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Sample records for diamond based composites

  1. Thermodynamic and kinetic study on interfacial reaction and diamond graphitization of Cu—Fe-based diamond composite

    NASA Astrophysics Data System (ADS)

    Li, Wen-Sheng; Zhang, Jie; Dong, Hong-Feng; Chu, Ke; Wang, Shun-Cai; Liu, Yi; Li, Ya-Ming

    2013-01-01

    Cu—Fe based diamond composites used for saw-blade segments are directly fabricated by vacuum and pressure-assisted sintering. The carbide forming elements Cr and Ti are added to improve interfacial bonding between diamond and the Cu—Fe matrix. The interfacial reactions between diamond/graphite and Cr or Ti, and diamond graphitization are investigated by thermodynamics/kinetics analyses and experimental methods. The results show that interfacial reactions and graphitization of diamond can automatically proceed thermodynamically. The Cr3C2, Cr7C3, Cr23C6, and TiC are formed at the interfaces of composites by reactions between diamond and Cr or Ti; diamond graphitization does not occur because of the kinetic difficulty at 1093 K under the pressure of 13 MPa.

  2. Diamond-silicon carbide composite

    DOEpatents

    Qian, Jiang; Zhao, Yusheng

    2006-06-13

    Fully dense, diamond-silicon carbide composites are prepared from ball-milled microcrystalline diamond/amorphous silicon powder mixture. The ball-milled powder is sintered (P=5–8 GPa, T=1400K–2300K) to form composites having high fracture toughness. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPa.dot.m1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness. X-ray diffraction patterns and Raman spectra indicate that amorphous silicon is partially transformed into nanocrystalline silicon at 5 GPa/873K, and nanocrystalline silicon carbide forms at higher temperatures.

  3. Diamond-silicon carbide composite and method

    DOEpatents

    Zhao, Yusheng

    2011-06-14

    Uniformly dense, diamond-silicon carbide composites having high hardness, high fracture toughness, and high thermal stability are prepared by consolidating a powder mixture of diamond and amorphous silicon. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPam.sup.1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness.

  4. Low temperature synthesis of diamond-based nano-carbon composite materials with high electron field emission properties

    SciTech Connect

    Saravanan, A.; Huang, B. R.; Yeh, C. J.; Leou, K. C.; Lin, I. N.

    2015-06-08

    A diamond-based nano-carbon composite (d/NCC) material, which contains needle-like diamond grains encased with the nano-graphite layers, was synthesized at low substrate temperature via a bias enhanced growth process using CH{sub 4}/N{sub 2} plasma. Such a unique granular structure renders the d/NCC material very conductive (σ = 714.8 S/cm), along with superior electron field emission (EFE) properties (E{sub 0} = 4.06 V/μm and J{sub e} = 3.18 mA/cm{sup 2}) and long lifetime (τ = 842 min at 2.41 mA/cm{sup 2}). Moreover, the electrical conductivity and EFE behavior of d/NCC material can be tuned in a wide range that is especially useful for different kind of applications.

  5. Composite and diamond cold cathode materials

    SciTech Connect

    Worthington, M.S.; Wheeland, C.L.; Ramacher, K.; Doyle, E.

    1996-12-31

    Cold-cathode technology for Crossed-Field Amplifiers (CFAs) has not changed significantly over the last thirty years. The material typically used for cold cathode CFAs is either platinum (Pt) or beryllium (Be), although numerous other materials with higher secondary electron emission ratios have been tested. Beryllium cathodes display higher secondary emission ratios, {approximately} 3.4, than Pt, but require a partial pressure of oxygen to maintain a beryllium oxide (BeO) surface layer. These dispensers limit the life of the CFA, both directly, due to oxygen-source filament burnout, and indirectly, by the production of undesirable gases which adversely affect the performance of the CFA. In an attempt to reduce or eliminate the required oxygen dispenser output level, cathodes were constructed from three varieties of Be/BeO composite material and tested in L-4808s, standard forward-wave AEGIS CFAs. Diamond and diamond-like carbons are desirable as cathode materials because of their extremely high secondary electron emission ratio, greater than 20, but their use has previously been prohibitive because of cost, available, and physical characteristics. Because of recent advances in diamond growth technology it is now possible to deposit thin layers of diamond on a variety of geometric objects. In coordination with Penn State University four annular diamond emitters have been fabricated. The diamond emitters will be tested in a standard AEGIS CFA, both under vacuum and with a partial pressure of hydrogen.

  6. Diamond based photonic crystal microcavities.

    PubMed

    Tomljenovic-Hanic, S; Steel, M J; de Sterke, C Martijn; Salzman, J

    2006-04-17

    Diamond based technologies offer a material platform for the implementation of qubits for quantum computing. The photonic crystal architecture provides the route for a scalable and controllable implementation of high quality factor (Q) nanocavities, operating in the strong coupling regime for cavity quantum electrodynamics. Here we compute the photonic band structures and quality factors of microcavities in photonic crystal slabs in diamond, and compare the results with those of the more commonly-used silicon platform. We find that, in spite of the lower index contrast, diamond based photonic crystal microcavities can exhibit quality factors of Q=3.0x10(4), sufficient for proof of principle demonstrations in the quantum regime. PMID:19516502

  7. Chemical vapor deposited diamond-on-diamond powder composites (LDRD final report)

    SciTech Connect

    Panitz, J.K.; Hsu, W.L.; Tallant, D.R.; McMaster, M.; Fox, C.; Staley, D.

    1995-12-01

    Densifying non-mined diamond powder precursors with diamond produced by chemical vapor infiltration (CVI) is an attractive approach for forming thick diamond deposits that avoids many potential manufacturability problems associated with predominantly chemical vapor deposition (CVD) processes. The authors developed techniques for forming diamond powder precursors and densified these precursors in a hot filament-assisted reactor and a microwave plasma-assisted reactor. Densification conditions were varied following a fractional factorial statistical design. A number of conclusions can be drawn as a result of this study. High density diamond powder green bodies that contain a mixture of particle sizes solidify more readily than more porous diamond powder green bodies with narrow distributions of particle sizes. No composite was completely densified although all of the deposits were densified to some degree. The hot filament-assisted reactor deposited more material below the exterior surface, in the interior of the powder deposits; in contrast, the microwave-assisted reactor tended to deposit a CVD diamond skin over the top of the powder precursors which inhibited vapor phase diamond growth in the interior of the powder deposits. There were subtle variations in diamond quality as a function of the CVI process parameters. Diamond and glassy carbon tended to form at the exterior surface of the composites directly exposed to either the hot filament or the microwave plasma. However, in the interior, e.g. the powder/substrate interface, diamond plus diamond-like-carbon formed. All of the diamond composites produced were grey and relatively opaque because they contained flawed diamond, diamond-like-carbon and glassy carbon. A large amount of flawed and non-diamond material could be removed by post-CVI oxygen heat treatments. Heat treatments in oxygen changed the color of the composites to white.

  8. Study on the anti-wear performance of Ni-base composite coating sucker joint that contains nano-diamond and nano-polytetrafluoroethylene.

    PubMed

    Wang, Wei-Zhang; Yan, Xiang-Zhen; Wang, Hai-Wen; Wang, Ming-Bo

    2009-02-01

    With the development of oilfields, the problem of eccentric wear between casing and sucker rod in rod-pumped wells operation is more and more severe. Investigations on the eccentric wear show that the abrasion of sucker rod joint is more serious than the sucker rod itself. A new method of producing the Ni-base composite coating that contains nano-diamond and nano-polytetrafluoroethylene (PTFE) on sucker joint obtained by electrodeposition is presented in this paper. The test results show that the anti-wear performance and hardness of the sucker rod improve significantly with the increase of nano-diamond. The addition of nano-PTFE particle is useful in reducing the friction factor. Field tests demonstrate that the life of the sucker rod joint is increased and the maintenance cycle of the rod-pumped well is prolonged. PMID:19441509

  9. Microstructure and thermal properties of copper–diamond composites with tungsten carbide coating on diamond particles

    SciTech Connect

    Kang, Qiping; He, Xinbo Ren, Shubin; Liu, Tingting; Liu, Qian; Wu, Mao; Qu, Xuanhui

    2015-07-15

    An effective method for preparing tungsten carbide coating on diamond surfaces was proposed to improve the interface bonding between diamond and copper. The WC coating was formed on the diamond surfaces with a reaction medium of WO{sub 3} in mixed molten NaCl–KCl salts and the copper–diamond composites were obtained by vacuum pressure infiltration of WC-coated diamond particles with pure copper. The microstructure of interface bonding between diamond and copper was discussed. Thermal conductivity and thermal expansion behavior of the obtained copper–diamond composites were investigated. Results indicated that the thermal conductivity of as-fabricated composite reached 658 W m{sup −} {sup 1} K{sup −} {sup 1}. Significant reduction in coefficient of thermal expansion of the composite compared with that of pure copper was obtained. - Highlights: • WC coating was successfully synthesized on diamond particles in molten salts. • WC coating obviously promoted the wettability of diamond and copper matrix. • WC coating greatly enhanced the thermal conductivity of Cu–diamond composite. • The composites are suitable candidates for heat sink applications.

  10. 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

  11. Carbonate-silicate composition of diamond-forming media of fibrous diamonds from the Snap Lake area (Canada)

    NASA Astrophysics Data System (ADS)

    Zedgenizov, D. A.; Pokhilenko, N. P.; Griffin, W. L.

    2015-03-01

    This study presents new data on the compositions of microinclusions in fibrous diamonds from the Snap Lake area in the eastern part of the Slave Craton (Canada). The compositional trends of diamond microinclusions are consistent with those of diamond-forming media ranging continuously between a highly carbonatitic endmember and a highly silicic endmember. The microinclusions exhibit general enrichment of most incompatible elements, which is probably indicative of their crystallization during partial melting of mantle peridotites and eclogites. Our results also suggest that the diamond analyzed in this study may have formed as a result of interaction between carbonate-silicate melts and peridotitic wall-rocks at the base of a thick lithospheric mantle at depths below 300 km. The trace element distributions in the studied diamond microinclusions show a general similarity to those previously found in the parental kimberlites and carbonatites. These data suggest that diamonds may have crystallized either directly from a kimberlitic/carbonatitic melt or from a proto-kimberlitic fluid/melt, which was derived from a source also common to kimberlites. This is supported by differences in the major element compositions of diamond-forming fluids/melts and kimberlites.

  12. Thermal characterization and properties of a copper-diamond composite

    SciTech Connect

    Yang, Pin; Chavez, Thomas P.; DiAntonio, Christopher Brian; Coker, Eric Nicholas

    2014-09-01

    The thermal properties of a commercial copper-diamond composite were measured from below -50°C to above 200°C. The results of thermal expansion, heat capacity, and thermal diffusivity were reported. These data were used to calculate the thermal conductivity of the composite as a function of temperature in the thickness direction. These results are compared with estimated values based on a simple mixing rule and the temperature dependence of these physical properties is represented by curve fitting equations. These fitting equations can be used for thermal modeling of practical devices/systems at their operation temperatures. The results of the mixing rule showed a consistent correlation between the amount of copper and diamond in the composite, based on density, thermal expansion, and heat capacity measurements. However, there was a disparity between measured and estimated thermal diffusivity and thermal conductivity. These discrepancies can be caused by many intrinsic material issues such as lattice defects and impurities, but the dominant factor is attributed to the large uncertainty of the interfacial thermal conductance between diamond and copper.

  13. Trace element compositions of submicroscopic inclusions in coated diamond: A tool for understanding diamond petrogenesis

    NASA Astrophysics Data System (ADS)

    Tomlinson, Emma; De Schrijver, Isabel; De Corte, Katrien; Jones, Adrian P.; Moens, Luc; Vanhaecke, Frank

    2005-10-01

    Trace element compositions of submicroscopic inclusions in both the core and the coat of five coated diamonds from the Democratic Republic of Congo (DRC, formerly Zaire) have been analyzed by Laser Ablation Inductively Coupled Mass Plasma Spectrometry (LA-ICP-MS). Both the diamond core and coat inclusions show a general 2-4-fold enrichment in incompatible elements relative to major elements. This level of enrichment is unlikely to be explained by the entrapment of silicate mantle minerals (olivine, garnet, clinopyroxene, phlogopite) alone and thus submicroscopic fluid or glass inclusions are inferred in both the diamond coat and in the gem quality diamond core. The diamond core fluids have elevated High Field Strength Element (Ti, Ta, Zr, Nb) concentrations and are enriched in U relative to inclusions in the diamond coats and relative to chondrite. The core fluids are also moderately enriched in LILE (Ba, Sr, K). Therefore, we suggest that the diamond cores contain inclusions of silicate melt. However, the Ni content and Ni/Fe ratio of the trapped fluid are very high for a silicate melt in equilibrium with mantle minerals; high Ni and Co concentrations in the diamond cores are attributed to the presence of a sulfide phase coexisting with silicate melt in the diamond core inclusions. Inclusions in the diamond coat are enriched in LILE (U, Ba, Sr, K) and La over the diamond core fluids and to chondrite. The coats have incompatible element ratios similar to natural carbonatite (coat fluid: Na/Ba ≈0.66, La/Ta≈130). The coat fluid is also moderately enriched in HFSE (Ta, Nb, Zr) when normalized to chondritic Al. LILE and La enrichment is related to the presence of a carbonatitic fluid in the diamond coat inclusions, which is mixed with a HFSE-rich hydrous silicate fluid similar to that in the core. The composition of the coat fluid is consistent with a genetic link to group 1 kimberlite.

  14. The carbon isotopic composition of Novo Urei diamonds

    NASA Technical Reports Server (NTRS)

    Fisenko, A. V.; Semjenova, L. F.; Verchovsky, A. B.; Russell, S. S.; Pillinger, C. T.

    1993-01-01

    The carbon isotopic composition of diamond grains isolated from the Novo Urei meteorite are discussed. A diamond separate was obtained from 2g of whole rock using the chemical treatments described aimed at obtaining very pure diamond. X ray diffraction of the residue, which represented 5000 ppm of the parent mass, indicated only the presence of the desired mineral. The diamond crystals were 1-30 microns in diameter, and some grains had a yellow color. The chemical treatments were followed by a size separation to give a 1-10 microns and a 5-30 microns fraction, which were named DNU-1 and DNU-2, respectively.

  15. Diamond/aluminium nitride composites for efficient thermal management applications

    SciTech Connect

    Cervenka, J.; Dontschuk, N.; Prawer, S.; Ladouceur, F.; Duvall, S. G.

    2012-07-30

    Synthetic diamond/AlN composite materials have been fabricated by a combination of microwave plasma-assisted chemical vapor deposition and molecular beam epitaxy. These wide band gap semiconductor heterojunctions show promises for many applications, including thermal management, deep ultraviolet light emitting devices, and high power and high temperature electronics. Here, we report results of an interface study of polycrystalline diamond layers grown on single crystal AlN(0001). High resolution transmission microscopy revealed atomically sharp interfaces between diamond and AlN. Temperature dependent Raman spectroscopy measurements showed reduced thermal resistance on diamond-coated AlN substrates compared to uncoated AlN at temperatures above 330 K.

  16. Diamond/aluminium nitride composites for efficient thermal management applications

    NASA Astrophysics Data System (ADS)

    Cervenka, J.; Dontschuk, N.; Ladouceur, F.; Duvall, S. G.; Prawer, S.

    2012-07-01

    Synthetic diamond/AlN composite materials have been fabricated by a combination of microwave plasma-assisted chemical vapor deposition and molecular beam epitaxy. These wide band gap semiconductor heterojunctions show promises for many applications, including thermal management, deep ultraviolet light emitting devices, and high power and high temperature electronics. Here, we report results of an interface study of polycrystalline diamond layers grown on single crystal AlN(0001). High resolution transmission microscopy revealed atomically sharp interfaces between diamond and AlN. Temperature dependent Raman spectroscopy measurements showed reduced thermal resistance on diamond-coated AlN substrates compared to uncoated AlN at temperatures above 330 K.

  17. Cu/Diamond composite heat-conducting shims

    NASA Astrophysics Data System (ADS)

    Galashov, E. N.; Yusuf, A. A.; Mandrik, E. M.

    2015-11-01

    Composite material with high thermal conductivity was obtained by the method of thermal sintering of a diamond (50 - 75%) with a size of 20 to 250 μm in a matrix of copper.Coefficient of thermal conductivity of copper diamond composite materials was measured and is 450 - 650 W·m-1·K-1. The coefficient of thermal expansion CTE was measured and is 5.5 - 7.5 · 10-6/°C. The obtained copper diamond composite materials are promising objects for use in THz and microwave devices.

  18. Understanding the source: The nitrogen isotope composition of Type II mantle diamonds

    NASA Astrophysics Data System (ADS)

    Mikhail, Sami; Howell, Dan; Jones, Adrian; Milledge, Judith; Verchovsky, Sasha

    2010-05-01

    Diamonds can be broadly subdivided into 2 groups based on their nitrogen content; type I with > 10ppm nitrogen and type II with < 10ppm (1). Roughly 98 % of upper mantle diamonds are classified as type I, interestingly nearly all lower mantle diamonds are of type II (2). This study aims to identify the processes involved or source of type II diamonds from several localities by measuring their carbon and nitrogen stable isotope compositions simultaneously for the first time. Samples have been categorised as type II using Fourier transform infra-red (FTIR) analysis. The carbon and nitrogen isotopes as well as additional nitrogen content data have been acquired using a custom made a hi-sensitivity gas sourced mass spectrometer built and housed at the Open University, UK. There are two ways in which we can model the petrogenesis of type II diamonds. 1- During diamond growth nitrogen can be incorporated into diamond as a compatible element in a closed system and therefore the N/C ratio in the source can be depleted by Rayleigh fractionation as the first diamonds to crystallise will partition nitrogen atoms into their lattice as a 1:1 substitution for carbon atoms (type I diamonds). However nitrogen may behave as an incompatible element in diamond (and be a compatible element in the metasomatic fluid), this coupled with an open system would lead to the removal of nitrogen by the metasomatic fluids, thus causing the source to progressively become depleted in nitrogen. Continued diamond crystallization in either system will produce diamonds with ever decreasing nitrogen concentrations with time, possibly to the point of them being almost nitrogen free. 2- It is conceivable that type I & II diamonds found in the same deposit and sharing a common paragenesis (eclogitic or peridotitic) may have formed from different metasomatic fluids in separate diamond forming events. The latter has been proposed for samples from the Cullinan mine (South Africa) based on their carbon

  19. Single-step route to diamond-nanotube composite

    NASA Astrophysics Data System (ADS)

    Varshney, Deepak; Ahmadi, Majid; Guinel, Maxime J.-F.; Weiner, Brad R.; Morell, Gerardo

    2012-09-01

    Candle wax was used as a precursor for the production of a diamond-nanotube composite in a single step. The composite films were fabricated by sulfur-assisted hot-filament chemical vapor deposition technique. The morphology of the composite films was analyzed by scanning electron microscopy and transmission electron microscopy. Raman spectra of the films show characteristic diamond band at 1,332 cm-1, D-band around 1,342 cm-1, and graphitic G-band around 1,582 cm-1. The electron energy-loss spectroscopy recorded at the carbon K-edge region shows signature features of diamond and carbon nanotube in the fabricated material. The ability to synthesize diamond-nanotube composites at relatively low temperatures by a single-step process opens up new possibilities for the fabrication of nanoelectronic devices.

  20. Single-step route to diamond-nanotube composite.

    PubMed

    Varshney, Deepak; Ahmadi, Majid; Guinel, Maxime J-F; Weiner, Brad R; Morell, Gerardo

    2012-01-01

    Candle wax was used as a precursor for the production of a diamond-nanotube composite in a single step. The composite films were fabricated by sulfur-assisted hot-filament chemical vapor deposition technique. The morphology of the composite films was analyzed by scanning electron microscopy and transmission electron microscopy. Raman spectra of the films show characteristic diamond band at 1,332 cm-1, D-band around 1,342 cm-1, and graphitic G-band around 1,582 cm-1. The electron energy-loss spectroscopy recorded at the carbon K-edge region shows signature features of diamond and carbon nanotube in the fabricated material. The ability to synthesize diamond-nanotube composites at relatively low temperatures by a single-step process opens up new possibilities for the fabrication of nanoelectronic devices. PMID:23013660

  1. Single-step route to diamond-nanotube composite

    PubMed Central

    2012-01-01

    Candle wax was used as a precursor for the production of a diamond-nanotube composite in a single step. The composite films were fabricated by sulfur-assisted hot-filament chemical vapor deposition technique. The morphology of the composite films was analyzed by scanning electron microscopy and transmission electron microscopy. Raman spectra of the films show characteristic diamond band at 1,332 cm−1, D-band around 1,342 cm−1, and graphitic G-band around 1,582 cm−1. The electron energy-loss spectroscopy recorded at the carbon K-edge region shows signature features of diamond and carbon nanotube in the fabricated material. The ability to synthesize diamond-nanotube composites at relatively low temperatures by a single-step process opens up new possibilities for the fabrication of nanoelectronic devices. PMID:23013660

  2. Raman spectroscopic investigation of graphitization of diamond during spark plasma sintering of UO2-diamond composite nuclear fuel

    NASA Astrophysics Data System (ADS)

    Chen, Zhichao; Subhash, Ghatu; Tulenko, James S.

    2016-07-01

    Micro-Raman spectroscopy (MRS) was utilized to investigate the graphitization of diamond particles within a UO2-diamond composite processed by spark plasma sintering (SPS). While pure diamond gives a sharp Raman peak at 1331.6 cm-1, the graphitized diamond shows broad peaks either at 1350 cm-1 (G-peak) or 1580 cm-1 (D-peak). The degree of graphitization was quantified by calculating the area beneath the diamond and graphite peaks. It was found that more than 20% of diamond was graphitized on the surface of the UO2-diamond pellet and only around 10% diamond was graphitized in the interior regions of the pellet. This current study highlights the necessity to review the implications of these results carefully while implementing UO2-diamond composite nuclear fuel.

  3. Processing of functionally graded tungsten carbide-cobalt-diamond composites

    NASA Astrophysics Data System (ADS)

    Jain, Mohit

    Polycrystalline diamond compacts (PDCs) are widely used as drill bit cutters in rock drilling and as tool bits in machining non-ferrous materials. A typical PDC comprises a thin layer of sintered polycrystalline diamond bonded to a tungsten carbide-cobalt substrate. A well recognized failure mechanism is delamination at the interface between diamond and cemented carbide. High stresses at the diamond/carbide interface, due to thermal expansion and modulus mismatch, are the primary cause of in-service failure under impact loading conditions. This work was undertaken to develop a tungsten carbide-cobalt-diamond composite, which has a continuously graded interface between the diamond and tungsten carbide. The process developed comprised the following steps: (i) generation of a pore size gradient by electrochemical etching of cobalt from the surface of a partially sintered tungsten carbide-cobalt preform; (ii) chemical vapor infiltration of the porous preform with carbon by catalytic decomposition of a methane/hydrogen mixture, resulting in a graded carbon concentration; and (iii) consolidation of the carbon infiltrated preforms at 8GPa/1500°C to complete densification and to transform the carbon into diamond. Thus, the final product consists of a functionally graded WC-Co-diamond composite, with controlled distribution of the constituent phases. Tungsten carbide-cobalt powders with mean tungsten carbide particle size of 0.8mum(micro-grain) and 100 nm(nano-grain) were used as starting materials. Processing conditions were adjusted to obtain an optimal distribution of carbon in porous preforms. After high pressure/high temperature consolidation, both micro- and nano-composites showed a diffused interface between inner and outer regions of the fully dense materials. A micro-composite showed columnar-like tungsten carbide grains and faceted diamond grains in the outer region of the sintered material. The grain size of the diamond in this region was ˜2mum, and the

  4. Optimizing the Growth of (111) Diamond for Diamond Based Magnetometry

    NASA Astrophysics Data System (ADS)

    Kamp, Eric; Godwin, Patrick; Samarth, Nitin; Snyder, David; de Las Casas, Charles; Awschalom, David D.

    Magnetometers based on nitrogen vacancy (NV) ensembles have recently achieved sub-picotesla sensitivities [Phys. Rev. X 5, 041001(2015)], putting the technique on par with SQUID and MFM magnetometry.Typically these sensors use (100) oriented diamond with NV centers forming along all four (111) crystal orientations.This allows for vector magnetometry, but is a hindrance to the absolute sensitivity. Diamond grown on (111) oriented substrates through microwave plasma enhanced chemical vapor deposition(MP-CVD) provides a promising route in this context since such films can exhibit preferential orientation greater than 99% [Appl. Phys. Lett.104, 102407 (2014)]. An important challenge though is to achieve sufficiently high NV center densities required for enhancing the sensitivity of an NV ensemble magnetometer.We report systematic studies of the MP-CVD growth and characterization of (111) oriented diamond, where we vary growth temperature, methane concentration, and nitrogen doping. For each film we study the Nitrogen to NV ratio, the NV- to NV0 ratio, and alignment percentage to minimize sources of decoherence and ensure preferential alignment. From these measurements we determine the optimal growth parameters for high sensitivity, NV center ensemble scalar magnetometry. Funded by NSF-DMR.

  5. Diamond-Silicon Carbide Composite And Method For Preparation Thereof

    DOEpatents

    Qian, Jiang; Zhao, Yusheng

    2005-09-06

    Fully dense, diamond-silicon carbide composites are prepared from ball-milled microcrystalline diamond/amorphous silicon powder mixture. The ball-milled powder is sintered (P=5-8 GPa, T=1400K-2300K) to form composites having high fracture toughness. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPa.multidot.m.sup.1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness. X-ray diffraction patterns and Raman spectra indicate that amorphous silicon is partially transformed into nanocrystalline silicon at 5 GPa/873K, and nanocrystalline silicon carbide forms at higher temperatures.

  6. Diamond-Glass Composite Processing in a Microgravity Condition

    NASA Astrophysics Data System (ADS)

    Noma, Tatsuo; Tanii, Jun; Kuwano, Ryushi; Sawaoka, Akira B.

    1986-12-01

    Diamond-glass composite was fabricated under microgravity in the Challenger, a space shuttle orbiter. Fracture toughness and hardness were compared with the composites fabricated on earth. Under microgravity, uniform distributions in toughness and hardness were obtained. On earth, the values decreased with the distance from the bottom of the crucible.

  7. Low Energy Sputter Yields for Diamond, Carbon-Carbon Composite, and Molybdenum Subject to Xenon Ion Nombardment

    NASA Technical Reports Server (NTRS)

    Blandino, J.; Goodwin, D.; Garner, C.

    1999-01-01

    Sputter yields have been measured for polycrystalline diamond, single crystal diamond, a carbon-carbon composite, and molybdenum subject to bombardment with xenon. The tests were performed using a 3 cm Kaufman ion source to produce incident ions with energy in the range of 150 - 750 eV and profilometry based technique to measure the amount of sputtered material.

  8. One step deposition of highly adhesive diamond films on cemented carbide substrates via diamond/β-SiC composite interlayers

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Zhuang, Hao; Jiang, Xin

    2015-12-01

    Deposition of adherent diamond films on cobalt-cemented tungsten carbide substrates has been realized by application of diamond/beta-silicon carbide composite interlayers. Diamond top layers and the interlayers were deposited in one single process by hot filament chemical vapor deposition technique. Two different kinds of interlayers have been employed, namely, gradient interlayer and interlayer with constant composition. The distribution of diamond and beta-silicon carbide phases was precisely controlled by manipulating the gas phase composition. X-ray diffraction and Raman spectroscopy were employed to determine the existence of diamond, beta-silicon carbide and cobalt silicides (Co2Si, CoSi) phases, as well as the quality of diamond crystal and the residual stress in the films. Rockwell-C indentation tests were carried out to evaluate the film adhesion. It is revealed that the adhesion of the diamond film is drastically improved by employing the interlayer. This is mainly influenced by the residual stress in the diamond top layer, which is induced by the different thermal expansion coefficient of the film and the substrate. It is even possible to further suppress the stress by manipulating the distribution of diamond and beta-silicon carbide in the interlayer. The most adhesive diamond film on cemented carbide is thus obtained by employing a gradient composite interlayer.

  9. Enhancement of the thermal properties of silver-diamond composites with chromium carbide coating

    NASA Astrophysics Data System (ADS)

    Tang, Yanxia; Wang, Lihua; Zhao, Chao

    2014-05-01

    The present work reports the enhancement of the thermal properties in Ag/diamond matrix composites reinforced with chromium carbide coated diamond particles. The coated diamond particles were characterized by x-ray diffraction, x-ray photoelectron spectroscopy and Raman spectra. The composites were synthesized by spark plasma sintering. The chromium carbide coating on the diamond particles resulted in composites exhibiting improved wettability and strong interfacial bonding between the diamond particles and Ag matrix. The composites with coated diamonds showed a low coefficient of thermal expansion of 8.24 × 10-6/K and a high thermal conductivity of 695 W/mK at 60 % particle volume fraction, which greatly outperformed the composites with uncoated diamonds at the same particle volume fraction. The obtained results are useful for synthesizing Ag/diamond composites with greatly improved thermal performance.

  10. Ultradisperse Diamond Regeneration from Composite Electrolytes of Chromium Plating

    NASA Astrophysics Data System (ADS)

    Gubarevich, T. M.; Chernukho, L. E.; Kulik, V. P.; Shtempljuk, R. G.

    Composite chromium-diamond electroplating is one of the most UDD consuming technologies among UDD applications. The exploitation includes periodic cleaning of the chroming bath from accumulated anodic sludges and contaminants. During the cleaning, the UDD must be extracted from the sludges and regenerated for re-use. We have suggested technique for UDD regeneration from sludges containing up to 80% of insoluble Cr, Pb and Sb compounds. The process includes mechanic, colloidal-chemical and chemical treatments which provide a fairly pure material only with 1-3% of noncarbon; the calculated diamond yield is 85-90%. We have analyzed the contaminants in regenerated UDD for their dispersion, sedimentative and aggregative stability, adsorptive and structural characteristics of the surface. Regenerated diamond is applicable for re-use in electroplating technologies.

  11. Effect of Thermally Softened Bronze Matrix on the Fracturing Behavior of Diamond Particles in Hybrid Sprayed Bronze/Diamond Composite

    NASA Astrophysics Data System (ADS)

    Na, Hyuntaek; Bae, Gyuyeol; Kang, Kicheol; Kim, Hyungjun; Kim, Jay-Jung; Lee, Changhee

    2010-09-01

    In our previous study (Na et al., Compos Sci Technol 69:463-468, 2009), optimized thickness of protective nickel film was proposed for smaller diamond feedstock to obtain reduced impact stress and uniform flight behavior of particles during kinetic (or cold) spraying. However, in this study, nickel-coated diamond particles were severely fractured with increasing particle size due to high kinetic energy. Hence, an innovative hybrid spraying technique (a combination of kinetic and thermal spraying) was introduced to embed relatively large diamond particles into the bronze matrix. Size distributions of the diamond particles in the composite coatings were analyzed by scanning electron microscopy, an electron probe micro analyzer, and image analysis methods. In addition, impact behaviors of diamond particles in kinetic and hybrid gas flows were simulated through finite element analysis (ABAQUS/Explicit 6.7-2). Diamond fracturing was significantly minimized by the reduced impact energy afforded by the thermally softened bronze matrix through hybrid spraying.

  12. Composite materials with viscoelastic stiffness greater than diamond.

    PubMed

    Jaglinski, T; Kochmann, D; Stone, D; Lakes, R S

    2007-02-01

    We show that composite materials can exhibit a viscoelastic modulus (Young's modulus) that is far greater than that of either constituent. The modulus, but not the strength, of the composite was observed to be substantially greater than that of diamond. These composites contain bariumtitanate inclusions, which undergo a volume-change phase transformation if they are not constrained. In the composite, the inclusions are partially constrained by the surrounding metal matrix. The constraint stabilizes the negative bulk modulus (inverse compressibility) of the inclusions. This negative modulus arises from stored elastic energy in the inclusions, in contrast to periodic composite metamaterials that exhibit negative refraction by inertial resonant effects. Conventional composites with positive-stiffness constituents have aggregate properties bounded by a weighted average of constituent properties; their modulus cannot exceed that of the stiffest constituent. PMID:17272714

  13. Lower pressure synthesis of diamond material

    DOEpatents

    Lueking, Angela; Gutierrez, Humberto; Narayanan, Deepa; Burgess Clifford, Caroline E.; Jain, Puja

    2010-07-13

    Methods of synthesizing a diamond material, particularly nanocrystalline diamond, diamond-like carbon and bucky diamond are provided. In particular embodiments, a composition including a carbon source, such as coal, is subjected to addition of energy, such as high energy reactive milling, producing a milling product enriched in hydrogenated tetrahedral amorphous diamond-like carbon compared to the coal. A milling product is treated with heat, acid and/or base to produce nanocrystalline diamond and/or crystalline diamond-like carbon. Energy is added to produced crystalline diamond-like carbon in particular embodiments to produce bucky diamonds.

  14. Potential for diamond in kimberlites from Michigan and Montana as indicated by garnet xenocryst compositions

    USGS Publications Warehouse

    McGee, E.S.

    1988-01-01

    The Williams kimberlite in north-central Montana and the Lake Ellen kimberlite in northern Michigan contain diagnostic xenoliths and xenocrysts which indicate that diamonds may be present. To date, however, no diamonds have been reported from either locality. In this study, particular compositions of garnet xenocrysts which are associated with diamond elsewhere were sought as an indication of the potential for diamond in the Williams and Lake Ellen kimberlites. For this study, garnets were carefully selected for purple color in order to increase the chance of finding the subcalcic chrome-rich compositions that are associated with the presence of diamond. -Author

  15. Diamond cutters' grinders

    NASA Astrophysics Data System (ADS)

    Romanov, B. F.

    1985-03-01

    The development of diamond tool designs is determined by the development of the technology for the synthesis of artificial diamonds. The technology of syntehsizing artificial diamonds involves the production of mono and polycrystalline diamonds and composition diamond-containing materials. High strength and thermally stable monocrystalline diamonds brands AS30 to AS80 in a size of up to 800 micrometers, and polycrystalline diamonds: black diamonds, ballas (Synthetic Fiber) in a size up to 10mm, are manufactured. Production of single-layer and double-layer diamond plates used in cutting tools is organized. The raw materials base with the constant decrease in the use of natural diamonds is the basis for the development of the manufacture of a wide array of diamond tools. New areas of applications for tools using natural diamonds, such as diamond cutters for turning high-precision parts, straightening tools, hardness gages are outlined. Diamond cutters with natural diamonds are used to grind surfaces which have exceptionally high requirements with respect to the reflecting capacity and roughness.

  16. Single-layer nano-carbon film, diamond film, and diamond/nano-carbon composite film field emission performance comparison

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoping; Wang, Jinye; Wang, Lijun

    2016-05-01

    A series of single-layer nano-carbon (SNC) films, diamond films, and diamond/nano-carbon (D/NC) composite films have been prepared on the highly doped silicon substrate by using microwave plasma chemical vapor deposition techniques. The films were characterised by scanning electron microscopy, Raman spectroscopy, and field emission I-V measurements. The experimental results indicated that the field emission maximum current density of D/NC composite films is 11.8-17.8 times that of diamond films. And the field emission current density of D/NC composite films is 2.9-5 times that of SNC films at an electric field of 3.0 V/μm. At the same time, the D/NC composite film exhibits the advantage of improved reproducibility and long term stability (both of the nano-carbon film within the D/NC composite cathode and the SNC cathode were prepared under the same experimental conditions). And for the D/NC composite sample, a high current density of 10 mA/cm2 at an electric field of 3.0 V/μm was obtained. Diamond layer can effectively improve the field emission characteristics of nano-carbon film. The reason may be due to the diamond film acts as the electron acceleration layer.

  17. Fiber-integrated diamond-based magnetometer

    NASA Astrophysics Data System (ADS)

    Liu, Xiaodi; Cui, Jinming; Sun, Fangwen; Song, Xuerui; Feng, Fupan; Wang, Junfeng; Zhu, Wei; Lou, Liren; Wang, Guanzhong

    2013-09-01

    We demonstrated a fiber-integrated diamond-based magnetometer in this paper. In the system, the fluorescence of nitrogen vacancy (NV) centers in nanodiamonds deposited on a tapered fiber was coupled to the tapered fiber effectively and detected at the output end of the fiber. By using this scheme, optically detected electron spin resonance spectra were recorded for single NV centers. The results confirmed that such a tapered fiber-nanodiamond system can act as a magnetometer. Featured with excellent portability, convenient fabrication, and potential for further integration, the constructed system has been demonstrated to be a practical magnetometer prototype.

  18. Diamond-based heat spreaders for power electronic packaging applications

    NASA Astrophysics Data System (ADS)

    Guillemet, Thomas

    As any semiconductor-based devices, power electronic packages are driven by the constant increase of operating speed (higher frequency), integration level (higher power), and decrease in feature size (higher packing density). Although research and innovation efforts have kept these trends continuous for now more than fifty years, the electronic packaging technology is currently facing a challenge that must be addressed in order to move toward any further improvements in terms of performances or miniaturization: thermal management. Thermal issues in high-power packages strongly affect their reliability and lifetime and have now become one of the major limiting factors of power modules development. Thus, there is a strong need for materials that can sustain higher heat flux levels while safely integrating into the electronic package architecture. In such context, diamond is an attractive candidate because of its outstanding thermal conductivity, low thermal expansion, and high electrical resistivity. Its low heat capacity relative to metals such as aluminum or copper makes it however preferable for heat spreading applications (as a heat-spreader) rather than for dissipating the heat flux itself (as a heat sink). In this study, a dual diamond-based heat-spreading solution is proposed. Polycrystalline diamond films were grown through laser-assisted combustion synthesis on electronic substrates (in the U.S) while, in parallel, diamond-reinforced copper-matrix composite films were fabricated through tape casting and hot pressing (in France). These two types of diamond-based heat-spreading films were characterized and their microstructure and chemical composition were related to their thermal performances. Particular emphasize was put on the influence of interfaces on the thermal properties of the materials, either inside a single material (grain boundaries) or between dissimilar materials (film/substrate interface, matrix/reinforcement interface). Finally, the packaging

  19. DEVELOPMENT OF ADVANCED DRILL COMPONENTS FOR BHA USING MICROWAVE TECHNOLOGY INCORPORATING CARBIDE, DIAMOND COMPOSITES AND FUNCTIONALLY GRADED MATERIALS

    SciTech Connect

    Dinesh Agrawal; Rustum Roy

    2003-01-01

    The microwave processing of materials is a new emerging technology with many attractive advantages over the conventional methods. The advantages of microwave technology for various ceramic systems has already been demonstrated and proven. The recent developments at Penn State have succeeded in applying the microwave technology for the commercialization of WC/Co and diamond based cutting and drilling tools, effectively sintering of metallic materials, and fabrication of transparent ceramics for advanced applications. In recent years, the Microwave Processing and Engineering Center at Penn State University in collaboration with our industrial partner, Dennis Tool Co. has succeeded in commercializing the developed microwave technology partially funded by DOE for WC/Co and diamond based cutting and drilling tools for gas and oil exploration operations. In this program we have further developed this technology to make diamond-carbide composites and metal-carbide-diamond functionally graded materials. Several actual product of diamond-carbide composites have been processed in microwave with better performance than the conventional product. The functionally graded composites with diamond as one of the components has been for the first time successfully developed. These are the highlights of the project.

  20. Origin of sub-lithospheric diamonds from the Juina-5 kimberlite (Brazil): constraints from carbon isotopes and inclusion compositions

    NASA Astrophysics Data System (ADS)

    Thomson, A. R.; Kohn, S. C.; Bulanova, G. P.; Smith, C. B.; Araujo, D.; Walter, M. J.

    2014-12-01

    Forty-one diamonds sourced from the Juina-5 kimberlite pipe in Southern Brazil, which contain optically identifiable inclusions, have been studied using an integrated approach. The diamonds contain <20 ppm nitrogen (N) that is fully aggregated as B centres. Internal structures in several diamonds revealed using cathodoluminescence (CL) are unlike those normally observed in lithospheric samples. The majority of the diamonds are composed of isotopically light carbon, and the collection has a unimodal distribution heavily skewed towards δ13C ~ -25 ‰. Individual diamonds can display large carbon isotope heterogeneity of up to ~15 ‰ and predominantly have isotopically lighter cores displaying blue CL, and heavier rims with green CL. The light carbon isotopic compositions are interpreted as evidence of diamond growth from abiotic organic carbon added to the oceanic crust during hydrothermal alteration. The bulk isotopic composition of the oceanic crust, carbonates plus organics, is equal to the composition of mantle carbon (-5 ‰), and we suggest that recycling/mixing of subducted material will replenish this reservoir over geological time. Several exposed, syngenetic inclusions have bulk compositions consistent with former eclogitic magnesium silicate perovskite, calcium silicate perovskite and NAL or CF phases that have re-equilibrated during their exhumation to the surface. There are multiple occurrences of majoritic garnet with pyroxene exsolution, coesite with and without kyanite exsolution, clinopyroxene, Fe or Fe-carbide and sulphide minerals alongside single occurrences of olivine and ferropericlase. As a group, the inclusions have eclogitic affinity and provide evidence for diamond formation at pressures extending to Earth's deep transition zone and possibly the lower mantle. It is observed that the major element composition of inclusions and isotopic compositions of host Juina-5 diamonds are not correlated. The diamond and inclusion compositions are

  1. Copper-diamond composite substrates for electronic components

    SciTech Connect

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

    1995-01-25

    High-power density electronic components such as fast microprocessors and power semiconductors are often limited by inability to keep the device junctions below their max rated operating temperature. Present high power multichip module and single chip package designs use substrate materials such as Si nitride or copper tungsten with thermal conductivity in the range of 200 W/m{center_dot}K. We have developed a copper-diamond composite (Dymalloy) with a thermal conductivity of 420 W/m{center_dot}K, better than Cu, and an adjustable thermal expansion coefficient (TCE=5.5 ppM/C at 25 C), compatible with Si and GaAs. Because of the matched TCE, it is possible to use low thermal resistance hard die attach methods. The mechanical properties of the composite also make it attractive as an electronic component substrate material.

  2. Ultrastable mirrors made from diamond reinforced SiC composites for high precision and power applications

    NASA Astrophysics Data System (ADS)

    Akbas, M. A.; Mastrobattisto, D.; Vance, W.; Jurgaitis, P.; Aghajanian, M. K.

    2012-10-01

    Diamond reinforced reaction bonded silicon carbide composites have unique properties such as very high stiffness, low density, low thermal expansion coefficient and high thermal conductivity making them attractive materials for high precision optical and structural components. However, their use in high precision equipments was limited due to significant difficulties in high tolerance machining of these super hard composites. In this present work, machineable diamond reinforced SiC composites were fabricated through forming hybrid monolithic microstructures with diamond free machineable surfaces. The resulting machineable composites were used to produce ultra-stable mirror substrates with optional internal cooling channels for high power laser optic applications.

  3. Fabrication of diamond based sensors for use in extreme environments

    DOE PAGESBeta

    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

  4. Fabrication of diamond based sensors for use in extreme environments

    SciTech Connect

    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 method 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.

  5. Cutting effectiveness of diamond points on commercial core composite resins and cements.

    PubMed

    Miyawaki, H; Taira, M; Yamaki, M

    1996-06-01

    In dental clinics, composite resin and cement cores are routinely cut and polished during abutment tooth preparation. To identify their characteristics during cutting, weight-load cutting tests were performed on eight commercial core composites and two cements, using diamond points driven by an air-turbine handpiece. It became evident that the cutting effectiveness of the diamond points on nine workpieces exceeded that on natural tooth dentine, while that on one composite containing Si3,N4 filler was analogous to that on dentine. With continued use, the cutting effectiveness of the diamond point on all workpieces gradually declined. SEM observations revealed that diamond particles of the diamond point wore out with repeated use. It is clinically advised to select the core material with material characteristics during cutting and mechanical strength similar to those of dentin. PMID:8809696

  6. Studies of phase composition of contact sites of diamond crystals and the surrounding rocks

    NASA Astrophysics Data System (ADS)

    Skvortsova, V. L.; Samoylovich, M. I.; Belyanin, A. F.

    2015-11-01

    The composition, structure, and morphology of iron-containing diamond-kimberlite contact sites were studied by means of scanning electron microscopy and Raman spectroscopy. The data obtained confirm the hypothesis of the similarity of mechanisms of diamond formation in nature and in experiments.

  7. Diamond fiber field emitters

    DOEpatents

    Blanchet-Fincher, Graciela B.; Coates, Don M.; Devlin, David J.; Eaton, David F.; Silzars, Aris K.; Valone, Steven M.

    1996-01-01

    A field emission electron emitter comprising an electrode formed of at least one diamond, diamond-like carbon or glassy carbon composite fiber, said composite fiber having a non-diamond core and a diamond, diamond-like carbon or glassy carbon coating on said non-diamond core, and electronic devices employing such a field emission electron emitter.

  8. Graded composite diamond coatings with top-layer nanocrystallinity and interfacial integrity: Cross-sectional Raman mapping

    NASA Astrophysics Data System (ADS)

    Dumpala, Ravikumar; Ramamoorthy, B.; Rao, M. S. Ramachandra

    2014-01-01

    Cross-sectional structural characteristics of the CVD diamond coatings deposited on the tungsten carbide (WC-Co) substrates were analysed using Raman imaging technique. The grain size of the nanocrystalline diamond (NCD) coatings was observed to deviate from the nanocrystallinity with increasing thickness and exhibited the surface characteristics of microcrystalline diamond (MCD). However, thick diamond coatings with surface nanocrystallinity is the key requirement for load-bearing tribological applications. Tribological tests have clearly indicated the significance and need for the top-layer nanocrystallinity. Graded composite diamond coatings with an architecture of NCD/transition-layer/MCD/WC-Co are potentail candiadates to realize thick diamond coatings with top-layer nanocrystallinity. Residual stresses along the cross-section of the graded composite diamond coatings were analysed using Raman imaging technique, which confirmed the improved interfacial integrity of the graded composite diamond coatings

  9. Diamond-based capacitive micromachined ultrasonic transducers in immersion.

    PubMed

    Cetin, Ahmet M; Bayram, Baris

    2013-02-01

    Diamond is a superior membrane material for capacitive micromachined ultrasonic transducers (CMUTs). By using ultrananocrystalline diamond (UNCD) membrane and plasma-activated wafer bonding technology, a single diamond-based circular CMUT is demonstrated and operated in immersion for the first time. The diamond-based CMUT, biased at 100 V, is excited with a 10-cycle burst of 36 V(p-p) sine signal at 3.5 MHz. Pressure generated on a 2-D plane coincident with the normal of the CMUT is measured using a broadband hydrophone. Peak-to-peak hydrophone voltage measurements along the scan area clearly indicate the main lobe and the side lobes, as theoretically predicted by our directivity function calculations. The peak-to-peak hydrophone voltage on the axial direction of the CMUT is found to be in agreement with our theoretical calculations in the Fraunhofer region (-45 mm diamond-based CMUT is measured for a dc bias of 100 V, and ac excitation with 30-cycle bursts of 9, 36, and 54 V(p-p) sine signal. A peak response at 5.6 MHz is measured for all ac amplitudes. Overall, diamond is shown to be an applicable membrane for CMUT devices and applications. PMID:23357916

  10. Crystallization of diamond from a silicate melt of kimberlite composition in high-pressure and high-temperature experiments

    SciTech Connect

    Arima, Makoto; Nakayama, Kazuhiro ); Akaishi, Minoru; Yamaoka, Shinobu; Kanda, Hisao )

    1993-11-01

    In high-pressure and high-temperature experiments (1800-2200[degrees]C and 7.0-7.7 GPa), diamond crystallized and grew in a volatile-rich silicate melt of kimberlite composition. This diamond has well-developed [111] faces, and its morphologic characteristics resemble those of natural diamond but differ from those of synthetic diamond grown from metallic solvent-catalysts. The kimberlite melt has a strong solvent-catalytic effect on diamond formation, supporting the view that some natural diamonds crystallized from volatile-rich melts in the upper mantle. 19 refs., 3 figs., 1 tab.

  11. 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.

