the experience of nondual being using the Almaas Diamond Approach of self-realization. The Diamond Approach is a transpersonal informed psychology…