  12. Sputtered tungsten-based ternary and quaternary layers for nanocrystalline diamond deposition.

    PubMed

    Walock, Michael J; Rahil, Issam; Zou, Yujiao; Imhoff, Luc; Catledge, Shane A; Nouveau, Corinne; Stanishevsky, Andrei V

    2012-06-01

    Many of today's demanding applications require thin-film coatings with high hardness, toughness, and thermal stability. In many cases, coating thickness in the range 2-20 microm and low surface roughness are required. Diamond films meet many of the stated requirements, but their crystalline nature leads to a high surface roughness. Nanocrystalline diamond offers a smoother surface, but significant surface modification of the substrate is necessary for successful nanocrystalline diamond deposition and adhesion. A hybrid hard and tough material may be required for either the desired applications, or as a basis for nanocrystalline diamond film growth. One possibility is a composite system based on carbides or nitrides. Many binary carbides and nitrides offer one or more mentioned properties. By combining these binary compounds in a ternary or quaternary nanocrystalline system, we can tailor the material for a desired combination of properties. Here, we describe the results on the structural and mechanical properties of the coating systems composed of tungsten-chromium-carbide and/or nitride. These WC-Cr-(N) coatings are deposited using magnetron sputtering. The growth of adherent nanocrystalline diamond films by microwave plasma chemical vapor deposition has been demonstrated on these coatings. The WC-Cr-(N) and WC-Cr-(N)-NCD coatings are characterized with atomic force microscopy and SEM, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and nanoindentation. PMID:22905536

  13. Fabry-Perot microcavity for diamond-based photonics

    NASA Astrophysics Data System (ADS)

    Janitz, Erika; Ruf, Maximilian; Dimock, Mark; Bourassa, Alexandre; Sankey, Jack; Childress, Lilian

    2015-10-01

    Open Fabry-Perot microcavities represent a promising route for achieving a quantum electrodynamics (cavity-QED) platform with diamond-based emitters. In particular, they offer the opportunity to introduce high-purity, minimally fabricated material into a tunable, high quality factor optical resonator. Here, we demonstrate a fiber-based microcavity incorporating a thick (>10 μ m ) diamond membrane with a finesse of 17 000, corresponding to a quality factor Q ˜106 . Such minimally fabricated thick samples can contain optically stable emitters similar to those found in bulk diamond. We observe modified microcavity spectra in the presence of the membrane, and we develop analytic and numerical models to describe the effect of the membrane on cavity modes, including loss and coupling to higher-order transverse modes. We estimate that a Purcell enhancement of approximately 20 should be possible for emitters within the diamond in this device, and we provide evidence that better diamond surface treatments and mirror coatings could increase this value to 200 in a realistic system.

  14. Selective detector of cosmic particles based on diamond sensitive elements

    NASA Astrophysics Data System (ADS)

    Altukhov, A. A.; Zaharchenko, K. V.; Kolyubin, V. A.; Lvov, S. A.; Nedosekin, P. G.; Tyurin, E. M.; Ibragimov, R. F.; Kadilin, V. V.; Nikolaev, I. V.

    2016-02-01

    The article describes the device for selective registration of electrons, protons and heavy ions fluxes from the solar and galactic cosmic rays in the twelve energy ranges, built on a base of diamond detector. The use of the diamond detectors allowed for the creation a device for registration of cosmic particles fluxes at the external spacecraft surface with the resource not less than 20 years. Selective detector is aimed for continuous monitoring of radiation situation on board the spacecrafts, in order to predict the residual life of their work and prompt measures to actively protect the spacecraft when the flow of cosmic particles is sharply increased.

  15. Interfacial characteristics of diamond/aluminum composites with high thermal conductivity fabricated by squeeze-casting method

    SciTech Connect

    Jiang, Longtao; Wang, Pingping; Xiu, Ziyang; Chen, Guoqin; Lin, Xiu; Dai, Chen; Wu, Gaohui

    2015-08-15

    In this work, aluminum matrix composites reinforced with diamond particles (diamond/aluminum composites) were fabricated by squeeze casting method. The material exhibited a thermal conductivity as high as 613 W / (m · K). The obtained composites were investigated by scanning electron microscope and transmission electron microscope in terms of the (100) and (111) facets of diamond particles. The diamond particles were observed to be homogeneously distributed in the aluminum matrix. The diamond{sub (111)}/Al interface was found to be devoid of reaction products. While at the diamond{sub (100)}/Al interface, large-sized aluminum carbides (Al{sub 4}C{sub 3}) with twin-crystal structure were identified. The interfacial characteristics were believed to be responsible for the excellent thermal conductivity of the material. - Graphical abstract: Display Omitted - Highlights: • Squeeze casting method was introduced to fabricate diamond/Al composite. • Sound interfacial bonding with excellent thermal conductivity was produced. • Diamond{sub (111)}/ aluminum interface was firstly characterized by TEM/HRTEM. • Physical combination was the controlling bonding for diamond{sub (111)}/aluminum. • The growth mechanism of Al{sub 4}C{sub 3} was analyzed by crystallography theory.

  16. Self-composite comprised of nanocrystalline diamond and a non-diamond component useful for thermoelectric applications

    DOEpatents

    Gruen, Dieter M.

    2012-09-04

    One provides nanocrystalline diamond material that comprises a plurality of substantially ordered diamond crystallites that are sized no larger than about 10 nanometers. One then disposes a non-diamond component within the nanocrystalline diamond material. By one approach this non-diamond component comprises an electrical conductor that is formed at the grain boundaries that separate the diamond crystallites from one another. The resultant nanowire is then able to exhibit a desired increase with respect to its ability to conduct electricity while also preserving the thermal conductivity behavior of the nanocrystalline diamond material.

  17. Self-composite comprised of nanocrystalline diamond and a non-diamond component useful for thermoelectric applications

    DOEpatents

    Gruen, Dieter M.

    2009-08-11

    One provides nanocrystalline diamond material that comprises a plurality of substantially ordered diamond crystallites that are sized no larger than about 10 nanometers. One then disposes a non-diamond component within the nanocrystalline diamond material. By one approach this non-diamond component comprises an electrical conductor that is formed at the grain boundaries that separate the diamond crystallites from one another. The resultant nanowire is then able to exhibit a desired increase with respect to its ability to conduct electricity while also preserving the thermal conductivity behavior of the nanocrystalline diamond material.

  18. Composition of primary kimberlite magma: constraints from melting and diamond dissolution experiments

    NASA Astrophysics Data System (ADS)

    Sokol, A. G.; Khokhryakov, A. F.; Palyanov, Yu. N.

    2015-09-01

    Experiments are applied to constrain the composition of primary kimberlitic magmas which were in equilibrium with lithospheric peridotite and could resorb the entrained diamond to form typical dissolution features. The experiments are run on samples of a model carbonatite and a melt of the Udachnaya kimberlite at 6.3 GPa and 1400 °C, and at unbuffered or Re-ReO2-buffered oxygen fugacity (1-2 log units above Ni-NiO). Near-liquidus dry Fe3+-free carbonatitic melt (derived from carbonated harzburgite) is saturated with the Ol-Grt-Opx-Mgs assemblage and is almost inert to diamond. Carbonatitic melts that bear 4.6-6.8 wt% Fe2O3 or 1.5 wt% H2O are in equilibrium only with Mgs ± Ol near the liquidus. Dissolution of diamond by these melts produces surface textures uncommon (corrosion sculptures) or common (negative-oriented trigons, shield-shaped laminae and elongate hillocks) to kimberlitic diamonds. The near-liquidus melt of the Udachnaya kimberlite (Yakutia) with 10-12 wt% H2O is saturated with the Ol-Grt-Cpx assemblage and may result from melting of carbonated garnet-bearing wehrlite. Hydrous kimberlitic melt likewise resorbs diamonds forming typical negative-oriented trigons, shield-shaped laminae and elongate hillocks on their surfaces. Therefore, the melts that could originate in the thermal conditions of subcratonic lithosphere, entrain diamond and dissolve it to produce dissolution features on crystal surfaces, were compositionally close to kimberlite (16-19 wt% SiO2) and rich in H2O. Dry Fe3+-bearing carbonatites with fO2 controlled by the ferric/ferrous equilibrium slightly above the Ni-NiO buffer cannot be diamond carriers.

  19. Beneficial effects of laser irradiation on the deposition process of diamond/Ni60 composite coating with cold spray

    NASA Astrophysics Data System (ADS)

    Yao, Jianhua; Yang, Lijing; Li, Bo; Li, Zhihong

    2015-03-01

    Although cold spray process has many unique advantages over other coating techniques, it has difficulties in depositing hard materials. This article presents a study in the beneficial effects of laser irradiation on the fabrication process of diamond/Ni60 composite coating using cold spray. The focus of this research is on the comparison between the composite coatings produced with laser cladding (LC) and with supersonic laser deposition (SLD), with respect to diamond graphitization and tribological properties, thus to demonstrate the beneficial effects of laser irradiation on the cold spray process. The influence of deposition temperature on the coating characteristics, such as deposition efficiency, diamond volume fraction, microstructure and phase is also investigated. The tribological properties of the diamond/Ni60 composite coating produced with SLD are determined using a pin-on-disc tribometer, along with the diamond/Ni60 coating produced using LC with the optimal process parameters for comparison. The experimental results show that with the assistance of laser irradiation, diamond/Ni60 composite coating can be successfully deposited using cold spray; the obtained coating is superior to that processed with LC, because SLD can suppress the graphitization of the diamond particles. The diamond/Ni60 composite coating fabricated with SLD has much better tribological properties than the LC coating.

  20. Focus on diamond-based photonics and spintronics

    NASA Astrophysics Data System (ADS)

    Jelezko, Fedor; Wrachtrup, Jörg

    2012-10-01

    The ability to control the state of individual atoms is a new challenge for science and technology in the 21st century. Currently, experiments on individual quantum systems such as trapped ions, single molecules, quantum dots, superconducting qubits and photons are crucial for the rapidly growing field of quantum information processing and communication. In general, solid state systems are preferable for scaling and the choice of material plays a crucial role; for example, in classical electronic devices continual performance enhancement and miniaturization is strongly linked to the success of silicon-based technology. For quantum applications, diamond has the potential to become the material of choice, because its large bandgap enables the control of optically active impurities and higher operation temperature. This focus issue collates original research contributions from some of the leading groups in the field as a showcase for the very latest developments in diamond-based quantum technologies.

  1. Thermodynamic characterization of a diamond-based electron emitter

    NASA Astrophysics Data System (ADS)

    Fisher, T. S.; Strauss, A. M.; Davidson, J. L.; Kang, W. P.

    2000-01-01

    This paper contains a thermodynamic analysis of electron emission from a micro-fabricated diamond tip array. The analysis is based on experimental measurements of the current-voltage characteristics of an actual device. Field enhancement, applied field, and electrical current density are shown to influence thermodynamic performance. The idealized thermodynamic analysis predicts cooling rates above 10 W/cm2 for an existing device under room temperature operation and that 100 W/cm2 may be possible for future devices. .

  2. Diamond/silicon carbide composites sintered under high pressure-high temperature conditions

    NASA Astrophysics Data System (ADS)

    Qian, Jiang

    In this dissertation work, novel bulk diamond composites with nano-size grain and nanocrystalline SiC bonding were sintered under high pressure-high temperature (HP-HT) conditions. While preserving the superior hardness, wear resistance of micron-composites, nano-composites have higher strength and fracture toughness due to effective blocking of microcrack propagation and dislocation movement by the nanocrystalline grains. New preparation method, wet mixing and high-energy ball milling, have been used to make starting materials to avoid the self-stop process due to pore closure in HP-HT liquid phase sintering. Key factors influencing the dynamics of the reaction between diamond and silicon, such as diamond graphitization process, phase composition and stress-strain, were thoroughly studied with Raman spectroscopy, x-ray diffraction, SEM and TEM techniques. Mechanical properties of the composites were characterized by ultrasonic interferometer and microindentation hardness measurements. Nanostructured composites represent a new field of fundamental science and manifest potential application in multiple industries.

  3. Using the diamond intermediate anastomosis in composite sequential bypass grafting for critical limb ischemia.

    PubMed

    Rogers, Ailín C; Reddy, Paul W; Cross, K Simon; McMonagle, Morgan P

    2016-04-01

    Composite sequential bypass grafting is an effective alternative in the treatment of peripheral vascular disease when autologous vein is limited. We describe a modified technique for composite sequential bypass grafting anastomosis using a combination of synthetic graft with native vein connected via a common intermediate anastomotic junction, which also benefits from having additional outflow at the native, noncontiguous arteriotomy in a diamond configuration. This technique was piloted on six patients to treat critical limb ischemia when no other revascularization options were deemed suitable. Limb salvage with resolution of symptoms was achieved in all six patients at the 6-month follow-up. The diamond anastomosis is a promising method to maximize limb salvage using a unique composite sequential bypass configuration when native vein is limited. PMID:27016861

  4. Picosecond pulsed laser processing of polycrystalline diamond and cubic boron nitride composite materials

    NASA Astrophysics Data System (ADS)

    Warhanek, Maximilian G.; Pfaff, Josquin; Meier, Linus; Walter, Christian; Wegener, Konrad

    2016-03-01

    Capabilities and advantages of laser ablation processes utilizing ultrashort pulses have been demonstrated in various applications of scientific and industrial nature. Of particular interest are applications that require high geometrical accuracy, excellent surface integrity and thus tolerate only a negligible heat-affected zone in the processed area. In this context, this work presents a detailed study of the ablation characteristics of common ultrahard composite materials utilized in the cutting tool industry, namely polycrystalline diamond (PCD) and polycrystalline cubic boron nitride composite (PCBN). Due to the high hardness of these materials, conventional mechanical processing is time consuming and costly. Herein, laser ablation is an appealing solution, since no process forces and no wear have to be taken into consideration. However, an industrially viable process requires a detailed understanding of the ablation characteristics of each material. Therefore, the influence of various process parameters on material removal and processing quality at 10 ps pulse duration are investigated for several PCD and PCBN grades. The main focus of this study examines the effect of different laser energy input distributions, such as pulse frequency and burst pulses, on the processing conditions in deep cutting kerfs and the resulting processing speed. Based on these results, recommendations for efficient processing of such materials are derived.

  5. Towards an NV Diamond Based Pressure Imager

    NASA Astrophysics Data System (ADS)

    Milbourne, Timothy; Barry, John; Turner, Matthew; Zhang, Huiliang; Arai, Keigo; Walsworth, Ronald

    2016-05-01

    The ability to image applied pressures is of great interest for various biological and physical applications. Using an array of wires printed on a thin layer of polydimethylsiloxane (PDMS), nitrogen-vacancy (NV) center-based magnetic field imaging techniques may be used to realize a combination of high sensitivity and spatial resolution not offered by current sensing technologies. Here we present the first steps toward such a NV-based pressure imager.

  6. First principles study of Fe in diamond: A diamond-based half metallic dilute magnetic semiconductor

    SciTech Connect

    Benecha, E. M.; Lombardi, E. B.

    2013-12-14

    Half-metallic ferromagnetic ordering in semiconductors, essential in the emerging field of spintronics for injection and transport of highly spin polarised currents, has up to now been considered mainly in III–V and II–VI materials. However, low Curie temperatures have limited implementation in room temperature device applications. We report ab initio Density Functional Theory calculations on the properties of Fe in diamond, considering the effects of lattice site, charge state, and Fermi level position. We show that the lattice sites and induced magnetic moments of Fe in diamond depend strongly on the Fermi level position and type of diamond co-doping, with Fe being energetically most favorable at the substitutional site in p-type and intrinsic diamond, while it is most stable at a divacancy site in n-type diamond. Fe induces spin polarized bands in the band gap, with strong hybridization between Fe-3d and C-2s,2p bands. We further consider Fe-Fe spin interactions in diamond and show that substitutional Fe{sup +1} in p-type diamond exhibits a half-metallic character, with a magnetic moment of 1.0 μ{sub B} per Fe atom and a large ferromagnetic stabilization energy of 33 meV, an order of magnitude larger than in other semiconductors, with correspondingly high Curie temperatures. These results, combined with diamond's unique properties, demonstrate that Fe doped p-type diamond is likely to be a highly suitable candidate material for spintronics applications.

  7. Paragenesis of Diamond and Minerals of Peridotites and Carbonatites in the Mantle Magma Chambers Based on Experiments Data

    NASA Astrophysics Data System (ADS)

    Kuzyura, Anastasia; Simonova, Dariya; Litvin, Yury

    2014-05-01

    It is considered that role of carbonate melts is important in processes of mantle metasomatism; according to other representations, it is also assumed that they could be formed at partial melting of carbonated peridotite. Dissolving of peridotite minerals and carbon in carbonate melts are responsible for formation of completely miscible carbonate-silicate-carbon magmas parental for diamonds. It can be expected that such carbonate magmas are capable to assimilate an form parental magama "chambers" within the hosting mantle peridotite. While natural cooling of the chambers dissolved in carbonate melts components of the peridotite crystallize forming minerals similar to these of the host mantle peridotite. The recrystallized peridotite minerals are fragmentarily included hermetically within growing diamonds and occur as syngenetic inclusions in them. Therefore experimental modeling of origin of the upper mantle carbonate-silicate diamond-forming melts, their consolidations in the magmatic chambers and evolutions at conditions of equilibrium and fractional crystallization are especially significant for understanding of processes of deep magmatic petrology and genetic mineralogy, including genesis of diamond. In the study at 6 GPa model approximations of mineral phases, significant in compositions of probable metasomatic agents, the upper mantle peridotites, and also syngenetic inclusions in diamonds were used: starting mixtures were model peridotite with composition Ol48Opx16Cpx16Grt20, close to model compositions of the primitive mantle and real mantle xenolithes, as well as multicomponent carbonate (CaCO3)20(Na2CO3)20(FeCO3)20(Na2CO3)20(K2CO3)20 modeling carbonatite inclusions in natural diamonds. Spectral pure graphite was used as a source of carbon in the system. Pressure and temperature were reached using apparatus of toroidal type 'anvil-with-hole'. Electron microprobe and SEM researches were carried out on the polished surfaces with carbon covering at IEM RAS

  8. Field emission from hybrid diamond-like carbon and carbon nanotube composite structures.

    PubMed

    Zanin, H; May, P W; Hamanaka, M H M O; Corat, E J

    2013-12-11

    A thin diamond-like carbon (DLC) film was deposited onto a densely packed "forest" of vertically aligned multiwalled carbon nanotubes (VACNT). DLC deposition caused the tips of the CNTs to clump together to form a microstructured surface. Field-emission tests of this new composite material show the typical low threshold voltages for carbon nanotube structures (2 V μm(-1)) but with greatly increased emission current, better stability, and longer lifetime. PMID:24224845

  9. Polycrystalline diamond based detector for Z-pinch plasma diagnosis

    SciTech Connect

    Liu Linyue; Zhao Jizhen; Chen Liang; Ouyang Xiaoping; Wang Lan

    2010-08-15

    A detector setup based on polycrystalline chemical-vapor-deposition diamond film is developed with great characteristics: low dark current (lower than 60 pA within 3 V/{mu}m), fast pulsed response time (rise time: 2-3 ns), flat spectral response (3-5 keV), easy acquisition, low cost, and relative large sensitive area. The characterizing data on Qiangguang-I accelerator show that this detector can satisfy the practical requirements in Z-pinch plasma diagnosis very well, which offers a promising prototype for the x-ray detection in Z-pinch diagnosis.

  10. Diffractive Optical Elements based in Diamond Like Carbon (DLC) films

    NASA Astrophysics Data System (ADS)

    Sparvoli, M. Marina; Mansano, Ronaldo D.

    2008-04-01

    In this work was developed a Diffractive Optical Elements (DOEs) based in amorphous hydrogenated carbon (Diamond Like Carbon) films. DOEs can be built in large scale with high reproducibility and eliminating almost stages used in optical elements tradicional fabrication, as abrasion and burnishing. These devices had been built by the etching of DLC deposited by sputtering process. The characterizations of these devices are realized by optical analyzes with a 633 nm HeNe laser. The DLC films roughness and etch rate after process were measured by high step meter.

  11. Advanced Diamond Anvil Techniques (Customized Diamond Anvils)

    SciTech Connect

    Weir, S

    2009-02-11

    A complete set of diamond-based fabrication tools now exists for making a wide range of different types of diamond anvils which are tailored for various high-P applications. Current tools include: CVD diamond deposition (making diamond); Diamond polishing, laser drilling, plasma etching (removal of diamond); and Lithography, 3D laser pantography (patterning features onto diamond); - Metal deposition (putting electrical circuits and metal masks onto diamond). Current applications include the following: Electrical Conductivity; Magnetic Susceptibility; and High-P/High-T. Future applications may include: NMR; Hall Effect; de Haas - Shubnikov (Fermi surface topology); Calorimetry; and thermal conductivity.

  12. Most diamonds were created equal

    NASA Astrophysics Data System (ADS)

    Jablon, Brooke Matat; Navon, Oded

    2016-06-01

    Diamonds crystallize deep in the mantle (>150 km), leaving their carbon sources and the mechanism of their crystallization debatable. They can form from elemental carbon, by oxidation of reduced species (e.g. methane) or reduction of oxidized ones (e.g. carbonate-bearing minerals or melts), in response to decreasing carbon solubility in melts or fluids or due to changes in pH. The mechanism of formation is clear for fibrous diamonds that grew from the carbonate-bearing fluids trapped in their microinclusions. However, these diamonds look different and, based on their lower level of nitrogen aggregation, are much younger than most monocrystalline (MC) diamonds. In the first systematic search for microinclusions in MC diamonds we examined twinned crystals (macles), assuming that during their growth, microinclusions were trapped along the twinning plane. Visible mineral inclusions (>10 μm) and nitrogen aggregation levels in these clear macles are similar to other MC diamonds. We found 32 microinclusions along the twinning planes in eight out of 30 diamonds. Eight inclusions are orthopyroxene; four contain >50% K2O (probably as K2(Mg, Ca)(CO3)2); but the major element compositions of the remaining 20 are similar to those of carbonate-bearing high-density fluids (HDFs) found in fibrous diamonds. We conclude that the source of carbon for these macles and for most diamonds is carbonate-bearing HDFs similar to those found here and in fibrous diamonds. Combined with the old ages of MC diamonds (up to 3.5 Ga), our new findings suggest that carbonates have been introduced into the reduced lithospheric mantle since the Archaean and that the mechanism of diamond formation is the same for most diamonds.

  13. Synthesis and Characterization of Single-Wall Carbon Nanotube-Amorphous Diamond Thin-Film Composites

    SciTech Connect

    Schittenhelm, Henrik; Geohegan, David B; Jellison Jr, Gerald Earle; Puretzky, Alexander A; Lance, Michael J; Britt, Phillip F

    2002-01-01

    Thin-film single-wall carbon nanotube (SWNT) composites synthesized by pulsed laser deposition (PLD) are reported. Ultrahard, transparent, pure-carbon, electrically insulating, amorphous diamond thin films were deposited by PLD as scratch-resistant, encapsulating matrices for disperse, electrically conductive mats of SWNT bundles. In situ resistance measurements of the mats during PLD, as well as ex situ Raman spectroscopy, current-voltage measurements, spectroscopic ellipsometry, and field-emission scanning electron microscopy, are used to understand the interaction between the SWNT and the highly energetic ({approx}100 eV) carbon species responsible for the formation of the amorphous diamond thin film. The results indicate that a large fraction of SWNT within the bundles survive the energetic bombardment from the PLD plume, preserving the metallic behavior of the interconnected nanotube mat, although with higher resistance. Amorphous diamond film thicknesses of only 50 nm protect the SWNT against wear, providing scratch hardness up to 25 GPa in an optically transmissive, all-carbon thin-film composite.

  14. Effect of sintering on the relative density of Cr-coated diamond/Cu composites prepared by spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Cui, Wei; Xu, Hui; Chen, Jian-hao; Ren, Shu-bin; He, Xin-bo; Qu, Xuan-hui

    2016-06-01

    Cr-coated diamond/Cu composites were prepared by spark plasma sintering. The effects of sintering pressure, sintering temperature, sintering duration, and Cu powder particle size on the relative density and thermal conductivity of the composites were investigated in this paper. The influence of these parameters on the properties and microstructures of the composites was also discussed. The results show that the relative density of Cr-coated diamond/Cu reaches ~100% when the composite is gradually compressed to 30 MPa during the heating process. The densification temperature increases from 880 to 915°C when the diamond content is increased from 45vol% to 60vol%. The densification temperature does not increase further when the content reaches 65vol%. Cu powder particles in larger size are beneficial for increasing the relative density of the composite.

  15. Copper Multiwall Carbon Nanotubes and Copper-Diamond Composites for Advanced Rocket Engines

    NASA Technical Reports Server (NTRS)

    Bhat, Biliyar N.; Ellis, Dave L.; Smelyanskiy, Vadim; Foygel, Michael; Singh, Jogender; Rape, Aaron; Vohra, Yogesh; Thomas, Vinoy; Li, Deyu; Otte, Kyle

    2013-01-01

    This paper reports on the research effort to improve the thermal conductivity of the copper-based alloy NARloy-Z (Cu-3 wt.%Ag-0.5 wt.% Zr), the state-of-the-art alloy used to make combustion chamber liners in regeneratively-cooled liquid rocket engines, using nanotechnology. The approach was to embed high thermal conductivity multiwall carbon nanotubes (MWCNTs) and diamond (D) particles in the NARloy-Z matrix using powder metallurgy techniques. The thermal conductivity of MWCNTs and D have been reported to be 5 to 10 times that of NARloy-Z. Hence, 10 to 20 vol. % MWCNT finely dispersed in NARloy-Z matrix could nearly double the thermal conductivity, provided there is a good thermal bond between MWCNTs and copper matrix. Quantum mechanics-based modeling showed that zirconium (Zr) in NARloy-Z should form ZrC at the MWCNT-Cu interface and provide a good thermal bond. In this study, NARloy-Z powder was blended with MWCNTs in a ball mill, and the resulting mixture was consolidated under high pressure and temperature using Field Assisted Sintering Technology (FAST). Microstructural analysis showed that the MWCNTs, which were provided as tangles of MWCNTs by the manufacturer, did not detangle well during blending and formed clumps at the prior particle boundaries. The composites made form these powders showed lower thermal conductivity than the base NARloy-Z. To eliminate the observed physical agglomeration, tangled multiwall MWCNTs were separated by acid treatment and electroless plated with a thin layer of chromium to keep them separated during further processing. Separately, the thermal conductivities of MWCNTs used in this work were measured, and the results showed very low values, a major factor in the low thermal conductivity of the composite. On the other hand, D particles embedded in NARloy-Z matrix showed much improved thermal conductivity. Elemental analysis showed migration of Zr to the NARloy-Z-D interface to form ZrC, which appeared to provide a low contact

  16. Copper-Multiwall Carbon Nanotubes and Copper-Diamond Composites for Advanced Rocket Engines

    NASA Technical Reports Server (NTRS)

    Bhat, Biliyar N.; Ellis, Dave L.; Smelyanskiy, Vadim; Foygel, Michael; Rape, Aaron; Singh, Jogender; Vohra, Yogesh K.; Thomas, Vinoy; Otte, Kyle G.; Li, Deyu

    2013-01-01

    This paper reports on the research effort to improve the thermal conductivity of the copper-based alloy NARloy-Z (Cu-3 wt.%Ag-0.5 wt.% Zr), the state-of-the-art alloy used to make combustion chamber liners in regeneratively-cooled liquid rocket engines, using nanotechnology. The approach was to embed high thermal conductivity multiwall carbon nanotubes (MWCNTs) and diamond (D) particles in the NARloy-Z matrix using powder metallurgy techniques. The thermal conductivity of MWCNTs and D have been reported to be 5 to 10 times that of NARloy-Z. Hence, 10 to 20 vol. % MWCNT finely dispersed in NARloy-Z matrix could nearly double the thermal conductivity, provided there is a good thermal bond between MWCNTs and copper matrix. Quantum mechanics-based modeling showed that zirconium (Zr) in NARloy-Z should form ZrC at the MWCNT-Cu interface and provide a good thermal bond. In this study, NARloy-Z powder was blended with MWCNTs in a ball mill, and the resulting mixture was consolidated under high pressure and temperature using Field Assisted Sintering Technology (FAST). Microstructural analysis showed that the MWCNTs, which were provided as tangles of MWCNTs by the manufacturer, did not detangle well during blending and formed clumps at the prior particle boundaries. The composites made form these powders showed lower thermal conductivity than the base NARloy-Z. To eliminate the observed physical agglomeration, tangled multiwall MWCNTs were separated by acid treatment and electroless plated with a thin layer of chromium to keep them separated during further processing. Separately, the thermal conductivities of MWCNTs used in this work were measured, and the results showed very low values, a major factor in the low thermal conductivity of the composite. On the other hand, D particles embedded in NARloy-Z matrix showed much improved thermal conductivity. Elemental analysis showed migration of Zr to the NARloy-Z-D interface to form ZrC, which appeared to provide a low contact

  17. Could one make a diamond-based quantum computer?

    PubMed

    Stoneham, A Marshall; Harker, A H; Morley, Gavin W

    2009-09-01

    We assess routes to a diamond-based quantum computer, where we specifically look towards scalable devices, with at least 10 linked quantum gates. Such a computer should satisfy the deVincenzo rules and might be used at convenient temperatures. The specific examples that we examine are based on the optical control of electron spins. For some such devices, nuclear spins give additional advantages. Since there have already been demonstrations of basic initialization and readout, our emphasis is on routes to two-qubit quantum gate operations and the linking of perhaps 10-20 such gates. We analyse the dopant properties necessary, especially centres containing N and P, and give results using simple scoping calculations for the key interactions determining gate performance. Our conclusions are cautiously optimistic: it may be possible to develop a useful quantum information processor that works above cryogenic temperatures. PMID:21832328

  18. Microstructure of nano and micron size diamond-silicon carbide composites sintered under high pressure high temperature conditions

    NASA Astrophysics Data System (ADS)

    Nauyoks, Stephen Edwin

    Compacts and composites were sintered under high pressure (2 GPa--10 GPa) and high temperature (1400--2300°C) conditions. The compacts were sintered using nano-SiC powder, micron-diamond powder, and nano-diamond powder. Composites were sintered using the liquid infiltration method from nano-silicon powder and nano or micron diamond powder. Under the high pressure, high temperature conditions the silicon powder would melt and react with carbon from the diamonds to form a SiC matrix. The microstructure and strain of the composites and compacts was analyzed using X-ray diffraction analysis. The extended convolutional multiple whole profile fitting method was used to analyze the X-ray line profiles to determine average crystallite size, dislocation density, and planar fault probability. The apparent lattice parameter method was used to analyze strain. Below a certain pressure there was subgrain growth. However, at the higher pressures there was a reduction in crystallite size. In the SiC phase there was a correlation between predominate defect, dislocation or planar fault, and the crystallite size. The defect structure of the diamonds seemed to be dependent on the initial diamond powder used. At higher temperatures there was evidence of recovery and or recrystallization.

  19. Development of diamond-lanthanide metal oxide affinity composites for the selective capture of endogenous serum phosphopeptides.

    PubMed

    Hussain, Dilshad; Musharraf, Syed Ghulam; Najam-ul-Haq, Muhammad

    2016-02-01

    Development of affinity materials for the selective enrichment of phosphopeptides has attracted attention during the last decade. In this work, diamond-lanthanum oxide and diamond-samarium oxide composites have been fabricated via the hydrothermal method. The composites are characterized by scanning electron microscopy (SEM), energy dispersive X-Ray spectroscopy (EDAX), and atomic force microscopy (AFM). The analyses confirm the size and composition of the nanocomposites. They have been applied to selectively capture phosphorylated peptides from standard proteins (β-casein and BSA). Selectivity is calculated as 1:3000 and 1:1500 while sensitivity down to 1 and 20 fmol for diamond-lanthanum oxide and diamond-samarium oxide nanocomposites, respectively. Enrichment efficiency has also been evaluated for non-fat milk digest where 18 phosphopeptides are enriched. Total of 213 and 187 phosphopeptides are captured from tryptic digest of HeLa cells extracted proteins by diamond-lanthanum oxide and diamond-samarium oxide, respectively. Finally, human serum, without any pre-treatment, is applied and nanocomposites capture the endogenous serum phosphopeptides. PMID:26758594

  20. Laser-based gluing of diamond-tipped saw blades

    NASA Astrophysics Data System (ADS)

    Hennigs, Christian; Lahdo, Rabi; Springer, André; Kaierle, Stefan; Hustedt, Michael; Brand, Helmut; Wloka, Richard; Zobel, Frank; Dültgen, Peter

    2016-03-01

    To process natural stone such as marble or granite, saw blades equipped with wear-resistant diamond grinding segments are used, typically joined to the blade by brazing. In case of damage or wear, they must be exchanged. Due to the large energy input during thermal loosening and subsequent brazing, the repair causes extended heat-affected zones with serious microstructure changes, resulting in shape distortions and disadvantageous stress distributions. Consequently, axial run-out deviations and cutting losses increase. In this work, a new near-infrared laser-based process chain is presented to overcome the deficits of conventional brazing-based repair of diamond-tipped steel saw blades. Thus, additional tensioning and straightening steps can be avoided. The process chain starts with thermal debonding of the worn grinding segments, using a continuous-wave laser to heat the segments gently and to exceed the adhesive's decomposition temperature. Afterwards, short-pulsed laser radiation removes remaining adhesive from the blade in order to achieve clean joining surfaces. The third step is roughening and activation of the joining surfaces, again using short-pulsed laser radiation. Finally, the grinding segments are glued onto the blade with a defined adhesive layer, using continuous-wave laser radiation. Here, the adhesive is heated to its curing temperature by irradiating the respective grinding segment, ensuring minimal thermal influence on the blade. For demonstration, a prototype unit was constructed to perform the different steps of the process chain on-site at the saw-blade user's facilities. This unit was used to re-equip a saw blade with a complete set of grinding segments. This saw blade was used successfully to cut different materials, amongst others granite.

  1. Electrically conductive polycrystalline diamond and particulate metal based electrodes

    DOEpatents

    Swain, Greg M.; Wang, Jian

    2005-04-26

    An electrically conducting and dimensionally stable diamond (12, 14) and metal particle (13) electrode produced by electrodepositing the metal on the diamond is described. The electrode is particularly useful in harsh chemical environments and at high current densities and potentials. The electrode is particularly useful for generating hydrogen, and for reducing oxygen and oxidizing methanol in reactions which are of importance in fuel cells.

  2. Enhanced capacitance of composite TiO2 nanotube/boron-doped diamond electrodes studied by impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Siuzdak, K.; Bogdanowicz, R.; Sawczak, M.; Sobaszek, M.

    2014-12-01

    We report on novel composite nanostructures based on boron-doped diamond thin films grown on top of TiO2 nanotubes. The nanostructures made of BDD-modified titania nanotubes showed an increase in activity and performance when used as electrodes in electrochemical environments. The BDD thin films (~200-500 nm) were deposited using microwave plasma assisted chemical vapor deposition (MW PA CVD) onto anodically fabricated TiO2 nanotube arrays. The influence of boron-doping level, methane admixture and growth time on the performance of the Ti/TiO2/BDD electrode was studied in detail. Scanning electron microscopy (SEM) was applied to investigate the surface morphology and grain size distribution. Moreover, the chemical composition of TiO2/BDD electrodes was investigated by means of micro-Raman spectroscopy. The composite electrodes TiO2/BDD are characterized by a significantly higher capacitive current compared to BDD films deposited directly onto a Ti substrate. The novel composite electrode of TiO2 nanotube arrays overgrown by boron-doped diamond (BDD) immersed in 0.1 M NaNO3 can deliver a specific capacitance of 2.10, 4.79, and 7.46 mF cm-2 at a scan rate of 10 mV s-1 for a [B]/[C] ratio of 2k, 5k and 10k, respectively. The substantial improvement of electrochemical performance and the excellent rate capability could be attributed to the synergistic effect of TiO2 treatment in CH4 : H2 plasma and the high electrical conductivity of BDD layers. The analysis of electrochemical impedance spectra using an electric equivalent circuit allowed us to determine the surface area on the basis of the value of constant phase element.

  3. Thermal Conductivity of Diamond Packed Electrospun PAN-Based Carbon Fibers Incorporated with Multi Wall Carbon Nanotubes.

    PubMed

    Dong, Qi; Lu, Chunyuan; Tulugan, Kelimu; Jin, Chunzi; Yoon, Soo Jong; Park, Yeong Min; Kim, Tae Gyu

    2016-02-01

    Multi wall carbon nanotubes (MWCNTs) and diamond are renowned as superlative material due to their relatively high thermal conductivity and hardness while comparing with any bulk materials. In this research, polyacrylonitrile (PAN) solution incorporated with MWCNTs at an alteration of mass fractions (0 wt%, 0.6 wt%, 1 wt%, 2 wt%) were fabricated via electrospinning under optimized parameters. Dried composite nanofibers were stabilized and carbonized, after which water base polytrafluorethylene (PTFE) mixed with nano diamond powder solution was spin coated on them. Scanning electron microscopy, Raman spectroscopy, X-ray scattering and Laserflash thermal conductivity were used to characterize the composite nanofiber sheets. The result shows that the thermal conductivity increased to 4.825 W/m K from 2.061 W/mK. The improvement of thermal conductivities is suggesting the incorporation of MWCNTs. PMID:27433684

  4. Thermal property characterization of single crystal diamond with varying isotopic composition

    SciTech Connect

    Wei, L.

    1993-01-01

    The mirage-effect/thermal wave technique as a modern technique for thermal property characterization is described. The thermal diffusivity of a material is determined by measuring the time and space varying temperature distribution (thermal wave) in the material generated by an intensity modulated heating laser beam. These thermal waves are detected through the deflection of a probe laser beam due to modulation of gradient of the index of refraction (mirage effect) either in the air above the specimens (the in-air technique) or in the specimen itself (the in-solid technique). Three-dimensional theories, for both in-air and in-solid mirage techniques, are represented. In order to extract the material parameters by comparing the theory with experimental data, an extensive data analysis procedure based on multiparameter-least-squares has been developed. The experimental and data analysis details are discussed. Topics concerns with the quality and reliability of the measurements are addressed. This technique has been successfully applied to the thermal property characterization of single crystal diamond with varying isotope contents. The results showed a 50% enhancement in the thermal conductivity by removal of C[sup 13] content from 1.1% to 0.1% in diamond at room temperature. The technique has also been adapted to function in cryogenic temperatures. The temperature dependence of thermal conductivity in the temperature range 80-378K for natural IIA specimen and 187-375K for isotopically enriched specimen are obtained, the former results agree with previous works and the latter results demonstrate the isotope effect on the thermal conductivity of single crystal diamond consistently in a large temperature range. The physical source of this enhancement in diffusivity due to the isotope effect in diamond is discussed. The discussion is based on the full Callaway's theory with emphasizing the role of N-processes in the phonon scattering mechanism.

  5. Growth of diamond film by CVD on near net shape fabricated {beta}-SiC/TiC composites synthesized using SHS

    SciTech Connect

    Raghunathan, R.; Chowdhury, R.; Jagannadham, K.; Narayan, J.

    1995-10-01

    {beta}-SiC/TiC composites were synthesized using the process of self propagating-high temperature combustion synthesis (SHS). The heat released during the exothermic reaction between Si and C powders (with a {Delta}H of {minus}14 kcal/mol) and that Ti and C powders (with a {Delta}H of {minus}44.1 kcal/mole) is sufficient to cause the melting of the powders into which the carbon diffuses and from which {beta}-SiC and TiC precipitate out of the supersaturated solution. The composite was characterized using X-ray diffraction techniques, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. An attempt was made to understand the mechanism of formation of the composite. The authors have proposed a mechanism to understand the formation of the SHS compounds based on dissolution, diffusion and precipitation from the supersaturated solution. There is no evidence for the presence of TiSi{sub 2} and an attempt was made to explain this observation based on three energy considerations. Diamond film was then grown on the pellet by hot filament CVD technique using methane and hydrogen gas as the reactants. The deposition was conducted for a period of four hours. A continuous film of diamond was found to grow on {beta}-SiC/TiC composite using this technique. The diamond film was characterized by using Raman spectroscopy and SEM. The diamond film showed both (001) and (111) facets with average grain size of 5 {micro}m.

  6. Formation of Ultrananocrystalline Diamond/Amorphous Carbon Composite Films in Vacuum Using Coaxial Arc Plasma Gun

    NASA Astrophysics Data System (ADS)

    Hanada, Kenji; Yoshida, Tomohiro; Nakagawa, You; Yoshitake, Tsuyoshi

    2010-12-01

    Ultrananocrystalline diamond (UNCD)/nonhydrogenated amorphous carbon (a-C) composite films were grown in vacuum using a coaxial arc plasma gun. From the X-ray diffraction measurement, the UNCD crystallite size was estimated to be 1.6 nm. This size is dramatically reduced from that (2.3 nm) of UNCD/hydrogenated amorphous carbon (a-C:H) composite films grown in a hydrogen atmosphere. The sp3/(sp3 + sp2) value, which was estimated from the X-ray photoemission spectrum, was also reduced to be 41%. A reason for it might be the reduction in the UNCD crystallite size. From the near-edge X-ray absorption fine-structure (NEXAFS) spectrum, it was found that the π*C=C and π*C≡C bonds are preferentially formed instead of the σ*C-H bonds in the UNCD/a-C:H films. Since the extremely small UNCD crystallites (1.6 nm) correspond to the nuclei of diamond, we consider that UNCD crystallite formation should be due predominantly to nucleation. The supersaturated condition required for nucleation is expected to be realized in the deposition using the coaxial arc plasma gun.

  7. High Thermal Conductivity NARloy-Z-Diamond Composite Combustion Chamber Liner For Advanced Rocket Engines

    NASA Technical Reports Server (NTRS)

    Bhat, Biliyar N.; Ellis, David; Singh, Jogender

    2014-01-01

    Advanced high thermal conductivity materials research conducted at NASA Marshall Space Flight Center (MSFC) with state of the art combustion chamber liner material NARloy-Z showed that its thermal conductivity can be increased significantly by adding diamond particles and sintering it at high temperatures. For instance, NARloy-Z containing 40 vol. percent diamond particles, sintered at 975C to full density by using the Field assisted Sintering Technology (FAST) showed 69 percent higher thermal conductivity than baseline NARloy-Z. Furthermore, NARloy-Z-40vol. percent D is 30 percent lighter than NARloy-Z and hence the density normalized thermal conductivity is 140 percent better. These attributes will improve the performance and life of the advanced rocket engines significantly. By one estimate, increased thermal conductivity will directly translate into increased turbopump power up to 2X and increased chamber pressure for improved thrust and ISP, resulting in an expected 20 percent improvement in engine performance. Follow on research is now being conducted to demonstrate the benefits of this high thermal conductivity NARloy-Z-D composite for combustion chamber liner applications in advanced rocket engines. The work consists of a) Optimizing the chemistry and heat treatment for NARloy-Z-D composite, b) Developing design properties (thermal and mechanical) for the optimized NARloy-Z-D, c) Fabrication of net shape subscale combustion chamber liner, and d) Hot fire testing of the liner for performance. FAST is used for consolidating and sintering NARlo-Z-D. The subscale cylindrical liner with built in channels for coolant flow is also fabricated near net shape using the FAST process. The liner will be assembled into a test rig and hot fire tested in the MSFC test facility to determine performance. This paper describes the development of this novel high thermal conductivity NARloy-Z-D composite material, and the advanced net shape technology to fabricate the combustion

  8. Novel electron devices based on the unique properties of diamond

    NASA Astrophysics Data System (ADS)

    Yoder, M. N.

    An account is given of the unique design principles that apply to such electron devices as metal-insulator-metal photodetectors, cascade and virtual-contact FETs, and high-electron-mobility transistors. It is noted that while diamond is a high-power, high-temperature, or extremely HF amplifier, it cannot accomplish all three functions simultaneously. Attention is given to the significance of diamond's heat-dissipation capabilities.

  9. 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.

  10. Transmission photocathodes based on stainless steel mesh coated with deuterated diamond like carbon films

    NASA Astrophysics Data System (ADS)

    Huran, J.; Balalykin, N. I.; Feshchenko, A. A.; Kobzev, A. P.; Kleinová, A.; Sasinková, V.; Hrubčín, L.

    2014-07-01

    In this study we report on the dependence of electron emission properties on the transmission photocathodes DC gun based on stainless steel mesh coated with diamond like carbon films prepared at various technological conditions. Diamond like carbon films were deposited on the stainless steel mesh and silicon substrate by plasma enhanced chemical vapor deposition from gas mixtures CH4+D2+Ar, CH4+H2+Ar and reactive magnetron sputtering using a carbon target and gas mixtures Ar+D2, Ar+H2. The concentration of elements in films was determined by Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERD) analytical methods simultaneously. Chemical compositions were analyzed by Fourier transform infrared spectroscopy (FT-IR). Raman spectroscopy at visible excitation wavelength was used for the intensity ratio determination of Gaussian fit D-peak and G-peak of Raman spectra. The quantum efficiency was calculated from the measured laser energy and the measured cathode charge. The quantum efficiency of a prepared transmission photocathode was increased with increasing intensity ratio of D-peak and G-peak, which was increased by adding deuterium to the gas mixture and using technology reactive magnetron sputtering.

  11. 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.

  12. Development of Innovative Accident Tolerant High Thermal Conductivity UO2-Diamond Composite Fuel Pellets

    SciTech Connect

    Tulenko, James; Subhash, Ghatu

    2016-01-01

    The University of Florida (UF) evaluated a composite fuel consisting of UO2 powder mixed with diamond micro particles as a candidate as an accident-tolerant fuel (ATF). The research group had previous extensive experience researching with diamond micro particles as an addition to reactor coolant for improved plant thermal performance. The purpose of this research work was to utilize diamond micro particles to develop UO2-Diamond composite fuel pellets with significantly enhanced thermal properties, beyond that already being measured in the previous UF research projects of UO2 – SiC and UO2 – Carbon Nanotube fuel pins. UF is proving with the current research results that the addition of diamond micro particles to UO2 may greatly enhanced the thermal conductivity of the UO2 pellets producing an accident-tolerant fuel. The Beginning of life benefits have been proven and fuel samples are being irradiated in the ATR reactor to confirm that the thermal conductivity improvements are still present under irradiation.

  13. Nanocrystalline diamond/carbon felt as a novel composite for electrochemical storage energy in capacitor

    NASA Astrophysics Data System (ADS)

    Almeida, E. C.; Azevedo, A. F.; Baldan, M. R.; Braga, N. A.; Rosolen, J. M.; Ferreira, N. G.

    2007-04-01

    A nanocrystalline diamond (NCD) grown on carbon fibers substrate (CF), has been developed for electric double-layer capacitor. Carbon fibers were treated at 1300 and 2300 K by using the temperature steps of 60 K/h in a nitrogen atmosphere. NCD films were grown from Ar/H 2/CH 4 mixtures on a hot-filament chemical vapor (HFCVD) deposition reactor. Scanning electron microscopy (SEM) images of NCD showed faceted diamond grains for both substrates. Raman spectra are characteristic of NCD films and confirm the existence of sp 2-bonded carbon in grain boundaries due to significant reduction of grain size. NCD/CF samples showed the characteristic behavior of an ideal current-potential capacitor with rectangular current-potential responses curves in 0.5 M sulfuric acid. The NCD/CF composite treated at 1300 K has the largest cathodic current and retains the rectangular-shaped CV up to a high scan rate of 100 mV/s.

  14. Theoretical and experimental investigations in characterizing and developing multiplexed diamond-based neutron spectrometers

    NASA Astrophysics Data System (ADS)

    Lukosi, Eric

    In this work a novel technique of multiplexing diamond is presented where electronic grade diamond plates are connected electrically in series and in parallel to increase the overall detection efficiency of diamond-based neutron detection systems. Theoretical results utilizing MCNPX indicate that further development in this simulation software is required to accurately predict the response of diamond to various interrogating neutron energies. However, the results were accurate enough to indicate that an equivalent diamond plate 1cm thick only lowers the energy resolution of the 12 C(n,αo)9Be peak from a 14.1 MeV interrogating neutron reference field by a factor of two compared to a single diamond plate 0.5mm thick while increasing the detection efficiency from 1.34 percent for a single diamond plate to 25.4 percent for the 1cm thick diamond plate. Further, the number of secondary neutron interactions is minimal, approximately 5.3 percent, with a detection medium this size. It is also shown that photons can interfere with lower energy neutron signals when multiplexing is used, especially at lower impinging photon energies, although the full energy peak still does not dominantly present itself in the pulse height spectrum for multiplexed arrays approaching 1cm with respect to the interrogating neutron reference field vector. Experimental results indicate that series multiplexing is not capable for use as a means of increasing the active detection volume of a diamond-based neutron spectrometer because of the interaction of diamond detection mediums in series with each other and the input capacitor of a charge sensitive preamplifier, where severe signal degradation is seen due to the equal impedances of the single crystal diamond plates. However, parallel multiplexing is shown to have great promise, although there are limitations to this technique due to the large capacitance at the preamplifier input for a large parallel multiplexed array. Still, the latter

  15. 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.

  16. Nano-inclusions in diamond: Evidence of diamond genesis

    NASA Astrophysics Data System (ADS)

    Wirth, R.

    2015-12-01

    The use of Focused Ion Beam technology (FIB) for TEM sample preparation introduced approximately 15 years ago revolutionized the application of TEM in Geosciences. For the first time, FIB enabled cutting samples for TEM use from exactly the location we are interested in. Applied to diamond investigation, this technique revealed the presence of nanometre-sized inclusions in diamond that have been simply unknown before. Nanoinclusions in diamond from different location and origin such as diamonds from the Lower and Upper Mantle, metamorphic diamonds (Kazakhstan, Erzgebirge, Bohemia), diamonds from ophiolites (Tibet, Mongolia, Xinjiang, Ural Mountains), diamonds from igneous rocks (Hawaii, Kamchatka) and impact diamonds (Popigai Crater, Siberia) have been investigated during the last 15 years. The major conclusion of all these TEM studies is, that the nanoinclusions, their phases and phase composition together with the micro- and nanostructure evidence the origin of diamond and genesis of diamond. We can discriminate Five different mechanisms of diamond genesis in nature are observed: Diamond crystallized from a high-density fluid (Upper mantle and metamorphic diamond). Diamond crystallized from carbonatitic melt (Lower mantle diamond). Diamond precipitates from a metal alloy melt (Diamond from ophiolites). Diamond crystallized by gas phase condensation or chemical vapour condensation (CVD) (Lavas from Kamchatka, xenoliths in Hawaiian lavas). Direct transformation of graphite into diamond.

  17. Diamond nanoparticles based biosensors for efficient glucose and lactate determination.

    PubMed

    Briones, M; Casero, E; Petit-Domínguez, M D; Ruiz, M A; Parra-Alfambra, A M; Pariente, F; Lorenzo, E; Vázquez, L

    2015-06-15

    In this work, we report the modification of a gold electrode with undoped diamond nanoparticles (DNPs) and its applicability to the fabrication of electrochemical biosensing platforms. DNPs were immobilized onto a gold electrode by direct adsorption and the electrochemical behavior of the resulting DNPs/Au platform was studied. Four well-defined peaks were observed corresponding to the DNPs oxidation/reduction at the underlying gold electrode, which demonstrate that, although undoped DNPs have an insulating character, they show electrochemical activity as a consequence of the presence of different functionalities with unsaturated bonding on their surface. In order to develop a DNPs-based biosensing platform, we have selected glucose oxidase (GOx), as a model enzyme. We have performed an exhaustive study of the different steps involved in the biosensing platform preparation (DNPs/Au and GOx/DNPs/Au systems) by atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM) and cyclic voltammetry (CV). The glucose biosensor shows a good electrocatalytic response in the presence of (hydroxymethyl)ferrocene as redox mediator. Once the suitability of the prototype system to determine glucose was verified, in a second step, we prepared a similar biosensor, but employing the enzyme lactate oxidase (LOx/DNPs/Au). As far as we know, this is the first electrochemical biosensor for lactate determination that includes DNPs as nanomaterial. A linear concentration range from 0.05 mM to 0.7 mM, a sensitivity of 4.0 µA mM(-1) and a detection limit of 15 µM were obtained. PMID:25636025

  18. Direct coating adherent diamond films on Fe-based alloy substrate: the roles of Al, Cr in enhancing interfacial adhesion and promoting diamond growth.

    PubMed

    Li, X J; He, L L; Li, Y S; Yang, Q; Hirose, A

    2013-08-14

    Direct CVD deposition of dense, continuous, and adherent diamond films on conventional Fe-based alloys has long been considered impossible. The current study demonstrates that such a deposition can be realized on Al, Cr-modified Fe-based alloy substrate (FeAl or FeCrAl). To clarify the fundamental mechanism of Al, Cr in promoting diamond growth and enhancing interfacial adhesion, fine structure and chemical analysis around the diamond film-substrate interface have been comprehensively characterized by transmission electron microscopy. An intermediate graphite layer forms on those Al-free substrates such as pure Fe and FeCr, which significantly deteriorates the interfacial adhesion of diamond. In contrast, such a graphite layer is absent on the FeAl and FeCrAl substrates, whereas a very thin Al-rich amorphous oxide sublayer is always identified between the diamond film and substrate interface. These comparative results indicate that the Al-rich interfacial oxide layer acts as an effective barrier to prevent the formation of graphite phase and consequently enhance diamond growth and adhesion. The adhesion of diamond film formed on FeCrAl is especially superior to that formed on FeAl substrate. This can be further attributed to a synergetic effect including the reduced fraction of Al and the decreased substrate thermal-expansion coefficient on FeCrAl in comparison with FeAl, and a mechanical interlocking effect due to the formation of interfacial chromium carbides. Accordingly, a mechanism model is proposed to account for the different interfacial adhesion of diamond grown on the various Fe-based substrates. PMID:23829602

  19. An insight into what superconducts in polycrystalline boron-doped diamonds based on investigations of microstructure

    PubMed Central

    Dubrovinskaia, N.; Wirth, R.; Wosnitza, J.; Papageorgiou, T.; Braun, H. F.; Miyajima, N.; Dubrovinsky, L.

    2008-01-01

    The discovery of superconductivity in polycrystalline boron-doped diamond (BDD) synthesized under high pressure and high temperatures [Ekimov, et al. (2004) Nature 428:542–545] has raised a number of questions on the origin of the superconducting state. It was suggested that the heavy boron doping of diamond eventually leads to superconductivity. To justify such statements more detailed information on the microstructure of the composite materials and on the exact boron content in the diamond grains is needed. For that we used high-resolution transmission electron microscopy and electron energy loss spectroscopy. For the studied superconducting BDD samples synthesized at high pressures and high temperatures the diamond grain sizes are ≈1–2 μm with a boron content between 0.2 (2) and 0.5 (1) at %. The grains are separated by 10- to 20-nm-thick layers and triangular-shaped pockets of predominantly (at least 95 at %) amorphous boron. These results render superconductivity caused by the heavy boron doping in diamond highly unlikely. PMID:18697937

  20. A neutron sensor based on synthetic single crystal diamond

    SciTech Connect

    Schmid, G J; Koch, J A; Lerche, R A; Moran, M J

    2003-10-17

    We report the first neutron data for a single crystal Chemical Vapor Deposition (CVD) diamond sensor. Results are presented for 2.5, 14.1, and 14.9 MeV incident neutrons. We show that the energy resolution for 14.1 MeV neutrons is at least 2.9% (as limited by the energy spread of the incident neutrons), and perhaps as good as 0.4% (as extrapolated from high resolution {alpha} particle data). This result could be relevant to fusion neutron spectroscopy at machines like the International Thermonuclear Experimental Reactor (ITER). We also show that our sensor has a high neutron linear attenuation coefficient, due to the high atomic density of diamond, and this could lead to applications in fission neutron detection.

  1. Diamond-bearing Rocks among Mantle Xenoliths in Kimberlites as Indicatory for the Chambers of Diamond-parental Carbonatite Magma

    NASA Astrophysics Data System (ADS)

    Litvin, Yuriy; Kuzyura, Anastasia

    2014-05-01

    Origin of diamond-bearing peridotite and eclogite rocks in kimberlites is cleared up using mantle-carbonatite model of diamond genesis (Litvin, 2007, 2009, 2013). Data of analytical mineralogy of primary inclusions in diamonds and results of physicochemical experiments on syngenetic diamond and inclusion phase relations are co-ordinated in this model (Litvin et al., 2012). It proved that diamond-parental media are presented by changeable carbon-saturated peridotite-carbonatite and eclogite-carbonatite melts. The melts are capable to form not diamonds only but their major and minor inclusions. The upper mantle is mainly composed of diamond-free peridotites which dominate over eclogites as 9 to 5 % (Mathias et al., 1970). Howewer diamond-bearing peridotites and eclogites occur rarely as demonstrated for S.Africa and Yakutia (Sobolev N., 1977). Nevertheless, origin of diamond-bearing rocks belongs to key problems of genetic mineralogy of diamond and mantle petrology due to dissimilar physicochemical and environmental conditions of formation of comparatively diamond-free rocks. Symptomatic that garnets included in diamond and these of diamond-bearing eclogite are compositionally similar (Sobolev V. et al., 1972). Garnets of diamond-bearing eclogites, inclusions in diamonds and intergrowths with them are marked by increased Na2O content (0.10-0.22%) because of Na-majorite component Na2MgSi5O12 (Bobrov & Litvin, 2011). Peridotitic garnets of diamond-bearing rocks, inclusions and intergrowths are indicated by high Cr2O3 and low CaO content over diamond-free ones. This compositional dissimilarity is compatible with formation of diamond-bearing rocks, inclusions and intergrowths in chambers of partially melted peridotite-eclogite-carbonatite-sulphide-carbon system of changeable composition. However, diamond-free rocks are products of upper-mantle magmatism based on carbonatite-free peridotite-eclogite-sulphide-carbon system. Chambers of diamond-parental carbonatite magma

  2. Excimer Laser Beam Analyzer Based on CVD Diamond

    NASA Astrophysics Data System (ADS)

    Girolami, Marco; Salvatori, Stefano; Conte, Gennaro

    2010-11-01

    1-D and 2-D detector arrays have been realized on CVD-diamond. The relatively high resistivity of diamond in the dark allowed the fabrication of photoconductive "sandwich" strip (1D) or pixel (2D) detectors: a semitransparent light-receiving back-side contact was used for detector biasing. Cross-talk between pixels was limited by using intermediate guard contacts connected at the same ground potential of the pixels. Each pixel photocurrent was conditioned by a read-out electronics composed by a high sensitive integrator and a Σ-Δ ADC converter. The overall 500 μs conversion time allowed a data acquisition rate up to 2 kSPS. The measured fast photoresponse of the samples in the ns time regime suggests to use the proposed devices for fine tuning feedback of high-power pulsed-laser cavities, whereas solar-blindness guarantees high performance in UV beam diagnostics also under high intensity background illumination. Offering unique properties in terms of thermal conductivity and visible-light transparency, diamond represents one of the most suitable candidate for the detection of high-power UV laser emission. The technology of laser beam profiling is evolving with the increase of excimer lasers applications that span from laser-cutting to VLSI and MEMS technologies. Indeed, to improve emission performances, fine tuning of the laser cavity is required. In such a view, the development of a beam-profiler, able to work in real-time between each laser pulse, is mandatory.

  3. Diamond nanophotonics

    PubMed Central

    Beha, Katja; Wolfer, Marco; Becker, Merle C; Siyushev, Petr; Jamali, Mohammad; Batalov, Anton; Hinz, Christopher; Hees, Jakob; Kirste, Lutz; Obloh, Harald; Gheeraert, Etienne; Naydenov, Boris; Jakobi, Ingmar; Dolde, Florian; Pezzagna, Sébastien; Twittchen, Daniel; Markham, Matthew; Dregely, Daniel; Giessen, Harald; Meijer, Jan; Jelezko, Fedor; Nebel, Christoph E; Bratschitsch, Rudolf; Leitenstorfer, Alfred; Wrachtrup, Jörg

    2012-01-01

    Summary We demonstrate the coupling of single color centers in diamond to plasmonic and dielectric photonic structures to realize novel nanophotonic devices. Nanometer spatial control in the creation of single color centers in diamond is achieved by implantation of nitrogen atoms through high-aspect-ratio channels in a mica mask. Enhanced broadband single-photon emission is demonstrated by coupling nitrogen–vacancy centers to plasmonic resonators, such as metallic nanoantennas. Improved photon-collection efficiency and directed emission is demonstrated by solid immersion lenses and micropillar cavities. Thereafter, the coupling of diamond nanocrystals to the guided modes of micropillar resonators is discussed along with experimental results. Finally, we present a gas-phase-doping approach to incorporate color centers based on nickel and tungsten, in situ into diamond using microwave-plasma-enhanced chemical vapor deposition. The fabrication of silicon–vacancy centers in nanodiamonds by microwave-plasma-enhanced chemical vapor deposition is discussed in addition. PMID:23365803

  4. Influence of Diamond Particles Coated with TiO2 Film on Wettability of Vitrified Bond and Transverse Rupture Strength (TRS) of Vitrified Bond Composites

    NASA Astrophysics Data System (ADS)

    Song, Dongdong; Wan, Long; Liu, Xiaopan; Hu, Weida; Li, Jianwei

    2016-06-01

    TiO2 films were prepared on the surface of the diamond particles using a classical sol-gel method. The results showed that the TiO2 covered on the diamond surface as a rough and dense film with anatase phase, and tightly combined with the diamond substrates via the Ti-O-C bond. The initial oxidation temperature and compression strength of diamond were improved to 725 °C and 23.8 N with TiO2 film coated. TiO2 film increased the roughness of the diamond surface, promoted its mutual solubility, and formed the chemical bonding (Ti-O-Si) between the vitrified bond and the diamond. Therefore, the TiO2 film decreased the interface energy of the diamond, and promoted the wetting angle of vitrified bond with diamond to 36.7°. As a result, the TRS of vitrified bond diamond composites was increased to 76.3 MPa.

  5. Study of diamond film growth and properties

    NASA Technical Reports Server (NTRS)

    Albin, Sacharial

    1990-01-01

    The objective was to study diamond film growth and its properties in order to enhance the laser damage threshold of substrate materials. Calculations were performed to evaluate laser induced thermal stress parameter, R(sub T) of diamond. It is found that diamond has several orders of magnitude higher in value for R(sub T) compared to other materials. Thus, the laser induced damage threshold (LIDT) of diamond is much higher. Diamond films were grown using a microwave plasma enhanced chemical vapor deposition (MPECVD) system at various conditions of gas composition, pressure, temperature, and substrate materials. A 0.5 percent CH4 in H2 at 20 torr were ideal conditions for growing of high quality diamond films on substrates maintained at 900 C. The diamond films were polycrystalline which were characterized by scanning electron microscopy (SEM) and Raman scattering spectroscopy. The top surface of the growing film is always rough due to the facets of polycrystalline film while the back surface of the film replicates the substrate surface. An analytical model based on two dimensional periodic heat flow was developed to calculate the effective in-plane (face parallel) diffusivity of a two layer system. The effective diffusivity of diamond/silicon samples was measured using a laser pulse technique. The thermal conductivity of the films was measured to be 13.5 W/cm K, which is better than that of a type Ia natural diamond. Laser induced damage experiments were performed on bare Si substrates, diamond film coated Si, and diamond film windows. Significant improvements in the LIDT were obtained for diamond film coated Si compared to the bare Si.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    '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...

  7. Garnets from kimberlites of northeast Angola and the relation of their composition to diamond content

    NASA Astrophysics Data System (ADS)

    Sobolev, N. V.; Mankenda, A.; Kaminskii, F. V.; Sobolev, V. N.

    High-chromium subcalcic pyropes were found in kimberlites from northeast Angola. A positive correlation between the content of these pyropes in concentrates with the diamond content of kimberlites is established, and it is thus concluded that such pyropes can serve as indicators in estimating the diamond content of kimberlites.

  8. An Isothermal Device Configuration for Diamond Based Photon-Enhanced Thermionic Solar Energy Conversion

    NASA Astrophysics Data System (ADS)

    Sun, Tianyin; Koeck, Franz; Nemanich, Robert

    2014-03-01

    Diamond can obtain a negative electron affinity (NEA) after hydrogen termination. With NEA and n-type doping, a low effective work function and efficient thermionic emission has been observed from these diamond films. Photo-induced electron emission from nitrogen doped diamond with visible light illumination has also been established by our group. Recently several reports have described efficient energy conversion based on the photon-enhanced thermionic emission (PETE) mechanism. This study proposes a multi-layer emitter and collector structure for an isothermal PETE converter. The emitter structure is based on an n-type NEA diamond film deposited on a p-type Si substrate to enable electron emission across a vacuum gap. In this structure the above-bandgap light is absorbed in the Si and establishs an enhanced electron population for emission through the low work function surface, while sub-bandgap light is absorbed in the collector for transfer to a heat engine. Spectroscopy measurements of the n-type diamond on Si indicate strong electron emissivity with photon illumination, and the emission intensity is significantly increased at elevated temperatures. A simplified model describing the efficiency and performance of an isothermal PETE device is presented. This research is supported through ONR under grant number # N00014-10-1-0540.

  9. Effect of reinforcement particle size on the tribological properties of nano-diamond filled polytetrafluoroethylene based coating.

    PubMed

    Lim, D P; Lee, J Y; Lim, D S; Ahn, S G; Lyo, I W

    2009-07-01

    The tribological properties of PTFE composite coatings reinforced by nano-diamonds were investigated. Mechanical particle size reduction and dispersion of nano-diamond aggregates were performed by milling with ceramic beads in an organic solvent. Particle size was controlled by the milling time. Pastes comprising a PTFE solution mixed with nano-diamond having various sizes were coated on the aluminum substrate. Ball-on-plate type wear test was performed to investigate the friction and wear behavior. The results indicated that the addition of nano-diamonds effectively improved tribological performance of the PTFE coating. The reduction in nano-diamond sizes were not always improved the wear resistance of PTFE coating. This unexpected behavior was explained by observation on the worn surfaces and wear debris. PMID:19916429

  10. Composition and properties of the so-called 'diamond-like' amorphous carbon films

    NASA Technical Reports Server (NTRS)

    Angus, J. C.; Stultz, J. E.; Shiller, P. J.; Macdonald, J. R.; Mirtich, M. J.

    1984-01-01

    The composition of amorphous 'diamond-like' films made by direct low energy ion beam deposition, R.F. discharge and sputtering was determined by nuclear reaction analysis, IR spectroscopy and microcombustion chemical analysis. The nuclear reaction analysis showed very similar hydrogen depth profiles for all three types of samples. The atomic ratio of hydrogen to carbon was approximately 0.2 at the film surface and rose to approximately 1.0 at a depth of 500 A. The integrated intensity of the C-H stretching band at about 2900 per cm indicates that the amount of chemically bonded hydrogen is less than the total hydrogen content. Combustion analysis confirmed the overall atomic ratio of hydrogen to carbon determined by nuclear reaction analysis. The chemical state of the non-bonded hydrogen was not determined; however, the effective diffusion coefficient computed from the hydrogen depth profile was extremely low. This indicates either that the films are exceedingly impermeable or that the non-bonded hydrogen requires an additional activated step to leave the films, e.g., desorption or chemical reaction.

  11. 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.

  12. Hybrid sensors based on colour centres in diamond and piezoactive layers

    NASA Astrophysics Data System (ADS)

    Cai, Jianming; Jelezko, Fedor; Plenio, Martin B.

    2014-06-01

    The ability to measure weak signals such as pressure, force, electric field and temperature with nanoscale devices and high spatial resolution offers a wide range of applications in fundamental and applied sciences. Here we present a proposal for a hybrid device composed of thin film layers of diamond with colour centres and piezoactive elements for the transduction and measurement of physical signals. The magnetic response of a piezomagnetic layer to an external stress or a stress induced by a signal is shown to affect significantly the spin properties of nitrogen-vacancy centres in diamond. Under ambient conditions, realistic environmental noise and material imperfections, we show that this hybrid device can achieve significant improvements in sensitivity over the pure diamond-based approach in combination with nanometre-scale spatial resolution. Furthermore, the proposed hybrid architecture offers novel possibilities for engineering strong coherent couplings between nanomechanical oscillator and solid state spin qubits.

  13. Development of wide-ranged diamond-based detector unit for gamma radiation measurement

    NASA Astrophysics Data System (ADS)

    Baranova, M. A.; Boyko, A. V.; Chebyshev, S. B.; Cherkashin, I. I.; Kireev, V. P.; Petrov, V. I.

    2016-02-01

    In the article the description of wide-ranged diamond-based detector unit is given. Characteristics of the diamond detector were studied in current and in impulse mode. As well it was studied how detector's sensitivity depends on power doze within the limits from 10-3 to 0,4Gy/h (impulse mode) and from 10-1to 2 104Gy/h (current mode). On the basis of the obtained data it is possible to estimate about the possibility of using the detector to prevent emergency accident on a nuclear power plant and for everyday control at a nuclear power plant.

  14. Microring resonator-based diamond optothermal switch: a building block for a quantum computing network

    NASA Astrophysics Data System (ADS)

    Huang, Zhihong; Faraon, Andrei; Santori, Charles; Acosta, Victor; Beausoleil, Raymond G.

    2013-03-01

    The negatively-charged nitrogen-vacancy centers in diamond has motivated many groups building scalable quantum information processors based on diamond photonics. This is owning to the long-lived electronic spin coherence and the capability for spin manipulation and readout of NV centers.1-4 The primitive operation is to create entanglement between two NV centers, based on schemes such as 'atom-photon entanglement' proposed by Cabrillo et al.5To scale this type of scheme beyond two qubits, one important component is an optical switch that allows light emitted from a particular device to be routed to multiple locations. With such a switch, one has choices of routing photons to specified paths and has the benefit of improving the entanglement speed by entangling multiple qubits at the same time. Yield of the existing diamond cavities coupled with NV centers are inevitably low, due to the nature of randomness for NV placement and orientation, variation of spectral stability, and variation of cavity resonance frequency and quality factor. An optical switch provides the capability to tolerate a large fraction of defective devices by routing only to the working devices. Many type of switching devices were built on conventional semiconductor materials with mechanisms from mechanical, thermal switching to carrier injection, photonics crystal, and polymer refractive index tuning .6-8 In this paper, we build an optical-thermal switch on diamond with micro-ring waveguides, mainly for the simplicity of the diamond fabrication. The the switching function was realized by locally tuning the temperature of the diamond waveguides. Switching efficiency of 31% at 'drop' port and 73% at 'through' port were obtained.

  15. Development and Experimental Study of Surface-Electrical Discharge Diamond Grinding of Al-10 wt%SiC Composite

    NASA Astrophysics Data System (ADS)

    Agrawal, Shyam Sunder; Yadava, Vinod

    2016-01-01

    As silicon carbide possesses small fracture toughness, it is difficult to grind because it leads to cracking. Metal matrix composites can be machined using electrical discharge machining (EDM) but the process is slow. Electrical discharge diamond grinding (EDDG), which consists of diamond grinding and EDM with a rotating disk which enhanced material removal rate (MRR) and produce better surface finish. This paper describes the machining characteristic of Al-SiC composite using EDDG in surface grinding configuration which is called as surface-electrical discharge diamond grinding (S-EDDG). A chain of experiments were performed on S-EDDG set up by mounting newly self designed and fabricated set up on conventional die sinking EDM machine using the approach of one parameter-at-a-time concept. Surface roughness (Ra) and MRR are taken as output parameters as both are important outcome in the manufacturing process and they materialize a major division in the manufacturing system. The effects of current, wheel speed and depth of cut is analyzed on MRR and Ra. Finally, optimization have been done through weighted principal component analysis.

  16. Effect of titanium addition on the thermal properties of diamond/cu-ti composites fabricated by pressureless liquid-phase sintering technique.

    PubMed

    Chung, Chih-Yu; Chu, Chao-Hung; Lee, Mu-Tse; Lin, Chun-Ming; Lin, Su-Jien

    2014-01-01

    In this study, minor-addition elements such as Si, Co, Cr, W, Mo, and Ti were added to matrix to improve the wettability between the diamonds and Cu matrix. The pressureless liquid-phase sintering technique adopted in this study provides a low-cost method for producing diamond/Cu composites with high potential for industrial mass production. Thermal properties of the diamond/Cu-Ti composites fabricated by pressureless liquid-phase sintering at 1373 K with variation in Ti contents were thoroughly investigated. XRD and TEM analysis show that TiC layer formed in the interface between Cu and diamond. The composites exhibited thermal conductivity as high as 620 W/m · K for 50 vol% diamond/Cu-0.6 at % Ti composite with diamond particle size of 300 µm. This value comes up to 85% of the thermal conductivity calculated by the Hasselman and Johnson (H-J) theoretical analysis. Under these conditions, a suitable coefficient of thermal expansion of 6.9 ppm/K was obtained. PMID:24715816

  17. Effect of Titanium Addition on the Thermal Properties of Diamond/Cu-Ti Composites Fabricated by Pressureless Liquid-Phase Sintering Technique

    PubMed Central

    Chung, Chih-Yu; Chu, Chao-Hung; Lee, Mu-Tse; Lin, Chun-Ming; Lin, Su-Jien

    2014-01-01

    In this study, minor-addition elements such as Si, Co, Cr, W, Mo, and Ti were added to matrix to improve the wettability between the diamonds and Cu matrix. The pressureless liquid-phase sintering technique adopted in this study provides a low-cost method for producing diamond/Cu composites with high potential for industrial mass production. Thermal properties of the diamond/Cu-Ti composites fabricated by pressureless liquid-phase sintering at 1373 K with variation in Ti contents were thoroughly investigated. XRD and TEM analysis show that TiC layer formed in the interface between Cu and diamond. The composites exhibited thermal conductivity as high as 620 W/m·K for 50 vol% diamond/Cu-0.6  at % Ti composite with diamond particle size of 300 µm. This value comes up to 85% of the thermal conductivity calculated by the Hasselman and Johnson (H-J) theoretical analysis. Under these conditions, a suitable coefficient of thermal expansion of 6.9 ppm/K was obtained. PMID:24715816

  18. The mechanical and strength properties of diamond.

    PubMed

    Field, J E

    2012-12-01

    Diamond is an exciting material with many outstanding properties; see, for example Field J E (ed) 1979 The Properties of Diamond (London: Academic) and Field J E (ed) 1992 The Properties of Natural and Synthetic Diamond (London: Academic). It is pre-eminent as a gemstone, an industrial tool and as a material for solid state research. Since natural diamonds grew deep below the Earth's surface before their ejection to mineable levels, they also contain valuable information for geologists. The key to many of diamond's properties is the rigidity of its structure which explains, for example, its exceptional hardness and its high thermal conductivity. Since 1953, it has been possible to grow synthetic diamond. Before then, it was effectively only possible to have natural diamond, with a small number of these found in the vicinity of meteorite impacts. Techniques are now available to grow gem quality synthetic diamonds greater than 1 carat (0.2 g) using high temperatures and pressures (HTHP) similar to those found in nature. However, the costs are high, and the largest commercially available industrial diamonds are about 0.01 carat in weight or about 1 mm in linear dimension. The bulk of synthetic diamonds used industrially are 600 µm or less. Over 75% of diamond used for industrial purposes today is synthetic material. In recent years, there have been two significant developments. The first is the production of composites based on diamond; these materials have a significantly greater toughness than diamond while still maintaining very high hardness and reasonable thermal conductivity. The second is the production at low pressures by metastable growth using chemical vapour deposition techniques. Deposition onto non-diamond substrates was first demonstrated by Spitsyn et al 1981 J. Cryst. Growth 52 219-26 and confirmed by Matsumoto et al 1982 Japan J. Appl. Phys. 21 L183-5. These developments have added further to the versatility of diamond. Two other groups of

  19. The mechanical and strength properties of diamond

    NASA Astrophysics Data System (ADS)

    Field, J. E.

    2012-12-01

    Diamond is an exciting material with many outstanding properties; see, for example Field J E (ed) 1979 The Properties of Diamond (London: Academic) and Field J E (ed) 1992 The Properties of Natural and Synthetic Diamond (London: Academic). It is pre-eminent as a gemstone, an industrial tool and as a material for solid state research. Since natural diamonds grew deep below the Earth's surface before their ejection to mineable levels, they also contain valuable information for geologists. The key to many of diamond's properties is the rigidity of its structure which explains, for example, its exceptional hardness and its high thermal conductivity. Since 1953, it has been possible to grow synthetic diamond. Before then, it was effectively only possible to have natural diamond, with a small number of these found in the vicinity of meteorite impacts. Techniques are now available to grow gem quality synthetic diamonds greater than 1 carat (0.2 g) using high temperatures and pressures (HTHP) similar to those found in nature. However, the costs are high, and the largest commercially available industrial diamonds are about 0.01 carat in weight or about 1 mm in linear dimension. The bulk of synthetic diamonds used industrially are 600 µm or less. Over 75% of diamond used for industrial purposes today is synthetic material. In recent years, there have been two significant developments. The first is the production of composites based on diamond; these materials have a significantly greater toughness than diamond while still maintaining very high hardness and reasonable thermal conductivity. The second is the production at low pressures by metastable growth using chemical vapour deposition techniques. Deposition onto non-diamond substrates was first demonstrated by Spitsyn et al 1981 J. Cryst. Growth 52 219-26 and confirmed by Matsumoto et al 1982 Japan J. Appl. Phys. 21 L183-5. These developments have added further to the versatility of diamond. Two other groups of materials

  20. Diamond like carbon coatings: Categorization by atomic number density

    NASA Technical Reports Server (NTRS)

    Angus, John C.

    1986-01-01

    Dense diamond-like hydrocarbon films grown at the NASA Lewis Research Center by radio frequency self bias discharge and by direct ion beam deposition were studied. A new method for categorizing hydrocarbons based on their atomic number density and elemental composition was developed and applied to the diamond-like hydrocarbon films. It was shown that the diamond-like hydrocarbon films are an entirely new class of hydrocarbons with atomic number densities lying between those of single crystal diamond and adamantanes. In addition, a major review article on these new materials was completed in cooperation with NASA Lewis Research Center personnel.

  1. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2001-01-01

    An overview of the industrial diamond industry is provided. More than 90 percent of the industrial diamond consumed in the U.S. and the rest of the world is manufactured diamond. Ireland, Japan, Russia, and the U.S. produce 75 percent of the global industrial diamond output. In 2000, the U.S. was the largest market for industrial diamond. Industrial diamond applications, prices for industrial diamonds, imports and exports of industrial diamonds, the National Defense Stockpile of industrial diamonds, and the outlook for the industrial diamond market are discussed.

  2. Assessing microleakage of composite restorations in class V cavities prepared by Er:YAG laser irradiation or diamond bur

    PubMed Central

    Arami, Sakineh; Shahabi, Sima; Tabatabaie, Masomeh; Chiniforush, Nasim; Morshedi, Ehsan; Torabi, Sara

    2014-01-01

    Introduction: The aim of this study was to make a comparison between microleakage of conventionally restored class V cavities using bur and acid etchant and, the ones prepared and conditioned by Er:YAG laser. Materials and Methods: 30 recently extracted intact caries and filling free human permanent molars were used for this study. Then, Cold cure acrylic resin was used to seal the apices. The samples were randomly assigned to 5 groups of six each. Class V cavities were prepared one on buccal and one on lingual surface of each sample. Group 1: cavity preparation by diamond bur and turbine + acid etch, Group 2: cavity preparation by Er:YAG laser + acid etch, Group 3: cavity preparation by Er:YAG laser + Laser etching, Group 4: cavity preparation by diamond bur and turbine + laser etching, Group 5: cavity preparation by Er:YAG laser with no conditioning procedure. The cavities restored with restorative composite resin. Samples were then immersed in 2% methylene blue solution for 24 hours. The data were then analyzed using Wilcoxon signed ranks test and Kruskal-Wallis statistical tests. Results: The Kruskal Wallis test showed a significant difference (P < 0.05) between enamel and cementum margin microleakage, while the higher microleakage was related to the cementum margin of restorations. Conclusion: There was no significant difference in evaluating microleakeage degree of cavities prepared by Er:YAG laser and diamond bur. PMID:24944442

  3. Metal/Diamond Composite Thin-Film Electrodes: New Carbon Supported Catalytic Electrodes

    SciTech Connect

    Greg M. Swain, PI

    2009-03-10

    The DOE-funded research conducted by the Swain group was focused on (i) understanding structure-function relationships at boron-doped diamond thin-film electrodes, (ii) understanding metal phase formation on diamond thin films and developing electrochemical approaches for producing highly dispersed electrocatalyst particles (e.g., Pt) of small nominal particle size, (iii) studying the electrochemical activity of the electrocatalytic electrodes for hydrogen oxidation and oxygen reduction and (iv) conducting the initial synthesis of high surface area diamond powders and evaluating their electrical and electrochemical properties when mixed with a Teflon binder. (Note: All potentials are reported versus Ag/AgCl (sat'd KCl) and cm{sup 2} refers to the electrode geometric area, unless otherwise stated).

  4. 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. PMID:19745488

  5. Microtensile bond strength of indirect resin composite to resin-coated dentin: interaction between diamond bur roughness and coating material.

    PubMed

    Kameyama, Atsushi; Oishi, Takumi; Sugawara, Toyotarou; Hirai, Yoshito

    2009-02-01

    This aim of this study was to determine the effect of type of bur and resin-coating material on microtensile bond strength (microTBS) of indirect composite to dentin. Dentin surfaces were first ground with two types of diamond bur and resin-coated using UniFil Bond (UB) or Adper Single Bond (SB), and then bonded to a resin composite disc for indirect restoration with adhesive resin cement. After storage for 24 hr in distilled water at 37 degrees C, microTBS was measured (crosshead speed 1 mm/min). When UB was applied to dentin prepared using the regular-grit diamond bur, microTBS was significantly lower than that in dentin prepared using the superfine-grit bur. In contrast, no significant difference was found between regular-grit and superfine-grit bur with SB. However, more than half of the superfine-grit specimens failed before microTBS testing. These results indicate that selection of bur type is important in improving the bond strength of adhesive resin cement between indirect resin composite and resin-coated dentin. PMID:19622875

  6. Carbon isotope ratios and impurities in diamonds from Southern Africa

    NASA Astrophysics Data System (ADS)

    Kidane, Abiel; Koch-Müller, Monika; Morales, Luiz; Wiedenbeck, Michael; De Wit, Maarten

    2015-04-01

    We are investigating the sources of diamonds from southern Africa by studying both their carbon isotopic composition and chemical impurities. Our samples include macro-sized diamonds from River Ranch kimberlite in Zimbabwe and the Helam and Klipspringer kimberlitic deposits from South Africa, as well as micro-sized diamonds from Klipspringer and Premier kimberlites in South Africa. We have characterized the samples for their structurally bounded nitrogen, hydrogen and platelets defect using a Fourier Transmission Infrared Spectroscopy (FTIR). Using the DiaMap routine, open source software (Howell et al., 2012), IR spectra were deconvulated and quantified for their nitrogen (A, B and D components) and hydrogen contents. High to moderate nitrogen concentrations (1810 to 400 µg/g; 400 to 50 µg/g respectively) were found in diamonds from Klipspringer and Helam. Moderate to low (<50 µg/g) nitrogen concentrations were observed in diamonds from Premier and River Ranch. Type II diamonds, i.e. diamonds with no N impurities, which are presumed to have been derived from ultramafic sources, are found in the River Ranch deposit. The macro- and micro-size diamonds from the Klipspringer deposit display similar nitrogen defects, with higher nitrogen concentration and more frequent D components found in the macro-size diamonds. One of the first steps towards reliable carbon isotope studies is the development of calibration materials for SIMS carbon isotopic analyses. We have investigated candidate materials both from a polycrystalline synthetic diamond sheet and two natural gem quality diamonds from Juina (Brazil). Electron-based images of the synthetic diamond sheet, obtained using GFZ Potsdam's dual beam FIB instrument, show many diamond grains with diameters greater than 35 µm. SIMS testing of the isotopic homogeneity of the back and front sides of the synthetic sheets reveal similar 13C/12C ratio within a RSD of <1 ‰ . SIMS isotopic analyses of the two natural diamond RMs

  7. Structural characterization of hard materials by transmission electron microscopy (TEM): Diamond-Silicon Carbide composites and Yttria-stabilized Zirconia

    NASA Astrophysics Data System (ADS)

    Park, Joon Seok

    2008-10-01

    Diamond-Silicon Carbide (SiC) composites are excellent heat spreaders for high performance microprocessors, owing to the unparalleled thermal conductivity of the former component. Such a combination is obtained by the infiltration of liquid silicon in a synthetic diamond compact, where a rigid SiC matrix forms by the reaction between the raw materials. As well as the outstanding thermal properties, this engineered compound also retains the extreme hardness of the artificial gem. This makes it difficult to perform structural analysis by transmission electron microscopy (TEM), for it is not possible to produce thin foils out of this solid by conventional polishing methods. For the first time, a dual-beam focused ion beam (FIB) instrument successfully allowed site-specific preparation of electron-transparent specimens by the lift-out technique. Subsequent TEM studies revealed that the highest concentration of structural defects occurs in the vicinity of the diamond-SiC interfaces, which are believed to act as the major barriers to the transport of thermal energy. Diffraction contrast analyses showed that the majority of the defects in diamond are isolated perfect screw or 60° dislocations. On the other hand, SiC grains contain partial dislocations and a variety of imperfections such as microtwins, stacking faults and planar defects that are conjectured to consist of antiphase (or inversion) boundaries. Clusters of nanocrystalline SiC were also observed at the diamond-SiC boundaries, and a specific heteroepitaxial orientation relationship was discovered for all cubic SiC that grows on diamond {111} facets. Yttria-stabilized Zirconia (YSZ) is the most common electrolyte material for solid oxide fuel cell (SOFC) applications. It is an ionic conductor in which charge transfer is achieved by the transport of oxygen ions (O 2-). Like the diamond composite above, it is hard and brittle, and difficult to make into electron transparent TEM samples. Provided an effective

  8. Ultrahard stitching of nanotwinned diamond and cubic boron nitride in C2-BN composite

    NASA Astrophysics Data System (ADS)

    Liu, Xiaobing; Chen, Xin; Ma, Hong-An; Jia, Xiaopeng; Wu, Jinsong; Yu, Tony; Wang, Yanbin; Guo, Jiangang; Petitgirard, Sylvain; Bina, Craig R.; Jacobsen, Steven D.

    2016-07-01

    Materials combining the hardness and strength of diamond with the higher thermal stability of cubic boron nitride (cBN) have broad potential value in science and engineering. Reacting nanodiamond with cBN at moderate pressures and high temperatures provides a pathway to such materials. Here we report the fabrication of Cx-BN nanocomposites, measuring up to 10 mm in longest dimension, by reacting nanodiamond with pre-synthesized cBN in a large-volume press. The nanocomposites consist of randomly-oriented diamond and cBN domains stitched together by sp3-hybridized C-B and C-N bonds, leading to p-type semiconductivity. Dislocations near the sutures accommodate lattice mismatch between diamond and cBN. Nanotwinning within both diamond and cBN domains further contributes to a bulk hardness ~50% higher than sintered cBN. The nanocomposite of C2-BN exhibits p-type semiconductivity with low activation energy and high thermal stability, making it a functional, ultrahard substance.

  9. Ultrahard stitching of nanotwinned diamond and cubic boron nitride in C2-BN composite.

    PubMed

    Liu, Xiaobing; Chen, Xin; Ma, Hong-An; Jia, Xiaopeng; Wu, Jinsong; Yu, Tony; Wang, Yanbin; Guo, Jiangang; Petitgirard, Sylvain; Bina, Craig R; Jacobsen, Steven D

    2016-01-01

    Materials combining the hardness and strength of diamond with the higher thermal stability of cubic boron nitride (cBN) have broad potential value in science and engineering. Reacting nanodiamond with cBN at moderate pressures and high temperatures provides a pathway to such materials. Here we report the fabrication of Cx-BN nanocomposites, measuring up to 10 mm in longest dimension, by reacting nanodiamond with pre-synthesized cBN in a large-volume press. The nanocomposites consist of randomly-oriented diamond and cBN domains stitched together by sp(3)-hybridized C-B and C-N bonds, leading to p-type semiconductivity. Dislocations near the sutures accommodate lattice mismatch between diamond and cBN. Nanotwinning within both diamond and cBN domains further contributes to a bulk hardness ~50% higher than sintered cBN. The nanocomposite of C2-BN exhibits p-type semiconductivity with low activation energy and high thermal stability, making it a functional, ultrahard substance. PMID:27461889

  10. Ultrahard stitching of nanotwinned diamond and cubic boron nitride in C2-BN composite

    PubMed Central

    Liu, Xiaobing; Chen, Xin; Ma, Hong-An; Jia, Xiaopeng; Wu, Jinsong; Yu, Tony; Wang, Yanbin; Guo, Jiangang; Petitgirard, Sylvain; Bina, Craig R.; Jacobsen, Steven D.

    2016-01-01

    Materials combining the hardness and strength of diamond with the higher thermal stability of cubic boron nitride (cBN) have broad potential value in science and engineering. Reacting nanodiamond with cBN at moderate pressures and high temperatures provides a pathway to such materials. Here we report the fabrication of Cx-BN nanocomposites, measuring up to 10 mm in longest dimension, by reacting nanodiamond with pre-synthesized cBN in a large-volume press. The nanocomposites consist of randomly-oriented diamond and cBN domains stitched together by sp3-hybridized C-B and C-N bonds, leading to p-type semiconductivity. Dislocations near the sutures accommodate lattice mismatch between diamond and cBN. Nanotwinning within both diamond and cBN domains further contributes to a bulk hardness ~50% higher than sintered cBN. The nanocomposite of C2-BN exhibits p-type semiconductivity with low activation energy and high thermal stability, making it a functional, ultrahard substance. PMID:27461889

  11. Beam-based model of broad-band impedance of the Diamond Light Source

    NASA Astrophysics Data System (ADS)

    Smaluk, Victor; Martin, Ian; Fielder, Richard; Bartolini, Riccardo

    2015-06-01

    In an electron storage ring, the interaction between a single-bunch beam and a vacuum chamber impedance affects the beam parameters, which can be measured rather precisely. So we can develop beam-based numerical models of longitudinal and transverse impedances. At the Diamond Light Source (DLS) to get the model parameters, a set of measured data has been used including current-dependent shift of betatron tunes and synchronous phase, chromatic damping rates, and bunch lengthening. A matlab code for multiparticle tracking has been developed. The tracking results and analytical estimations are quite consistent with the measured data. Since Diamond has the shortest natural bunch length among all light sources in standard operation, the studies of collective effects with short bunches are relevant to many facilities including next generation of light sources.

  12. Figure of merit of diamond power devices based on accurately estimated impact ionization processes

    NASA Astrophysics Data System (ADS)

    Hiraiwa, Atsushi; Kawarada, Hiroshi

    2013-07-01

    Although a high breakdown voltage or field is considered as a major advantage of diamond, there has been a large difference in breakdown voltages or fields of diamond devices in literature. Most of these apparently contradictory results did not correctly reflect material properties because of specific device designs, such as punch-through structure and insufficient edge termination. Once these data were removed, the remaining few results, including a record-high breakdown field of 20 MV/cm, were theoretically reproduced, exactly calculating ionization integrals based on the ionization coefficients that were obtained after compensating for possible errors involved in reported theoretical values. In this compensation, we newly developed a method for extracting an ionization coefficient from an arbitrary relationship between breakdown voltage and doping density in the Chynoweth's framework. The breakdown field of diamond was estimated to depend on the doping density more than other materials, and accordingly required to be compared at the same doping density. The figure of merit (FOM) of diamond devices, obtained using these breakdown data, was comparable to the FOMs of 4H-SiC and Wurtzite-GaN devices at room temperature, but was projected to be larger than the latter by more than one order of magnitude at higher temperatures about 300 °C. Considering the relatively undeveloped state of diamond technology, there is room for further enhancement of the diamond FOM, improving breakdown voltage and mobility. Through these investigations, junction breakdown was found to be initiated by electrons or holes in a p--type or n--type drift layer, respectively. The breakdown voltages in the two types of drift layers differed from each other in a strict sense but were practically the same. Hence, we do not need to care about the conduction type of drift layers, but should rather exactly calculate the ionization integral without approximating ionization coefficients by a power

  13. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2003-01-01

    Statistics on the production, consumption, cost, trade, and government stockpile of natural and synthetic industrial diamond are provided. The outlook for the industrial diamond market is also considered.

  14. Diamonds from the V. Grib pipe, Arkhangelsk kimberlite province, Russia

    NASA Astrophysics Data System (ADS)

    Rubanova, E. V.; Palazhchenko, O. V.; Garanin, V. K.

    2009-11-01

    A large collection (717 samples) of diamonds from the V. Grib deposit, discovered in 1996 in the Verhotinskoe field of the Arkhangelsk kimberlite province, was studied. The diamond crystals are characterized by high transparency and preservation. The collection consists of complete crystals (71%), chipped and damaged crystals (preservation > 50%; 14%), and fragments (preservation < 50%; 15%). Resorption is generally moderate resulting in a dominance of octahedral and mixed octahedral-dodecahedral shapes. Moderate resorption points to rapid ascent of the transporting kimberlite magma. A characteristic feature of V. Grib is a large number of green diamonds. This may relate to the close proximity of radioactive deposits. Microscopic green surface spots have no cathodoluminescence. The internal diamond morphology was studied by UV- and cathodoluminescence. The main typomorphic feature of diamond crystals from the V. Grib pipe is a high percentage of crystals without UV-luminescence. Presence of sectorial growth was also identified by luminescence. Analysis of mineral inclusions, carbon isotopic composition, nitrogen content and nitrogen aggregation state provided important genetic information. Peridotitic inclusions (olivine, chromian spinel and pyrope) predominate, sulfides are almost completely absent. The carbon isotopic composition of the host diamonds is typical for peridotitic diamonds worldwide. IR-spectroscopy suggests the presence of two diamond populations with low and high nitrogen concentrations. Three sub-populations may be identified based on a combination of morphology, nitrogen and hydrogen defects. Residence temperatures ( TNitrogen), based on a mantle residence time of 3 Ga, fall between 1050 and 1170 °C. Diamond crystallization in V. Grib occurred in multiple stages. This is documented through luminescence patterns, data on nitrogen concentration and aggregation state, and the presence of "diamond-in-diamond" inclusions.

  15. Piezoelectric actuated micro-resonators based on the growth of diamond on aluminum nitride thin films.

    PubMed

    Hees, J; Heidrich, N; Pletschen, W; Sah, R E; Wolfer, M; Williams, O A; Lebedev, V; Nebel, C E; Ambacher, O

    2013-01-18

    Unimorph heterostructures based on piezoelectric aluminum nitride (AlN) and diamond thin films are highly desirable for applications in micro- and nanoelectromechanical systems. In this paper, we present a new approach to combine thin conductive boron-doped as well as insulating nanocrystalline diamond (NCD) with sputtered AlN films without the need for any buffer layers between AlN and NCD or polishing steps. The zeta potentials of differently treated nanodiamond (ND) particles in aqueous colloids are adjusted to the zeta potential of AlN in water. Thereby, the nucleation density for the initial growth of diamond on AlN can be varied from very low (10(8) cm(-2)), in the case of hydrogen-treated ND seeding particles, to very high values of 10(11) cm(-2) for oxidized ND particles. Our approach yielding high nucleation densities allows the growth of very thin NCD films on AlN with thicknesses as low as 40 nm for applications such as microelectromechanical beam resonators. Fabricated piezo-actuated micro-resonators exhibit enhanced mechanical properties due to the incorporation of boron-doped NCD films. Highly boron-doped NCD thin films which replace the metal top electrode offer Young's moduli of more than 1000 GPa. PMID:23220817

  16. Diamond Smoothing Tools

    NASA Technical Reports Server (NTRS)

    Voronov, Oleg

    2007-01-01

    Diamond smoothing tools have been proposed for use in conjunction with diamond cutting tools that are used in many finish-machining operations. Diamond machining (including finishing) is often used, for example, in fabrication of precise metal mirrors. A diamond smoothing tool according to the proposal would have a smooth spherical surface. For a given finish machining operation, the smoothing tool would be mounted next to the cutting tool. The smoothing tool would slide on the machined surface left behind by the cutting tool, plastically deforming the surface material and thereby reducing the roughness of the surface, closing microcracks and otherwise generally reducing or eliminating microscopic surface and subsurface defects, and increasing the microhardness of the surface layer. It has been estimated that if smoothing tools of this type were used in conjunction with cutting tools on sufficiently precise lathes, it would be possible to reduce the roughness of machined surfaces to as little as 3 nm. A tool according to the proposal would consist of a smoothing insert in a metal holder. The smoothing insert would be made from a diamond/metal functionally graded composite rod preform, which, in turn, would be made by sintering together a bulk single-crystal or polycrystalline diamond, a diamond powder, and a metallic alloy at high pressure. To form the spherical smoothing tip, the diamond end of the preform would be subjected to flat grinding, conical grinding, spherical grinding using diamond wheels, and finally spherical polishing and/or buffing using diamond powders. If the diamond were a single crystal, then it would be crystallographically oriented, relative to the machining motion, to minimize its wear and maximize its hardness. Spherically polished diamonds could also be useful for purposes other than smoothing in finish machining: They would likely also be suitable for use as heat-resistant, wear-resistant, unlubricated sliding-fit bearing inserts.

  17. Conditions for forming composite carbon nanotube-diamond like carbon material that retain the good properties of both materials

    NASA Astrophysics Data System (ADS)

    Ren, Wei; Iyer, Ajai; Koskinen, Jari; Kaskela, Antti; Kauppinen, Esko I.; Avchaciov, Konstantin; Nordlund, Kai

    2015-11-01

    Carbon nanotubes are of wide interest due to their excellent properties such as tensile strength and electrical and thermal conductivity, but are not, when placed alone on a substrate, well resistant to mechanical wear. Diamond-like carbon (DLC), on the other hand, is widely used in applications due to its very good wear resistance. Combining the two materials could provide a very durable pure carbon nanomaterial enabling to benefit from the best properties of both carbon allotropes. However, the synthesis of high-quality diamond-like carbon uses energetic plasmas, which can damage the nanotubes. From previous works it is neither clear whether the quality of the tubes remains good after DLC deposition, nor whether the DLC above the tubes retains the high sp3 bonding fraction. In this work, we use experiments and classical molecular dynamics simulations to study the mechanisms of DLC formation on various carbon nanotube compositions. The results show that high-sp3-content DLC can be formed provided the deposition conditions allow for sidewards pressure to form from a substrate close beneath the tubes. Under optimal DLC formation energies of around 40-70 eV, the top two nanotube atom layers are fully destroyed by the plasma deposition, but layers below this can retain their structural integrity.

  18. Conditions for forming composite carbon nanotube-diamond like carbon material that retain the good properties of both materials

    SciTech Connect

    Ren, Wei Avchaciov, Konstantin; Nordlund, Kai; Iyer, Ajai; Koskinen, Jari; Kaskela, Antti; Kauppinen, Esko I.

    2015-11-21

    Carbon nanotubes are of wide interest due to their excellent properties such as tensile strength and electrical and thermal conductivity, but are not, when placed alone on a substrate, well resistant to mechanical wear. Diamond-like carbon (DLC), on the other hand, is widely used in applications due to its very good wear resistance. Combining the two materials could provide a very durable pure carbon nanomaterial enabling to benefit from the best properties of both carbon allotropes. However, the synthesis of high-quality diamond-like carbon uses energetic plasmas, which can damage the nanotubes. From previous works it is neither clear whether the quality of the tubes remains good after DLC deposition, nor whether the DLC above the tubes retains the high sp{sup 3} bonding fraction. In this work, we use experiments and classical molecular dynamics simulations to study the mechanisms of DLC formation on various carbon nanotube compositions. The results show that high-sp{sup 3}-content DLC can be formed provided the deposition conditions allow for sidewards pressure to form from a substrate close beneath the tubes. Under optimal DLC formation energies of around 40–70 eV, the top two nanotube atom layers are fully destroyed by the plasma deposition, but layers below this can retain their structural integrity.

  19. Design of a three-dimensional photonic crystal nanocavity based on a \\langle 110\\rangle -layered diamond structure

    NASA Astrophysics Data System (ADS)

    Tajiri, Takeyoshi; Takahashi, Shun; Tandaechanurat, Aniwat; Iwamoto, Satoshi; Arakawa, Yasuhiko

    2014-01-01

    We design a three-dimensional (3D) photonic crystal (PC) nanocavity based on a \\langle 110\\rangle -layered diamond structure. The designed structure, comprised of self-sustainable layers, is suitable for fabrication by layer stacking techniques. Quality factors (Q-factors) of nanocavities were calculated for the \\langle 110\\rangle -layered diamond and a commonly-used woodpile structures, both of which are generated from the same diamond lattice with a lattice constant adiamond. The Q-factor of the designed nanocavity can reach as high as 230,000 with 35 stacked layers and a square in-plane PC area of the length of one side of 5\\sqrt{2} a^{\\text{diamond}}. This is 1.5 times higher than that of a 3D PC nanocavity based on the woodpile structure with the same in-plane PC size and with the same number of stacked layers. The higher Q-factor in the \\langle 110\\rangle -layered diamond structure originates from its stronger in-plane light confinement over the woodpile structure. The \\langle 110\\rangle -layered diamond structure will be beneficial for improving experimentally attainable Q-factors of 3D PC nanocavities particularly fabricated by a micromanipulation method.

  20. Nitrogen isotope systematics and origins of mixed-habit diamonds

    NASA Astrophysics Data System (ADS)

    Howell, D.; Stern, R. A.; Griffin, W. L.; Southworth, R.; Mikhail, S.; Stachel, T.

    2015-05-01

    mantle fluid/melt by prior diamond precipitation. The homogeneous nature of both the carbon and nitrogen isotopic compositions of all three diamonds, however, documents continuous and unlimited supply of diamond forming fluid/melt, with a constant composition. Such homogenous isotopic compositions exclude fluid mixing or isotopic fractionation close to the site of diamond formation and preclude distinguishing between these two processes based on diamond analyses alone.

  1. Electron energy loss spectrometry of interstellar diamonds

    NASA Technical Reports Server (NTRS)

    Bernatowicz, Thomas J.; Gibbons, Patrick C.; Lewis, Roy S.

    1990-01-01

    The results are reported of electron energy loss spectra (EELS) measurements on diamond residues from carbonaceous meteorites designed to elucidate the structure and composition of interstellar diamonds. Dynamic effective medium theory is used to model the dielectric properties of the diamonds and in particular to synthesize the observed spectra as mixtures of diamond and various pi-bonded carbons. The results are shown to be quantitatively consistent with the idea that diamonds and their surfaces are the only contributors to the electron energy loss spectra of the diamond residues and that these peculiar spectra are the result of the exceptionally small grain size and large specific surface area of the interstellar diamonds.

  2. Earth's Core Formation and Composition : New Constraints from Diamond Anvil Cell Experiments

    NASA Astrophysics Data System (ADS)

    Siebert, J.; Badro, J.; Antonangeli, D.; Ryerson, F. J.

    2011-12-01

    The pattern of siderophile (iron-loving) element abundance in the silicate portion of the Earth is a consequence of metal separation during core formation. Thermodynamic expressions used to constrain the metal-silicate partitioning behavior of siderophile elements are mainly established from large volume press experiments that do not cover the full range of potential P-T conditions for core-mantle equilibrium. The diamond anvil cell is the only static technique capable of achieving required P-T conditions but until now its capabilities to perform quantitative metal-silicate partitioning experiments at extreme conditions has been untapped. We use protocols that effectively link high P-T diamond anvil cell with analytical techniques such as focused ion beam device (FIB); NanoSIMS; electron microprobe; transmission electron microscopes; and in-situ synchrotron X-ray diffraction measurements allow us to obtain quantitative data on element partitioning at superliquidus conditions above 30 GPa and 3000 K. Here we present our advances in both experimental and analytical methods. We look at the partitioning of 6 siderophile elements (Ni, Co, Cr, V, Mn, and Nb) that have been extensively studied at lower P-T conditions and constrain the solubility of light elements (Si and O) at these extreme conditions. We then update expressions that describe the partitioning behavior of these elements to address the validity of proposed core formation models (i.e. single-stage core formation model and continuous core formation model).

  3. Nonuniformity correction for an infrared focal plane array based on diamond search block matching.

    PubMed

    Sheng-Hui, Rong; Hui-Xin, Zhou; Han-Lin, Qin; Rui, Lai; Kun, Qian

    2016-05-01

    In scene-based nonuniformity correction algorithms, artificial ghosting and image blurring degrade the correction quality severely. In this paper, an improved algorithm based on the diamond search block matching algorithm and the adaptive learning rate is proposed. First, accurate transform pairs between two adjacent frames are estimated by the diamond search block matching algorithm. Then, based on the error between the corresponding transform pairs, the gradient descent algorithm is applied to update correction parameters. During the process of gradient descent, the local standard deviation and a threshold are utilized to control the learning rate to avoid the accumulation of matching error. Finally, the nonuniformity correction would be realized by a linear model with updated correction parameters. The performance of the proposed algorithm is thoroughly studied with four real infrared image sequences. Experimental results indicate that the proposed algorithm can reduce the nonuniformity with less ghosting artifacts in moving areas and can also overcome the problem of image blurring in static areas. PMID:27140891

  4. Morphological response of diamond films in dry sliding contact

    NASA Astrophysics Data System (ADS)

    Languell, M. L.; George, M. A.; Wert, J. J.; Davidson, T. L.

    1994-07-01

    Reciprocating dry sliding friction tests performed on diamond-coated tungsten substrates produced changes in the surface morphology. A right-cylinder-on-flat geometry was used for the tribotesting. The morphological changes were investigated with scanning electron and atomic force microscopy. The composition of the diamond film was determined with Raman spectroscopy. The frictional response of the coating is examined in relation to the surface changes. A wear model for diamond films in dry sliding contact based on the morphological response is presented.

  5. Multiple growth events, processes and fluid sources involved in diamond genesis: A micro-analytical study of sulphide-bearing diamonds from Finsch mine, RSA

    NASA Astrophysics Data System (ADS)

    Palot, M.; Pearson, D. G.; Stern, R. A.; Stachel, T.; Harris, J. W.

    2013-04-01

    Twenty-one sulphide inclusion-bearing diamonds from the Finsch mine, South Africa, were analysed for nitrogen abundances and carbon isotope compositions by microbeam methods. On the basis of sulphide Ni contents, one diamond is of peridotitic affinity, the rest belongs to the eclogitic suite. FTIR analyses show nitrogen abundances and aggregation states from 21 to 1093 at.ppm and 0% to 83% IaB, statistically indistinguishable from previous results for Finsch eclogitic silicate inclusion-bearing diamonds (Appleyard et al., 2004) but significantly higher than observed before for diamonds of the peridotitic suite (Deines et al., 1989). Detailed analyses revealed marked variations in nitrogen characteristics within individual diamonds, demonstrating a complex mantle residence, consistent with multiple episodes of diamond growth over time. Linked to the growth stratigraphy of the diamond, SIMS micro-analyses show variations in δ13C from -8.90‰ to -2.80‰ with a mean value of -5.54 ± 1.80‰ (1 standard deviation), closely overlapping the typical worldwide value. The C-isotopic variability within individual diamonds ranges up to 3.26‰. SIMS based nitrogen abundances are 3-2221 at.ppm with heterogeneous distribution within individual diamond. From the δ13C-[N] co-variations within individual diamonds, three major processes of diamond growth for sulphide inclusion-bearing samples at Finsch are proposed. (1) Some diamonds were precipitated during a single event of open system isotopic fractionation, in fluids that varied from oxidised (carbonatitic) to reduced (CH4-rich). In this growth scenario, nitrogen is either compatible or incompatible during diamond growth. (2) Other diamonds show abrupt δ13C-[N] changes indicative of diamond growth involving mixing of several fluid sources. (3) Some diamonds grow from a combination of the two previous processes. The models are consistent with metasomatic diamond growth involving single and multiple fluid sources. Multiple

  6. Growth of single diamond crystallites around nanometer-scale silicon wires

    SciTech Connect

    Dennig, P.A.; Liu, H.I.; Stevenson, D.A.; Pease, R.F.W.

    1995-08-14

    Diamond crystallites were nucleated and grown from the vapor phase on silicon substrates previously processed into arrays of nanometer-scale silicon wires. We found that the nanowires did not aid nucleation, and that the nucleation density on the nanowire base was very low ({lt}10{sup 4} cm{sup {minus}2}). Most importantly, we discovered that single diamond crystallites grew around the nanowires, infiltrating the nanowire arrays, forming new composite structures. This discovery clearly shows how inclusions can be trapped in vapor grown diamond crystallites, and challenges the common assumption that growth precursors on the diamond surface are relatively immobile. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  7. Presentation of a research project addressed to the realisation of a diamond-based cellular biosensing device

    NASA Astrophysics Data System (ADS)

    Boarino, Luca; Carabelli, Valentina; Carbone, Emilio; Genovese, Marco; Gosso, Sara; Olivero, Paolo; Pasquarelli, Alberto; Picollo, Federico; Traina, Paolo

    2012-02-01

    In this proceedings we will present a research project financed by Piedmont regional government (Italy; finalized to the realization and commercialization of functional devices for cellular bio-sensing based on diamond. Partners of the project are: Crisel Instruments, Torino University, Torino Polytechnic, INRIM, Politronica, Bionica Tech, Ulm University Here the main features of the final devices will be briefly summarized. We envisage an active diamond-based cellular substrate that can simultaneously stimulate and detect a variety of signals (chemical, optical, electrical) to and from neuroendocrine cells, in a fully biocompatible environment for the cellular system under test. Such a device can be realized by fully exploiting the peculiar properties of diamond: optical transparency, biocompatibility, chemical inertness, accessibility to a conductive graphite-like phase; properties that will be further explored and tested during the project.

  8. Microstructural evolution of diamond growth during HFCVD

    NASA Technical Reports Server (NTRS)

    Singh, J.

    1994-01-01

    High resolution transmission electron microscopy (HRTEM) was used to study the nucleation and growth mechanism of diamond by hot filament chemical vapor deposition (HFCVD) process. A novel technique has shown a direct evidence for the formation of the diamond-like carbon layer 8-14 nm thick in which small diamond micro-crystallites were embedded. These diamond micro-crystallites were formed as a result of transformation of diamond-like carbon into diamond. The diamond micro-crystallites present in the amorphous diamond-like carbon layer provided nucleation sites for diamond growth. Large diamond crystallites were observed to grow from these micro-crystallites. The mechanism of diamond growth will be presented based on experimental findings.

  9. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2012-01-01

    Estimated 2011 world production of natural and synthetic industrial diamond was about 4.45 billion carats. During 2011, natural industrial diamonds were produced in more than 20 countries, and synthetic industrial diamond was produced in at least 13 countries. About 98 percent of the combined natural and synthetic global output was produced in China, Ireland, Japan, Russia, South Africa and the United States. China is the world's leading producer of synthetic industrial diamond followed by Russia and the United States.

  10. A stacking-fault based microscopic model for platelets in diamond

    NASA Astrophysics Data System (ADS)

    Antonelli, Alex; Nunes, Ricardo

    2005-03-01

    We propose a new microscopic model for the 001 planar defects in diamond commonly called platelets. This model is based on the formation of a metastable stacking fault, which can occur because of the ability of carbon to stabilize in different bonding configurations. In our model the core of the planar defect is basically a double layer of three-fold coordinated sp^2 carbon atoms embedded in the common sp^3 diamond structure. The properties of the model were determined using ab initio total energy calculations. All significant experimental signatures attributed to the platelets, namely, the lattice displacement along the [001] direction, the asymmetry between the [110] and the [11 0] directions, the infrared absorption peak B^' , and broad luminescence lines that indicate the introduction of levels in the band gap, are naturally accounted for in our model. The model is also very appealing from the point of view of kinetics, since naturally occurring shearing processes will lead to the formation of the metastable fault.Authors acknowledge financial support from the Brazilian agencies FAPESP, CNPq, FAEP-UNICAMP, FAPEMIG, and Instituto do Milênio em Nanociências-MCT

  11. A Diamond-Based Electrode for Detection of Neurochemicals in the Human Brain

    PubMed Central

    Bennet, Kevin E.; Tomshine, Jonathan R.; Min, Hoon-Ki; Manciu, Felicia S.; Marsh, Michael P.; Paek, Seungleal B.; Settell, Megan L.; Nicolai, Evan N.; Blaha, Charles D.; Kouzani, Abbas Z.; Chang, Su-Youne; Lee, Kendall H.

    2016-01-01

    Deep brain stimulation (DBS), a surgical technique to treat certain neurologic and psychiatric conditions, relies on pre-determined stimulation parameters in an open-loop configuration. The major advancement in DBS devices is a closed-loop system that uses neurophysiologic feedback to dynamically adjust stimulation frequency and amplitude. Stimulation-driven neurochemical release can be measured by fast-scan cyclic voltammetry (FSCV), but existing FSCV electrodes rely on carbon fiber, which degrades quickly during use and is therefore unsuitable for chronic neurochemical recording. To address this issue, we developed durable, synthetic boron-doped diamond-based electrodes capable of measuring neurochemical release in humans. Compared to carbon fiber electrodes, they were more than two orders-of-magnitude more physically-robust and demonstrated longevity in vitro without deterioration. Applied for the first time in humans, diamond electrode recordings from thalamic targets in patients (n = 4) undergoing DBS for tremor produced signals consistent with adenosine release at a sensitivity comparable to carbon fiber electrodes. (Clinical trials # NCT01705301). PMID:27014033

  12. A Diamond-Based Electrode for Detection of Neurochemicals in the Human Brain.

    PubMed

    Bennet, Kevin E; Tomshine, Jonathan R; Min, Hoon-Ki; Manciu, Felicia S; Marsh, Michael P; Paek, Seungleal B; Settell, Megan L; Nicolai, Evan N; Blaha, Charles D; Kouzani, Abbas Z; Chang, Su-Youne; Lee, Kendall H

    2016-01-01

    Deep brain stimulation (DBS), a surgical technique to treat certain neurologic and psychiatric conditions, relies on pre-determined stimulation parameters in an open-loop configuration. The major advancement in DBS devices is a closed-loop system that uses neurophysiologic feedback to dynamically adjust stimulation frequency and amplitude. Stimulation-driven neurochemical release can be measured by fast-scan cyclic voltammetry (FSCV), but existing FSCV electrodes rely on carbon fiber, which degrades quickly during use and is therefore unsuitable for chronic neurochemical recording. To address this issue, we developed durable, synthetic boron-doped diamond-based electrodes capable of measuring neurochemical release in humans. Compared to carbon fiber electrodes, they were more than two orders-of-magnitude more physically-robust and demonstrated longevity in vitro without deterioration. Applied for the first time in humans, diamond electrode recordings from thalamic targets in patients (n = 4) undergoing DBS for tremor produced signals consistent with adenosine release at a sensitivity comparable to carbon fiber electrodes. (Clinical trials # NCT01705301). PMID:27014033

  13. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2011-01-01

    Estimated world production of natural and synthetic industrial diamond was about 4.44 billion carats in 2010. Natural industrial diamond deposits have been found in more than 35 countries, and synthetic industrial diamond is produced in at least 15 countries.

  14. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2006-01-01

    In 2005, estimated world production of natural and synthetic industrial diamond was 630 million carats. Natural industrial diamond deposits were found in more than 35 countries. Synthetic industrial diamond is produced in at least 15 countries. More than 81% of the combined natural and synthetic global output was produced in Ireland, Japan, Russia, South Africa and the United States.

  15. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2013-01-01

    Estimated 2012 world production of natural and synthetic industrial diamond was about 4.45 billion carats. During 2012, natural industrial diamonds were produced in at least 20 countries, and synthetic industrial diamond was produced in at least 12 countries. About 99 percent of the combined natural and synthetic global output was produced in Belarus, China, Ireland, Japan, Russia, South Africa and the United States. During 2012, China was the world’s leading producer of synthetic industrial diamond followed by the United States and Russia. In 2012, the two U.S. synthetic producers, one in Pennsylvania and the other in Ohio, had an estimated output of 103 million carats, valued at about $70.6 million. This was an estimated 43.7 million carats of synthetic diamond bort, grit, and dust and powder with a value of $14.5 million combined with an estimated 59.7 million carats of synthetic diamond stone with a value of $56.1 million. Also in 2012, nine U.S. firms manufactured polycrystalline diamond (PCD) from synthetic diamond grit and powder. The United States government does not collect or maintain data for either domestic PCD producers or domestic chemical vapor deposition (CVD) diamond producers for quantity or value of annual production. Current trade and consumption quantity data are not available for PCD or for CVD diamond. For these reasons, PCD and CVD diamond are not included in the industrial diamond quantitative data reported here.

  16. Method to fabricate portable electron source based on nitrogen incorporated ultrananocrystalline diamond (N-UNCD)

    DOEpatents

    Sumant, Anirudha V.; Divan, Ralu; Posada, Chrystian M.; Castano, Carlos H.; Grant, Edwin J.; Lee, Hyoung K.

    2016-03-29

    A source cold cathode field emission array (FEA) source based on ultra-nanocrystalline diamond (UNCD) field emitters. This system was constructed as an alternative for detection of obscured objects and material. Depending on the geometry of the given situation a flat-panel source can be used in tomography, radiography, or tomosynthesis. Furthermore, the unit can be used as a portable electron or X-ray scanner or an integral part of an existing detection system. UNCD field emitters show great field emission output and can be deposited over large areas as the case with carbon nanotube "forest" (CNT) cathodes. Furthermore, UNCDs have better mechanical and thermal properties as compared to CNT tips which further extend the lifetime of UNCD based FEA.

  17. Development of an Amorphous Selenium-Based Photodetector Driven by a Diamond Cold Cathode

    PubMed Central

    Masuzawa, Tomoaki; Saito, Ichitaro; Yamada, Takatoshi; Onishi, Masanori; Yamaguchi, Hisato; Suzuki, Yu; Oonuki, Kousuke; Kato, Nanako; Ogawa, Shuichi; Takakuwa, Yuji; Koh, Angel T. T.; Chua, Daniel H. C.; Mori, Yusuke; Shimosawa, Tatsuo; Okano, Ken

    2013-01-01

    Amorphous-selenium (a-Se) based photodetectors are promising candidates for imaging devices, due to their high spatial resolution and response speed, as well as extremely high sensitivity enhanced by an internal carrier multiplication. In addition, a-Se is reported to show sensitivity against wide variety of wavelengths, including visible, UV and X-ray, where a-Se based flat-panel X-ray detector was proposed. In order to develop an ultra high-sensitivity photodetector with a wide detectable wavelength range, a photodetector was fabricated using a-Se photoconductor and a nitrogen-doped diamond cold cathode. In the study, a prototype photodetector has been developed, and its response to visible and ultraviolet light are characterized. PMID:24152932

  18. Nanofocusing of hard X-ray free electron laser pulses using diamond based Fresnel zone plates

    NASA Astrophysics Data System (ADS)

    David, C.; Gorelick, S.; Rutishauser, S.; Krzywinski, J.; Vila-Comamala, J.; Guzenko, V. A.; Bunk, O.; Färm, E.; Ritala, M.; Cammarata, M.; Fritz, D. M.; Barrett, R.; Samoylova, L.; Grünert, J.; Sinn, H.

    2011-08-01

    A growing number of X-ray sources based on the free-electron laser (XFEL) principle are presently under construction or have recently started operation. The intense, ultrashort pulses of these sources will enable new insights in many different fields of science. A key problem is to provide x-ray optical elements capable of collecting the largest possible fraction of the radiation and to focus into the smallest possible focus. As a key step towards this goal, we demonstrate here the first nanofocusing of hard XFEL pulses. We developed diamond based Fresnel zone plates capable of withstanding the full beam of the world's most powerful x-ray laser. Using an imprint technique, we measured the focal spot size, which was limited to 320 nm FWHM by the spectral band width of the source. A peak power density in the focal spot of 4×1017 W/cm2 was obtained at 70 fs pulse length.

  19. Nanofocusing of hard X-ray free electron laser pulses using diamond based Fresnel zone plates.

    PubMed

    David, C; Gorelick, S; Rutishauser, S; Krzywinski, J; Vila-Comamala, J; Guzenko, V A; Bunk, O; Färm, E; Ritala, M; Cammarata, M; Fritz, D M; Barrett, R; Samoylova, L; Grünert, J; Sinn, H

    2011-01-01

    A growing number of X-ray sources based on the free-electron laser (XFEL) principle are presently under construction or have recently started operation. The intense, ultrashort pulses of these sources will enable new insights in many different fields of science. A key problem is to provide x-ray optical elements capable of collecting the largest possible fraction of the radiation and to focus into the smallest possible focus. As a key step towards this goal, we demonstrate here the first nanofocusing of hard XFEL pulses. We developed diamond based Fresnel zone plates capable of withstanding the full beam of the world's most powerful x-ray laser. Using an imprint technique, we measured the focal spot size, which was limited to 320 nm FWHM by the spectral band width of the source. A peak power density in the focal spot of 4×10(17)W/cm(2) was obtained at 70 fs pulse length. PMID:22355576

  20. Corrosive Resistant Diamond Coatings for the Acid Based Thermo-Chemical Hydrogen Cycles

    SciTech Connect

    Mark A. Prelas

    2009-06-25

    This project was designed to test diamond, diamond-like and related materials in environments that are expected in thermochemical cycles. Our goals were to build a High Temperature Corrosion Resistance (HTCR) test stand and begin testing the corrosive properties of barious materials in a high temperature acidic environment in the first year. Overall, we planned to test 54 samples each of diamond and diamond-like films (of 1 cm x 1 cm area). In addition we use a corrosion acceleration method by treating the samples at a temperature much larger than the expected operating temperature. Half of the samples will be treated with boron using the FEDOA process.

  1. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2000-01-01

    Part of the 1999 Industrial Minerals Review. A review of the state of the global industrial diamond industry in 1999 is presented. World consumption of industrial diamond has increased annually in recent years, with an estimated 500 million carats valued between $650 million and $800 million consumed in 1999. In 1999, the U.S. was the world's largest market for industrial diamond and was also one of the world's main producers; the others were Ireland, Russia, and South Africa. Uses of industrial diamonds are discussed, and prices of natural and synthetic industrial diamond are reported.

  2. C and N isotopic composition and the infrared absorption spectra of coated diamonds: evidence for the regional uniformity of CO2sbnd H2O rich fluids in lithospheric mantle

    NASA Astrophysics Data System (ADS)

    Boyd, S. R.; Pillinger, C. T.; Milledge, H. J.; Mendelssohn, M. J.; Seal, M.

    1992-04-01

    Theδ13C andδ15N values, nitrogen abundances and nitrogen aggregation states of coated diamonds from Botswana, Angola, Sierra Leone and Siberia have been determined. A single cubic micro-diamond from the Northern Territory, Australia was also analysed. The (cubic) coats of the diamonds and the cubic diamond from Australia had a restricted range in isotope composition:δ13C= -7.2 to -4.1‰,δ15N= -8.7 to -1.7‰. In contrast, the cores of the coated diamonds were found to be highly variable:δ13C= -21.1‰ to -1.9‰, andδ15N= -2.8‰ to +12.1‰ (with the majority being positive). All of the coats gave the type IaA absorption spectra, together with others due to micro-inclusions dominated by H2O and CO2, whereas the cores contained nitrogen that was more highly aggregated. The results suggest that coated diamonds were formed following the influx of CO2sbnd H2O rich fluids into diamond-bearing lithosphere. Pre-existing diamonds acted as seeds for renewed growth and these are now the cores of the diamonds. These cores may be very variable in terms of morphology, isotopic composition, age, nitrogen aggregation state and crystallinity depending on the particular history of the source regions and the conditions of diamond growth. It is believed that the influx of volatiles and the growth of the coats was linked to kimberlite magmatism. Theδ13C andδ15N results for the coats indicate that, in terms of C and N isotope composition, the source of CO2sbnd H2O rich fluids is globally quite homogeneous. It is probably located beneath continental lithosphere and, in addition, may have characteristics similar to the source of the ocean island basalts.

  3. C and N isotopic composition and the infrared absorption spectra of coated diamonds: evidence for the regional uniformity of CO 2F&z.sbnd;H 2O rich fluids in lithospheric mantle

    NASA Astrophysics Data System (ADS)

    Boyd, S. R.; Pillinger, C. T.; Milledge, H. J.; Seal, M. J.

    1992-01-01

    The δ 13C and δ 15N values, nitrogen abundances and nitrogen aggregation states of coated diamonds from Botswana, Angola, Sierra Leone and Siberia have been determined. A single cubic micro-diamond from the Northern Territory, Australia was also analysed. The (cubic) coats of the diamonds and the cubic diamond from Australia had a restricted range in isotope composition: δ 13C= -7.2to-4.1‰ δ 15N= -8.7to-1.7‰ . In contrast, the cores of the coated diamonds were found to be highly variable: δ 13C= -21.1‰to-1.9‰ , and δ 15N= -2.8‰to+12.1‰ (with the majority being positive). All of the coats gave the type IaA absorption spectra, together with others due to micro-inclusions dominated by H 2O and CO 2, whereas the cores contained nitrogen that was more highly aggregated. The results suggest that coated diamonds were formed following the influx of CO 2&z.sbnd;H 2O rich fluids into diamond-bearing lithosphere. Pre-existing diamonds acted as seeds for renewed growth and these are now the cores of the diamonds. These cores may be very variable in terms of morphology, isotopic composition, age, nitrogen aggregation state and crystallinity depending on the particular history of the source regions and the conditions of diamond growth. It is believed that the influx of volatiles and the growth of the coats was linked to kimberlite magmatism. The δ 13C and δ 15N results for the coats indicate that, in terms of C and N isotope composition, the source of CO 2&z.sbnd;H 2O rich fluids is globally quite homogeneous. It is probably located beneath continental lithosphere and, in addition, may have characteristics similar to the source of the ocean island basalts.

  4. Structure and properties of diamond and diamond-like films

    SciTech Connect

    Clausing, R.E.

    1993-01-01

    This section is broken into four parts: (1) introduction, (2) natural IIa diamond, (3) importance of structure and composition, and (4) control of structure and properties. Conclusions of this discussion are that properties of chemical vapor deposited diamond films can compare favorably with natural diamond, that properties are anisotropic and are a strong function of structure and crystal perfection, that crystal perfection and morphology are functions of growth conditions and can be controlled, and that the manipulation of texture and thereby surface morphology and internal crystal perfection is an important step in optimizing chemically deposited diamond films for applications.

  5. Hard coating of ultrananocrystalline diamond/nonhydrogenated amorphous carbon composite films on cemented tungsten carbide by coaxial arc plasma deposition

    NASA Astrophysics Data System (ADS)

    Naragino, Hiroshi; Egiza, Mohamed; Tominaga, Aki; Murasawa, Koki; Gonda, Hidenobu; Sakurai, Masatoshi; Yoshitake, Tsuyoshi

    2016-08-01

    Ultrananocrystalline diamond (UNCD)/nonhydrogenated amorphous carbon (a-C) composite (UNCD/a-C) films were deposited on cemented carbide containing Co by coaxial arc plasma deposition. With decreasing substrate temperature, the hardness was enhanced accompanied by an enhancement in the sp3/(sp2 + sp3). Energy-dispersive X-ray and secondary ion mass spectrometry spectroscopic measurements exhibited that the diffusion of Co atoms from the substrates into the films hardly occurs. The film deposited at room temperature exhibited the maximum hardness of 51.3 GPa and Young's modulus of 520.2 GPa, which evidently indicates that graphitization induced by Co in the WC substrates, and thermal deformation from sp3 to sp2 bonding are suppressed. The hard UNCD/a-C films can be deposited at a thickness of approximately 3 μm, which is an order larger than that of comparably hard a-C films. The internal compressive stress of the 51.3-GPa film is 4.5 GPa, which is evidently smaller than that of comparably hard a-C films. This is a reason for the thick deposition. The presence of a large number of grain boundaries in the film, which is a structural specific to UNCD/a-C films, might play a role in releasing the internal stress of the films.

  6. Hardness and modulus of ultrananocrystalline diamond/hydrogenated amorphous carbon composite films prepared by coaxial arc plasma deposition

    NASA Astrophysics Data System (ADS)

    Hanada, Kenji; Yoshida, Tomohiro; Nakagawa, You; Gima, Hiroki; Tominaga, Aki; Hirakawa, Masaaki; Agawa, Yoshiaki; Sugiyama, Takeharu; Yoshitake, Tsuyoshi

    2015-04-01

    Ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) composite (UNCD/a-C:H) films were deposited in hydrogen atmospheres by coaxial arc plasma deposition, and the effects of hydrogenation on the mechanical properties were studied on the basis of spectroscopic structural evaluations. The existence of UNCD grains in the films was confirmed by transmission electron microscopy and X-ray diffraction. Non-hydrogenated films prepared in no hydrogen atmosphere exhibited a 22 GPa hardness and 222 GPa Young's modulus, and the sp 3/( sp 2 + sp 3) ratio estimated from the X-ray photoemission spectra was 41 %. For the films prepared in a 53.3-Pa hydrogen atmosphere, whereas the hardness increases to 23 GPa, the modulus decreases to 184 GPa. The UNCD grain size estimated using Scherrer's equation and the sp 3/( sp 2 + sp 3) ratio were 2.3 nm and 64 %, respectively, both of which are remarkably increased as compared with those of the non-hydrogenated films. From the near-edge X-ray absorption fine structure spectra, it is considered that σ*C-H bonds are alternatively formed instead of π*C=C, which probably results in the enhanced hardness and reduced modulus by hydrogenation. In addition, it was found that the formation of olefinic and aromatic structures remarkably softens the UNCD/a-C:H film.

  7. Wavelet-based fast time-resolved magnetic sensing with electronic spins in diamond

    NASA Astrophysics Data System (ADS)

    Xu, Nanyang; Jiang, Fengjian; Tian, Yu; Ye, Jianfeng; Shi, Fazhan; Lv, Haijiang; Wang, Ya; Wrachtrup, Jörg; Du, Jiangfeng

    2016-04-01

    Time-resolved magnetic sensing is of great importance from fundamental studies to applications in physical and biological sciences. Recently, the nitrogen-vacancy defect center in diamond has been developed as a promising sensor of magnetic fields under ambient conditions. However, methods to reconstruct time-resolved magnetic fields with high sensitivity are not yet fully developed. Here, we propose and demonstrate a sensing method based on spin echo and Haar wavelet transformation. Our method is exponentially faster in reconstructing time-resolved magnetic fields with comparable sensitivity than existing methods. It is also easier to implement in experiments. Furthermore, the wavelet's unique features enable our method to extract information from the whole signal with only part of the measuring sequences. We then explore this feature for a fast detection of simulated nerve impulses. These results will be useful to time-resolved magnetic sensing with quantum probes at nanoscale.

  8. Kimberlite emplacement record in diamond morphology

    NASA Astrophysics Data System (ADS)

    Fedortchouk, Y.; Chinn, I.

    2015-12-01

    Diamond resorption morphology reflects conditions and events in the host kimberlite magma and in diamond sources in subcratonic mantle. Recent experimental studies on diamond dissolution enable us now to use surface features of diamonds to examine magmatic fluid in kimberlites. This study uses optical and scanning electron microscopy examination of ~750 macro-diamonds from two kimberlites in Orapa cluster, Botswana. Kimberlite A is a simple body filled with coherent kimberlite facies (CK); kimberlite B is a complex body with two facies of coherent kimberlite and a massive volcaniclastic kimberlite facies (MVK). Distinction between kimberlite-induced and mantle-derived resorption was based on: the type of the most abundant resorption style, morphology of crystals with attached kimberlite fragments, and the study of pseudohemimorphic diamonds. Kimberlite-induced resorption is the focus of this work. The three facies in the pipe B show three contrasting diamond resorption types. Resorption in MVK facies leads to glossy rounded surfaces with fine striation and hillocks, and is identical to the resorption style in CK facies of pipe A. This type of resorption is typical for volcaniclastic facies and indicates emplacement in the presence of abundant COH fluid with high H2O:CO2 ratio (>50mol% of H2O). We propose that pipe A is a root zone supplying material to a larger kimberlite body filled with VK. The two CK in pipe B have very different resorption style. One forms similar glossy surfaces but with regular small cavities of rounded outline, while the other seems more corrosive and develops extremely rough features and deep cavities. Comparison to the experimental data suggests that the former had almost pure H2O fluid at low pressure (where solubility of SiO2 is low). The later CK facies was emplaced in the absence or very low abundance of a free fluid, and possibly in melt closer to carbonatitic composition.

  9. Picosecond laser fabrication of micro cutting tool geometries on polycrystalline diamond composites using a high-numerical aperture micro scanning system

    NASA Astrophysics Data System (ADS)

    Eberle, Gregory; Dold, Claus; Wegener, Konrad

    2015-03-01

    The generation of microsized components found in LEDs, watches, molds as well as other types of micromechanics and microelectronics require a corresponding micro cutting tool in order to be manufactured, typically by milling or turning. Micro cutting tools are made of cemented tungsten carbide and are conventionally fabricated either by electrical discharge machining (EDM) or by grinding. An alternative method is proposed through a laser-based solution operating in the picosecond pulse duration whereby the beam is deflected using a modified galvanometer-driven micro scanning system exhibiting a high numerical aperture. A micro cutting tool material which cannot be easily processed using conventional methods is investigated, which is a fine grain polycrystalline diamond composite (PCD). The generation of various micro cutting tool relevant geometries, such as chip breakers and cutting edges, are demonstrated. The generated geometries are subsequently evaluated using scanning electron microscopy (SEM) and quality is measured in terms of surface roughness and cutting edge sharpness. Additionally, two processing strategies in which the laser beam processes tangentially and orthogonally are compared in terms of quality.

  10. Films and Disperse Materials Based on Diamond-Like and Related Structures

    NASA Astrophysics Data System (ADS)

    Gun'ko, V. M.; Mikhalovsky, S. V.; Mikhalovska, L. I.; Tomlins, P.; Field, S.; Teer, D. G.; Fitzgerald, S.; Fucassi, F.; Bogatyrev, V. M.; Semikina, T. V.; Turanska, S. P.; Borysenko, M. V.; Turov, V. V.; Gorbyk, P. P.

    Structural, adsorption, mechanical and other properties of diamond-like carbon (DLC) films, ultradisperse diamonds and porous diamond compacts were studied in comparison with Ti, TiO X , TiN X , TiC, Zr, ZrO X , ZrN X , ZrC, SiO2, graphite-like carbon film and graphitised carbon black. Control of the properties of DLC materials by doping or surface modification, high mechanical characteristics and tribological behaviour, chemical passivity, biocompatibility and nontoxicity allow the use of these materials in industry and medicine.

  11. Applications of diamond films and related materials; Proceedings of the 1st International Conference, Auburn, AL, Aug. 17-22, 1991

    NASA Technical Reports Server (NTRS)

    Tzeng, Yonhua (Editor); Yoshikawa, Manasori (Editor); Murakawa, Masao (Editor); Feldman, Albert (Editor)

    1991-01-01

    The present conference discusses the nucleation and growth of diamond from hydrocarbons, the cutting tool performance of CVD thick-film diamond, the characterization of CVD diamond grinding powder, industrial applications of crystalline diamond-coated tools, standardized SEM tribometry of diamond-coated substrates, residual stress in CVD diamond films, the optical properties of CVD diamond films, polycrystalline diamond films for optical applications, and diamond growth on ferrous metals. Also discussed are ion beam-irradiation smoothing of diamond films, electronic circuits on diamond substrates, diamond-laminated surfaces for evaporative spray cooling, electron devices based on the unique properties of diamond, diamond cold cathodes, thin-film diamond microstructure applications, Schottky diodes from flame-grown diamond, diamond films for thermionic applications, methods of diamond nucleation and selective deposition, high-rate/large-area diamond film production, halogen-assisted diamond growth, the economics of diamond technology, and the optical and mechanical properties of diamondlike films.

  12. 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

  13. Endo-Fullerenes and Doped Diamond Nanocrystallite Based Solid-State Qubits

    NASA Technical Reports Server (NTRS)

    Park, Seongjun; Srivastava, Deepak; Cho, K.

    2001-01-01

    This viewgraph presentation provides information on the use of endo-fullerenes and doped diamond nanocrystallites in the development of a solid state quantum computer. Arrays of qubits, which have 1/2 nuclear spin, are more easily fabricated than arrays of similar bare atoms. H-1 can be encapsulated in a C20D20 fullerene, while P-31 can be encapsulated in a diamond nanocrystallite.

  14. On origin of lower-mantle diamonds and their primary inclusions

    NASA Astrophysics Data System (ADS)

    Litvin, Yuriy; Spivak, Anna; Solopova, Natalia; Dubrovinsky, Leonid

    2014-03-01

    Knowledge of mineralogy and petrology of unattainable lower mantle material is usually founded on high-pressure experiments with pyrolite (‘in situ’ material) and oceanic MORB basalt (subducted material). Primary inclusions in transition zone and lower-mantle ‘super-deep’ diamonds represent heterogeneous fragments of diamond-parental medium (not the unaltered lower mantle material). Inclusions of magnesiowustite and stishovite intergrowths (‘stishovite paradox’) give experimentally-supported evidence that stishovite, similarly to magnesiowustite, is not subducted but in situ lower mantle mineral. Primary Ca-, Mg-, Na-carbonate inclusions are symptomatic for multicomponent carbonatite (carbonate-oxide-silicate) parental melts for the lower-mantle diamonds and inclusions. We investigated melting phase relations of simple carbonates of Ca, Mg, Na and multicomponent Mg-Fe-Na-carbonate up to 60 GPa and 3500-4000 K (using multianvil press and diamond-anvil cell with laser heating) and determined a congruent melting of the carbonates and stability of PT-extended phase fields of the carbonate melts. ‘Super-deep’ diamonds are experimentally crystallized in melts of the lower mantle diamond-parental carbonate - magnesiowustite - Mg-perovskite - carbon system. Based on experimental and mineralogical evidence for the lower mantle diamonds inclusions, genetic links between diamonds and inclusions are determined and a generalized composition diagram of parental media for lower mantle diamonds and inclusions is constructed.

  15. Polymer compositions based on PXE

    SciTech Connect

    Yang, Jin; Eitouni, Hany Basam; Singh, Mohit

    2015-09-15

    New polymer compositions based on poly(2,6-dimethyl-1,4-phenylene oxide) and other high-softening-temperature polymers are disclosed. These materials have a microphase domain structure that has an ionically-conductive phase and a phase with good mechanical strength and a high softening temperature. In one arrangement, the structural block has a softening temperature of about 210.degree. C. These materials can be made with either homopolymers or with block copolymers.

  16. Nanofocusing of hard X-ray free electron laser pulses using diamond based Fresnel zone plates

    PubMed Central

    David, C.; Gorelick, S.; Rutishauser, S.; Krzywinski, J.; Vila-Comamala, J.; Guzenko, V. A.; Bunk, O.; Färm, E.; Ritala, M.; Cammarata, M.; Fritz, D. M.; Barrett, R.; Samoylova, L.; Grünert, J.; Sinn, H.

    2011-01-01

    A growing number of X-ray sources based on the free-electron laser (XFEL) principle are presently under construction or have recently started operation. The intense, ultrashort pulses of these sources will enable new insights in many different fields of science. A key problem is to provide x-ray optical elements capable of collecting the largest possible fraction of the radiation and to focus into the smallest possible focus. As a key step towards this goal, we demonstrate here the first nanofocusing of hard XFEL pulses. We developed diamond based Fresnel zone plates capable of withstanding the full beam of the world's most powerful x-ray laser. Using an imprint technique, we measured the focal spot size, which was limited to 320 nm FWHM by the spectral band width of the source. A peak power density in the focal spot of 4×1017 W/cm2 was obtained at 70 fs pulse length. PMID:22355576

  17. Microleakage of repaired class V silorane and nano-hybrid composite restorations after preparation with erbium:yttrium-aluminum-garnet laser and diamond bur.

    PubMed

    Yaman, Batu Can; Efes, Begüm Güray; Dörter, Can; Gömeç, Yavuz; Erdilek, Dina; Yazıcıoğlu, Oktay

    2011-03-01

    The aim of this in vitro study was to compare the microleakage of repaired class V resin composite restorations prepared either by Er:YAG laser or a diamond bur. Ninety-six intact human molar teeth were randomly distributed into eight groups. In the first four groups, class V cavities (3 × 3 × 3 mm) prepared on the buccal and lingual surfaces of the teeth using an erbium:yttrium-aluminum-garnet laser (VersaWave, HOYA ConBio, Japan). Similar class V cavities were prepared in the second four groups using a diamond bur (S-Class, Komet, UK). Teeth in groups 1, 2, and 5, 6 were restored with a nano-ceramic composite (Ceram.X duo, DENTSPLY), whereas a silorane material (Filtek Silorane, 3M ESPE) was used to restore cavities in groups 3, 4, and 7, 8. Two different adhesive systems (XP Bond, DENTSPLY, and Silorane System Adhesive, 3M ESPE) were also used. All specimens were aged for 7 days. New cavities (3 × 3 × 3 mm) were prepared adjacent to the old restorations with Er:YAG laser (groups I-IV) or diamond bur (groups V-VIII). Different repair materials were then applied to the new cavities using the previous two restorative materials and two adhesive systems. All teeth were subjected to thermocycling (5,000 cycles between 5 and 55°C) and axial loadcycling (30 N, 1 Hz, 2,000 cycles). Specimens were immersed in 50% w/w silver nitrate solution. Teeth were sectioned longitudinally in buccolingual direction. Stereomicroscope (Nikon SMZ 800) and SEM (JEOL JSM 5600) were used to evaluate the microleakage that existed at the interface between the old restorations and the repair materials. Data were analyzed statistically with one-way ANOVA and Tukey tests (p < 0.05). Even though no statistically significant differences were found between any of the groups, the cavities repaired with different restoratives showed slight microleakage, especially those prepared by Er:YAG laser (p > 0.05). No microleakage scores were obtained in the groups repaired with Filtek Silorane

  18. A procedure for diamond turning KDP crystals

    SciTech Connect

    Montesanti, R.C.; Thompson, S.L.

    1995-07-07

    A procedure and the equipment necessary for single-point diamond flycutting (loosely referred to as diamond turning) potassium di-hydrogen phosphate (KDP) crystals are described. It is based on current KDP diamond turning activities at the Lawrence Livermore National Laboratory (LLNL), drawing upon knowledge from the Nova crystal finishing development during the 1980`s and incorporating refinements from our efforts during 1995. In addition to describing a step-by-step process for diamond turning KDP, specific discussions are included on the necessary diamond tool geometry and edge sharpness, cutting fluid, and crystal preparation, handling, cleaning, and inspection. The authors presuppose that the reader is already familiar with diamond turning practices.

  19. Microfluidic platform for environmental contaminants sensing and degradation based on boron-doped diamond electrodes.

    PubMed

    Medina-Sánchez, Mariana; Mayorga-Martinez, CarmenC; Watanabe, Takeshi; Ivandini, TribidasariA; Honda, Yuki; Pino, Flavio; Nakata, Kazuya; Fujishima, Akira; Einaga, Yasuaki; Merkoçi, Arben

    2016-01-15

    We have developed a lab-on-a-chip (LOC) platform for electrochemical detection and degradation of the pesticide atrazine (Atz). It is based on boron-doped diamond (BDD) electrodes and a competitive magneto-enzyme immunoassay (EIA) that enables high sensitivity. To detect the enzymatic reaction, we employed a BDD electrode modified with platinum nanoparticles (PtNPs), as a highly conductive catalytic transducer. Chronoamperometry revealed a limit of detection (LOD) of 3.5 pM for atrazine, which, to the best of our knowledge, is one of the lowest value published to date. Finally, we degraded Atz in the same platform, using a bare BDD electrode that features remarkable corrosion stability, a wide potential window, and much higher O2 overvoltage as compared to conventional electrodes. These characteristics enable the electrode to produce a greater amount of HO• on the anode surface than do conventional electrodes and consequently, to destroy the pollutant more rapidly. Our new LOC platform might prove interesting as a smart system for detection and remediation of diverse pesticides and other contaminants. PMID:26339934

  20. High-performance diamond-based single-photon sources for quantum communication

    NASA Astrophysics Data System (ADS)

    Su, Chun-Hsu; Greentree, Andrew D.; Hollenberg, Lloyd C. L.

    2009-11-01

    Quantum communication places stringent requirements on single-photon sources. Here we report a theoretical study of the cavity Purcell enhancement of two diamond point defects, the nickel-nitrogen (NE8) and silicon-vacancy (SiV) centers, for high-performance, near on-demand single-photon generation. By coupling the centers strongly to high-finesse optical photonic-band-gap cavities with modest quality factor Q=O(104) and small mode volume V=O(λ3) , these system can deliver picosecond single-photon pulses at their zero-phonon lines with probabilities of 0.954 (NE8) and 0.812 (SiV) under a realistic optical excitation scheme. The undesirable blinking effect due to transitions via metastable states can also be suppressed with O(10-4) blinking probability. We analyze the application of these enhanced centers, including the previously studied cavity-enhanced nitrogen-vacancy (NV) center, to long-distance Bennett-Brassard 1984 protocol quantum key distribution (QKD) in fiber-based, open-air terrestrial and satellite-ground setups. In this comparative study, we show that they can deliver performance comparable with decoy state implementation with weak coherent sources, and are most suitable for open-air communication.

  1. Diamond Coatings

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Advances in materials technology have demonstrated that it is possible to get the advantages of diamond in a number of applications without the cost penalty, by coating and chemically bonding an inexpensive substrate with a thin film of diamond-like carbon (DLC). Diamond films offer tremendous technical and economic potential in such advances as chemically inert protective coatings; machine tools and parts capable of resisting wear 10 times longer; ball bearings and metal cutting tools; a broad variety of optical instruments and systems; and consumer products. Among the American companies engaged in DLC commercialization is Diamonex, Inc., a diamond coating spinoff of Air Products and Chemicals, Inc. Along with its own proprietary technology for both polycrystalline diamond and DLC coatings, Diamonex is using, under an exclusive license, NASA technology for depositing DLC on a substrate. Diamonex is developing, and offering commercially, under the trade name Diamond Aegis, a line of polycrystalline diamond-coated products that can be custom tailored for optical, electronic and engineering applications. Diamonex's initial focus is on optical products and the first commercial product is expected in late 1990. Other target applications include electronic heat sink substrates, x-ray lithography masks, metal cutting tools and bearings.

  2. Analysis of the Cytotoxicity of Carbon-Based Nanoparticles, Diamond and Graphite, in Human Glioblastoma and Hepatoma Cell Lines

    PubMed Central

    Wierzbicki, Mateusz; Jaworski, Sławomir; Kutwin, Marta; Sawosz, Ewa; Chwalibog, André; Pijanowska, Dorota Genowefa; Pluta, Krzysztof Dariusz

    2015-01-01

    Nanoparticles have attracted a great deal of attention as carriers for drug delivery to cancer cells. However, reports on their potential cytotoxicity raise questions of their safety and this matter needs attentive consideration. In this paper, for the first time, the cytotoxic effects of two carbon based nanoparticles, diamond and graphite, on glioblastoma and hepatoma cells were compared. First, we confirmed previous results that diamond nanoparticles are practically nontoxic. Second, graphite nanoparticles exhibited a negative impact on glioblastoma, but not on hepatoma cells. The studied carbon nanoparticles could be a potentially useful tool for therapeutics delivery to the brain tissue with minimal side effects on the hepatocytes. Furthermore, we showed the influence of the nanoparticles on the stable, fluorescently labeled tumor cell lines and concluded that the labeled cells are suitable for drug cytotoxicity tests. PMID:25816103

  3. Silicon-based nanoenergetic composites

    SciTech Connect

    Asay, Blaine; Son, Steven; Mason, Aaron; Yarrington, Cole; Cho, K Y; Gesner, J; Yetter, R A

    2009-01-01

    Fundamental combustion properties of silicon-based nano-energetic composites was studied by performing equilibrium calculations, 'flame tests', and instrumented burn-tube tests. That the nominal maximum flame temperature and for many Si-oxidizer systems is about 3000 K, with exceptions. Some of these exceptions are Si-metal oxides with temperatures ranging from 2282 to 2978 K. Theoretical maximum gas production of the Si composites ranged from 350-6500 cm{sup 3}/g of reactant with NH{sub 4}ClO{sub 4} - Si producing the most gas at 6500 cm{sup 3}/g and Fe{sub 2}O{sub 3} producing the least. Of the composites tested NH{sub 4}ClO{sub 4} - Si showed the fastest burning rates with the fastest at 2.1 km/s. The Si metal oxide burning rates where on the order of 0.03-75 mls the slowest of which was nFe{sub 2}O{sub 3} - Si.

  4. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2007-01-01

    World production of natural and synthetic industrial diamond was about 648 million carats in 2006, with 79 percent of the production coming from Ireland, Japan, Russia, South Africa, and the U.S. U.S. consumption was was an estimated 602 million carats, imports were over 391 million carats, and exports were about 83 million carats. About 87 percent of the industrial diamonds market uses synthetic diamonds, which are expected to become less expensive as technology improves and competition from low-cost producers increases.

  5. Raman barometry of diamond formation

    NASA Astrophysics Data System (ADS)

    Izraeli, E. S.; Harris, J. W.; Navon, O.

    1999-11-01

    Pressures and temperatures of the diamond source region are commonly estimated using chemical equilibria between coexisting mineral inclusions. Here we present another type of geobarometer, based on determination of the internal pressure in olivine inclusions and the stresses in the surrounding diamond. Using Raman spectroscopy, pressures of 0.13 to 0.65 GPa were measured inside olivine inclusions in three diamonds from the Udachnaya mine in Siberia. Stresses in the diamond surrounding the inclusions indicated similar pressures (0.11-0.41 GPa). Nitrogen concentration and aggregation state in two of the diamonds yielded mantle residence temperatures of ˜1200°C. Using this temperature and the bulk moduli and thermal expansion of olivine and diamond, we calculated source pressures of 4.4-5.2 GPa. We also derived a linear approximation for the general dependence of the source pressure ( P0, GPa) on source temperature ( T0, °C) and the measured internal pressure in the inclusion ( Pi): P0=(3.259×10 -4Pi+3.285×10 -3) T0+0.9246 Pi+0.319. Raman barometry may be applied to other inclusions in diamonds or other inclusion-host systems. If combined with IR determination of the mantle residence temperature of the diamond, it allows estimation of the pressure at the source based on a non-destructive examination of a single diamond containing a single inclusion.

  6. Compositional analysis of diamond like carbon and carbon nitride films deposited by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Kayani, Asghar; Ingram, David

    2003-03-01

    The growing influence of the amorphous carbon not only as mechanical protective coating , but also of its possible use as electronic semiconducting material have made this material an important one. Incorporation of Nitrogen in a-C:H is believed to improve the semiconducting properties[1]. Moreover Carbon-Nitrogen films are a possible candidate for dielectric, insulating and passivating layers in a variety gallium nitride based device applications. Thin films amorphous carbon, non-hydrogenated, hydrogenated and nitrogenated were deposited on glassy carbon, silicon and quartz using magnetron sputtering of graphite target. Argon and Nitrogen were used as a sputtering gases. For Elemental concentration, films deposited on glassy carbon were used. 2.2 Mev of He++ beam is extracted from accelerator and in directed to the target films. Back and Forward scattered He++ particles were detected by solid-state detectors. The number and the energy of the particles striking the detector is stored electronically. The areal density in atoms per cm2, on the substrate surface was obtained from the shift in the substrate edge and area of carbon and other elements signals in Rutherford Backscattering Spectrum (RBS). Total Hydrogen content of the films were measured with Elastic Recoil Spectroscopy (ERS). Spectrum were simulated using Rutherford Universal Manipulation Program (RUMP).

  7. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2004-01-01

    Part of the 2003 industrial minerals review. Supply and demand data for industrial diamond are provided. Topics discussed are consumption, prices, imports and exports, government stockpiles, and the outlook for 2004.

  8. 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). PMID:19504935

  9. 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

  10. Toward a Boron-Doped Ultrananocrystalline Diamond Electrode-Based Dielectrophoretic Preconcentrator.

    PubMed

    Zhang, Wenli; Radadia, Adarsh D

    2016-03-01

    This paper presents results on immunobeads-based isolation of rare bacteria and their capture at a boron-doped ultrananocrystalline diamond (BD-UNCD) electrode in a microfluidic dielectrophoretic preconcentrator. We systematically vary the bead surface chemistry and the BD-UNCD surface chemistry and apply dielectrophoresis to improve the specific and the nonspecific capture of bacteria or beads. Immunobeads were synthesized by conjugating antibodies to epoxy-/sulfate, aldehyde-/sulfate, or carboxylate-modified beads with or without poly(ethylene glycol) (PEG) coimmobilization. The carboxylate-modified beads with PEG provided the highest capture efficiency (∼65%) and selectivity (∼95%) in isolating live Escherichia coli O157:H7 from cultures containing 1000 E. coli O157:H7 colony-forming units (cfu)/mL, or ∼500 E. coli O157:H7 and ∼500 E. coli K12 cfu/mL. Higher specificity was achieved with the addition of PEG to the antibody-functionalized bead surface, highest with epoxy-/sulfate beads (85-86%), followed by carboxylate-modified beads (76-78%) and aldehyde-/sulfate beads (74-76%). The bare BD-UNCD electrodes of the preconcentrator successfully withstood 240 kV/m for 100 min that was required for the microfluidic dielectrophoresis of 1 mL of sample. As expected, the application of dielectrophoresis increased the specific and the nonspecific capture of immunobeads at the BD-UNCD electrodes; however, the capture specificity remained unaltered. The addition of PEG to the antibody-functionalized BD-UNCD surface had little effect on the specificity in immunobeads capture. These results warrant the fabrication of electrical biosensors with BD-UNCD so that dielectrophoretic preconcentration can be performed directly at the biosensing electrodes. PMID:26829879

  11. Composition optimization of self-lubricating chromium-carbide-based composite coatings for use to 760 C

    NASA Technical Reports Server (NTRS)

    Dellacorte, Chris; Sliney, Harold E.

    1987-01-01

    This paper describes new compositions of self-lubricating coatings that contain chromium carbide. A bonded chromium carbide was used as the base stock because of the known excellent wear resistance and the chemical stability of chromium carbide. Additives were silver and barium fluoride/calcium fluoride eutectic. The coating constituents were treated as a ternary system consisting of: (1) the bonded carbide base material, (2) silver, and (3) the eutectic. A study to determine the optimum amounts of each constituent was performed. The various compositions were prepared by powder blending. The blended powders were then plasma sprayed onto superalloy substrates and diamond ground to the desired coating thickness. Friction and wear studies were performed at temperatures from 25 to 760 C in helium and hydrogen. A variety of counterface materials were evaluated with the objective of discovering a satisfactory metal/coating sliding combination for potential applications such as piston ring/cylinder liner couples for Stirling engines.

  12. Composition optimization of self-lubricating chromium carbide-based composite coatings for use to 760 deg C

    NASA Technical Reports Server (NTRS)

    Dellacorte, C.; Sliney, H. E.

    1986-01-01

    This paper describes new compositions of self-lubricating coatings that contain chromium carbide. A bonded chromium carbide was used as the base stock because of the known excellent wear resistance and the chemical stability of chromium carbide. Additives were silver and barium fluoride/calcium fluoride eutectic. The coating constituents were treated as a ternary system consisting of: (1) the bonded carbide base material, (2) silver, and (3) the eutectic. A study to determine the optimum amounts of each constituent was performed. The various compositions were prepared by powder blending. The blended powders were then plasma sprayed onto superalloy substrates and diamond ground to the desired coating thickness. Friction and wear studies were performed at temperatures from 25 to 760 C in helium and hydrogen. A variety of counterface materials were evaluated with the objective of discovering a satisfactory metal/coating sliding combination for potential applications such as piston ring/cylinder liner couples for Stirling engines.

  13. Graphene-based Composite Materials

    NASA Astrophysics Data System (ADS)

    Rafiee, Mohammad Ali

    We investigated the mechanical properties, such as fracture toughness (KIc), fracture energy (GIc), ultimate tensile strength (UTS), Young¡¦s modulus (E), and fatigue crack propagation rate (FCPR) of epoxy-matrix composites with different weight fractions of carbon-based fillers, including graphene platelets (GPL), graphene nanoribbons (GNR), single-walled carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT), and fullerenes (C60). Only ˜0.125 wt.% GPL was found to increase the KIc of the pure epoxy by ˜65% and the GIc by ˜115%. To get similar improvement, CNT and nanoparticle epoxy composites required one to two orders of magnitude greater weight fraction of nanofillers. Moreover, ˜0.125% wt.% GPL also decreased the fatigue crack propagation rate in the epoxy by ˜30-fold. The E value of 0.1 wt.% GPL/epoxy nanocomposite was ˜31% larger than the pure epoxy while there was only an increase of ˜3% for the SWNT composites. The UTS of the pristine epoxy was improved by ˜40% with GPLs in comparison with ˜14% enhancement for the MWNTs. The KIc of the GPL nanocomposite enhanced by ˜53% over the pristine epoxy compared to a ˜20% increase for the MWNT-reinforced composites. The results of the FCPR tests for the GPL nanocomposites showed a different trend. While the CNT nanocomposites were not effective enough to suppress the crack growth at high values of the stress intensity factor (DeltaK), the reverse behavior is observed for the GPL nanocomposites. The advantage of the GPLs over CNTs in terms of mechanical properties enhancement is due to their enormous specific surface area, enhanced adhesion at filler/epoxy interface (because of the wrinkled surfaces of GPLs), as well as the planar structure of the GPLs. We also show that unzipping of MWNTs into graphene nanoribbons (GNRs) enhances the load transfer effectiveness in epoxy nanocomposites. For instance, at ˜0.3 wt.% of fillers, the Young's modulus (E) of the epoxy nanocomposite with GNRs increased

  14. Effect of Mechanical Surface Treatment on the Repair Bond Strength of the Silorane-based Composite Resin

    PubMed Central

    Alizadeh Oskoee, Parnian; Kimyai, Soodabeh; Talatahari, Elham; Rikhtegaran, Sahand; Pournaghi-Azar, Fatemeh; Sajadi Oskoee, Jafar

    2014-01-01

    Background and aims. A proper bond must be created between the existing composite resin and the new one for successful repair. The aim of this study was to compare the effect of three mechanical surface treatments, using diamond bur, air abrasion, and Er,Cr:YSGG laser, on the repair bond strength of the silorane-based composite resin. Materials and methods. Sixty cylindrical composite resin specimens (Filtek Silorane) were fabricated and randomly divided into four groups according to surface treatment: group 1 (control group) without any mechanical surface treatment, groups 24 were treated with air abrasion, Er,Cr:YSGG laser, and diamond bur, respectively. In addition, a positive control group was assigned in order to measure the cohesive strength. Silorane bonding agent was used in groups 14 before adding the new composite resin. Then, the specimens were subjected to a shear bond strength test and data was analyzed using one-way ANOVA and post hoc Tukey tests at a significance level of P &0.05. The topographical effects of surface treatments were characterized under a scanning electron microscope. Results. There were statistically significant differences in the repair bond strength values between groups 1 and 2 and groups 3 and 4 (P &0.001). There were no significant differences between groups 1 and 2 (P = 0.98) and groups 3 and 4 (P= 0.97). Conclusion. Surface treatment using Er,Cr:YSGG laser and diamond bur were effective in silorane-based composite resin repair. PMID:25093047

  15. 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.

  16. Novel polymer composite having diamond particles and boron nitride platelets for thermal management of electric vehicle motors

    NASA Astrophysics Data System (ADS)

    Nakajima, Anri; Shoji, Atsushi; Yonemori, Kei; Seo, Nobuhide

    2016-02-01

    Thermal conductivities of silicone matrix polymers including fillers of diamond particles and/or hexagonal boron nitride (h-BN) platelets were systematically investigated in an attempt to find a thermal interface material (TIM) having high isotropic thermal conductivity and high electrical insulating ability to enable efficient heat dissipation from the motor coil ends of electric vehicles. The TIM with mixed fillers of diamond particles and h-BN platelets had a maximum thermal conductivity of 6.1 W m-1 K-1 that was almost isotropic. This is the highest value among the thermal conductivities of TIMs with silicone matrix polymer reported to date. The mechanism behind the thermal conductivity of the TIMs was also examined from the viewpoint of the change in the number of thermally conductive networks and/or a decrease in the thermal resistivity of junctions of neighboring diamond particles through the incorporation of h-BN platelets. The TIMs developed in this study will make it possible to manage the heat of electric motors and will help to popularize electric vehicles.

  17. 77 FR 20817 - Diamond State Generation Partners, LLC; Supplemental Notice That Initial Market-Based Rate Filing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-06

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Diamond State Generation Partners, LLC; Supplemental Notice That Initial... notice in the above-referenced proceeding of Diamond State Generation Partners, LLC's application...

  18. Isotope fractionation related to kimberlite magmatism and diamond formation

    SciTech Connect

    Galimov, E.M. )

    1991-06-01

    This paper deals with a model of carbon isotope fractionation presumed to accompany the movement of mantle fluids. In the first part of the article, the experimental data and the relationships revealed are generalized and discussed; the remainder of the paper describes the model. The isotope compositions of different forms of carbon related to kimberlite magmatism vary widely. In diamonds, {delta}{sup 13}C values range from {minus}34.5 to +2.8{per thousand}. Carbonate-bearing autholiths in kimberlites occur enriched in {sup 13}C up to +35{per thousand}. Organic matter, including that occurring in fluid inclusions of magmatic minerals of kimberlites, is depleted in {sup 13}C down to {minus}30{per thousand}. It is concluded that the {delta}{sup 13}C-distribution for diamonds is specific for a particular occurrence. Principal differences in isotopic distribution patterns for diamonds of ultrabasic and basic paragenesis exist. Isotopically light diamonds are related only to the latter. The intention of the model is to explain the observed variations of carbon isotope composition of diamond and other carbonaceous substances related to kimberlite magmatism. The model is based on the interaction of reduced sub-asthenospehric fluid with a relatively oxidized lithosphere. It is suggested that diamonds of ultrabasic paragenesis are produced during interaction of the fluid with sheared garnet lbherzolite which is considered to be primitive mantle rock. During contact with the more oxidized mantle, reduced carbon (CH{sub 4}) may partially be converted to CO{sub 2}. Isotope exchange in CO{sub 2}-CH{sub 4} system, conbined with Rayleigh distillation, may provide a significant isotope fractionation. Diamonds of the basic (eclogitic) paragenesis are considered to be realted to this fractionated carbon. Also, occurrence of carbonate material highly enriched in {sup 13}C is explained by the model.

  19. Defect characterization in the diamond cutting tools

    SciTech Connect

    Zeren, Muzaffer . E-mail: zeren@kou.edu.tr; Karagoez, Sadi

    2006-08-15

    In this study, a general defect characterization in the diamond cutting tools used in natural stone cutting has been investigated. Transverse rupture tests were carried out with different matrix and diamond compositions. In these defect characterization studies on diamond cutting tool materials various microstructural analyses were performed using the techniques of light microscopy (LM), scanning electron microscopy (SEM), energy-dispersed X-ray spectrography (EDX) and image analysis (IA)

  20. Alumina-based ceramic composite

    DOEpatents

    Alexander, Kathleen B.; Tiegs, Terry N.; Becher, Paul F.; Waters, Shirley B.

    1996-01-01

    An improved ceramic composite comprising oxide ceramic particulates, nonoxide ceramic particulates selected from the group consisting of carbides, borides, nitrides of silicon and transition metals and mixtures thereof, and a ductile binder selected from the group consisting of metallic, intermetallic alloys and mixtures thereof is described. The ceramic composite is made by blending powders of the ceramic particulates and the ductile to form a mixture and consolidating the mixture of under conditions of temperature and pressure sufficient to produce a densified ceramic composite.

  1. Method of plasma enhanced chemical vapor deposition of diamond using methanol-based solutions

    NASA Technical Reports Server (NTRS)

    Tzeng, Yonhua (Inventor)

    2009-01-01

    Briefly described, methods of forming diamond are described. A representative method, among others, includes: providing a substrate in a reaction chamber in a non-magnetic-field microwave plasma system; introducing, in the absence of a gas stream, a liquid precursor substantially free of water and containing methanol and at least one carbon and oxygen containing compound having a carbon to oxygen ratio greater than one, into an inlet of the reaction chamber; vaporizing the liquid precursor; and subjecting the vaporized precursor, in the absence of a carrier gas and in the absence in a reactive gas, to a plasma under conditions effective to disassociate the vaporized precursor and promote diamond growth on the substrate in a pressure range from about 70 to 130 Torr.

  2. Spectrally dependent photovoltages in Schottky photodiode based on (100) B-doped diamond

    SciTech Connect

    Čermák, Jan Rezek, Bohuslav; Koide, Yasuo; Takeuchi, Daisuke

    2014-02-07

    Spectrally and spatially resolved photovoltages were measured by Kelvin probe force microscopy (KPFM) on a Schottky photo-diode made of a 4 nm thin tungsten-carbide (WC) layer on a 500 nm oxygen-terminated boron-doped diamond epitaxial layer (O-BDD) that was grown on a Ib (100) diamond substrate. The diode was grounded by the sideways ohmic contact (Ti/WC), and the semitransparent Schottky contact was let unconnected. The electrical potentials across the device were measured in dark (only 650 nm LED of KPFM being on), under broad-band white light (halogen lamp), UV (365 nm diode), and deep ultraviolet (deuterium lamp) illumination. Illumination induced shift of the electrical potential remains within 210 mV. We propose that the photovoltage actually corresponds to a shift of Fermi level inside the BDD channel and thereby explains orders of magnitude changes in photocurrent.

  3. Planar Field Emitters and High Efficiency Photocathodes Based on Ultrananocrystalline Diamond

    NASA Technical Reports Server (NTRS)

    Sumant, Anirudha V. (Inventor); Baryshev, Sergey V. (Inventor); Antipov, Sergey P. (Inventor)

    2016-01-01

    A method of forming a field emitter comprises disposing a first layer on a substrate. The first layer is seeded with nanodiamond particles. The substrate with the first layer disposed thereon is maintained at a first temperature and a first pressure in a mixture of gases which includes nitrogen. The first layer is exposed to a microwave plasma to form a nitrogen doped ultrananocrystalline diamond film on the first layer, which has a percentage of nitrogen in the range of about 0.05 atom % to about 0.5 atom %. The field emitter has about 10.sup.12 to about 10.sup.14 emitting sites per cm.sup.2. A photocathode can also be formed similarly by forming a nitrogen doped ultrananocrystalline diamond film on a substrate similar to the field emitter, and then hydrogen terminating the film. The photocathode is responsive to near ultraviolet light as well as to visible light.

  4. Planar field emitters and high efficiency photocathodes based on ultrananocrystalline diamond

    DOEpatents

    Sumant, Anirudha V.; Baryshev, Sergey V.; Antipov, Sergey P.

    2016-08-16

    A method of forming a field emitter comprises disposing a first layer on a substrate. The first layer is seeded with nanodiamond particles. The substrate with the first layer disposed thereon is maintained at a first temperature and a first pressure in a mixture of gases which includes nitrogen. The first layer is exposed to a microwave plasma to form a nitrogen doped ultrananocrystalline diamond film on the first layer, which has a percentage of nitrogen in the range of about 0.05 atom % to about 0.5 atom %. The field emitter has about 10.sup.12 to about 10.sup.14 emitting sites per cm.sup.2. A photocathode can also be formed similarly by forming a nitrogen doped ultrananocrystalline diamond film on a substrate similar to the field emitter, and then hydrogen terminating the film. The photocathode is responsive to near ultraviolet light as well as to visible light.

  5. Development of diamond-based X-ray detection for high-flux beamline diagnostics

    PubMed Central

    Bohon, Jen; Muller, Erik; Smedley, John

    2010-01-01

    High-quality single-crystal and polycrystalline chemical-vapor-deposition diamond detectors with platinum contacts have been tested at the white-beam X28C beamline at the National Synchrotron Light Source under high-flux conditions. The voltage dependence of these devices has been measured under both DC and pulsed-bias conditions, establishing the presence or absence of photoconductive gain in each device. Linear response consistent with the theoretically determined ionization energy has been achieved over eleven orders of magnitude when combined with previous low-flux studies. Temporal measurements with single-crystal diamond detectors have resolved the nanosecond-scale pulse structures of both the NSLS and the APS. Prototype single-crystal quadrant detectors have provided the ability to simultaneously resolve the X-ray beam position and obtain a quantitative measurement of the flux. PMID:20975215

  6. Quantum Computation and Quantum Metrology based on Single Electron Spin in Diamond

    NASA Astrophysics Data System (ADS)

    Du, Jiangfeng

    2015-03-01

    It is of great challenge to perform the accurate controlling the electron spin qubits in realistic system, due to the noises aroused from the noisy spin bath and the driving field. Firstly, we adopted dynamically corrected gates to realize robust and high-fidelity quantum gates. In this work, the quantum gate's performance was pushed to T1r limit. Then, a new Rabi Oscillations (ROs) resulting from Landau-Zener (LZ) transitions is observed useful to suppress the fluctuations of the driving field. Besides, quantum error correction is experimentally employed to overcome the noise effect in diamonds. Precise quantum control and effectively supressing noise of the environment are of great importance for quantum metrology. We succeeded in sensing and atomic-scale analysis of single nuclear spin clusters in diamond at room temperature, and also have succeed to detect a few nuclear spins with single spin sensitivity.

  7. Electronic properties of CVD diamond

    NASA Astrophysics Data System (ADS)

    Nebel, C. E.

    2003-03-01

    The electronic properties of chemical vapour deposited (CVD) diamond are reviewed based on data measured by transient and spectrally resolved photoconductivity experiments, photo-thermal deflection spectroscopy (PDS) and electron paramagnetic resonance (EPR) where substitutional nitrogen (P1-centre) and carbon defects (H1-centre) are detected. The results show that nominally undoped high quality polycrystalline CVD diamond is a n-type semiconductor due to the presence of substitutional nitrogen. The sub-band-gap optical absorption is governed by amorphous graphite present at grain boundaries. Spectrally resolved photoconductivity experiments measured in the same regime are partially dominated by diamond bulk properties which are comparable to single crystalline Ib and IIa diamond and partially by grain boundaries. Mobilities and drift length of carriers are discussed and compared to properties of single crystalline diamond.

  8. Structural aspects of metal-organic framework-based energy materials research at Diamond

    PubMed Central

    Allan, David R.; Blake, Alexander J.; Schröder, Martin; Tang, Chiu C.; Yang, Sihai

    2015-01-01

    Large-scale central facilities such as Diamond Light Source fulfil an increasingly pivotal role in many large-scale scientific research programmes. We illustrate these developments by reference to energy-centred projects at the University of Nottingham, the progress of which depends crucially on access to these facilities. Continuing access to beamtime has now become a major priority for those who direct such programmes. PMID:25624515

  9. A beam radiation monitor based on CVD diamonds for SuperB

    NASA Astrophysics Data System (ADS)

    Cardarelli, R.; Di Ciaccio, A.

    2013-08-01

    Chemical Vapor Deposition (CVD) diamond particle detectors are in use in the CERN experiments at LHC and at particle accelerator laboratories in Europe, USA and Japan mainly as beam monitors. Nowadays it is considered a proven technology with a very fast signal read-out and a very high radiation tolerance suitable for measurements in high radiation environment zones i.e. near the accelerators beam pipes. The specific properties of CVD diamonds make them a prime candidate for measuring single particles as well as high-intensity particle cascades, for timing measurements on the sub-nanosecond scale and for beam protection systems in hostile environments. A single-crystalline CVD (scCVD) diamond sensor, read out with a new generation of fast and high transition frequency SiGe bipolar transistor amplifiers, has been tested for an application as radiation monitor to safeguard the silicon vertex tracker in the SuperB detector from excessive radiation damage, cumulative dose and instantaneous dose rates. Test results with 5.5 MeV alpha particles from a 241Am radioactive source and from electrons from a 90Sr radioactive source are presented in this paper.

  10. Diamond-based off-line dosimeters for environmental control in space flights

    NASA Astrophysics Data System (ADS)

    De Sio, Antonio; Pace, Emanuele; Giannini, A.; Bruzzi, Mara; Miglio, Stefania; Scaringella, Monica; Bucciolini, Marta; Woerner, Eckhard; Wild, Christoph; Donati, Alessandro; Zolesi, Valfredo; Cotronei, Vittorio

    2010-01-01

    Biological experiments in space and ongoing human space missions devoted to the solar system exploration require significant advancements in the radiation environment monitoring systems. Radiation hazard has to be continuously monitored and the evaluation of the biological damage suffered should be calculated within short time. In this paper we demonstrate the feasibility of using polycrystalline diamond films as dosimeters for space applications. The charge trapped into deep intra-gap defect levels during radiation exposure, and released during a high-temperature thermal scan to give thermally stimulated current (TSC), has been integrated as a function of time to evaluate the absorbed dose. The capability of diamond films to detect low doses has been demonstrated down to the mGys range. First application of these dosimeters in a real twelve-day, low Earth orbit, space mission has been carried out. TSC results have been proved to give correct evaluation of the dose absorbed during the space mission, assessing the capabilities of synthetic diamond and TSC read-out system as a proper dosimetry technique for space applications.

  11. Electron Microscopy of Natural and Epitaxial Diamond

    NASA Technical Reports Server (NTRS)

    Posthill, J. B.; George, T.; Malta, D. P.; Humphreys, T. P.; Rudder, R. A.; Hudson, G. C.; Thomas, R. E.; Markunas, R. J.

    1993-01-01

    Semiconducting diamond films have the potential for use as a material in which to build active electronic devices capable of operating at high temperatures or in high radiation environments. Ultimately, it is preferable to use low-defect-density single crystal diamond for device fabrication. We have previously investigated polycrystalline diamond films with transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and homoepitaxial films with SEM-based techniques. This contribution describes some of our most recent observations of the microstructure of natural diamond single crystals and homoepitaxial diamond thin films using TEM.

  12. Spectroscopic properties and radiation damage investigation of a diamond based Schottky diode for ion-beam therapy microdosimetry

    SciTech Connect

    Verona, C.; Marinelli, Marco; Verona-Rinati, G.; Magrin, G.; Solevi, P.; Mayer, R.; Grilj, V.; Jakšić, M.

    2015-11-14

    In this work, a detailed analysis of the properties of a novel microdosimeter based on a synthetic single crystal diamond is reported. Focused ion microbeams were used to investigate the device spectropscopic properties as well as the induced radiation damage effects. A diamond based Schottky diode was fabricated by chemical vapor deposition with a very thin detecting region, about 400 nm thick (approximately 1.4 μm water equivalent thickness), corresponding to the typical size in microdosimetric measurements. A 200 × 200 μm{sup 2} square metallic contact was patterned on the diamond surface by standard photolithography to define the sensitive area. Experimental measurements were carried out at the Ruder Boškovic′ Institute microbeam facility using 4 MeV carbon and 5 MeV silicon ions. Ion beam induced charge maps were employed to characterize the microdosimeter response in terms of its charge collection properties. A stable response with no evidence of polarization or memory effects was observed up to the maximum investigated ion beam flux of about 1.7 × 10{sup 9} ions·cm{sup −2}·s{sup −1}. A homogeneity of the response about 6% was found over the sensitive region with a well-defined confinement of the response within the active area. Tests of the radiation damage effect were performed by selectively irradiating small areas of the device with different ion fluences, up to about 10{sup 12} ions/cm{sup 2}. An exponential decrease of the charge collection efficiency was observed with a characteristic decay constant of about 4.8 MGy and 1 MGy for C and Si ions, respectively. The experimental data were analyzed by means of GEANT4 Monte Carlo simulations. A direct correlation between the diamond damaging effect and the Non Ionizing Energy Loss (NIEL) fraction was found. In particular, an exponential decay of the charge collection efficiency with an exponential decay as a function of NIEL is observed, with a characteristic constant of about

  13. Room-temperature hard coating of ultrananocrystalline diamond/nonhydrogenated amorphous carbon composite films on tungsten carbide by coaxial arc plasma deposition

    NASA Astrophysics Data System (ADS)

    Naragino, Hiroshi; Egiza, Mohamed; Tominaga, Aki; Murasawa, Koki; Gonda, Hidenobu; Sakurai, Masatoshi; Yoshitake, Tsuyoshi

    2016-03-01

    Ultrananocrystalline diamond (UNCD)/nonhydrogenated amorphous carbon (a-C) composite films were deposited on unheated WC containing Co by coaxial arc plasma deposition. The hardness of the film is 51.3 GPa, which is comparable with the highest values of hard a-C films deposited on nonbiased substrates. The deposited film is approximately 3 µm thick, which is one order larger than that of hard a-C films. The internal compressive stress is 4.5 GPa, which is evidently smaller than that of comparably hard a-C films. The existence of a large number of grain boundaries in the UNCD/a-C film might play a role in the release of the internal stress.

  14. Time-Resolved Spectroscopic Observation of Deposition Processes of Ultrananocrystalline Diamond/Amorphous Carbon Composite Films by Using a Coaxial Arc Plasma Gun

    NASA Astrophysics Data System (ADS)

    Hanada, Kenji; Yoshitake, Tsuyoshi; Nishiyama, Takashi; Nagayama, Kunihito

    2010-08-01

    The deposition of ultrananocrystalline diamond (UNCD)/amorphous carbon composite films using a coaxial arc plasma gun in vacuum and, for comparison, in a 53.3 Pa hydrogen atmosphere was spectroscopically observed using a high-speed camera equipped with narrow-band-pass filters. UNCD crystallites with diameters of approximately 1.6 nm were formed even in vacuum. These extremely small crystallites imply that the formation is predominantly due to nucleation without the subsequent growth. Even in vacuum, emissions from C+ ions, C atoms, and C2 dimers lasted for approximately 100 µs, although the emission lifetimes of these species are generally 10 ns. We consider that the nucleation is due to the supersaturated environment containing excited carbon species with large number densities.

  15. Alumina-based ceramic composite

    DOEpatents

    Alexander, K.B.; Tiegs, T.N.; Becher, P.F.; Waters, S.B.

    1996-07-23

    An improved ceramic composite comprising oxide ceramic particulates, nonoxide ceramic particulates selected from the group consisting of carbides, borides, nitrides of silicon and transition metals and mixtures thereof, and a ductile binder selected from the group consisting of metallic, intermetallic alloys and mixtures thereof is described. The ceramic composite is made by blending powders of the ceramic particulates and the ductile to form a mixture and consolidating the mixture of under conditions of temperature and pressure sufficient to produce a densified ceramic composite. 5 figs.

  16. A Competency-Based System for Composition.

    ERIC Educational Resources Information Center

    Lewis, Nancy; Sbaratta, Philip

    This packet of competency-based instructional materials was developed for use in all sections of North Shore Community College's developmental composition course. Introductory material traces the development of the competency-based system at the college, which stemmed from a need for a more consistent approach in the composition classes. Next, the…

  17. Study on tribological behavior and cutting performance of CVD diamond and DLC films on Co-cemented tungsten carbide substrates

    NASA Astrophysics Data System (ADS)

    Zhang, Dongcan; Shen, Bin; Sun, Fanghong

    2010-02-01

    The tribological behaviors of diamond and diamond-like carbon (DLC) films play a major role on their machining and mechanical applications. In this study, diamond and diamond-like carbon (DLC) films are deposited on the cobalt cemented tungsten carbide (WC-Co) substrate respectively adopting the hot filament chemical vapor deposition (HFCVD) technique and the vacuum arc discharge with a graphite cathode, and their friction properties are evaluated on a reciprocating ball-on-plate tribometer with counterfaces of silicon nitride (Si 3N 4) ceramic, cemented tungsten carbide (WC) and ball-bearing steel materials, under the ambient air without lubricating condition. Moreover, to evaluate their cutting performance, comparative turning tests are conducted using the uncoated WC-Co and as-fabricated CVD diamond and DLC coated inserts, with glass fiber reinforced plastics (GFRP) composite materials as the workpiece. The as-deposited HFCVD diamond and DLC films are characterized with energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), Raman spectroscopy and 3D surface topography based on white-light interferometry. Furthermore, Rocwell C indentation tests are conducted to evaluate the adhesion of HFCVD diamond and DLC films grown onto WC-Co substrates. SEM and 3D surface topography based on white-light interferometry are also used to investigate the worn region on the surfaces of diamond and DLC films. The friction tests suggest that the obtained friction coefficient curves that of various contacts exhibit similar evolution tendency. For a given counterface, DLC films present lower stable friction coefficients than HFCVD diamond films under the same sliding conditions. The cutting tests results indicate that flank wear of the HFCVD diamond coated insert is lower than that of DLC coated insert before diamond films peeling off.

  18. New volcanogenic-eruptive genetic type of diamond occurrence (based on studying the 2012-2013 Fissure Tolbachik Eruption in Kamchatka)

    NASA Astrophysics Data System (ADS)

    Karpov, Gennady; Anikin, Leonid; Filatov, Stanislav; Silaev, Valery; Petrovsky, Vitaly; Zolotarev, Andrey; Dunin-Barkovsky, Romuald; Volynets, Anna

    2014-05-01

    During the 2012-2013 Fissure Tolbachik eruption, diamonds were found both in fresh pyroclastics and in the effusive lava pores. Lavas are aphyric and subaphyric porous aluminous basaltic trachyandesites with rare megacrysts and subphenocrysts of plagioclase, olivine and pyroxene. Groundmass is hyalopilitic, pilotaxitic, occasionally hyaline, with abundant plagioclase microlites. So far, over 750 diamond grains have been found sized mostly 100-500 mkm. Generally, grains are well formed isometric, plane-faced and sharp-edged monocrystals of cubic-octahedral habit and green color, rarer colorless. Faces of rhombic-dodecahedron, tetragonal-trisoctahedron and trigonal-trisoctahedron also occur. Crystal cubic faces host pits of diffusive depletion, and pits with induction surfaces formed after the breakoff of syngenetic inclusions. Octahedral faces often show pyramidal etching pits formed at the dislocation outcrops. Pits contain coatings whose composition includes Fe, Mg, Ca, Si, and Cu-Sn (Zn) alloy films. Diamond X-ray diffraction data (Bruker APEX DUO, STOE IPDS II, MoKα-radiation, 788 reflections) show space group Fd-3m, cubic unit cell parameter a = 3.574(3) A and major reflections (111), (220), (311) etc. at Gandolfi pattern. Raman spectra with red beam reveal only one strong line at 1332 cm-1 typical for diamonds. Spectra excited by the 785 nm beam reveal a wide line with the peak at 1370 cm-1, whose intensity oscillates from 1% to 70% of the diamond line intensity at 1332 cm-1. Infrared absorption spectra reflect two lines with peaks at 1345 and 1130 cm-1, corresponding to structural C-defects (isolated N atoms). Partially, these defects occur in the positive charge state - N+. Structural nitrogen concentration in the form of C-defects varies from 150 to 500 ppm, while that in the form of N+ - from 10 to 30 ppm. Lines of infrared absorption on A and B1 nitrogen defects, as well as those on hydrogen defects typical for most natural diamonds, are not detected for

  19. Nanostructure TEM analysis of diamond cold cathode field emitters

    SciTech Connect

    Wade, Travis S.; Ghosh, Nikkon; Wittig, James Edward; Kang, Weng; Allard Jr, Lawrence Frederick; Unocic, Kinga A; Davidson, James; Tolk, Norman H.

    2012-01-01

    Diamond cold cathode devices have demonstrated significant potential as electron field emitters. Ultra-sharp diamond pyramidal tips (~5nm tip radius) have been fabricated and show improvement in emission when compared to conventional field emitters. However, the emission mechanisms in these complex diamond nanostructures are not well understood. Transmission electron microscopy performed in this study provides new insight into tip structure and composition with implications for field emission and diamond growth.

  20. 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

  1. 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.

  2. 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.

  3. Study of high-overtone bulk acoustic resonators based on the Me1/AlN/Me2/(100) diamond piezoelectric layered structure

    NASA Astrophysics Data System (ADS)

    Sorokin, B. P.; Kvashnin, G. M.; Telichko, A. V.; Gordeev, G. I.; Burkov, S. I.; Blank, V. D.

    2015-07-01

    The Me1/AlN/Me2/(100) diamond structure has been theoretically analyzed and experimentally investigated in the range 0.5-10 GHz using high-overtone bulk acoustic resonators with different electrodes topologies based on the Al/AlN/Mo/(100) diamond structure. The maximum quality parameter Q × f ≈ 1014 Hz was obtained at f = 9.5 GHz. The layered structure has been analyzed using the developed HBAR software v. 2.3. It is demonstrated that the features in the frequency dependences of the parameters of such resonators are related to the behavior of a loaded thin-film piezoelectric transducer. The calculation results are in good agreement with the experiment. The frequency dependences of the equivalent parameters of the resonators have been calculated. It is shown that the synthetic type IIa diamond single crystal in combination with aluminum nitride is promising for implementation of high-Q acoustoelectronic microwave devices.

  4. Structural and Physical Characteristics of Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films Deposited Using a Coaxial Arc Plasma Gun

    NASA Astrophysics Data System (ADS)

    Yoshitake, Tsuyoshi; Nakagawa, You; Nagano, Akira; Ohtani, Ryota; Setoyama, Hiroyuki; Kobayashi, Eiichi; Sumitani, Kazushi; Agawa, Yoshiaki; Nagayama, Kunihito

    2010-01-01

    Ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) films were formed without initial nucleation using a coaxial arc plasma gun. The UNCD crystallite diameters estimated from the X-ray diffraction peaks were approximately 2 nm. The Fourier transform infrared absorption spectrum exhibited an intense sp3-CH peak that might originate from the grain boundaries between UNCD crystallites whose dangling bonds are terminated with hydrogen atoms. A narrow sp3 peak in the photoemission spectrum implied that the film comprises a large number of UNCD crystallites. Large optical absorption coefficients at photon energies larger than 3 eV that might be due to the grain boundaries are specific to the UNCD/a-C:H films.

  5. A diamond based neutron spectrometer for diagnostics of deuterium-tritium fusion plasmas.

    PubMed

    Cazzaniga, C; Nocente, M; Rebai, M; Tardocchi, M; Calvani, P; Croci, G; Giacomelli, L; Girolami, M; Griesmayer, E; Grosso, G; Pillon, M; Trucchi, D M; Gorini, G

    2014-11-01

    Single crystal Diamond Detectors (SDD) are being increasingly exploited for neutron diagnostics in high power fusion devices, given their significant radiation hardness and high energy resolution capabilities. The geometrical efficiency of SDDs is limited by the size of commercially available crystals, which is often smaller than the dimension of neutron beams along collimated lines of sight in tokamak devices. In this work, we present the design and fabrication of a 14 MeV neutron spectrometer consisting of 12 diamond pixels arranged in a matrix, so to achieve an improved geometrical efficiency. Each pixel is equipped with an independent high voltage supply and read-out electronics optimized to combine high energy resolution and fast signals (<30 ns), which are essential to enable high counting rate (>1 MHz) spectroscopy. The response function of a prototype SDD to 14 MeV neutrons has been measured at the Frascati Neutron Generator by observation of the 8.3 MeV peak from the (12)C(n, α)(9)Be reaction occurring between neutrons and (12)C nuclei in the detector. The measured energy resolution (2.5% FWHM) meets the requirements for neutron spectroscopy applications in deuterium-tritium plasmas. PMID:25430280

  6. Amperometric oxygen sensor based on a platinum nanoparticle-modified polycrystalline boron doped diamond disk electrode.

    PubMed

    Hutton, Laura; Newton, Mark E; Unwin, Patrick R; Macpherson, Julie V

    2009-02-01

    Pt nanoparticle (NP)-modified polycrystalline boron-doped diamond (pBDD) disk electrodes have been fabricated and employed as amperometric sensors for the determination of dissolved oxygen concentration in aqueous solution. pBDD columns were cut using laser micromachining techniques and sealed in glass, in order to make disk electrodes which were then characterized electrochemically. Electrodeposition of Pt onto the diamond electrodes was optimized so as to give the maximum oxygen reduction peak current with the lowest background signal. Pt NPs, >0-10 nm diameter, were found to deposit randomly across the pBDD electrode, with no preference for grain boundaries. The more conductive grains were found to promote the formation of smaller nanoparticles at higher density. With the use of potential step chronoamperometry, in which the potential was stepped to a diffusion-limited value, a four electron oxygen reduction process was found to occur at the Pt NP-modified pBDD electrode. Furthermore the chronoamperometric response scaled linearly with dissolved oxygen concentration, varied by changing the oxygen/nitrogen ratio of gas flowed into solution. The sensor was used to detect dissolved oxygen concentrations with high precision over the pH range 4-10. PMID:19117391

  7. A diamond based neutron spectrometer for diagnostics of deuterium-tritium fusion plasmas

    NASA Astrophysics Data System (ADS)

    Cazzaniga, C.; Nocente, M.; Rebai, M.; Tardocchi, M.; Calvani, P.; Croci, G.; Giacomelli, L.; Girolami, M.; Griesmayer, E.; Grosso, G.; Pillon, M.; Trucchi, D. M.; Gorini, G.

    2014-11-01

    Single crystal Diamond Detectors (SDD) are being increasingly exploited for neutron diagnostics in high power fusion devices, given their significant radiation hardness and high energy resolution capabilities. The geometrical efficiency of SDDs is limited by the size of commercially available crystals, which is often smaller than the dimension of neutron beams along collimated lines of sight in tokamak devices. In this work, we present the design and fabrication of a 14 MeV neutron spectrometer consisting of 12 diamond pixels arranged in a matrix, so to achieve an improved geometrical efficiency. Each pixel is equipped with an independent high voltage supply and read-out electronics optimized to combine high energy resolution and fast signals (<30 ns), which are essential to enable high counting rate (>1 MHz) spectroscopy. The response function of a prototype SDD to 14 MeV neutrons has been measured at the Frascati Neutron Generator by observation of the 8.3 MeV peak from the 12C(n, α)9Be reaction occurring between neutrons and 12C nuclei in the detector. The measured energy resolution (2.5% FWHM) meets the requirements for neutron spectroscopy applications in deuterium-tritium plasmas.

  8. A diamond based neutron spectrometer for diagnostics of deuterium-tritium fusion plasmas

    SciTech Connect

    Cazzaniga, C. Nocente, M.; Gorini, G.; Rebai, M.; Giacomelli, L.; Tardocchi, M.; Croci, G.; Grosso, G.; Calvani, P.; Girolami, M.; Trucchi, D. M.; Griesmayer, E.; Pillon, M.

    2014-11-15

    Single crystal Diamond Detectors (SDD) are being increasingly exploited for neutron diagnostics in high power fusion devices, given their significant radiation hardness and high energy resolution capabilities. The geometrical efficiency of SDDs is limited by the size of commercially available crystals, which is often smaller than the dimension of neutron beams along collimated lines of sight in tokamak devices. In this work, we present the design and fabrication of a 14 MeV neutron spectrometer consisting of 12 diamond pixels arranged in a matrix, so to achieve an improved geometrical efficiency. Each pixel is equipped with an independent high voltage supply and read-out electronics optimized to combine high energy resolution and fast signals (<30 ns), which are essential to enable high counting rate (>1 MHz) spectroscopy. The response function of a prototype SDD to 14 MeV neutrons has been measured at the Frascati Neutron Generator by observation of the 8.3 MeV peak from the {sup 12}C(n, α){sup 9}Be reaction occurring between neutrons and {sup 12}C nuclei in the detector. The measured energy resolution (2.5% FWHM) meets the requirements for neutron spectroscopy applications in deuterium-tritium plasmas.

  9. Diamond Tours

    NASA Technical Reports Server (NTRS)

    2007-01-01

    On April 24, a group traveling with Diamond Tours visited StenniSphere, the visitor center at NASA John C. Stennis Space Center in South Mississippi. The trip marked Diamond Tours' return to StenniSphere since Hurricane Katrina struck the Gulf Coast on Aug. 29, 2005. About 25 business professionals from Georgia enjoyed the day's tour of America's largest rocket engine test complex, along with the many displays and exhibits at the museum. Before Hurricane Katrina, the nationwide company brought more than 1,000 visitors to StenniSphere each month. That contributed to more than 100,000 visitors from around the world touring the space center each year. In past years StenniSphere's visitor relations specialists booked Diamond Tours two or three times a week, averaging 40 to 50 people per visit. SSC was established in the 1960s to test the huge engines for the Saturn V moon rockets. Now 40 years later, the center tests every main engine for the space shuttle. SSC will soon begin testing the rocket engines that will power spacecraft carrying Americans back to the moon and on to Mars. For more information or to book a tour, visit http://www.nasa.gov/centers/stennis/home/index.html and click on the StenniSphere logo; or call 800-237-1821 or 228-688-2370.

  10. The in situ observation of epitaxial diamond thin film nucleation and growth using emission electron microscopy

    NASA Astrophysics Data System (ADS)

    Kordesch, Martin E.

    1994-05-01

    A method for activation of high resistivity, (100) texture CVD diamond films with gold, to improve low field electron emission is described. A model based on the dielectric breakdown of the diamond film is proposed and a test experiment, which consists of heating the gold layer to a point where the gold forms sub-micron spheroids on the diamond surface, is described which supports the model. The deposition of carbon and sulfur on Mo(310) is characterized with scanning Auger Microscopy. Correlation between Photoelectron emission Microscopy, scanning Auger Microscopy and Auger spectroscopy can be made, so that individual features in PEEM and SAM images can be identified by elemental composition. The initial design of a Seeded Supersonic Molecular Beam system for diamond deposition is described.

  11. Electronic transition imaging of carbon based materials: The photothreshold of melanin and thermionic field emission from diamond

    NASA Astrophysics Data System (ADS)

    Garguilo, Jacob

    This study explores electronic transitions in carbon based materials through the use of a custom built, non rastering electron emission microscope. The specifics and history of electron emission are described as well as the equipment used in this study. The materials examined fall into two groups, melanosome films isolated from the human body and polycrystalline diamond tip arrays. A novel technique for determining the photothreshold of a heterogeneous material on a microscopic or smaller scale is developed and applied to melanosome films isolated from the hair, eyes, and brain of human donors. The conversion of the measured photothreshold on the vacuum scale to an electrochemical oxidation potential is discussed and the obtained data is considered based on this conversion. Pheomelanosomes isolated from human hair are shown to have significantly lower photoionization energy than eumelanosomes, indicating their likelihood as sources of oxidative stress. The ionization energies of the hair melanosomes are checked with complimentary procedures. Ocular melanosomes from the retinal pigment epithelium are measured as a function of patient age and melanosome shape. Lipofuscin, also found in the eye, is examined with the same microscopy technique and shown to have a significantly lower ionization threshold than RPE melanosomes. Neuromelanin from the substantia nigra is also examined and shown to have an ionization threshold close to that of eumelanin. A neuromelanin formation model is proposed based on these results. Polycrystalline diamond tip arrays are examined for their use as thermionic energy converter emitters. Thermionic energy conversion is accomplished through the combination of a hot electron emitter in conjunction with a somewhat cooler electron collector. The generated electron current can be used to do work in an external load. It is shown that the tipped structures of these samples result in enhanced emission over the surrounding flat areas, which may prove

  12. Estimating Decision Indices Based on Composite Scores

    ERIC Educational Resources Information Center

    Knupp, Tawnya Lee

    2009-01-01

    The purpose of this study was to develop an IRT model that would enable the estimation of decision indices based on composite scores. The composite scores, defined as a combination of unidimensional test scores, were either a total raw score or an average scale score. Additionally, estimation methods for the normal and compound multinomial models…

  13. Diamond-modified AFM probes: from diamond nanowires to atomic force microscopy-integrated boron-doped diamond electrodes.

    PubMed

    Smirnov, Waldemar; Kriele, Armin; Hoffmann, René; Sillero, Eugenio; Hees, Jakob; Williams, Oliver A; Yang, Nianjun; Kranz, Christine; Nebel, Christoph E

    2011-06-15

    In atomic force microscopy (AFM), sharp and wear-resistant tips are a critical issue. Regarding scanning electrochemical microscopy (SECM), electrodes are required to be mechanically and chemically stable. Diamond is the perfect candidate for both AFM probes as well as for electrode materials if doped, due to diamond's unrivaled mechanical, chemical, and electrochemical properties. In this study, standard AFM tips were overgrown with typically 300 nm thick nanocrystalline diamond (NCD) layers and modified to obtain ultra sharp diamond nanowire-based AFM probes and probes that were used for combined AFM-SECM measurements based on integrated boron-doped conductive diamond electrodes. Analysis of the resonance properties of the diamond overgrown AFM cantilevers showed increasing resonance frequencies with increasing diamond coating thicknesses (i.e., from 160 to 260 kHz). The measured data were compared to performed simulations and show excellent correlation. A strong enhancement of the quality factor upon overgrowth was also observed (120 to 710). AFM tips with integrated diamond nanowires are shown to have apex radii as small as 5 nm and where fabricated by selectively etching diamond in a plasma etching process using self-organized metal nanomasks. These scanning tips showed superior imaging performance as compared to standard Si-tips or commercially available diamond-coated tips. The high imaging resolution and low tip wear are demonstrated using tapping and contact mode AFM measurements by imaging ultra hard substrates and DNA. Furthermore, AFM probes were coated with conductive boron-doped and insulating diamond layers to achieve bifunctional AFM-SECM probes. For this, focused ion beam (FIB) technology was used to expose the boron-doped diamond as a recessed electrode near the apex of the scanning tip. Such a modified probe was used to perform proof-of-concept AFM-SECM measurements. The results show that high-quality diamond probes can be fabricated, which are

  14. High-resolution vector microwave magnetometry based on solid-state spins in diamond

    PubMed Central

    Wang, Pengfei; Yuan, Zhenheng; Huang, Pu; Rong, Xing; Wang, Mengqi; Xu, Xiangkun; Duan, Changkui; Ju, Chenyong; Shi, Fazhan; Du, Jiangfeng

    2015-01-01

    The measurement of the microwave field is crucial for many developments in microwave technology and related applications. However, measuring microwave fields with high sensitivity and spatial resolution under ambient conditions remains elusive. In this work, we propose and experimentally demonstrate a scheme to measure both the strength and orientation of the microwave magnetic field by utilizing the quantum coherent dynamics of nitrogen vacancy centres in diamond. An angular resolution of 5.7 mrad and a sensitivity of 1.0 μT Hz−1/2 are achieved at a microwave frequency of 2.6000 GHz, and the microwave magnetic field vectors generated by a copper wire are precisely reconstructed. The solid-state microwave magnetometry with high resolution and wide frequency range that can work under ambient conditions proposed here enables unique potential applications over other state-of-art microwave magnetometry. PMID:25799155

  15. Ultrafast quantum nondemolition measurements based on a diamond-shaped artificial atom

    NASA Astrophysics Data System (ADS)

    Diniz, I.; Dumur, E.; Buisson, O.; Auffèves, A.

    2013-03-01

    We propose a quantum nondemolition (QND) readout scheme for a superconducting artificial atom coupled to a resonator in a circuit QED architecture, for which we estimate a very high measurement fidelity without Purcell effect limitations. The device consists of two transmons coupled by a large inductance, giving rise to a diamond-shaped artificial atom with a logical qubit and an ancilla qubit interacting through a cross-Kerr-like term. The ancilla is strongly coupled to a transmission line resonator. Depending on the qubit state, the ancilla is resonantly or dispersively coupled to the resonator, leading to a large contrast in the transmitted microwave signal amplitude. This original method can be implemented with a state-of-the-art Josephson parametric amplifier, leading to QND measurements in a few tens of nanoseconds with fidelity as large as 99.9%.

  16. A diamond-based scanning probe spin sensor operating at low temperature in ultra-high vacuum

    NASA Astrophysics Data System (ADS)

    Schaefer-Nolte, E.; Reinhard, F.; Ternes, M.; Wrachtrup, J.; Kern, K.

    2014-01-01

    We present the design and performance of an ultra-high vacuum (UHV) low temperature scanning probe microscope employing the nitrogen-vacancy color center in diamond as an ultrasensitive magnetic field sensor. Using this center as an atomic-size scanning probe has enabled imaging of nanoscale magnetic fields and single spins under ambient conditions. In this article we describe an experimental setup to operate this sensor in a cryogenic UHV environment. This will extend the applicability to a variety of molecular systems due to the enhanced target spin lifetimes at low temperature and the controlled sample preparation under UHV conditions. The instrument combines a tuning-fork based atomic force microscope (AFM) with a high numeric aperture confocal microscope and the facilities for application of radio-frequency (RF) fields for spin manipulation. We verify a sample temperature of <50 K even for strong laser and RF excitation and demonstrate magnetic resonance imaging with a magnetic AFM tip.

  17. A diamond-based scanning probe spin sensor operating at low temperature in ultra-high vacuum

    SciTech Connect

    Schaefer-Nolte, E.; Wrachtrup, J.; 3rd Institute of Physics and Research Center SCoPE, University Stuttgart, 70569 Stuttgart ; Reinhard, F.; Ternes, M.; Kern, K.; Institut de Physique de la Matière Condenseé, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne

    2014-01-15

    We present the design and performance of an ultra-high vacuum (UHV) low temperature scanning probe microscope employing the nitrogen-vacancy color center in diamond as an ultrasensitive magnetic field sensor. Using this center as an atomic-size scanning probe has enabled imaging of nanoscale magnetic fields and single spins under ambient conditions. In this article we describe an experimental setup to operate this sensor in a cryogenic UHV environment. This will extend the applicability to a variety of molecular systems due to the enhanced target spin lifetimes at low temperature and the controlled sample preparation under UHV conditions. The instrument combines a tuning-fork based atomic force microscope (AFM) with a high numeric aperture confocal microscope and the facilities for application of radio-frequency (RF) fields for spin manipulation. We verify a sample temperature of <50 K even for strong laser and RF excitation and demonstrate magnetic resonance imaging with a magnetic AFM tip.

  18. DEVELOPMENT OF ADVANCED DRILL COMPONENTS FOR BHA USING MICROWAVE TECHNOLOGY INCORPORATING CARBIDE, DIAMOND COMPOSITES AND FUNCTIONALLY GRADED MATERIALS

    SciTech Connect

    Dinesh Agrawal; Rustum Roy

    2000-11-01

    The main objective of this program was to develop an efficient and economically viable microwave processing technique to process cobalt cemented tungsten carbide with improved properties for drill-bits for advanced drilling operations for oil, gas, geothermal and excavation industries. The program was completed in three years and successfully accomplished all the states goals in the original proposal. In three years of the program, we designed and built several laboratory scale microwave sintering systems for conducting experiments on Tungsten carbide (WC) based composites in controlled atmosphere. The processing conditions were optimized and various properties were measured. The design of the system was then modified to enable it to process large commercial parts of WC/Co and in large quantities. Two high power (3-6 kW) microwave systems of 2.45 GHz were built for multi samples runs in a batch process. Once the process was optimized for best results, the technology was successfully transferred to our industrial partner, Dennis Tool Co. We helped them to built couple of prototype microwave sintering systems for carbide tool manufacturing. It was found that the microwave processed WC/Co tools are not only cost effective but also exhibited much better overall performance than the standard tools. The results of the field tests performed by Dennis Tool Co. showed remarkable advantage and improvement in their overall performance. For example: wear test shows an increase of 20-30%, corrosion test showed much higher resistance to the acid attack, erosion test exhibited about 15% better resistance than standard sinter-HIP parts. This proves the success of microwave technology for WC/Co based drilling tools. While we have successfully transferred the technology to our industrial partner Dennis Tool Co., they have signed an agreement with Valenite, a world leading WC producer of cutting and drilling tools and wear parts, to push aggressively the new microwave technology in

  19. In situ Analysis of North American Diamond: Implications for Diamond Growth Modeling

    NASA Astrophysics Data System (ADS)

    Schulze, D. J.; Van Rythoven, A. D.; Hauri, E.; Wang, J.

    2014-12-01

    Diamond crystals from three North American kimberlite occurrences were investigated with cathodoluminescence (CL) and secondary ion mass spectrometry (SIMS) to determine their growth history, carbon isotope composition and nitrogen content. Samples analyzed include sixteen from Lynx (Quebec), twelve from Kelsey Lake (Colorado) and eighteen from A154 South (Diavik mine, Northwest Territories). Growth histories for the samples vary from simple to highly complex based on their CL images and depending on the individual stone. Deformation lamellae are evident in CL images of the Lynx crystals which typically are brownish in color. Two to five points per diamond were analyzed by SIMS for carbon isotope composition (δ13CPDB) and three to seven points for nitrogen content. The results for the A154 South (δ13CPDB = -6.76 to -1.68 ‰) and Kelsey Lake (δ13CPDB = -11.81 to -2.43 ‰) stones (mixed peridotitic and eclogitic suites) are similar to earlier reported values. The Lynx kimberlite stones have anomalously high carbon isotope ratios and range from -3.58 to +1.74 ‰. The Lynx diamond suite is almost entirely peridotitic. The unusually high (i.e. >-5‰) δ13C values of the Lynx diamonds, as well as those from Wawa, Ontario and Renard, Quebec, may indicate an anomalous carbon reservoir for the Superior cratonic mantle relative to other cratons. In addition to the heavier carbon isotope values, the Lynx samples have very low nitrogen contents (<100 ppm). Nitrogen contents for Kelsey Lake and Diavik samples are more typical and range to ~1100 ppm. Comparison of observed core to rim variations in nitrogen content and carbon isotopes with modeled Rayleigh fractionation trends for published diamond growth mechanisms allows for evaluation of carbon speciation and other parent fluid conditions. Observed trends that closely follow modeled data are rare, but appear to suggest diamond growth from carbonate-bearing fluids at Lynx and Diavik, and growth from a methane

  20. Detection and analysis of diamond fingerprinting feature and its application

    NASA Astrophysics Data System (ADS)

    Li, Xin; Huang, Guoliang; Li, Qiang; Chen, Shengyi

    2011-01-01

    Before becoming a jewelry diamonds need to be carved artistically with some special geometric features as the structure of the polyhedron. There are subtle differences in the structure of this polyhedron in each diamond. With the spatial frequency spectrum analysis of diamond surface structure, we can obtain the diamond fingerprint information which represents the "Diamond ID" and has good specificity. Based on the optical Fourier Transform spatial spectrum analysis, the fingerprinting identification of surface structure of diamond in spatial frequency domain was studied in this paper. We constructed both the completely coherent diamond fingerprinting detection system illuminated by laser and the partially coherent diamond fingerprinting detection system illuminated by led, and analyzed the effect of the coherence of light source to the diamond fingerprinting feature. We studied rotation invariance and translation invariance of the diamond fingerprinting and verified the feasibility of real-time and accurate identification of diamond fingerprint. With the profit of this work, we can provide customs, jewelers and consumers with a real-time and reliable diamonds identification instrument, which will curb diamond smuggling, theft and other crimes, and ensure the healthy development of the diamond industry.

  1. Effect of an Extra Hydrophobic Resin Layer on Repair Shear Bond Strength of a Silorane-Based Composite Resin

    PubMed Central

    Mohammadi, Narmin; Bahari, Mahmoud; Kimyai, Soodabeh; Rahbani Nobar, Behnam

    2015-01-01

    Objectives: Composite repair is a minimally invasive and conservative approach. This study aimed to evaluate the effect of an additional hydrophobic resin layer on the repair shear bond strength of a silorane-based composite repaired with silorane or methacrylate-based composite. Materials and Methods: Sixty bar-shaped composite blocks were fabricated and stored in saline for 72 hours. The surface of the samples were roughened by diamond burs and etched with phosphoric acid; then, they were randomly divided into three groups according to the repairing process: Group 1: Silorane composite-silorane bonding agent-silorane composite; group 2: Silorane composite-silorane bonding agent-hydrophobic resin-silorane composite, and group 3: Silorane composite-silorane bonding agent-hydrophobic resin methacrylate-based composite. Repairing composite blocks measured 2.5×2.5×5mm. After repairing, the samples were stored in saline for 24 hours and thermocycled for 1500 cycles. The repair bond strength was measured at a strain rate of 1mm/min. Twenty additional cylindrical composite blocks (diameter: 2.5mm, height: 6mm) were also fabricated for measuring the cohesive strength of silorane-based composite. The data were analyzed using One-way ANOVA and the post hoc Tukey’s test (α=0.05). Results: Cohesive bond strength of silorane composite was significantly higher than the repair bond strengths in other groups (P<0.001). The repair bond strength of group 3 was significantly higher than that of group 1 (P=0.001). Conclusion: Application of an additional hydrophobic resin layer for repair of silorane-based composite with a methacrylate-based composite enhanced the repair shear bond strength. PMID:27559348

  2. Properties of interfaces of diamond

    NASA Astrophysics Data System (ADS)

    Nemanich, R. J.; Bergman, L.; Turner, K. F.; van der Weide, J.; Humphreys, T. P.

    1993-04-01

    Results related to two different interface aspects involving diamond are described: (1) the initial states of CVD diamond film growth, and (2) the negative electron affinity and formation of metal-diamond interfaces. The surface and interface properties are probed with STM, Raman scattering/photoluminescence and angle-resolved UV photoemission spectroscopy (ARUPS). STM measurements of diamond nuclei on Si after various plasma growth processes show both flat and hillocked structures characteristics of 2-dimensional and 3-dimensional growth modes, respectively. STS measurements show distinct I- V characteristics of the nuclei and the substrate. The presence of optical defects and the diamond quality are studied with micro-Raman/photoluminescence measurements. The results indicate an increased density of impurity-related defects during the initial stages of growth. The interface properties of Ti on natural crystal (1 1 1) and (1 0 0) surfaces are studied with ARUPS using 21.2 eV HeI emission. Prior to deposition the diamond (1 1 1) is chemically cleaned, and a sharp (0.5 eV FWHM) peak is observed at the position of the conduction band minimum, indicating a negative electron affinity surface. After a subsequent argon plasma clean this peak disappears, while the spectrum shows a shift of 0.5 eV towards higher energies. Upon sub-monolayer titanium deposition on (1 1 1) diamond, the negative electron affinity peak reappears. Further titanium depositions causes this titanium-induced negative electron affinity peak to be attenuated, indicating that the emission originates from the interface. A similar experiment, done on the diamond (1 0 0) surface, however, does not result in a negative electron affinity. By determining the relative positions of the diamond valence band edge and the titanium Fermi level, the Schottky barrier height of titanium on diamond is measured. A model, based on the Schottky barrier height of titanium on diamond, and the work function of titanium, is

  3. Yeast-based Biochemical Oxygen Demand Sensors Using Gold-modified Boron-doped Diamond Electrodes.

    PubMed

    Ivandini, Tribidasari A; Harmesa; Saepudin, Endang; Einaga, Yasuaki

    2015-01-01

    A gold nanoparticle modified boron-doped diamond electrode was developed as a transducer for biochemical oxygen demand (BOD) measurements. Rhodotorula mucilaginosa UICC Y-181 was immobilized in a sodium alginate matrix, and used as a biosensing agent. Cyclic voltammetry was applied to study the oxygen reduction reaction at the electrode, while amperometry was employed to detect oxygen, which was not consumed by the microorganisms. The optimum waiting time of 25 min was observed using 1-mm thickness of yeast film. A comparison against the system with free yeast cells shows less sensitivity of the current responses with a linear dynamic range (R(2) = 0.99) of from 0.10 mM to 0.90 mM glucose (equivalent to 10 - 90 mg/L BOD) with an estimated limit of detection of 1.90 mg/L BOD. However, a better stability of the current responses could be achieved with an RSD of 3.35%. Moreover, less influence from the presence of copper ions was observed. The results indicate that the yeast-immobilized BOD sensors is more suitable to be applied in a real condition. PMID:26179128

  4. Secondary electron emission in extreme-UV detectors: Application to diamond based devices

    NASA Astrophysics Data System (ADS)

    Ciancaglioni, I.; Marinelli, Marco; Milani, E.; Prestopino, G.; Verona, C.; Verona-Rinati, G.; Angelone, M.; Pillon, M.

    2011-07-01

    A study on the effect of secondary electron emission, which strongly affects the detection of extreme-UV radiation, was performed on diamond detectors. Two different structures were compared: interdigitated contacts and a transverse Schottky diode configuration. Both devices were electrically characterized by I-V measurements and their responsivity was measured in the extreme UV spectral region (20-120 nm) by using He-Ne gas discharge radiation sources and a toroidal grating vacuum monochromator. Through an ad-hoc measurement configuration, the contributions of the internal photocurrent and of the photoemission current have been analyzed and separately evaluated. The results showed that secondary electron emission, which clearly depends on the experimental conditions (e.g., external electric field, pressure, etc.), is one of the most relevant processes affecting the spectral responsivity in the extreme UV band. In particular, for interdigitated devices, extreme care must be taken in order to obtain an absolute value of their responsivity, while detectors in the transverse configuration can be shielded in such a way to avoid secondary electron current contribution and therefore provide a more correct and reliable response.

  5. Wide bandwidth instantaneous radio frequency spectrum analyzer based on nitrogen vacancy centers in diamond

    NASA Astrophysics Data System (ADS)

    Chipaux, M.; Toraille, L.; Larat, C.; Morvan, L.; Pezzagna, S.; Meijer, J.; Debuisschert, T.

    2015-12-01

    We propose an original analog method to perform instantaneous and quantitative spectral analysis of microwave signals. An ensemble of nitrogen-vacancy (NV) centers held in a diamond plate is pumped by a 532 nm laser. Its photoluminescence is imaged through an optical microscope and monitored by a digital camera. An incoming microwave signal is converted into a microwave field in the area of the NV centers by a loop shaped antenna. The resonances induced by the magnetic component of that field are detected through a decrease of the NV centers photoluminescence. A magnetic field gradient induces a Zeeman shift of the resonances and transforms the frequency information into spatial information, which allows for the simultaneous analysis of the microwave signal in the entire frequency bandwidth of the device. The time dependent spectral analysis of an amplitude modulated microwave signal is demonstrated over a bandwidth of 600 MHz , associated to a frequency resolution of 7 MHz , and a refresh rate of 4 ms . With such integration time, a field of a few hundreds of μ W can be detected. Since the optical properties of NV centers can be maintained even in high magnetic field, we estimate that an optimized device could allow frequency analysis in a range of 30 GHz , only limited by the amplitude of the magnetic field gradient. In addition, an increase of the NV centers quantity could lead both to an increase of the microwave sensitivity and to a decrease of the minimum refresh rate down to a few μ s .

  6. Tantalum-Based Ceramics for Refractory Composites

    NASA Technical Reports Server (NTRS)

    Stewart, David A.; Leiser, Daniel; DiFiore, Robert; Kalvala, Victor

    2006-01-01

    A family of tantalum-based ceramics has been invented as ingredients of high-temperature composite insulating tiles. These materials are suitable for coating and/or permeating the outer layers of rigid porous (foam-like or fibrous) ceramic substrates to (1) render the resulting composite ceramic tiles impervious to hot gases and (2) enable the tiles to survive high heat fluxes at temperatures that can exceed 3,000 F ( 1,600 C).

  7. Influence of surface preparation on fracture load of resin composite-based repairs

    PubMed Central

    Mateos-Palacios, Rocío; Román-Rodríguez, Juan-Luis; Solá-Ruíz, María-Fernanda; Fons-Font, Antonio

    2015-01-01

    The purpose of the present study is to evaluate the fracture load of composite-based repairs to fractured zirconium oxide (Z) crowns and to ceramic-fused-to-metal (CM) crowns, comparing different mechanical surface preparation methods. A total of 75 crowns were repaired; samples then underwent dynamic loading and thermocycling. Final fracture load values for failure of the repaired crowns were measured and the type of fracture registered. Group I: CM: Surface preparation with a diamond bur + 9.5% Hydrofluoric Acid (HF) etching; Group II): CM: air-particle (Al2O3) + 9.5% HF; Group III: CM: Silica coating (SiO2); Group IV): Z: air-particle (Al2O3) + HF 9.5%; Group V) Z: Silica coating (SiO2). Of the three CM groups, Group I (CM-diamond bur) showed the highest mean failure value, with significant difference in comparison with Group III (CM-silica coating). For the zirconia groups, the highest value was obtained by Group V (silica coating). Key words:Crown, ceramic-fused-to-metal, zirconia, resin-composite, ceramic covering. PMID:25810848

  8. Sulfide inclusion chemistry and carbon isotopes of African diamonds

    NASA Astrophysics Data System (ADS)

    Deines, Peter; Harris, J. W.

    1995-08-01

    Significant differences in the composition of sulfide mineral inclusions among diamond suites from Koffiefontein, Orapa, Premier, Roberts Victor, Jagersfontein, Sierra Leone, Star, and Mwadui have been found. The mode of the Ni content of the monosulfide (mss) inclusions lies between 8 and 10 wt%, i.e., between the means for mss from Siberian diamonds with inclusion of the eclogitic (3 wt% Ni) and peridotitic (23 wt% Ni) paragenesis. Considering the Ni/Fe ratios of the diamond mss inclusions and mantle olivines, together with experimental and naturally observed Ni/Fe distribution coefficients, we conclude that less than 20% of the mss inclusions of the African diamonds (mostly from Koffiefontein) could have been in chemical equilibrium with mantle olivine. This observation is in sharp contrast with the reported relative abundance of silicate inclusions in Koffiefontein diamonds (93% peridotitic, 7% eclogitic) and lends support to the proposal that a separate sulfide diamond paragenesis should be recognized. The δ 13C distributions of sulfide containing diamonds differs among kimberlites, however, for each kimberlite sulfide and silicate inclusion containing diamonds cover the same δ 13C range. Sulfides with high Ni concentrations can occur in diamonds of low as well as high 13C content. The current observations, in conjunction with other chemical properties of diamonds suggest that fluid reactions rather than silica melt equilibria may be important in diamond formation. A dominance of fluid processes would have significant implications for the interpretation of the chemical and geochronological record of diamond inclusions.

  9. Stable isotope evidence for crustal recycling as recorded by superdeep diamonds

    NASA Astrophysics Data System (ADS)

    Burnham, A. D.; Thomson, A. R.; Bulanova, G. P.; Kohn, S. C.; Smith, C. B.; Walter, M. J.

    2015-12-01

    Sub-lithospheric diamonds from the Juina-5 and Collier-4 kimberlites and the Machado River alluvial deposit in Brazil have carbon isotopic compositions that co-vary with the oxygen isotopic compositions of their inclusions, which implies that they formed by a mixing process. The proposed model for this mixing process, based on interaction of slab-derived carbonate melt with reduced (carbide- or metal-bearing) ambient mantle, explains these isotopic observations. It is also consistent with the observed trace element chemistries of diamond inclusions from these localities and with the experimental phase relations of carbonated subducted crust. The 18O-enriched nature of the inclusions demonstrates that they incorporate material from crustal protoliths that previously interacted with seawater, thus confirming the subduction-related origin of superdeep diamonds. These samples also provide direct evidence of an isotopically anomalous reservoir in the deep (≥350 km) mantle.

  10. Formation of diamond in the Earth's mantle.

    PubMed

    Stachel, Thomas; Harris, Jeff W

    2009-09-01

    The principal sources of natural diamonds are peridotitic (about 2/3 of diamonds) and eclogitic (1/3) domains located at 140-200 km depth in the subcratonic lithospheric mantle. There, diamonds probably form during redox reactions in the presence of melt (likely for eclogitic and lherzolitic diamonds) or under subsolidus conditions in the presence of CHO fluids (likely for harzburgitic diamonds). Co-variations of δ(13)C and the nitrogen content of diamonds suggest that two modes of formation may have been operational in peridotitic sources: (1) reduction of carbonates, that during closed system fractionation drives diamond compositions to higher δ(13)C values and lower nitrogen concentrations and (2) oxidation of methane, that in a closed system leads to a trend of decreasing δ(13)C with decreasing nitrogen. The present day redox state of subcratonic lithospheric mantle is generally too reduced to allow for methane oxidation to be a widespread process. Therefore, reduction of carbonate dissolved in melts and fluids is likely the dominant mode of diamond formation for the Phanerozoic (545 Ma-present) and Proterozoic (2.5 Ga-545 Ma). Model calculations indicate, however, that for predominantly Paleoarchean (3.6-3.2 Ga) to Mesoarchean (3.2-2.8 Ga) harzburgitic diamonds, methane reduction is the principal mode of precipitation. This suggests that the reduced present day character (oxygen fugacity below carbonate stability) of peridotitic diamond sources may be a secondary feature, possibly acquired during reducing Archean (>2.5 Ga) metasomatism. Recycling of biogenic carbonates back into the mantle through subduction only became an important process in the Paleoproterozoic (2.5-1.6 Ga) and diamonds forming during carbonate reduction, therefore, may predominantly be post-Archean in age. For eclogitic diamonds, open system fractionation processes involving separation of a CO(2) fluid appear to dominate, but in principal the same two modes of formation

  11. Nanotwinned diamond with unprecedented hardness and stability

    NASA Astrophysics Data System (ADS)

    Huang, Quan; Yu, Dongli; Xu, Bo; Hu, Wentao; Ma, Yanming; Wang, Yanbin; Zhao, Zhisheng; Wen, Bin; He, Julong; Liu, Zhongyuan; Tian, Yongjun

    2014-06-01

    Although diamond is the hardest material for cutting tools, poor thermal stability has limited its applications, especially at high temperatures. Simultaneous improvement of the hardness and thermal stability of diamond has long been desirable. According to the Hall-Petch effect, the hardness of diamond can be enhanced by nanostructuring (by means of nanograined and nanotwinned microstructures), as shown in previous studies. However, for well-sintered nanograined diamonds, the grain sizes are technically limited to 10-30 nm (ref. 3), with degraded thermal stability compared with that of natural diamond. Recent success in synthesizing nanotwinned cubic boron nitride (nt-cBN) with a twin thickness down to ~3.8 nm makes it feasible to simultaneously achieve smaller nanosize, ultrahardness and superior thermal stability. At present, nanotwinned diamond (nt-diamond) has not been fabricated successfully through direct conversions of various carbon precursors (such as graphite, amorphous carbon, glassy carbon and C60). Here we report the direct synthesis of nt-diamond with an average twin thickness of ~5 nm, using a precursor of onion carbon nanoparticles at high pressure and high temperature, and the observation of a new monoclinic crystalline form of diamond coexisting with nt-diamond. The pure synthetic bulk nt-diamond material shows unprecedented hardness and thermal stability, with Vickers hardness up to ~200 GPa and an in-air oxidization temperature more than 200 °C higher than that of natural diamond. The creation of nanotwinned microstructures offers a general pathway for manufacturing new advanced carbon-based materials with exceptional thermal stability and mechanical properties.

  12. Diamond resorption features as a new method for examining conditions of kimberlite emplacement

    NASA Astrophysics Data System (ADS)

    Fedortchouk, Yana

    2015-10-01

    The study develops a new approach utilizing parameters of trigonal etch pits on diamond crystals to infer the conditions of diamond residence in kimberlite magma. Diamond crystals from dissolution experiments conducted at 1 GPa and 1150-1350 °C in the presence of H2O-rich or CO2-rich fluid were studied with atomic force microscopy (AFM). The AFM data of resorbed diamond surfaces show that much deeper surface relief was produced in CO2 fluid. It also clearly distinguishes the profiles of the trigonal etch pits forming regular flat-bottomed trigons in H2O fluid, and round- or pointed-bottomed trigons in CO2 fluid. The relationship between the diameter and the depth of the trigonal pits is found to be another important indicator of the fluid composition. Dissolution in H2O fluid develops trigons with constant diameter and variable depth where the diameter increases with temperature. Trigons developed in CO2 fluid have a large range of diameters showing a strong positive correlation with the depth. The developed criteria applied to the natural diamond crystals from three Ekati Mine kimberlites indicate significant variation in CO2-H2O ratio and temperature of their magmatic fluid. This conclusion based on diamond resorption agrees with the mineralogy of microphenocrysts and groundmass of the studied kimberlites offering new method to study crystallization conditions of kimberlite magma.

  13. Diamond genesis, seismic structure, and evolution of the Kaapvaal-Zimbabwe craton.

    PubMed

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

    2002-09-01

    The lithospheric mantle beneath the Kaapvaal-Zimbabwe craton of southern Africa shows variations in seismic P-wave velocity at depths within the diamond stability field that correlate with differences in the composition of diamonds and their syngenetic inclusions. Middle Archean mantle depletion events initiated craton keel formation and early harzburgitic diamond formation. Late Archean accretionary events involving an oceanic lithosphere component stabilized the craton and contributed a younger Archean generation of eclogitic diamonds. Subsequent Proterozoic tectonic and magmatic events altered the composition of the continental lithosphere and added new lherzolitic and eclogitic diamonds to the Archean diamond suite. PMID:12215642

  14. Surface acoustic wave properties of (100) AlN films on diamond with different IDT positions.

    PubMed

    Lin, Zhi-Xun; Wu, Sean; Ro, Ruyen; Lee, Maw-Shung

    2009-06-01

    (100) AlN films have better surface acoustic wave (SAW) properties than (002) AlN films. In this research, (100) AlN films were combined with diamonds as a new composite SAW substrate. The SAW properties of (100) AlN films on diamonds were analyzed with 4 composite structures: interdigital transducer (IDT)/(100) AlN/diamond, (100) AlN/IDT/diamond, IDT/(100) AlN/metal/diamond, and metal/IDT/(100) AlN/diamond, and they exhibited some excellent SAW properties. Our research results provide a predictable and theoretical basis for further application on high-velocity SAW devices. PMID:19574132

  15. Theoretical predictions of a bucky-diamond SiC cluster

    NASA Astrophysics Data System (ADS)

    Yu, Ming; Jayanthi, C. S.; Wu, S. Y.

    2012-06-01

    A study of structural relaxations of SinCm clusters corresponding to different compositions, different relative arrangements of Si/C atoms, and different types of initial structure, reveals that the SinCm bucky-diamond structure can be obtained for an initial network structure constructed from a truncated bulk 3C-SiC for a magic composition corresponding to n = 68 and m = 79. This study was performed using a semi-empirical Hamiltonian (SCED-LCAO) since it allowed an extensive search of different types of initial structures. However, the bucky-diamond structure predicted by this method was also confirmed by a more accurate density functional theory (DFT) based method. The bucky-diamond structure exhibited by a SiC-based system represents an interesting paradigm where a Si atom can form three-coordinated as well as four-coordinated networks with carbon atoms and vice versa and with both types of network co-existing in the same structure. Specifically, the bucky-diamond structure of the Si68C79 cluster consists of a 35-atom diamond-like inner core (four-atom coordinations) suspended inside a 112-atom fullerene-like shell (three-atom coordinations).

  16. Theoretical predictions of a bucky-diamond SiC cluster.

    PubMed

    Yu, Ming; Jayanthi, C S; Wu, S Y

    2012-06-15

    A study of structural relaxations of Si(n)C(m) clusters corresponding to different compositions, different relative arrangements of Si/C atoms, and different types of initial structure, reveals that the Si(n)C(m) bucky-diamond structure can be obtained for an initial network structure constructed from a truncated bulk 3C-SiC for a magic composition corresponding to n = 68 and m = 79. This study was performed using a semi-empirical Hamiltonian (SCED-LCAO) since it allowed an extensive search of different types of initial structures. However, the bucky-diamond structure predicted by this method was also confirmed by a more accurate density functional theory (DFT) based method. The bucky-diamond structure exhibited by a SiC-based system represents an interesting paradigm where a Si atom can form three-coordinated as well as four-coordinated networks with carbon atoms and vice versa and with both types of network co-existing in the same structure. Specifically, the bucky-diamond structure of the Si(68)C(79) cluster consists of a 35-atom diamond-like inner core (four-atom coordinations) suspended inside a 112-atom fullerene-like shell (three-atom coordinations). PMID:22595915

  17. Fast bolometer built in an artificial HPHT diamond matrix

    SciTech Connect

    Klokov, A Yu; Sharkov, A I; Galkina, T I; Khmelnitskii, R A; Dravin, V A; Gippius, Aleksei A

    2010-05-26

    A fast bolometer built in a plate of diamond grown at high pressure by the gradient growth method is developed and fabricated. The parameters of this structure are compared with these of the structures investigated earlier, which were fabricated based on chemical vapour deposited (CVD) diamond and natural type IIa diamond.

  18. Iterative stability analysis of spatial domain decomposition based on block Jacobi algorithm for the diamond-difference scheme

    NASA Astrophysics Data System (ADS)

    Anistratov, Dmitriy Y.; Azmy, Yousry Y.

    2015-09-01

    We study convergence of the integral transport matrix method (ITMM) based on a parallel block Jacobi (PBJ) iterative strategy for solving particle transport problems. The ITMM is a spatial domain decomposition method proposed for massively parallel computations. A Fourier analysis of the PBJ-based iterations applied to SN diamond-difference equations in 1D slab and 2D Cartesian geometries is performed. It is carried out for infinite-medium problems with homogeneous material properties. To analyze the performance of the ITMM with the PBJ algorithm and evaluate its potential in scalability we consider a limiting case of one spatial cell per subdomain. The analysis shows that in such limit the spectral radius of the iteration method is one without regard to values of the scattering ratio and optical thickness of the spatial cells. This implies lack of convergence in infinite medium. Numerical results of finite-medium problems are presented. They demonstrate effects of finite size of spatial domain on the performance of the iteration algorithm as well as its asymptotic behavior when the extent of the spatial domain increases. These numerical experiments also show that for finite domains iterative convergence to a finite criterion is achievable in a multiple of the sum of number of cells in each dimension.

  19. High pressure low temperature studies on 1-2-2 iron-based superconductors using designer diamond cells

    DOE PAGESBeta

    Uhoya, Walter O.; Tsoi, Georgiy M.; Vohra, Yogesh K.; Mitchell, Jonathan, E.; Safa-Sefat, Athena; Weir, Samuel

    2013-01-01

    In this study, high pressure low temperature electrical resistance measurements were carried out on a series of 122 iron-based superconductors using a designer diamond anvil cell. These studies were complemented by image plate x-ray diffraction measurements under high pressures and low temperatures at beamline 16-BM-D, HPCAT, Advanced Photon Source. A common feature of the 1-2-2 iron-based materials is the observation of anomalous compressibility effects under pressure and a Tetragonal (T) to Collapsed Tetragonal (CT) phase transition under high pressures. Specific studies on antiferromagnetic spin-density-wave Ba0.5Sr0.5Fe2As2 and Ba(Fe0.9Ru0.1)2As2 samples are presented to 10 K and 41 GPa. The collapsed tetragonal phasemore » was observed at a pressure of 14 GPa in Ba0.5Sr0.5Fe2As2 at ambient temperature. The highest superconducting transition temperature in Ba0.5Sr0.5Fe2As2 was observed to be at 32 K at a pressure of 4.7 GPa. The superconductivity was observed to be suppressed on transformation to the CT phase in 122 materials.« less

  20. Nitrogen incorporated ultrananocrystalline diamond based field emitter array for a flat-panel x-ray source

    NASA Astrophysics Data System (ADS)

    Posada, Chrystian M.; Grant, Edwin J.; Divan, Ralu; Sumant, Anirudha V.; Rosenmann, Daniel; Stan, Liliana; Lee, Hyoung K.; Castaño, Carlos H.

    2014-04-01

    A field emission based flat-panel transmission x-ray source is being developed as an alternative for medical and industrial imaging. A field emitter array (FEA) prototype based on nitrogen incorporated ultrananocrystalline diamond film has been fabricated to be used as the electron source of this flat panel x-ray source. The FEA prototype was developed using conventional microfabrication techniques. The field emission characteristics of the FEA prototype were evaluated. Results indicated that emission current densities of the order of 6 mA/cm2 could be obtained at electric fields as low as 10 V/μm to 20 V/μm. During the prototype microfabrication process, issues such as delamination of the extraction gate and poor etching of the SiO2 insulating layer located between the emitters and the extraction layer were encountered. Consequently, alternative FEA designs were investigated. Experimental and simulation data from the first FEA prototype were compared and the results were used to evaluate the performance of alternative single and double gate designs that would yield better field emission characteristics compared to the first FEA prototype. The best simulation results are obtained for the double gate FEA design, when the diameter of the collimator gate is around 2.6 times the diameter of the extraction gate.

  1. Diamonds: Exploration, mines and marketing

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

    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).

  2. Sources of carbon in inclusion bearing diamonds

    NASA Astrophysics Data System (ADS)

    Stachel, Thomas; Harris, Jeff W.; Muehlenbachs, Karlis

    2009-11-01

    The carbon isotopic composition ( δ13C) of diamonds containing peridotitic, eclogitic, websteritic and ultra-deep inclusions is re-evaluated on a detailed level. Applying a binning interval of 0.25‰, the previously recognized mode of peridotitic and eclogitic diamonds at about - 5‰ is shown to reflect at least two subpopulations with abundance peaks at ˜ - 5.75 to - 4.75‰ and ˜ - 4.50 to - 3.50‰. Within the peridotitic suite, diamonds with lherzolitic inclusions overall show higher δ13C values. Evolution away from a δ13C value of ˜ - 5‰, towards both 13C depleted and enriched compositions, is accompanied by decreasing maximum nitrogen contents of peridotitic diamonds. In combination with data on diamonds synthesized under reducing (metal melts) and more oxidizing conditions (carbonate-silicate interactions), this is taken to indicate that nitrogen is a compatible element in diamond that becomes depleted in the growth medium during progressive diamond precipitation. The observed co-variations of nitrogen content and δ13C around - 5‰ can then be modelled as reflecting closed system Rayleigh fractionation during crystallization of diamond from fluids/melts that are both reducing (i.e. methane bearing; evolution from ˜ - 5 to - 10‰) and oxidizing (i.e. CO 32- bearing; evolution from starting points varying between ˜ - 9 to - 5‰ and extending to about 0‰). Lherzolitic diamonds are believed to be mainly derived from diamond forming events subsequent to precipitation of predominantly Mesoarchean harzburgitic diamonds. The shift of lherzolitic diamonds towards higher δ13C values thus may relate to a temporal evolution, with carbonate bearing fluids with an initial isotopic composition ranging between about - 5.5 and - 1.5‰, derived from subducting oceanic crust, becoming increasingly important subsequent to the Mesoarchean. Devolatilization of marine carbonates ( δ13C ˜ 0‰) drives their isotopic composition towards mantle like values and

  3. The evaluation of chemical wear on single crystal diamond tools while diamond turning a binary Cu-Ni alloy system

    NASA Astrophysics Data System (ADS)

    Browy, Eric Calmer

    The current work describes the evaluation of chemical wear on diamond tools while diamond turning copper nickel alloys of varying composition. The primary goal of my project is to quantify the chemical wear of single crystal diamond tools while diamond turning Cu-Ni alloys of different compositions. Pure copper is commonly understood to give negligible tool wear, while pure nickel is reported to give rapid wear. The Cu-Ni equilibrium phase diagram shows a single phase at all compositions. The development and testing of a method to evaluate and quantify diamond tool wear is also described within the current work. The method chosen for development is the metrology of the progressive edge recession of the diamond. A procedure of progressive plunge cuts into an ultra-bright acid copper before and after diamond turning of the workpiece takes a snapshot of the edge of the diamond tool as the cutting distance increases. An algorithm executed in MatLabRTM displays the residual tool wear after removal of the initial diamond tool geometry. A theoretical model has been developed to predict the chemical diamond tool wear and the results will be shown within the body of work.

  4. Heat expanded starch-based compositions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A heat expansion process similar to that used for expanded bead polystyrene was used to expand starch-based compositions. Foam beads made by solvent extraction had the appearance of polystyrene beads but their open-cell structure precluded them from expanding further when heated. Non-porous beads, p...

  5. 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.

  6. Diamond Sheet: A new diamond tool material

    NASA Technical Reports Server (NTRS)

    Mackey, C. R.

    1982-01-01

    Diamond sheet is termed a diamond tool material because it is not a cutting tool, but rather a new material from which a variety of different tools may be fabricated. In appearance and properties, it resembles a sheet of copper alloy with diamond abrasive dispersed throughout it. It is capable of being cut, formed, and joined by conventional methods, and subsequently used for cutting as a metal bonded diamond tool. Diamond sheet is normally made with industrial diamond as the abrasive material. The metal matrix in diamond sheet is a medium hard copper alloy which has performed well in most applications. This alloy has the capability of being made harder or softer if specific cutting conditions require it. Other alloys have also been used including a precipitation hardened aluminum alloy with very free cutting characteristics. The material is suitable for use in a variety of cutting, surfacing, and ring type tools, as well as in such mundane items as files and sandpaper. It can also be used as a bearing surface (diamond to diamond) and in wear resistant surfaces.

  7. Thermodynamics of Metal Composites Based on Polyvinylchloride

    NASA Astrophysics Data System (ADS)

    Kolupaev, B. B.; Lyashuk, T. G.; Kolupaev, B. S.

    2014-03-01

    We present the results of experimental investigations of the thermodynamic properties of composites based on polyvinylchloride and copper nanoparticles obtained by electrical explosion of the conductor. It has been established that the thermodynamic potentials H and G in determining the system parameters (s, T, p, V) depend nonlinearly on the temperature and content of the filler. β- and α-relaxation transitions as a general phenomenon characteristic of the fluctuation structure of polyvinylchloride are observed thereby. The introduction of a nanodispersed metal filler into polyvinylchloride increases the amount of activation energy and the time of "settled" life of the structural elements, changing the thermodynamic stability of the composite.

  8. MoSi2-Base Composites

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G.

    2003-01-01

    Addition of 30 to 50 vol% of Si3N4 particulate to MoSi2 eliminated its low temperature catastrophic failure, improved room temperature fracture toughness and the creep resistance. The hybrid composite SCS-6/MoSi2-Si3N4 did not show any matrix cracking and exhibited excellent mechanical and environmental properties. Hi-Nicalon continuous fiber reinforced MoSi2-Si3N4 also showed good strength and toughness. A new MoSi2-base composite containing in-situ whisker-type (Beta)Si3N4 grains in a MoSi2 matrix is also described.

  9. Scanning tunneling microscopy-based in situ measurement of fast tool servo-assisted diamond turning micro-structures

    NASA Astrophysics Data System (ADS)

    Ju, Bing-Feng; Zhu, Wu-Le; Yang, Shunyao; Yang, Keji

    2014-05-01

    We propose a new in situ measurement system based on scanning tunneling microscopy (STM) to realize spiral scanning of a micro-structure without removing it after fast tool servo (FTS) cutting. To avoid distortion of the machined and measured surface, the center alignment of the FTS tool and the STM tip was first implemented by an STM in situ raster scan of two circular grooves cut by the machine tool. To originally observe the machined surface, the trace of the STM tip is put in accord with that of the FTS by setting the same start and end points of cutting and scanning and the same feed rate, and both are triggered by the subdivided rotary encoder of the spindle of the diamond turning machine. The profile data of the in situ spiral scanning of the machined micro-lens array can be fed back to compensate the depth of the cut to guarantee sub-micron form accuracy after second machining. The efficient spiral scanning, proper matching and accurate evaluation results demonstrate that the proposed STM in situ measurement approach is of great significance to the fabrication process.

  10. Detection of diamonds in kimberlite by the tagged neutron method

    NASA Astrophysics Data System (ADS)

    Alexakhin, V. Yu.; Bystritsky, V. M.; Zamyatin, N. I.; Zubarev, E. V.; Krasnoperov, A. V.; Rapatsky, V. L.; Rogov, Yu. N.; Sadovsky, A. B.; Salamatin, A. V.; Salmin, R. A.; Sapozhnikov, M. G.; Slepnev, V. M.; Khabarov, S. V.; Razinkov, E. A.; Tarasov, O. G.; Nikitin, G. M.

    2015-06-01

    A new technology for diamond detection in kimberlite based on the tagged neutron method is proposed. The results of experimental researches on irradiation of kimberlite samples with 14.1-MeV tagged neutrons are discussed. The source of the tagged neutron flux is a portable neutron generator with a built-in 64-pixel silicon alpha-detector with double-sided stripped readout. Characteristic gamma rays resulting from inelastic neutron scattering on nuclei of elements included in the composition of kimberlite are registered by six gamma-detectors based on BGO crystals. The criterion for diamond presence in kimberlite is an increased carbon concentration within a certain volume of the kimberlite sample.

  11. Crack Formation in Cement-Based Composites

    NASA Astrophysics Data System (ADS)

    Sprince, A.; Pakrastinsh, L.; Vatin, N.

    2016-04-01

    The cracking properties in cement-based composites widely influences mechanical behavior of construction structures. The challenge of present investigation is to evaluate the crack propagation near the crack tip. During experiments the tension strength and crack mouth opening displacement of several types of concrete compositions was determined. For each composition the Compact Tension (CT) specimens were prepared with dimensions 150×150×12 mm. Specimens were subjected to a tensile load. Deformations and crack mouth opening displacement were measured with extensometers. Cracks initiation and propagation were analyzed using a digital image analysis technique. The formation and propagation of the tensile cracks was traced on the surface of the specimens using a high resolution digital camera with 60 mm focal length. Images were captured during testing with a time interval of one second. The obtained experimental curve shows the stages of crack development.

  12. Synthetic 3D diamond-based electrodes for flexible retinal neuroprostheses: Model, production and in vivo biocompatibility.

    PubMed

    Bendali, Amel; Rousseau, Lionel; Lissorgues, Gaëlle; Scorsone, Emmanuel; Djilas, Milan; Dégardin, Julie; Dubus, Elisabeth; Fouquet, Stéphane; Benosman, Ryad; Bergonzo, Philippe; Sahel, José-Alain; Picaud, Serge

    2015-10-01

    Two retinal implants have recently received the CE mark and one has obtained FDA approval for the restoration of useful vision in blind patients. Since the spatial resolution of current vision prostheses is not sufficient for most patients to detect faces or perform activities of daily living, more electrodes with less crosstalk are needed to transfer complex images to the retina. In this study, we modelled planar and three-dimensional (3D) implants with a distant ground or a ground grid, to demonstrate greater spatial resolution with 3D structures. Using such flexible 3D implant prototypes, we showed that the degenerated retina could mould itself to the inside of the wells, thereby isolating bipolar neurons for specific, independent stimulation. To investigate the in vivo biocompatibility of diamond as an electrode or an isolating material, we developed a procedure for depositing diamond onto flexible 3D retinal implants. Taking polyimide 3D implants as a reference, we compared the number of neurones integrating the 3D diamond structures and their ratio to the numbers of all cells, including glial cells. Bipolar neurones were increased whereas there was no increase even a decrease in the total cell number. SEM examinations of implants confirmed the stability of the diamond after its implantation in vivo. This study further demonstrates the potential of 3D designs for increasing the resolution of retinal implants and validates the safety of diamond materials for retinal implants and neuroprostheses in general. PMID:26210174

  13. [The possibilities for the application of the fluoroplast-based prostheses with a diamond-like carbon nanocoating in ear surgery (an experimental study)].

    PubMed

    Sitnikov, V P; Shil'ko, S V; Khusam, Él'-Refaĭ; Nadyrov, É A; Kazachenko, V P; Dzhaĭnakbaev, N T

    2014-01-01

    The objective of the present study was to elucidate general and local characteristics of the tissue reactions to the implantation of radiation-modified polytetrafluoroethylene (PTFE)-based fluoroplast F-4PM20 with a diamond-like carbon (DLC) nanocoating or with the diamond-like carbon coating containing the dispersed nano-sized silver particles to the experimental animals (rats). A total of 150 inbred white rats were included into the experiment; they were divided into 3 groups comprised of 50 animals each. The rats in group 1 were implanted with the 5 nm thick strips of fluoroplast F-4PM20 having the diamond-like carbon nanocoating. The animals of group 2 were implanted with the same material containing nanoparticles of chemically pure silver dispersed in the coating, those in group 3 (controls) were implanted with the fluoroplast F-4PM20 without a coating. The animals were sacrificed on days 7, 21, 30, and 60 days after the onset of the experiment. The tissues surrounding the implant as well as heart, lung, spleen, liver, and kidney tissues were taken for the histological study. The local reactions of different tissues were found to be uniform even though there was an apparent tendency toward the less pronounced granulation and scarification processes in the animals implanted with the diamond-like carbon coating containing the dispersed nano-sized silver particles. In none of the groups, the animals exhibited statistically significant lymphoid tissue hyperplasia in the spleen which suggested the activation of the immune system in response to implantation. It is concluded that the PTFE-based fluoroplast F-4PM20 implants with the 5 nm thick DLC coating and a similar coating containing the dispersed nano-sized silver particles can be applied for middle ear reconstructive surgery, being a histologically compatible material that does not cause an inflammatory degenerative response of the tissues. PMID:25246203

  14. 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

  15. Electrically conductive diamond electrodes

    DOEpatents

    Swain, Greg; Fischer, Anne ,; Bennett, Jason; Lowe, Michael

    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.

  16. Petrochemical types of kimberlites and their diamond-bearing capacity

    NASA Astrophysics Data System (ADS)

    Kostrovitsky, Sergey

    2010-05-01

    Kimberlite rocks of Yakutian province (belong to 1 group of kimberlites after Smith, 1983) are characterized by wide variations of rock-forming oxides [Ilupin et al., 1986; Milashev, 1965; Kharkiv et al., 1991]. A number of factors could be discussed to explain the variety of chemical compositions of rocks. The first factor, explaining the regional differences in the kimberlite composition with primarily different composition of source kimberlite melt-fluid, is conventionally called «primary». All other factors are connected with the secondary redistribution of chemical components of kimberlites. Irrespective of intensity of secondary factors, the primary composition of kimberlites varies broadly, which is noticeable in kimberlites of some provinces, kimberlites fields, pipe clusters and individual pipes. The petrochemical types are classified based on the contents of such oxides as FeO, TiO2 and K2O, being relatively inert in the secondary processes. In the Yakutian Province we have distinguished 5 petrochemical types of kimberlites (Kostrovitsky et al, 2007); with principal ones - high-Mg, magnesium-ferruginous (Mg-Fe) and ferruginous-titaniferous, their composition: < 6; 6-9; 8-15 % FeOtotal and < 1; 1-2.5; 1.5-5.0 % TiO2). Some petrochemical and mineralogical criteria of diamond-bearing capacity of kimberlites were identified some time before. The essence of petrochemical criterion consists of the inverse correlation dependence between the contents FeOtotal, TiO2 in kimberlite rocks and their diamond-bearing capacity (Milashev, 1965; Krivonos, 1998). The mineralogical criteria of diamond-bearing capacity infer presence of direct dependence of the rate of capacity on the content in kimberlites of low-Ca, high-Cr garnet and chrome spinellids with Cr2O3 > 62% and TiO2 < 0.5%, of dunite-harzburgite paragenesis (Sobolev, 1974; Meyer, 1968). The acquired results are applied to evaluate «efficiency» of criteria of diamond-bearing capacity exemplified by the

  17. Discovery of carbonatitic microinclusions in diamonds with highly aggregated nitrogen

    NASA Astrophysics Data System (ADS)

    Jablon, B. M.; Navon, O.

    2014-12-01

    It is accepted that fibrous diamonds grew from the high-density fluids (HDFs) they trapped as microinclusions. Such fluids are not found in monocrystalline (MC) diamonds, leaving their source of carbon a mystery. Fibrous diamonds carry nitrogen in A centers and are young (106 years), while most MC diamonds carry aggregated nitrogen in both A and B centers and are older (109 years). Weiss et al. (2014) found saline HDFs in the core of a coated diamond from Guinea and carbonatitic and saline fluids in a South African diamond, both with low concentrations of B centers (5-27%). Here we report finding microinclusions with high-Mg carbonatitic HDFs in MC diamonds. The infrared spectrum of these diamonds confirms their highly aggregated nature (>60%). We studied a suite of twinned diamonds, macles, from the Venetia mine in South Africa. The diamonds were polished perpendicular to their twinning plane and cleaned in HF and HNO3. We identified the twinning planes in cathodoluminescence images and methodically searched along and next to these planes, assuming that inclusions were preferentially trapped there. Shallow, sub-surface inclusions were analyzed using a JEOL JXA-8230 EPMA and an EDS detector. In two out of 11 diamonds we found inclusions with high concentrations of MgO (26-31 wt%), CaO (21-34%), K2O (9-16%), FeO (7-12%) and SiO2 (8-13%). These compositions are similar to those of HDFs in fibrous diamonds from Guinea and Yakutia (Weiss et al., 2009; Klein-BenDavid et al., 2009; Zedgenizov et al., 2009). Eight carbonatitic inclusions were found in diamond ON-VNT-608 and three in ON-VNT-605. Five microinclusions in 608 and one in 605 carry high concentrations of SiO2, MgO and FeO, with little else. Their compositions fall close to that of orthopyroxene, suggesting that both diamonds belong to the peridotitic paragenesis. Other inclusions, rich in SiO2 and Al2O3 in variable proportions were found in 8 of the 11 diamonds. The nature of these inclusions is not yet clear

  18. Microfabrication of diamond-based slow-wave circuits for mm-wave and THz vacuum electronic sources

    NASA Astrophysics Data System (ADS)

    Lueck, M. R.; Malta, D. M.; Gilchrist, K. H.; Kory, C. L.; Mearini, G. T.; Dayton, J. A.

    2011-06-01

    Planar and helical slow-wave circuits for THz radiation sources have been made using novel microfabrication and assembly methods. A biplanar slow-wave circuit for a 650 GHz backward wave oscillator (BWO) was fabricated through the growth of diamond into high aspect ratio silicon molds and the selective metallization of the tops and sidewalls of 90 µm tall diamond features using lithographically created shadow masks. Helical slow-wave circuits for a 650 GHz BWO and a 95 GHz traveling wave tube were created through the patterning of trenches in thin film diamond, electroplating of gold half-helices, and high accuracy bonding of helix halves. The development of new techniques for the microfabrication of vacuum electronic components will help to facilitate compact and high-power sources for terahertz range radiation.

  19. 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

  20. Diamond Quantum Devices in Biology.

    PubMed

    Wu, Yuzhou; Jelezko, Fedor; Plenio, Martin B; Weil, Tanja

    2016-06-01

    The currently available techniques for molecular imaging capable of reaching atomic resolution are limited to low temperatures, vacuum conditions, or large amounts of sample. Quantum sensors based on the spin-dependent photoluminescence of nitrogen-vacancy (NV) centers in diamond offer great potential to achieve single-molecule detection with atomic resolution under ambient conditions. Diamond nanoparticles could also be prepared with implanted NV centers, thereby generating unique nanosensors that are able to traffic into living biological systems. Therefore, this technique might provide unprecedented access and insight into the structure and function of individual biomolecules under physiological conditions as well as observation of biological processes down to the quantum level with atomic resolution. The theory of diamond quantum sensors and the current developments from their preparation to sensing techniques have been critically discussed in this Minireview. PMID:27120692

  1. Soy-based fillers for thermoset composites

    NASA Astrophysics Data System (ADS)

    Watt, Paula

    Considerable work has been done with bio-based fillers in thermoplastics. Wood dust has been used for decades in wood plastic composites in conjunction with recycled high HDPE and PET. In recent years rapidly renewable fillers derived from dried distillery grains and from wood have been introduced commercially for thermoset polymers. These fillers provide bio-content and weight reduction to thermoset molding compounds but issues with moisture absorption and polymerization inhibition have limited their commercial acceptance. The intent of this research was to develop a bio-based filler suitable for thermoset composites. This filler would provide a low density alternative to mined mineral filler, such as CaCO3 or clay. Composites made with these fillers would be lighter in weight, which is desirable for many markets, particularly transportation. Cost parity to the mineral fillers, on a volume basis, was desirable and the use of green chemistry principles was a key objective of the project. This work provides a basis from which further development of modified soy flours as fillers for thermoset composites will continue. Biomass has been evaluated as fillers for thermoset composites since the early 1980s but failed to gain commercial acceptance due to excessive water absorption and inhibition issues with free radical curing. Biomass, with a large percentage of carbohydrates, are very hydrophilic due to their abundance of hydroxyl groups, while biomass, high in lignin, resulted in inhibition of the free radical cure of the unsaturated styrenated polyester matrix systems. Generally protein use as a filler is not desirable due to its food value. Torrefaction has proved to be a good, cost effective, process to reduce hydrophilicity of high cellulose feedstock. Surprising, however, some levels of torrefaction were found to induce the inhibition effect of the filler. Scientific inquiry into this problem proved that aromatics form during the torrefaction process and can

  2. High pressure low temperature studies on 1-2-2 iron-based superconductors using designer diamond cells

    SciTech Connect

    Uhoya, Walter O.; Tsoi, Georgiy M.; Vohra, Yogesh K.; Mitchell, Jonathan, E.; Safa-Sefat, Athena; Weir, Samuel

    2013-01-01

    In this study, high pressure low temperature electrical resistance measurements were carried out on a series of 122 iron-based superconductors using a designer diamond anvil cell. These studies were complemented by image plate x-ray diffraction measurements under high pressures and low temperatures at beamline 16-BM-D, HPCAT, Advanced Photon Source. A common feature of the 1-2-2 iron-based materials is the observation of anomalous compressibility effects under pressure and a Tetragonal (T) to Collapsed Tetragonal (CT) phase transition under high pressures. Specific studies on antiferromagnetic spin-density-wave Ba0.5Sr0.5Fe2As2 and Ba(Fe0.9Ru0.1)2As2 samples are presented to 10 K and 41 GPa. The collapsed tetragonal phase was observed at a pressure of 14 GPa in Ba0.5Sr0.5Fe2As2 at ambient temperature. The highest superconducting transition temperature in Ba0.5Sr0.5Fe2As2 was observed to be at 32 K at a pressure of 4.7 GPa. The superconductivity was observed to be suppressed on transformation to the CT phase in 122 materials.

  3. Diamond heteroepitaxial lateral overgrowth

    NASA Astrophysics Data System (ADS)

    Tang, Yung-Hsiu

    This dissertation describes improvements in the growth of single crystal diamond by microwave plasma-assisted chemical vapor deposition (CVD). Heteroepitaxial (001) diamond was grown on 1 cm. 2 a-plane sapphiresubstrates using an epitaxial (001) Ir thin-film as a buffer layer. Low-energy ion bombardment of the Ir layer, a process known as bias-enhanced nucleation, is a key step in achieving a high density of diamond nuclei. Bias conditions were optimized to form uniformly-high nucleation densities across the substrates, which led to well-coalesced diamond thin films after short growth times. Epitaxial lateral overgrowth (ELO) was used as a means of decreasing diamond internal stress by impeding the propagation of threading dislocations into the growing material. Its use in diamond growth requires adaptation to the aggressive chemical and thermal environment of the hydrogen plasma in a CVD reactor. Three ELO variants were developed. The most successful utilized a gold (Au) mask prepared by vacuum evaporation onto the surface of a thin heteroepitaxial diamond layer. The Au mask pattern, a series of parallel stripes on the micrometer scale, was produced by standard lift-off photolithography. When diamond overgrows the mask, dislocations are largely confined to the substrate. Differing degrees of confinement were studied by varying the stripe geometry and orientation. Significant improvement in diamond quality was found in the overgrown regions, as evidenced by reduction of the Raman scattering linewidth. The Au layer was found to remain intact during diamond overgrowth and did not chemically bond with the diamond surface. Besides impeding the propagation of threading dislocations, it was discovered that the thermally-induced stress in the CVD diamond was significantly reduced as a result of the ductile Au layer. Cracking and delamination of the diamond from the substrate was mostly eliminated. When diamond was grown to thicknesses above 0.1 mm it was found that

  4. Diamond Synthesis Employing Nanoparticle Seeds

    NASA Technical Reports Server (NTRS)

    Uppireddi, Kishore (Inventor); Morell, Gerardo (Inventor); Weiner, Brad R. (Inventor)

    2014-01-01

    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. 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.

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

    SciTech Connect

    Yeh, Chien-Jui; Leou, Keh-Chyang; Manoharan, Divinah; Chang, Hsin-Tzer; Lin, I-Nan

    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.

  6. Diamonds for beam instrumentation

    SciTech Connect

    Griesmayer, Erich

    2013-04-19

    Diamond is perhaps the most versatile, efficient and radiation tolerant material available for use in beam detectors with a correspondingly wide range of applications in beam instrumentation. Numerous practical applications have demonstrated and exploited the sensitivity of diamond to charged particles, photons and neutrons. In this paper, a brief description of a generic diamond detector is given and the interaction of the CVD diamond detector material with protons, electrons, photons and neutrons is presented. Latest results of the interaction of sCVD diamond with 14 MeV mono-energetic neutrons are shown.

  7. Diamonds in space: a brief history and recent laboratory studies

    NASA Astrophysics Data System (ADS)

    Chang, Huan-Cheng

    2016-07-01

    Stardust grains exist in outer space. However, due to their low abundance, structural heterogeneities, and lack of distinct spectroscopic features, unambiguous identification of their chemical composition has been a challenge. Diamond is a notable exception because it is composed of carbon and has several unique physicochemical properties that make the identification possible. Here, we provide a brief review on how diamonds were discovered in space based on the remarkable spectral matching between laboratory spectra and astronomical observations of the infrared emission at 3.43 and 3.53 µm, followed by a discussion of fluorescent nanodiamond as a possible carrier for extended red emission at 600 — 800 nm. Recent evidence to support the latter suggestion is provided.

  8. Multimode model based defect characterization in composites

    NASA Astrophysics Data System (ADS)

    Roberts, R.; Holland, S.; Gregory, E.

    2016-02-01

    A newly-initiated research program for model-based defect characterization in CFRP composites is summarized. The work utilizes computational models of the interaction of NDE probing energy fields (ultrasound and thermography), to determine 1) the measured signal dependence on material and defect properties (forward problem), and 2) an assessment of performance-critical defect properties from analysis of measured NDE signals (inverse problem). Work is reported on model implementation for inspection of CFRP laminates containing delamination and porosity. Forward predictions of measurement response are presented, as well as examples of model-based inversion of measured data for the estimation of defect parameters.

  9. Below-Band-Gap Laser Ablation Of Diamond For TEM

    NASA Technical Reports Server (NTRS)

    George, Thomas; Foote, Marc C.; Vasquez, Richard P.; Fortier, Edward P.; Posthill, John B.

    1995-01-01

    Thin, electron-transparent layers of diamond for examination in transmission electron microscope (TEM) fabricated from thicker diamond substrates by using laser beam to ablate surface of substrate. Involves use of photon energy below band gap. Growing interest in use of diamond as bulk substrate and as coating material in variety of applications has given rise to increasing need for TEM for characterization of diamond-based materials. Below-band-gap laser ablation method helps to satisfy this need. Also applied in general to cutting and etching of diamonds.

  10. Mechanism for direct graphite-to-diamond phase transition

    PubMed Central

    Xie, Hongxian; Yin, Fuxing; Yu, Tao; Wang, Jian-Tao; Liang, Chunyong

    2014-01-01

    Using classical molecular dynamics with a more reliable reactive LCBOPII potential, we have performed a detailed study on the direct graphite-to-diamond phase transition. Our results reveal a new so-called “wave-like buckling and slipping” mechanism, which controls the transformation from hexagonal graphite to cubic diamond. Based on this mechanism, we have explained how polycrystalline cubic diamond is converted from hexagonal graphite, and demonstrated that the initial interlayer distance of compressed hexagonal graphite play a key role to determine the grain size of cubic diamond. These results can broaden our understanding of the high pressure graphite-to-diamond phase transition. PMID:25088720

  11. Thermally stable diamond brazing

    DOEpatents

    Radtke, Robert P.

    2009-02-10

    A cutting element and a method for forming a cutting element is described and shown. The cutting element includes a substrate, a TSP diamond layer, a metal interlayer between the substrate and the diamond layer, and a braze joint securing the diamond layer to the substrate. The thickness of the metal interlayer is determined according to a formula. The formula takes into account the thickness and modulus of elasticity of the metal interlayer and the thickness of the TSP diamond. This prevents the use of a too thin or too thick metal interlayer. A metal interlayer that is too thin is not capable of absorbing enough energy to prevent the TSP diamond from fracturing. A metal interlayer that is too thick may allow the TSP diamond to fracture by reason of bending stress. A coating may be provided between the TSP diamond layer and the metal interlayer. This coating serves as a thermal barrier and to control residual thermal stress.

  12. Chemical microsensors based on polymer fiber composites

    NASA Astrophysics Data System (ADS)

    Kessick, Royal F.; Levit, Natalia; Tepper, Gary C.

    2005-05-01

    There is an urgent need for new chemical sensors for defense and security applications. In particular, sensors are required that can provide higher sensitivity and faster response in the field than existing baseline technologies. We have been developing a new solid-state chemical sensor technology based on microscale polymer composite fiber arrays. The fibers consist of an insulating polymer doped with conducting particles and are electrospun directly onto the surface of an interdigitated microelectrode. The concentration of the conducting particles within the fiber is controlled and is near the percolation threshold. Thus, the electrical resistance of the polymer fiber composite is very sensitive to volumetric changes produced in the polymer by vapor absorption. Preliminary results are presented on the fabrication and testing of the new microsensor. The objective is to take advantage of the very high surface to volume ratio, low thermal mass and linear geometry of the composite fibers to produce sensors exhibiting an extremely high vapor sensitivity and rapid response. The simplicity and low cost of a resistance-based chemical microsensor makes this sensing approach an attractive alternative to devices requiring RF electronics or time-of-flight analysis. Potential applications of this technology include battlespace awareness, homeland security, environmental surveillance, medical diagnostics and food process monitoring.

  13. Mantle-derived fluids in diamond micro-inclusions

    NASA Technical Reports Server (NTRS)

    Navon, O.; Hutcheon, I. D.; Rossman, G. R.; Wasserburg, G. J.

    1988-01-01

    Microinclusions in diamonds from Zaire and Botswana differ in composition from the more common large inclusions of the peridotitic or eclogitic assemblages. These sub-micrometer inclusions resemble potassic magmas in their composition, but are enriched in H2O, CO2(3-), and K2O and depleted in MgO. This composition represents a volatile-rich fluid or melt from the upper mantle, which was trapped in the diamonds as they grew.

  14. 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.

  15. Catalysis by diamonds and other forms of carbon

    SciTech Connect

    Farcasiu, M.; Kaufman, P.B.; Lavin, J.G.

    1996-10-01

    Some activated carbons and carbon blacks are known to be good catalysts for a variety of liquid phase reactions such as selective carbon-carbon cleavage and dehalogenation of halogenated hydrocarbons. We will present data on the catalytic activity of well characterized, relatively simple forms of carbons such as diamonds and diamond-graphite composites. Both industrial and natural diamonds have been used. TEM provided detailed information on the nature of the carbons at the surface of the carbon materials used as catalysts. Clean surfaces of natural diamond particles are active catalysts in reactions such as debromination of 1-Br-naphthalene and 1-Br-adamantane.

  16. 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

  17. Fermentation based carbon nanotube multifunctional bionic composites

    PubMed Central

    Valentini, Luca; Bon, Silvia Bittolo; Signetti, Stefano; Tripathi, Manoj; Iacob, Erica; Pugno, Nicola M.

    2016-01-01

    The exploitation of the processes used by microorganisms to digest nutrients for their growth can be a viable method for the formation of a wide range of so called biogenic materials that have unique properties that are not produced by abiotic processes. Here we produced living hybrid materials by giving to unicellular organisms the nutrient to grow. Based on bread fermentation, a bionic composite made of carbon nanotubes (CNTs) and a single-cell fungi, the Saccharomyces cerevisiae yeast extract, was prepared by fermentation of such microorganisms at room temperature. Scanning electron microscopy analysis suggests that the CNTs were internalized by the cell after fermentation bridging the cells. Tensile tests on dried composite films have been rationalized in terms of a CNT cell bridging mechanism where the strongly enhanced strength of the composite is governed by the adhesion energy between the bridging carbon nanotubes and the matrix. The addition of CNTs also significantly improved the electrical conductivity along with a higher photoconductive activity. The proposed process could lead to the development of more complex and interactive structures programmed to self-assemble into specific patterns, such as those on strain or light sensors that could sense damage or convert light stimulus in an electrical signal. PMID:27279425

  18. Fermentation based carbon nanotube multifunctional bionic composites.

    PubMed

    Valentini, Luca; Bon, Silvia Bittolo; Signetti, Stefano; Tripathi, Manoj; Iacob, Erica; Pugno, Nicola M

    2016-01-01

    The exploitation of the processes used by microorganisms to digest nutrients for their growth can be a viable method for the formation of a wide range of so called biogenic materials that have unique properties that are not produced by abiotic processes. Here we produced living hybrid materials by giving to unicellular organisms the nutrient to grow. Based on bread fermentation, a bionic composite made of carbon nanotubes (CNTs) and a single-cell fungi, the Saccharomyces cerevisiae yeast extract, was prepared by fermentation of such microorganisms at room temperature. Scanning electron microscopy analysis suggests that the CNTs were internalized by the cell after fermentation bridging the cells. Tensile tests on dried composite films have been rationalized in terms of a CNT cell bridging mechanism where the strongly enhanced strength of the composite is governed by the adhesion energy between the bridging carbon nanotubes and the matrix. The addition of CNTs also significantly improved the electrical conductivity along with a higher photoconductive activity. The proposed process could lead to the development of more complex and interactive structures programmed to self-assemble into specific patterns, such as those on strain or light sensors that could sense damage or convert light stimulus in an electrical signal. PMID:27279425

  19. Fermentation based carbon nanotube multifunctional bionic composites

    NASA Astrophysics Data System (ADS)

    Valentini, Luca; Bon, Silvia Bittolo; Signetti, Stefano; Tripathi, Manoj; Iacob, Erica; Pugno, Nicola M.

    2016-06-01

    The exploitation of the processes used by microorganisms to digest nutrients for their growth can be a viable method for the formation of a wide range of so called biogenic materials that have unique properties that are not produced by abiotic processes. Here we produced living hybrid materials by giving to unicellular organisms the nutrient to grow. Based on bread fermentation, a bionic composite made of carbon nanotubes (CNTs) and a single-cell fungi, the Saccharomyces cerevisiae yeast extract, was prepared by fermentation of such microorganisms at room temperature. Scanning electron microscopy analysis suggests that the CNTs were internalized by the cell after fermentation bridging the cells. Tensile tests on dried composite films have been rationalized in terms of a CNT cell bridging mechanism where the strongly enhanced strength of the composite is governed by the adhesion energy between the bridging carbon nanotubes and the matrix. The addition of CNTs also significantly improved the electrical conductivity along with a higher photoconductive activity. The proposed process could lead to the development of more complex and interactive structures programmed to self-assemble into specific patterns, such as those on strain or light sensors that could sense damage or convert light stimulus in an electrical signal.

  20. CVD diamond for nuclear detection applications

    NASA Astrophysics Data System (ADS)

    Bergonzo, P.; Brambilla, A.; Tromson, D.; Mer, C.; Guizard, B.; Marshall, R. D.; Foulon, F.

    2002-01-01

    Chemically vapour deposited (CVD) diamond is a remarkable material for the fabrication of radiation detectors. In fact, there exist several applications where other standard semiconductor detectors do not fulfil the specific requirements imposed by corrosive, hot and/or high radiation dose environments. The improvement of the electronic properties of CVD diamond has been under intensive investigations and led to the development of a few applications that are addressing specific industrial needs. Here, we report on CVD diamond-based detector developments and we describe how this material, even though of a polycrystalline nature, is readily of great interest for applications in the nuclear industry as well as for physics experiments. Improvements in the material synthesis as well as on device fabrication especially concern the synthesis of films that do not exhibit space charge build up effects which are often encountered in CVD diamond materials and that are highly detrimental for detection devices. On a pre-industrial basis, CVD diamond detectors have been fabricated for nuclear industry applications in hostile environments. Such devices can operate in harsh environments and overcome limitations encountered with the standard semiconductor materials. Of these, this paper presents devices for the monitoring of the alpha activity in corrosive nuclear waste solutions, such as those encountered in nuclear fuel assembly reprocessing facilities, as well as diamond-based thermal neutron detectors exhibiting a high neutron to gamma selectivity. All these demonstrate the effectiveness of a demanding industrial need that relies on the remarkable resilience of CVD diamond.

  1. 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.

  2. Diamond tool machining of materials which react with diamond

    DOEpatents

    Lundin, Ralph L.; Stewart, Delbert D.; Evans, Christopher J.

    1992-01-01

    Apparatus for the diamond machining of materials which detrimentally react with diamond cutting tools in which the cutting tool and the workpiece are chilled to very low temperatures. This chilling halts or retards the chemical reaction between the workpiece and the diamond cutting tool so that wear rates of the diamond tool on previously detrimental materials are comparable with the diamond turning of materials which do not react with diamond.

  3. Diamond tool machining of materials which react with diamond

    DOEpatents

    Lundin, R.L.; Stewart, D.D.; Evans, C.J.

    1992-04-14

    An apparatus is described for the diamond machining of materials which detrimentally react with diamond cutting tools in which the cutting tool and the workpiece are chilled to very low temperatures. This chilling halts or retards the chemical reaction between the workpiece and the diamond cutting tool so that wear rates of the diamond tool on previously detrimental materials are comparable with the diamond turning of materials which do not react with diamond. 1 figs.

  4. Charge multiplication effect in thin diamond films

    NASA Astrophysics Data System (ADS)

    Skukan, N.; Grilj, V.; Sudić, I.; Pomorski, M.; Kada, W.; Makino, T.; Kambayashi, Y.; Andoh, Y.; Onoda, S.; Sato, S.; Ohshima, T.; Kamiya, T.; Jakšić, M.

    2016-07-01

    Herein, we report on the enhanced sensitivity for the detection of charged particles in single crystal chemical vapour deposition (scCVD) diamond radiation detectors. The experimental results demonstrate charge multiplication in thin planar diamond membrane detectors, upon impact of 18 MeV O ions, under high electric field conditions. Avalanche multiplication is widely exploited in devices such as avalanche photo diodes, but has never before been reproducibly observed in intrinsic CVD diamond. Because enhanced sensitivity for charged particle detection is obtained for short charge drift lengths without dark counts, this effect could be further exploited in the development of sensors based on avalanche multiplication and radiation detectors with extreme radiation hardness.

  5. Permeability of rayon based polymer composites

    NASA Technical Reports Server (NTRS)

    Stokes, E. H.

    1992-01-01

    Several types of anomalous rayon based phenolic behavior have been observed in post-fired nozzles and exit cones. Many of these events have been shown to be related to the development of internal gas pressure within the material. The development of internal gas pressure is a function of the amount of gas produced within the material and the rate at which that gas is allowed to escape. The latter property of the material is referred to as the material's permeability. The permeability of two dimensional carbonized rayon based phenolic composites is a function of material direction, temperature, and stress/strain state. Recently significant differences in the permeability of these materials has been uncovered which may explain their inconsistent performance. This paper summarizes what is known about the permeability of these materials to date and gives possible implications of these finding to the performance of these materials in an ablative environment.

  6. Rhombic Coulomb diamonds in a single-electron transistor based on an Au nanoparticle chemically anchored at both ends.

    PubMed

    Azuma, Yasuo; Onuma, Yuto; Sakamoto, Masanori; Teranishi, Toshiharu; Majima, Yutaka

    2016-02-28

    Rhombic Coulomb diamonds are clearly observed in a chemically anchored Au nanoparticle single-electron transistor. The stability diagrams show stable Coulomb blockade phenomena and agree with the theoretical curve calculated using the orthodox model. The resistances and capacitances of the double-barrier tunneling junctions between the source electrode and the Au core (R1 and C1, respectively), and those between the Au core and the drain electrode (R2 and C2, respectively), are evaluated as 4.5 MΩ, 1.4 aF, 4.8 MΩ, and 1.3 aF, respectively. This is determined by fitting the theoretical curve against the experimental Coulomb staircases. Two-methylene-group short octanedithiols (C8S2) in a C8S2/hexanethiol (C6S) mixed self-assembled monolayer is concluded to chemically anchor the core of the Au nanoparticle at both ends between the electroless-Au-plated nanogap electrodes even when the Au nanoparticle is protected by decanethiol (C10S). This is because the R1 value is identical to that of R2 and corresponds to the tunneling resistances of the octanedithiol chemically bonded with the Au core and the Au electrodes. The dependence of the Coulomb diamond shapes on the tunneling resistance ratio (R1/R2) is also discussed, especially in the case of the rhombic Coulomb diamonds. Rhombic Coulomb diamonds result from chemical anchoring of the core of the Au nanoparticle at both ends between the electroless-Au-plated nanogap electrodes. PMID:26856419

  7. 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.

  8. Spectrally based mapping of riverbed composition

    NASA Astrophysics Data System (ADS)

    Legleiter, Carl J.; Stegman, Tobin K.; Overstreet, Brandon T.

    2016-07-01

    Remote sensing methods provide an efficient means of characterizing fluvial systems. This study evaluated the potential to map riverbed composition based on in situ and/or remote measurements of reflectance. Field spectra and substrate photos from the Snake River, Wyoming, USA, were used to identify different sediment facies and degrees of algal development and to quantify their optical characteristics. We hypothesized that accounting for the effects of depth and water column attenuation to isolate the reflectance of the streambed would enhance distinctions among bottom types and facilitate substrate classification. A bottom reflectance retrieval algorithm adapted from coastal research yielded realistic spectra for the 450 to 700 nm range; but bottom reflectance-based substrate classifications, generated using a random forest technique, were no more accurate than classifications derived from above-water field spectra. Additional hypothesis testing indicated that a combination of reflectance magnitude (brightness) and indices of spectral shape provided the most accurate riverbed classifications. Convolving field spectra to the response functions of a multispectral satellite and a hyperspectral imaging system did not reduce classification accuracies, implying that high spectral resolution was not essential. Supervised classifications of algal density produced from hyperspectral data and an inferred bottom reflectance image were not highly accurate, but unsupervised classification of the bottom reflectance image revealed distinct spectrally based clusters, suggesting that such an image could provide additional river information. We attribute the failure of bottom reflectance retrieval to yield more reliable substrate maps to a latent correlation between depth and bottom type. Accounting for the effects of depth might have eliminated a key distinction among substrates and thus reduced discriminatory power. Although further, more systematic study across a broader range

  9. Multilayer diamond coated WC tools

    SciTech Connect

    Fan, W.D.; Jagannaham, K.; Narayan, J.

    1995-12-31

    To increase adhesion of diamond coatings, a multilayer structure was developed. The multilayer diamond coating consisted of a first discontinuous diamond layer, an interposing layer, and a top continuous diamond layer. The diamond layer was grown on WC substrates by hot filament chemical vapor deposition and the interposing layer was grown by pulsed laser deposition. Machining tests were used to characterize adhesion properties of the multilayer diamond coatings on WC(Co) substrates. Results indicate that diamond coatings exhibit good adhesion on the WC tool substrates. The wear resistance of the WC tool is improved significantly by the diamond coatings.

  10. Amperometric biosensors based on carbon composite transducers

    NASA Astrophysics Data System (ADS)

    Lu, Fang

    1998-12-01

    Much current work in analytical chemistry is devoted to design of biosensors. One particular area in this field is the development of enzyme-based amperometric biosensors for the quantitative determination of a series of substrates in clinical, environmental, industrial and agricultural significance. This dissertation focuses on the design of improved amperometric biosensors based on carbon composite transducers. The use of metallized carbons as transducer materials results in remarkably selective amperometric biosensors. Such enzyme-based transducers eliminate major electroactive interferences, and hence circumvent the need for mediators or membrane barriers. The remarkable selectivity of metal-dispersed carbons is attributed to their strong, preferential, electrocatalytic capacity towards the reductive detection of biologically-generated hydrogen peroxide. Such electrocatalytic activity allows metal-dispersed biosensors to be operated at the optimal potential region between +0.1 and -0.2 V, where the unwanted reactions are neglected resulting in the lowest noise level. Several new materials (e.g., ruthenium on carbon, rhodium on carbon, etc.) and constructions (e.g., carbon fiber, electrochemical co-deposition transducer, etc.) were applied in the development of novel enzyme-based transducers in order to improve the selectivity and applicability of amperometric biosensors. The susceptibility of first-generation oxidase amperometric biosensing to oxygen fluctuations can be improved by using oxygen-rich fluorocarbons as the pasting binders in carbon paste enzyme transducers. Such binders provide an internal supply of oxygen resulting in efficient detection in oxygen-deficit conditions. In particular, the use of poly-chlorotrifluorethylene (Kel-F) oil as carbon paste binder results in a well-defined response and an identical signal up to 40 mM glucose in both the presence and absence of oxygen. Comparing with mediated or wired enzyme-based transducers, such internal

  11. Method and article of manufacture corresponding to a composite comprised of ultra nonacrystalline diamond, metal, and other nanocarbons useful for thermoelectric and other applications

    DOEpatents

    Gruen, Dieter M.

    2010-05-18

    One provides (101) disperse ultra-nanocrystalline diamond powder material that comprises a plurality of substantially ordered crystallites that are each sized no larger than about 10 nanometers. One then reacts (102) these crystallites with a metallic component. The resultant nanowire is then able to exhibit a desired increase with respect to its ability to conduct electricity while also substantially preserving the thermal conductivity behavior of the disperse ultra-nanocrystalline diamond powder material. The reaction process can comprise combining (201) the crystallites with one or more metal salts in an aqueous solution and then heating (203) that aqueous solution to remove the water. This heating can occur in a reducing atmosphere (comprising, for example, hydrogen and/or methane) to also reduce the salt to metal.

  12. Deep Mantle Fluids Bottled Up in Diamonds

    NASA Astrophysics Data System (ADS)

    Weiss, Y.; Pearson, D. G.

    2015-12-01

    Many mantle xenoliths and mineral inclusions in diamonds reflect refertilisation and enrichment by mantle metasomatism, a key mechanism for controlling abrupt changes in the chemical and physical properties of the continental lithospheric mantle (CLM) globally. However, the nature of the fluids involved can normally only be constrained indirectly from geochemical proxies or calculated using mineral/melt partition coefficients. Direct samples of mantle metasomatic fluids, shielded from any late stage alteration, are encased as microinclusions in fast-growing diamonds - "fibrous diamonds". These trapped high-density fluids (HDFs) provide a unique chemical and physical record for tracing the sources of deep mantle fluids and constraining the processes that shape their nature.Diamond HDFs vary between four major compositional types: saline, silicic and high-Mg plus low-Mg carbonatitic. A strong connection has been established between high-Mg carbonatitic HDFs and a carbonated peridotite source. In addition, the silicic and low-Mg carbonatitic HDFs have been related to hydrous eclogite (±carbonate). However, the compositionally extreme saline fluid endmember remained enigmatic and its source in the deep lithosphere has remained ambiguous. Our new data on fluid-rich diamonds show the geochemical fingerprints of a subducting slab as the source of deep mantle fluids of saline composition. In addition, for the first time, we show that these deep saline fluids are parental, via fluid rock interaction, to in-situ forming carbonatitic and silicic melts in the lithosphere. This model provides a strong platform for resolving the effects of the compositional spectrum of mantle fluids, which alter the deep lithosphere globally and play key roles in diamond formation.

  13. Diamond formation - Where, when and how?

    NASA Astrophysics Data System (ADS)

    Stachel, T.; Luth, R. W.

    2015-04-01

    Geothermobarometric calculations for a worldwide database of inclusions in diamond indicate that formation of the dominant harzburgitic diamond association occurred predominantly (90%) under subsolidus conditions. Diamonds in eclogitic and lherzolitic lithologies grew in the presence of a melt, unless their formation is related to strongly reducing CHO fluids that would increase the solidus temperature or occurred at pressure-temperature conditions below about 5 GPa and 1050 °C. Three quarters of peridotitic garnet inclusions in diamond classify as "depleted" due to their low Y and Zr contents but, based on LREEN-HREEN ratios invariably near or greater than one, they nevertheless reflect re-enrichment through either highly fractionated fluids or small amounts of melt. The trace element signatures of harzburgitic and lherzolitic garnet inclusions are broadly consistent with formation under subsolidus and supersolidus conditions, respectively. Diamond formation may be followed by cooling in the range of ~ 60-180 °C as a consequence of slow thermal relaxation or, in the case of the Kimberley area in South Africa, possibly uplift due to extension in the lithospheric mantle. In other cases, diamond formation and final residence took place at comparable temperatures or even associated with small temperature increases over time. Diamond formation in peridotitic substrates can only occur at conditions at least as reducing as the EMOD buffer. Evaluation of the redox state of 225 garnet peridotite xenoliths from cratons worldwide indicates that the vast majority of samples deriving from within the diamond stability field represent fO2 conditions below EMOD. Modeling reveals that less than 50 ppm fluid are required to completely reset the redox state of depleted cratonic peridotite to that of the fluid. Consequently, the overall reduced state of diamond stable peridotites implies that the last fluids to interact with the deep cratonic lithosphere were generally reducing in

  14. The Geopolitical Setting of Conflict Diamonds.

    NASA Astrophysics Data System (ADS)

    Haggerty, S. E.

    2002-05-01

    ) in the Earth's mantle, are old (about 3 Ga), and are emplaced volcanically into continental crust (cratons), at specific times geologically. Clusters of diamond volcanoes are common throughout the world, and in Africa spill over into several countries. Although there are subtle distinctions in geology, geophysics, and geochemistry of diamondiferous settings globally, these differences decrease within provinces (1000 sq km), and are minor at the district level (10-100 sq km). For diamonds: clear, sharp edged octahedra are typical of Siberia; pink stones are mostly from W. Australia; Cape yellow and blue diamonds occur in South Africa and India; corroded and etched diamonds are prevalent in E. Africa; and fibrous diamonds, once considered the domain of the Congo Republic and Sierra Leone were recently discovered in the non conflict, Slave Province, Canada. These examples are neither craton nor site specific. Is there a non destructive analytical method to uniquivocally identify diamonds regionally, or ideally at a more localized level? The intrinsic approach (vs applied) is challenging because geographical boundaries do not correspond to geological contacts. Spectroscopy, trace elements, isotopes, mineral inclusions, and the conductivities of diamonds show some promise but the overlaps are large. Refinements will evolve and analytical innovations will develop. However, legally acquired conflict diamonds are needed on which to perform basic experiments, establish background levels, and develop a data base for global comparisons. US assistance, UN permission, and funding (e.g. NSF, DOD) are urgently required if this geoscientific initiative is to move forward in stopping the flow of conflict diamonds into the hands of terrorist organizations. We have a scientific obligation to society.

  15. Synthesizing Diamond from Liquid Feedstock

    NASA Technical Reports Server (NTRS)

    Tzeng, Yonhua

    2005-01-01

    other suitable flow controller. When the liquid enters the low-pressure environment inside the chamber, it evaporates to form a vapor mixture of the same chemical composition. In addition to the inlet for the feedstock liquid, the chamber is fitted with an outlet connected to a vacuum pump (not shown) through a throttle valve (also not shown) that is automatically controlled to keep the pressure at or near the required value throughout the deposition process. Inside the chamber, a spiral filament made of tungsten, tantalum, graphite, or other high-melting-temperature material is electrically heated to a temperature >2,000 C high enough to cause dissociation of vapor molecules into the aforementioned radicals. A deposition substrate typically, a diamond-polished silicon wafer about 2.5 cm square is positioned about 2 cm away from the filament. The exact location of the substrate is chosen so that the substrate becomes heated by the filament to a deposition temperature in the approximate range of 800 to 1,000 C.

  16. Polyurea-Based Aerogel Monoliths and Composites

    NASA Technical Reports Server (NTRS)

    Lee, Je Kyun

    2012-01-01

    aerogel insulation material was developed that will provide superior thermal insulation and inherent radiation protection for government and commercial applications. The rubbery polyureabased aerogel exhibits little dustiness, good flexibility and toughness, and durability typical of the parent polyurea polymer, yet with the low density and superior insulation properties associated with aerogels. The thermal conductivity values of polyurea-based aerogels at lower temperature under vacuum pressures are very low and better than that of silica aerogels. Flexible, rubbery polyurea-based aerogels are able to overcome the weak and brittle nature of conventional inorganic and organic aerogels, including polyisocyanurate aerogels, which are generally prepared with the one similar component to polyurethane rubber aerogels. Additionally, with higher content of hydrogen in their structures, the polyurea rubber-based aerogels will also provide inherently better radiation protection than those of inorganic and carbon aerogels. The aerogel materials also demonstrate good hydrophobicity due to their hydrocarbon molecular structure. There are several strategies to overcoming the drawbacks associated with the weakness and brittleness of silica aerogels. Development of the flexible fiber-reinforced silica aerogel composite blanket has proven to be one promising approach, providing a conveniently fielded form factor that is relatively robust in industrial environments compared to silica aerogel monoliths. However, the flexible, silica aerogel composites still have a brittle, dusty character that may be undesirable, or even intolerable, in certain application environments. Although the cross - linked organic aerogels, such as resorcinol- formaldehyde (RF), polyisocyanurate, and cellulose aerogels, show very high impact strength, they are also very brittle with little elongation (i.e., less rubbery). Also, silica and carbon aerogels are less efficient radiation shielding materials due

  17. Diamond network: template-free fabrication and properties.

    PubMed

    Zhuang, Hao; Yang, Nianjun; Fu, Haiyuan; Zhang, Lei; Wang, Chun; Huang, Nan; Jiang, Xin

    2015-03-11

    A porous diamond network with three-dimensionally interconnected pores is of technical importance but difficult to be produced. In this contribution, we demonstrate a simple, controllable, and "template-free" approach to fabricate diamond networks. It combines the deposition of diamond/β-SiC nanocomposite film with a wet-chemical selective etching of the β-SiC phase. The porosity of these networks was tuned from 15 to 68%, determined by the ratio of the β-SiC phase in the composite films. The electrochemical working potential and the reactivity of redox probes on the diamond networks are similar to those of a flat nanocrystalline diamond film, while their surface areas are hundreds of times larger than that of a flat diamond film (e.g., 490-fold enhancement for a 3 μm thick diamond network). The marriage of the unprecedented physical/chemical features of diamond with inherent advantages of the porous structure makes the diamond network a potential candidate for various applications such as water treatment, energy conversion (batteries or fuel cells), and storage (capacitors), as well as electrochemical and biochemical sensing. PMID:25697278

  18. Electrical Characterization of Diamond/Boron Doped Diamond Nanostructures for Use in Harsh Environment Applications

    NASA Astrophysics Data System (ADS)

    Gołuński, Ł.; Zwolski, K.; Płotka, P.

    2016-01-01

    The polycrystalline boron doped diamond (BDD) shows stable electrical properties and high tolerance for harsh environments (e.g. high temperature or aggressive chemical compounds) comparing to other materials used in semiconductor devices. In this study authors have designed electronic devices fabricated from non-intentionally (NiD) films and highly boron doped diamond structures. Presented semiconductor devices consist of highly boron doped structures grown on NiD diamond films. Fabricated structures were analyzed by electrical measurements for use in harsh environment applications. Moreover, the boron-doping level and influence of oxygen content on chemical composition of diamond films were particularly investigated. Microwave Plasma Enhanced Chemical Vapour Deposition (MW PE CVD) has been used for thin diamond films growth. Non-intentionally doped diamond (0 ppm [B]/[C]) films have been deposited on the Si/SiO2 wafers with different content of carbon, boron and oxygen in the gas phase. Then, the shape of the highly doped diamond structures were obtained by pyrolysis of SiO2 on NiD film and standard lithography process. The highly doped structures were obtained for different growth time and [B]/[C] ratio (4000 - 10000 ppm). The narrowest distance between two highly doped structures was 5pm. The standard Ti/Au ohmic contacts were deposited using physical vapour deposition for electrical characterization of NiD/BDD devices. The influence of diffusion boron from highly doped diamond into non-doped/low-doped diamond film was investigated. Surface morphology of designed structures was analyzed by Scanning Electron Microscope and optical microscope. The resistivity of the NiD and film was studied using four-point probe measurements also DC studies were done.

  19. Global mantle convection: Evidence from carbon and nitrogen isotopes in super-deep diamonds (Invited)

    NASA Astrophysics Data System (ADS)

    Palot, M.; Cartigny, P.; Harris, J.; Kaminsky, F. V.; Stachel, T.

    2009-12-01

    Constraining the convective regime of the Earth’s mantle has profound implications for our understanding of the Earth’s cooling and the geodynamics of plate tectonics. Although subducting plates seem to be occasionally deflected at 660 km, evidence from seismic tomography and fluid dynamics suggest that substantial amounts of material reach the core-mantle boundary. Most geochemists, on the other hand, based on evidence from noble gases, would argue for the presence of separate upper and lower mantle reservoirs. Diamond provides a unique opportunity to sample those parts of the mantle that remains inaccessible by any other means. Some mineral associations in diamond, such as majoritic garnet, calcic and magnesian perovskite and manganoan ilmenite with ferropericlase have been recognised as originated from the transition zone down to the lower mantle (Stachel et al., 1999; Kaminsky et al., 2001). In addition, nitrogen in these diamonds is potentially a good tracer for mantle geodynamics. Exchanges between an inner reservoir (characterised by negative δ15N) via degassing at oceanic ridges with an outer reservoir (characterised by positive δ15N) via recycling at a subduction zones can lead to isotopic contrast in a stratified mantle. Because of common super-deep mineral inclusion assemblages in diamonds from Juina (Brazil) and Kankan (Guinea), we carried out a detailed study of nitrogen and carbon isotopes. The Juina diamonds show broadly similar ranges of δ15N from +3.8‰ down to -8.8‰ for both upper (UM) and lower (LM) mantle diamonds. This important feature is also found for UM and LM diamonds from Kankan, although the range of δ15N differs with values from +9.6‰ down to -39.4‰. Both sets of results suggest extensive material-isotopic exchange through the 660km discontinuity, contrary to the idea of an isolated reservoir. Transition zone (TZ) diamonds are enriched in 13C with δ13C from -3.1‰ up to +3.8‰ at Kankan but those of Juina are depleted

  20. Diamond nucleation using polyethene

    DOEpatents

    Morell, Gerardo; Makarov, Vladimir; Varshney, Deepak; Weiner, Brad

    2013-07-23

    The invention presents a simple, non-destructive and non-abrasive method of diamond nucleation using polyethene. It particularly describes the nucleation of diamond on an electrically viable substrate surface using polyethene via chemical vapor deposition (CVD) technique in a gaseous environment.

  1. Diamond Nucleation Using Polyethene

    NASA Technical Reports Server (NTRS)

    Morell, Gerardo (Inventor); Makarov, Vladimir (Inventor); Varshney, Deepak (Inventor); Weiner, Brad (Inventor)

    2013-01-01

    The invention presents a simple, non-destructive and non-abrasive method of diamond nucleation using polyethene. It particularly describes the nucleation of diamond on an electrically viable substrate surface using polyethene via chemical vapor deposition (CVD) technique in a gaseous environment.

  2. Diamond films: Historical perspective

    SciTech Connect

    Messier, R.

    1993-01-01

    This section is a compilation of notes and published international articles about the development of methods of depositing diamond films. Vapor deposition articles are included from American, Russian, and Japanese publications. The international competition to develop new deposition methodologies is stressed. The current status of chemical vapor deposition of diamond is assessed.

  3. Diamond particle detectors systems in high energy physics

    NASA Astrophysics Data System (ADS)

    Oh, A.

    2015-04-01

    With the first three years of the LHC running complete, ATLAS and CMS are planning to upgrade their innermost tracking layers with more radiation hard technologies. Chemical Vapor Deposition (CVD) diamond is one such technology. CVD diamond has been used extensively in beam condition monitors as the innermost detectors in the highest radiation areas of BaBar, Belle, CDF and all LHC experiments. The lessons learned in constructing the ATLAS Beam Conditions Monitor (BCM), Diamond Beam Monitor (DBM) and the CMS Pixel Luminosity Telescope (PLT) all of which are based on CVD diamond with the goal of elucidating the issues that should be addressed for future diamond based detector systems. The first beam test results of prototype diamond devices with 3D detector geometry should further enhance the radiation tolerance of this material.

  4. Diamond coated silicon field emitter array

    SciTech Connect

    S. Albin; W. Fu; A. Varghese; A. C. Lavarias; G. R. Myneni

    1999-07-01

    Diamond coated silicon tip arrays, with and without a self-aligned gate, were fabricated, and current-voltage characteristics of 400 tips were measured. Diamond films were grown uniformly on Si tips using microwave plasma after nucleation with 10 nm diamond suspension and substrate bias. An emission current of 57 ?A was obtained at 5 V from the ungated array tips separated from an anode at 2 ?m. In the case of the gated arrays with 1.5 ?m aperture, an emission current of 3.4 ?A was measured at a gate voltage of 80 V for an anode separation of 200 ?m. The turn-on voltages for these two types of devices were 0.2 and 40 V, respectively. Diamond coated Si tip arrays have potential applications in field emission based low voltage vacuum electronic devices and microsensors.

  5. Semantics-based composition of EMBOSS services

    PubMed Central

    2011-01-01

    Background More than in other domains the heterogeneous services world in bioinformatics demands for a methodology to classify and relate resources in a both human and machine accessible manner. The Semantic Web, which is meant to address exactly this challenge, is currently one of the most ambitious projects in computer science. Collective efforts within the community have already led to a basis of standards for semantic service descriptions and meta-information. In combination with process synthesis and planning methods, such knowledge about types and services can facilitate the automatic composition of workflows for particular research questions. Results In this study we apply the synthesis methodology that is available in the Bio-jETI workflow management framework for the semantics-based composition of EMBOSS services. EMBOSS (European Molecular Biology Open Software Suite) is a collection of 350 tools (March 2010) for various sequence analysis tasks, and thus a rich source of services and types that imply comprehensive domain models for planning and synthesis approaches. We use and compare two different setups of our EMBOSS synthesis domain: 1) a manually defined domain setup where an intuitive, high-level, semantically meaningful nomenclature is applied to describe the input/output behavior of the single EMBOSS tools and their classifications, and 2) a domain setup where this information has been automatically derived from the EMBOSS Ajax Command Definition (ACD) files and the EMBRACE Data and Methods ontology (EDAM). Our experiments demonstrate that these domain models in combination with our synthesis methodology greatly simplify working with the large, heterogeneous, and hence manually intractable EMBOSS collection. However, they also show that with the information that can be derived from the (current) ACD files and EDAM ontology alone, some essential connections between services can not be recognized. Conclusions Our results show that adequate domain

  6. Grade-tonnage and other models for diamond kimberlite pipes

    USGS Publications Warehouse

    Bliss, J.D.

    1992-01-01

    Grade-tonnage and other quantitative models help give reasonable answers to questions about diamond kimberlite pipes. Diamond kimberlite pipes are those diamondiferous kimberlite pipes that either have been worked or are expected to be worked for diamonds. These models are not applicable to kimberlite dikes and sills or to lamproite pipes. Diamond kimberlite pipes contain a median 26 million metric tons (mt); the median diamond grade is 0.25 carat/metric ton (ct/mt). Deposit-specific models suggest that the median of the average diamond size is 0.07 ct and the median percentage of diamonds that are industrial quality is 67 percent. The percentage of diamonds that are industrial quality can be predicted from deposit grade using a regression model (log[industrial diamonds (percent)]=1.9+0.2 log[grade (ct/mt)]). The largest diamond in a diamond kimberlite pipe can be predicted from deposit tonnage using a regression model (log[largest diamond (ct)]=-1.5+0.54 log[size (mt]). The median outcrop area of diamond pipes is 12 hectares (ha). Because the pipes have similar forms, the tonnage of the deposits can be predicted by the outcrop area (log[size (mt)]=6.5+1.0 log[outcrop area (ha)]). Once a kimberlite pipe is identified, the probability is approximately .005 that it can be worked for diamonds. If a newly discovered pipe is a member of a cluster that contains a known diamond kimberlite pipe, the probability that the new discovery can be mined for diamonds is 56 times that for a newly discovered kimberlite pipe in a cluster without a diamond kimberlite pipe. About 30 percent of pipes with worked residual caps at the surface will be worked at depth. Based on the number of discovered deposits and the area of stable craton rocks thought to be well explored in South Africa, about 10-5 diamond kimberlite pipes are present per square kilometer. If this density is applicable to the South American Precambrian Shield, more than 70 undiscovered kimberlite pipes are predicted to

  7. Microwave Resonators Containing Diamond Disks

    NASA Technical Reports Server (NTRS)

    Dick, G. John; Maleki, Lutfollah; Wang, Rabi T.

    1996-01-01

    Synthetic diamond dielectric bodies proposed for use in cylindrical resonators helping to stabilize frequencies of some microwave oscillators. Acting in conjunction with metal resonator cavities in which mounted, such dielectric bodies support "whispering-gallery" waveguide modes characterized by desired frequencies of resonance and by electro-magnetic-field configurations limiting dissipation of power on metal surfaces outside dielectric bodies. Performances at room temperature might exceed those of liquid-nitrogen-cooled sapphire-based resonators.

  8. Asphaltenes-based polymer nano-composites

    DOEpatents

    Bowen, III, Daniel E

    2013-12-17

    Inventive composite materials are provided. The composite is preferably a nano-composite, and comprises an asphaltene, or a mixture of asphaltenes, blended with a polymer. The polymer can be any polymer in need of altered properties, including those selected from the group consisting of epoxies, acrylics, urethanes, silicones, cyanoacrylates, vulcanized rubber, phenol-formaldehyde, melamine-formaldehyde, urea-formaldehyde, imides, esters, cyanate esters, allyl resins.

  9. High-Current Cold Cathode Employing Diamond and Related Materials

    SciTech Connect

    Hirshfield, Jay L.

    2014-10-22

    The essence of this project was for diamond films to be deposited on cold cathodes to improve their emission properties. Films with varying morphology, composition, and size of the crystals were deposited and the emission properties of the cathodes that utilize such films were studied. The prototype cathodes fabricated by the methods developed during Phase I were tested and evaluated in an actual high-power RF device during Phase II. These high-power tests used the novel active RF pulse compression system and the X-band magnicon test facility at US Naval Research Laboratory. In earlier tests, plasma switches were employed, while tests under this project utilized electron-beam switching. The intense electron beams required in the switches were supplied from cold cathodes embodying diamond films with varying morphology, including uncoated molybdenum cathodes in the preliminary tests. Tests with uncoated molybdenum cathodes produced compressed X-band RF pulses with a peak power of 91 MW, and a maximum power gain of 16.5:1. Tests were also carried out with switches employing diamond coated cathodes. The pulse compressor was based on use of switches employing electron beam triggering to effect mode conversion. In experimental tests, the compressor produced 165 MW in a ~ 20 ns pulse at ~18× power gain and ~ 140 MW at ~ 16× power gain in a 16 ns pulse with a ~ 7 ns flat-top. In these tests, molybdenum blade cathodes with thin diamond coatings demonstrated good reproducible emission uniformity with a 100 kV, 100 ns high voltage pulse. The new compressor does not have the limitations of earlier types of active pulse compressors and can operate at significantly higher electric fields without breakdown.

  10. Magnetically Orchestrated Formation of Diamond at Lower Temperatures and Pressures

    NASA Astrophysics Data System (ADS)

    Little, Reginald B.; Lochner, Eric; Goddard, Robert

    2005-01-01

    Man's curiosity and fascination with diamonds date back to ancient times. The knowledge of the many properties of diamond is recorded during Biblical times. Antoine Lavoisier determined the composition of diamond by burning in O2 to form CO2. With the then existing awareness of graphite as carbon, the race began to convert graphite to diamond. The selective chemical synthesis of diamond has been pursued by Cagniard, Hannay, Moisson and Parson. On the basis of the thermodynamically predicted equilibrium line of diamond and graphite, P W Bridgman attempted extraordinary conditions of high temperature (>2200°C) and pressure (>100,000 atm) for the allotropic conversion of graphite to diamond. H T Hall was the first to successfully form bulk diamond by realizing the kinetic restrictions to Bridgman's (thermodynamic) high pressure high temperature direct allotropic conversion. Moreover, Hall identified catalysts for the faster kinetics of diamond formation. H M Strong determined the import of the liquid catalyst during Hall's catalytic synthesis. W G Eversole discovered the slow metastable low pressure diamond formation by pyrolytic chemical vapor deposition with the molecular hydrogen etching of the rapidly forming stable graphitic carbon. J C Angus determined the import of atomic hydrogen for faster etching for faster diamond growth at low pressure. S Matsumoto has developed plasma and hot filament technology for faster hydrogen and carbon radical generations at low pressure for faster diamond formation. However the metastable low pressure chemical vapor depositions by plasma and hot filament are prone to polycrystalline films. From Bridgman to Hall to Eversole, Angus and Matsumoto, much knowledge has developed of the importance of pressure, temperature, transition metal catalyst, liquid state of metal (metal radicals atoms) and the carbon radical intermediates for diamond synthesis. Here we advance this understanding of diamond formation by demonstrating the external

  11. The Petrography of Meteoritic Nano-Diamonds

    NASA Technical Reports Server (NTRS)

    Dai, Z. R.; Bradley, J. P.; Brownlee, D. E.; Joswiak, D. J.

    2003-01-01

    At least some meteoritic nanodiamonds are likely of presolar origin because of their association with anomalous Xe-HL and Te isotopic components indicative of a supernova (SN) origin. But the abundance of Xe is such that only approx. 1 in 10(exp 6) nano-diamonds contains a Xe atom, and the bulk C-13/C-12 composition of nano-diamond acid residues is chondritic (solar). Therefore, it is possible that a significant fraction of meteoritic nano-diamonds formed within the solar nebula. Nano-diamonds have recently been detected for the first time within the accretion discs of young stars by the Infrared Space Observatory (ISO). No comparable evidence of nanodiamonds in the interstellar medium has yet been found. We have identified nano-diamonds in acid etched thin-sections of meteorites, polar micrometeorites, and interplanetary dust particles (IDPs) with the goal of determining their distribution as a function of heliocentric distance. (It is assumed the meteorites and the polar micrometeorites are from asteroids at 2-4 AU and at least some of the IDPs are from comets at >50AU). We found that nano-diamonds are heterogeneously distributed throughout carbon-rich meteoritic materials (we identified them in some IDPs and not in others), and that their abundance may actually decrease with heliocentric distance, consistent with the hypothesis that some of them formed within the inner solar system and not in a presolar (SN) environment. In order to gain further insight about the origins of meteoritic nano-diamonds we are currently investigating their distribution in unetched thin-sections. We have examined a chondritic cluster IDP (U220GCA), fragments of the Tagish Lake (CM1) meteorite, and a SN graphite spherule (KE3d8) isolated from the Murchison (CM) meteorite. We selected U220GCA because its nano-diamond abundance (in acid etched thin-sections) appears to be as much as approx. 10X higher than in Murchison matrix, Tagish Lake because it has a higher reported nano-diamond

  12. Heat expanded starch-based compositions.

    PubMed

    Glenn, Gregory M; Klamczynski, Artur K; Holtman, Kevin M; Shey, Justin; Chiou, Bor-Sen; Berrios, Jose; Wood, Delilah; Orts, William J; Imam, Syed H

    2007-05-16

    A heat expansion process similar to that used for expanded bead polystyrene was used to expand starch-based compositions. Foam beads made by solvent extraction had the appearance of polystyrene beads but did not expand when heated due to an open-cell structure. Nonporous beads, pellets, or particles were made by extrusion or by drying and milling cooked starch slurries. The samples expanded into a low-density foam by heating 190-210 degrees C for more than 20 s at ambient pressures. Formulations containing starch (50-85%), sorbitol (5-15%), glycerol (4-12%), ethylene vinyl alcohol (EVAL, 5-15%), and water (10-20%) were studied. The bulk density was negatively correlated to sorbitol, glycerol, and water content. Increasing the EVAL content increased the bulk density, especially at concentrations higher than 15%. Poly(vinyl alcohol) (PVAL) increased the bulk density more than EVAL. The bulk density was lowest in samples made of wheat and potato starch as compared to corn starch. The expansion temperature for the starch pellets decreased more than 20 degrees C as the moisture content was increased from 10 to 25%. The addition of EVAL in the formulations decreased the equilibrium moisture content of the foam and reduced the water absorption during a 1 h soaking period. PMID:17432870

  13. Flexible hydrogel-based functional composite materials

    SciTech Connect

    Song, Jie; Saiz, Eduardo; Bertozzi, Carolyn R; Tomasia, Antoni P

    2013-10-08

    A composite having a flexible hydrogel polymer formed by mixing an organic phase with an inorganic composition, the organic phase selected from the group consisting of a hydrogel monomer, a crosslinker, a radical initiator, and/or a solvent. A polymerization mixture is formed and polymerized into a desired shape and size.

  14. A Optical Study of Defects in Diamond.

    NASA Astrophysics Data System (ADS)

    Beard, Darren R.

    Available from UMI in association with The British Library. The one-phonon defect-induced infrared absorption in Type I diamonds has been studied. The previously reported spectral forms of the F and G spectra have been altered. Three components labelled J, K and L, are presented. A data base of 75 infrared spectra has been decomposed and classified. New computer programs have been produced to cope with up to 12 components in the one-phonon region simultaneously. Black diamond surfaces have been examined using photoluminescence spectroscopy. Laser cutting in air is found to result in black surfaces. Diamonds were examined both before and after cutting and changes in the spectra monitored. In Type Ib and Type IIb diamonds, the typical diamond spectrum was changed into a broad band spectrum. The first order diamond Raman was not detectable after laser cutting. Type Ia and Type IIa diamonds did not show any changes due to being cut. To investigate the graphitization process further, diamonds were heated to 850^circC in gas flows at 0.38 torr (50.7 Pa). Using oxygen, it was found that the intensity of H3 luminescence was reduced and that a broad band spectrum was produced. The spectral changes were reversed by treating with hydrogen. Two types of thin carbonaceous films have been examined, those grown by vapour deposition and those produced by scanning a high energy density laser beam across an amorphous carbon sample. The photoluminescence spectra obtained from the two sample types were different. Discs of sintered diamond have also been examined with a view to determining the strain distribution within the samples. Finally, the production mechanism of the H3 defect has been considered. A grown-in theory is developed. It is supported quantitatively with experimental results and explains the ubiquity of H3, even in synthetic crystals. The C centre is thought to be incorporated equally on all of the low index faces of diamond. Consideration of the A centre showed that it

  15. Conditions of origin of natural diamonds of peridotite affinity

    NASA Technical Reports Server (NTRS)

    Boyd, F. R.; Finnerty, A. A.

    1980-01-01

    Studies of mineral inclusions in natural diamonds and rare diamondiferous xenoliths from kimberlites show that most diamonds are associated with a dunite or harzburgite paragenesis. The diamondiferous periodites and dunites have predominantly coarse or tabular textures that suggest low-temperature (less than 1100 C) equilibration. Application of the K(D) Fe/Mg(Ga/Ol) geothermometer of O'Neill and Wood to analytical data for the minerals in these rocks shows that most have equilibrated below 1100 C. Application of this thermometer to pairs of olivine and garnet crystals included in individual diamonds indicates that the diamonds have crystallized in the range 900-1300 C, with a majority of estimated equilibration temperatures falling in the range below 1150 C. Comparison of these estimates of equilibration temperature with the zone of invariant vapor composition solidus for kimberlite and garnet lherzolite determined by Eggler and Wendlandt (1979) suggests that many diamonds may have formed in subsolidus events.

  16. 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).

  17. Diamond of Possibly Metallurgical and Seismic Origin: PART 3: Additional Specimens and a Proposal Calling for adjusted Methodologies for Diamondism

    NASA Astrophysics Data System (ADS)

    Giamn, M.

    2007-05-01

    Per Giamn [1,2,3], additional or potential specimens have been sought after. Examination was made of known specimens located in the proximity of iron ores, a number with template-like or proportionate (the larger bodies of diamond associated with the larger bodies of iron)arrangements.An exercise was made to illustrate my theory by utilizing a hypothetical iron ore in the Democratic Republic of Congo, Tanzania, respectively, which is seismically induced by recent real seismic events into diamond-bearing. If I were to suggest that the study of a number of major phases, for instance the olivines, pyroxenes, feldspars, oxides, sulfides, be based upon data of small (the top 1 of 1,000,000) number of large sized grains only and from limited geographical regions, ages, modes of occurrence only, I would be confronted with (i) enormous opposition since such methodology would impede mineralogy, which is a form of generally specimen-based science; and questions of (ii) what the purposes may be in such a deviantly unusual pursuit? What is being achieved by knowing omission of the majority of specimen population? (iii) A simpler and fairer solution is not unavailable. (iv) What is wrong with underaddressed average and small sized grains especially most of them workable with current analytical instruments except those extremely fine grained; (v) Placing greater importance to grains of lager economic value is historically common among the most topical economic minerals, yet not necessary. For instance, the platinum group elements (PGE)is pluralistic. Research of PGE has been a rigorous institution based not solely upon ingot-sized grains; (vi) Is this not a clear manifestation of prejudice and misrepresentation, endemic blind excessive blatant sensationalism and objectification of basic science? There is no rational basis. Yet the knowledge of diamond is based primarily upon a small number of morbidly obese specimens irrepresentative of the real diamond population. A realistic

  18. Improving Hardness and Toughness of Boride Composites Based on AIMgB14

    SciTech Connect

    Justin Steven Peters

    2007-12-01

    The search for new super-hard materials has usually focused on strongly bonded, highly symmetric crystal structures similar to diamond. The two hardest single-phase materials, diamond and cubic boron nitride (cBN), are metastable, and both must be produced at high temperatures and pressures, which makes their production costly. In 2000, a superhard composite based on a low-symmetry, boron-rich compound was reported. Since then, many advances have been made in the study of this AlMgB{sub 14}-TiB{sub 2} composite. The composite has been shown to exhibit hardness greater than either of its constituent phases, relying on its sub-micron microstructure to provide hardening and strengthening mechanisms. With possible hardness around 40 GPa, an AlMgB{sub 14} - 60 vol% TiB{sub 2} approaches the hardness of cBN, yet is amenable to processing under ambient pressure conditions. There are interesting aspects of both the AlMgB{sub 14} and TiB{sub 2} phases. AlMgB{sub 14} is comprised of a framework of boron, mostly in icosahedral arrangements. It is part of a family of 12 known compounds with the same boron lattice, with the metal atoms replaced by Li, Na, Y or a number of Lanthanides. Another peculiar trait of this family of compounds is that every one contains a certain amount of intrinsic vacancies on one or both of the metal sites. These vacancies are significant, ranging from 3 to 43% of sites depending on the composition. TiB{sub 2} is a popular specialty ceramic material due to its high hardness, moderate toughness, good corrosion resistance, and high thermal and electrical conductivity. The major drawback is the difficulty of densification of pure TiB2 ceramics. A combination of sintering aids, pressure, and temperatures of 1800 C are often required to achieve near full density articles. The AlMgB{sub 14} - TiB{sub 2} composites can achieve 99% density from hot-pressing at 1400 C. This is mostly due to the preparation of powders by a high-energy milling technique known

  19. Characterization of diamond thin films: Diamond phase identification, surface morphology, and defect structures

    SciTech Connect

    Williams, B.E.; Glass, J.T.

    1989-03-01

    Thin carbon films grown from a low pressure methane-hydrogen gas mixture by microwave plasma enhanced CVD have been examined by Auger electron spectroscopy, secondary ion mass spectrometry, electron and x-ray diffraction, electron energy loss spectroscopy, and electron microscopy. They were determined to be similar to natural diamond in terms of composition, structure, and bonding. The surface morphology of the diamond films was a function of position on the sample surface and the methane concentration in the feedgas. Well-faceted diamond crystals were observed near the center of the sample whereas a less faceted, cauliflower texture was observed near the edge of the sample, presumably due to variations in temperature across the surface of the sample. Regarding methane concentration effects, threefold /111/ faceted diamond crystals were predominant on a film grown at 0.3% CH/sub 4/ in H/sub 2/ while fourfold /100/ facets were observed on films grown in 1.0% and 2.0% CH/sub 4/ in H/sub 2/. Transmission electron microscopy of the diamond films has shown that the majority of diamond crystals have a very high defect density comprised of /111/ twins, /111/ stacking faults, and dislocations. In addition, cross-sectional TEM has revealed a 50 A epitaxial layer of ..beta..--SiC at the diamond-silicon interface of a film grown with 0.3% CH/sub 4/ in H/sub 2/ while no such layer was observed on a diamond film grown in 2.0% CH/sub 4/ in H/sub 2/.

  20. 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.

  1. A magnetoelectric composite based signal generator

    NASA Astrophysics Data System (ADS)

    Fetisov, Y. K.; Serov, V. N.; Fetisov, L. Y.; Makovkin, S. A.; Viehland, D.; Srinivasan, G.

    2016-05-01

    Self-oscillations in an active loop consisting of a wide-band amplifier and a magnetoelectric composite in the feedback circuit have been observed. The composite with a ferroelectric lead zirconate titanate bimorph and ferromagnetic Metglas serves as a resonator that determines the frequency of oscillations and provides the feedback voltage. Under amplitude balance and phase matching conditions, the device generated signals at 2.3 kHz, at the bending resonance frequency of the composite. The oscillations were observed over a specific range of magnetic bias H. The shape of the signal generated is dependent on electrical circuit parameters and magnitude and orientation of H.

  2. Three generations of diamonds from old continental mantle

    NASA Astrophysics Data System (ADS)

    Richardson, S. H.; Harris, J. W.; Gurney, J. J.

    1993-11-01

    INCLUSION-BEARING diamonds erupted by kimberlites are time capsules from the sub-continental mantle. Diamonds with peridotitic mineral inclusions ('peridotitic diamonds') from Cretaceous kimberlites in southern Africa have resided in stable mantle beneath the Kaapvaal craton since the Archaean1. Diamonds with eclogitic inclusions ('eclogitic diamonds') reflect episodic mantle events during the Proterozoic2-3. Here we discuss and present isotope data for a further category of diamonds from the Proterozoic Premier kimberlite, in which peridotitic inclusion minerals have compositions reflecting an origin in both harzburgitic (clinopyroxene-free) and Iherzolitic (clinopyroxene-bearing) assemblages. The harzburgitic garnet inclusions and their counterparts found as isolated minerals ('macrocrysts') in the kimberlite host rock4 have neodym-ium and strontium isotope signatures consistent with an Archaean age (>3,000 Myr) and metasomatized mantle source. Lherzolitic garnet and clinopyroxene inclusions yield a preferred Sm-Nd isochron age of 1,930 Myr, which is ~100 Myr less than that of the adjacent Bushveld Complex5, suggesting a link analogous to that between harzburgitic diamond formation and komatiitic magma tism in the Archaean1. The final generation of diamonds, those with eclogitic inclusions, were formed ~1,150 Myr ago, just before kimberlite emplacement6.

  3. Impact Diamonds in the Craters of the Ukrainian Shield

    NASA Astrophysics Data System (ADS)

    Gurov, E. P.; Gurova, E. P.; Rakitskaya, R. B.

    1995-09-01

    The impact diamonds discovery and investigations in the rocks of the Popigay crater [1,2] stimulated the search of the carbon high pressure phases in the craters of the Ukrainian shield. Seven impact craters are located on the territory of the Ukrainian Shield and its North-Eastern slope. Impact diamonds were discovered in the rocks of the Ilyinets, Zapadnaya, Obolon craters and some other impact structures. The highest concentration of impact diamonds was determined in the Zapadnaya crater. The Zapadnaya impact crater, about 3 km in diameter, is located in the Western part of the Ukrainian shield. The target of the crater is presented by granites and gneisses of the Precambrian crystalline basement. The Zapadnaya crater is represented the intensively eroded astrobleme of a complex structure. The inner crater with the conelike central uplift preserves only at the recent erosional level [3,4]. The allochthonous rocks complex in the crater is presented by the suevites, breccia and impactites. The allochthonous breccia forms the lowermost layer in the crater. The suevites with the glass content from 10-15 to 40-50% compose the upper annular layer around the central uplift. The massive impactites form the dykelike veins in the brecciated rocks of the subcrater basement. The impact diamonds occur in suevites and massive impactites of the crater. The diamonds are represented with the tabular grains from tens of micron up to 0.4-0.5 mm in diameter. The colour of the diamond grains changes from colourless, white and yellowish to grey, dark grey and black. The diamonds are anisotropic, their birefringence is up to 0.015. The impact diamonds phase composition was investigated with X-ray methods. The diamond grains are represented by the submicroscopic aggregates of cubic and hexagonal phases. The cubic phase prevalents in all investigated diamonds; the hexagonal phase content in the diamonds from the Zapadnaya crater changes from 5-10 to 40-50%. The direct dependence of the

  4. Pitch-based carbon foam and composites

    DOEpatents

    Klett, James W.

    2001-01-01

    A process for producing carbon foam or a composite is disclosed which obviates the need for conventional oxidative stabilization. The process employs mesophase or isotropic pitch and a simplified process using a single mold. The foam has a relatively uniform distribution of pore sizes and a highly aligned graphic structure in the struts. The foam material can be made into a composite which is useful in high temperature sandwich panels for both thermal and structural applications.

  5. Pitch-based carbon foam and composites

    DOEpatents

    Klett, James W.

    2002-01-01

    A process for producing carbon foam or a composite is disclosed which obviates the need for conventional oxidative stabilization. The process employs mesophase or isotropic pitch and a simplified process using a single mold. The foam has a relatively uniform distribution of pore sizes and a highly aligned graphic structure in the struts. The foam material can be made into a composite which is useful in high temperature sandwich panels for both thermal and structural applications.

  6. Pitch-based carbon foam and composites

    DOEpatents

    Klett, James W.

    2003-12-02

    A process for producing carbon foam or a composite is disclosed which obviates the need for conventional oxidative stabilization. The process employs mesophase or isotropic pitch and a simplified process using a single mold. The foam has a relatively uniform distribution of pore sizes and a highly aligned graphic structure in the struts. The foam material can be made into a composite which is useful in high temperature sandwich panels for both thermal and structural applications.

  7. Pitch-based carbon foam and composites

    DOEpatents

    Klett, James W.

    2003-12-16

    A process for producing carbon foam or a composite is disclosed which obviates the need for conventional oxidative stabilization. The process employs mesophase or isotropic pitch and a simplified process using a single mold. The foam has a relatively uniform distribution of pore sizes and a highly aligned graphic structure in the struts. The foam material can be made into a composite which is useful in high temperature sandwich panels for both thermal and structural applications.

  8. Experimental study of diamond resorption during mantle metasomatism

    NASA Astrophysics Data System (ADS)

    Fedorchuk, Yana; Schmidt, Max W.; Liebske, Christian

    2014-05-01

    Many of kimberlite-derived diamonds are partially dissolved to various degree but show similar resorption style. This resorption style has been observed in experiments with aqueous fluid at the conditions corresponding to kimberlite emplacement (1-2 GPa). At the same time, each diamond population has more than ten percent of diamond crystals with several drastically different resorption styles, which have not been observed in experiments, and may represent partial dissolution of diamonds during metasomatism in different mantle domains. Metasomatic processes modify the composition of subcratonic mantle, may trigger the formation of kimberlite magma, and result in the growth and partial dissolution of diamonds. Composition of metasomatic agents as constrained from studies of the reaction rims on mantle minerals (garnet, clinopyroxene) and experimental studies vary between carbonatitic melt, aqueous silicate melt, and CHO fluid. However, complex chemical pattern of mantle minerals and estimates of redox regime in subcratonic mantle allow different interpretations. Here we explore diamond dissolution morphology as an indicator of the composition of mantle metasomatic agents. Towards this end we examine diamond dissolution morphologies developed in experiments at the conditions of mantle metasomatism in different reacting media and compare them to the mantle-derived dissolution features of natural diamonds. The experiments were conducted in multi-anvil (Walker-Type) apparatus at 6 GPa and 1200-1500oC. Dissolution morphology of natural octahedral diamond crystals (0.5 mg) was examined in various compositions in synthetic system MgO-CaO- SiO2-CO2-H2O. The runs had the following phases present: solid crystals with fluid (various ratio of H2O-CO2-SiO2, and in the air), carbonate melt, carbonate-silicate melt, and carbonate melt with CHO fluid. Experiments produced three different styles of diamond resorption. In the presence of a fluid phase with variable proportions of H2O

  9. Diamond Ranch High School.

    ERIC Educational Resources Information Center

    Betsky, Aaron

    2000-01-01

    Highlights award-winning Diamond Ranch High School (California) that was designed and built on a steep site around Los Angeles considered unsatisfactory for building due to its unstable soils. Building organization is discussed, and photos are provided. (GR)

  10. Amorphous diamond films

    DOEpatents

    Falabella, S.

    1998-06-09

    Amorphous diamond films having a significant reduction in intrinsic stress are prepared by biasing a substrate to be coated and depositing carbon ions thereon under controlled temperature conditions. 1 fig.

  11. 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.

  12. Micrometer-scale cavities in fibrous and cloudy diamonds — A glance into diamond dissolution events

    NASA Astrophysics Data System (ADS)

    Klein-BenDavid, Ofra; Wirth, Richard; Navon, Oded

    2007-12-01

    Micrometer sized internal cavities in diamonds preserve evidence of diamond dissolution events. Combining the methods of focused ion beam (FIB) sample preparation and transmission electron microscopy (TEM) enables these features to be studied in detail. Micrometer-scale cavities are found in the inner parts of fibrous and cloudy kimberlitic diamonds. Their filling consists of amorphous matrix, secondary nano-crystals, volatiles and in some cases larger resorbed crystals. Trapped minerals include corundum, Kappa-alumina, quartz, olivine, moissanite-6H and Ca-Mg carbonates. This is the first observation of Kappa-alumina in nature. Secondary nano-minerals are observed within the amorphous matrix and include carbonates, Al-oxide, fluorite, ilmenite and secondary diamond crystals. The amorphous matrix is spongy and its composition is dominated by amorphous carbon, nitrogen, chlorine and also contains water. When no crystalline phases are observed, the matrix is also enriched in alumina, silica and in some cases calcium. We propose that micrometer scale cavities in diamonds form during dissolution events induced by the introduction of oxidizing hydrous fluids into the diamond growth area. Hydrous fluids are the main dissolving agents for most kimberlitic diamonds [Fedortchouk, Y., Canil, D., Semenets, E., 2007. Mechanisms of diamond oxidation and their bearing on the fluid composition in kimberlite magmas. Am. Mineral. 92, 1200-1212]. At diamond forming conditions silica and alumina are enriched in hydrous fluids that are in equilibrium with eclogites [Kessel, R., Ulmer, P., Pettke, T., Schmidt, M.W., Thompson, A.B., 2005. The water-basalt system at 4 to 6 GPa: Phase relations and second critical endpoint in a K-free eclogite at 700 to 1400 °C. Earth Planet. Sci. Lett. 237, 873-892]; this is consistent with the increased solubility of alumina with increased pressure and temperature in the Na-Cl bearing fluids [Manning, C.E., 2006. Mobilizing aluminum in crustal and

  13. High Performance Graphene Oxide Based Rubber Composites

    NASA Astrophysics Data System (ADS)

    Mao, Yingyan; Wen, Shipeng; Chen, Yulong; Zhang, Fazhong; Panine, Pierre; Chan, Tung W.; Zhang, Liqun; Liang, Yongri; Liu, Li

    2013-08-01

    In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications.

  14. High Performance Graphene Oxide Based Rubber Composites

    PubMed Central

    Mao, Yingyan; Wen, Shipeng; Chen, Yulong; Zhang, Fazhong; Panine, Pierre; Chan, Tung W.; Zhang, Liqun; Liang, Yongri; Liu, Li

    2013-01-01

    In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications. PMID:23974435

  15. Diamond nanoimprint lithography

    NASA Astrophysics Data System (ADS)

    Taniguchi, Jun; Tokano, Yuji; Miyamoto, Iwao; Komuro, Masanori; Hiroshima, Hiroshi

    2002-10-01

    Electron beam (EB) lithography using polymethylmethacrylate (PMMA) and oxygen gas reactive ion etching (RIE) were used to fabricate fine patterns in a diamond mould. To prevent charge-up during EB lithography, thin conductive polymer was spin-coated over the PMMA resist, yielding dented line patterns 2 μ m wide and 270 nm deep. The diamond mould was pressed into PMMA on a silicon substrate heated to 130, 150 and 170ºC at 43.6, 65.4 and 87.2 MPa. All transferred PMMA convex line patterns were 2 μ m wide. Imprinted pattern depth increased with rising temperature and pressure. PMMA patterns on diamond were transferred by the diamond mould at 150ºC and 65.4 MPa, yielding convex line patterns 2 μ m wide and 200 nm high. Direct aluminium and copper patterns were obtained using the diamond mould at room temperature and 130.8 MPa. The diamond mould is thus useful for replicating patterns on PMMA and metals.

  16. High-mobility diamond

    NASA Astrophysics Data System (ADS)

    Landstrass, Maurice I.

    1994-04-01

    Recent improvements in the CVD diamond deposition process have made possible the fabrication of diamond photoconductive diodes with carrier mobility and lifetime exceeding the values typical of natural gemstones. One of the more surprising recent results is that the best room-temperature carrier properties have been measured on polycrystalline diamond films. The combined electron- hole mobility, as measured by transient photoconductivity at low carrier densities, is 4000 square centimeters per volt per second at electric field of 200 volts per centimeter and is comparable to that of the best single-crystal IIa natural diamonds. Carrier lifetimes measured under the same conditions are 150 picoseconds for the CVD diamond films. The collection distance within the diamond films, at the highest applied fields, is comparable to the average film grain size, indicative of little or no carrier scattering at grain boundaries. A comparison of SIMS measurements with electrical results suggest that impurity incorporation in the near grain boundary regions are responsible for controlling the carrier mobility.

  17. Fluid/melt inclusions in alluvial Northeast Siberian diamonds: new approach on diamond formation.

    NASA Astrophysics Data System (ADS)

    Logvinova, Alla M.; Wirth, Richard; Sobolev, Nikolai V.

    2010-05-01

    The origin of alluvial Northeast Siberian diamonds is still a subject of controversy. Fluid/melt inclusions in diamonds are the deepest available samples of mantle fluids and provide the unique information on the medium in which diamonds have grown. These inclusions carry high-density fluids (HDFs), the compositional variability is in the range of hydrous-silicic, carbonatitic (high-Mg and low-Mg) and saline end-members. Previous studies of the bulk composition and internal morphology of microinclusions in alluvial Northeast Siberian diamonds suggested that they contain fluids, but distribution and structure of their constitutional phases could not be determined. We investigated two populations of diamonds from Northeast Siberian Platform placers (Ebelyakh area) using TEM, FTIR, EPMA methods: (I) rounded single-crystals (dodecahedrons, octahedrons and irregular stones with a black central zone rich in microinclusions. Some of them frequently exhibit growth twinning; (II) rounded dark crystals, related to variety V according to the classification by Orlov (1977). This group of stones has their own typical features: dark color due to abundant black microinclusions and high dislocation density; mosaic-block internal structure; very light carbon isotopic composition; the high degree of nitrogen aggregation and nearly total absence of mineral inclusions. Diamonds of the first population are characterized by two types of fluid/melt nanoinclusions:1) multi-phase high- Mg assemblages, which include solid phases (magnesite, dolomite, clinohumite, Fe-spinel, graphite) and fluid bubbles; 2) oriented sulfide melt nanoinclusions in association with halides (KCl, NaCl), high-Si mica and fluid bubbles. All of them ranging between 5 and 200 nm in diameter are reflecting the diamond habit. Sulfides are homogeneous in composition. The Ni/(Ni+Fe) ratio of the inclusions is 0.037±0.04. Still closed fluid bubbles were identified in TEM studies as changing absorption contrast due to

  18. Mantle–slab interaction and redox mechanism of diamond formation

    PubMed Central

    Palyanov, Yuri N.; Bataleva, Yuliya V.; Sokol, Alexander G.; Borzdov, Yuri M.; Kupriyanov, Igor N.; Reutsky, Vadim N.; Sobolev, Nikolai V.

    2013-01-01

    Subduction tectonics imposes an important role in the evolution of the interior of the Earth and its global carbon cycle; however, the mechanism of the mantle–slab interaction remains unclear. Here, we demonstrate the results of high-pressure redox-gradient experiments on the interactions between Mg-Ca-carbonate and metallic iron, modeling the processes at the mantle–slab boundary; thereby, we present mechanisms of diamond formation both ahead of and behind the redox front. It is determined that, at oxidized conditions, a low-temperature Ca-rich carbonate melt is generated. This melt acts as both the carbon source and crystallization medium for diamond, whereas at reduced conditions, diamond crystallizes only from the Fe-C melt. The redox mechanism revealed in this study is used to explain the contrasting heterogeneity of natural diamonds, as seen in the composition of inclusions, carbon isotopic composition, and nitrogen impurity content. PMID:24297876

  19. Mantle-slab interaction and redox mechanism of diamond formation.

    PubMed

    Palyanov, Yuri N; Bataleva, Yuliya V; Sokol, Alexander G; Borzdov, Yuri M; Kupriyanov, Igor N; Reutsky, Vadim N; Sobolev, Nikolai V

    2013-12-17

    Subduction tectonics imposes an important role in the evolution of the interior of the Earth and its global carbon cycle; however, the mechanism of the mantle-slab interaction remains unclear. Here, we demonstrate the results of high-pressure redox-gradient experiments on the interactions between Mg-Ca-carbonate and metallic iron, modeling the processes at the mantle-slab boundary; thereby, we present mechanisms of diamond formation both ahead of and behind the redox front. It is determined that, at oxidized conditions, a low-temperature Ca-rich carbonate melt is generated. This melt acts as both the carbon source and crystallization medium for diamond, whereas at reduced conditions, diamond crystallizes only from the Fe-C melt. The redox mechanism revealed in this study is used to explain the contrasting heterogeneity of natural diamonds, as seen in the composition of inclusions, carbon isotopic composition, and nitrogen impurity content. PMID:24297876

  20. 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

  1. A perspective on MoSi sub 2 based composites

    SciTech Connect

    Petrovic, J.J. ); Vasudevan, A.K. )

    1992-01-01

    MoSi{sub 2} based composites represent an important new class of high temperature structural silicides,'' with significant potential for elevated temperature structural applications in the range of 1200--1600{degrees}C in oxidizing and aggressive environments. The properties of MoSi{sub 2} which make it an attractive matrix for high temperature composites are described and the development history of these materials traced. Latest results on elevated temperature creep resistance, low temperature fracture toughness, and composite oxidation behavior are summarized. Important avenues for future MoSi{sub 2} based composite development are suggested.

  2. Finite element based micro-mechanics modeling of textile composites

    NASA Technical Reports Server (NTRS)

    Glaessgen, E. H.; Griffin, O. H., Jr.

    1995-01-01

    Textile composites have the advantage over laminated composites of a significantly greater damage tolerance and resistance to delamination. Currently, a disadvantage of textile composites is the inability to examine the details of the internal response of these materials under load. Traditional approaches to the study fo textile based composite materials neglect many of the geometric details that affect the performance of the material. The present three dimensional analysis, based on the representative volume element (RVE) of a plain weave, allows prediction of the internal details of displacement, strain, stress, and failure quantities. Through this analysis, the effect of geometric and material parameters on the aforementioned quantities are studied.

  3. Helium isotopic variability within single diamonds from the Orapa kimberlite pipe

    NASA Technical Reports Server (NTRS)

    Kurz, Mark D.; Jenkins, William J.; Lott, Dempsey E., III; Gurney, John J.

    1987-01-01

    The possible relationships between diamond mineralogy and helium isotopes were investigated by measuring the distribution and isotopic composition of He in a suite of well-characterized one-carat diamonds from the Orapa kimberlite, Botswana. The results of crushing in vacuo experiments indicated that most of He was contained in the matrix, rather than in the inclusions of the diamonds. Step-heating of individual diamonds at 2000 C released He of He-3/He-4 ratios that differed by up to a factor of 100 among the two heating steps, revealing large isotopic variations within individual diamonds. It is suggested that this internal isotopic variability is the result of stepwise graphitization: the first heating step initiates graphitization which nucleates around defects in a diamond, and the second step graphitizes the relatively defect-free regions of the diamond. This explanation predicts that the highest He-3/He-4 ratios should be found in most perfect crystals.

  4. Hydrogen termination of CVD diamond films by high-temperature annealing at atmospheric pressure.

    PubMed

    Seshan, V; Ullien, D; Castellanos-Gomez, A; Sachdeva, S; Murthy, D H K; Savenije, T J; Ahmad, H A; Nunney, T S; Janssens, S D; Haenen, K; Nesládek, M; van der Zant, H S J; Sudhölter, E J R; de Smet, L C P M

    2013-06-21

    A high-temperature procedure to hydrogenate diamond films using molecular hydrogen at atmospheric pressure was explored. Undoped and doped chemical vapour deposited (CVD) polycrystalline diamond films were treated according to our annealing method using a H2 gas flow down to ~50 ml∕min (STP) at ~850 °C. The films were extensively evaluated by surface wettability, electron affinity, elemental composition, photoconductivity, and redox studies. In addition, electrografting experiments were performed. The surface characteristics as well as the optoelectronic and redox properties of the annealed films were found to be very similar to hydrogen plasma-treated films. Moreover, the presented method is compatible with atmospheric pressure and provides a low-cost solution to hydrogenate CVD diamond, which makes it interesting for industrial applications. The plausible mechanism for the hydrogen termination of CVD diamond films is based on the formation of surface carbon dangling bonds and carbon-carbon unsaturated bonds at the applied tempera-ture, which react with molecular hydrogen to produce a hydrogen-terminated surface. PMID:23802976

  5. Hydrogen termination of CVD diamond films by high-temperature annealing at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Seshan, V.; Ullien, D.; Castellanos-Gomez, A.; Sachdeva, S.; Murthy, D. H. K.; Savenije, T. J.; Ahmad, H. A.; Nunney, T. S.; Janssens, S. D.; Haenen, K.; Nesládek, M.; van der Zant, H. S. J.; Sudhölter, E. J. R.; de Smet, L. C. P. M.

    2013-06-01

    A high-temperature procedure to hydrogenate diamond films using molecular hydrogen at atmospheric pressure was explored. Undoped and doped chemical vapour deposited (CVD) polycrystalline diamond films were treated according to our annealing method using a H2 gas flow down to ˜50 ml/min (STP) at ˜850 °C. The films were extensively evaluated by surface wettability, electron affinity, elemental composition, photoconductivity, and redox studies. In addition, electrografting experiments were performed. The surface characteristics as well as the optoelectronic and redox properties of the annealed films were found to be very similar to hydrogen plasma-treated films. Moreover, the presented method is compatible with atmospheric pressure and provides a low-cost solution to hydrogenate CVD diamond, which makes it interesting for industrial applications. The plausible mechanism for the hydrogen termination of CVD diamond films is based on the formation of surface carbon dangling bonds and carbon-carbon unsaturated bonds at the applied tempera-ture, which react with molecular hydrogen to produce a hydrogen-terminated surface.

  6. Diamonds in Abee: The Nobel Gas Signature

    NASA Astrophysics Data System (ADS)

    Ott, U.; Lohr, H. P.; Arden, J. W.

    1992-07-01

    Russell et al. (1992) have reported the discovery of diamond in the enstatite chondrite Abee that, in contrast to other meteoritic diamonds, appears to be of solar system, although not shock-produced, origin. We have completed our noble gas analysis by combustion up to 1200 degrees C. The results are summarized in Table 1. Carbon and noble gases released by combustion above 600 degrees C (maximum included in Russell et al. (1992)) are minor (<7% of total). There is no evidence for Ne-E(H) and s-process-Kr/Xe that would indicate the presence in our sample of presolar SiC. A remarkable feature is the presence of cosmogenic He and Ne, which is unambiguous proof of the indigenous nature of the Abee diamonds (Russell et al., 1992). ^21Ne(sub)c approaches, but does not fully reach, the abundance reported for Abee bulk samples (Schultz and Kruse, 1989; with the exception of one clast). Since the sample consisted of more than 70% carbon, ^21Ne(sub)c must have been produced in surrounding silicates and recoiled into the diamonds. This is in accordance with the average size of the diamonds (0.1-1 micrometers) being on the order of the ^21Ne recoil range. With the presence of cosmogenic Ne, the presence of radiogenic ^4He and fission Xe is to be expected as well. For ^4He this is borne out by the release pattern during combustion, which is intermediate between that for cosmogenic ^21Ne and that for trapped ^36Ar (Fig. 1). While the elemental abundance ratios are within the range observed in ureilites, ordinary chondrites, or enstatite chondrites with subsolar component (Gobel et al., 1978; Crabb and Anders, 1982), there are differences in isotopic composition. Xenon is clearly different from Xe in other Xe-HL-free (-poor) Xe reservoirs such as Q-Xe (Wieler et al., 1991), OC-Xe (Schelhaas et al., 1990) or Xe measured in some bulk enstatite chondrites (Crabb and Anders, 1982). Since the amount of recoil fission Xe expected (based on ^4He content) is insufficient for a

  7. Arguing for Computer-Based Composition Instruction.

    ERIC Educational Resources Information Center

    Larsen, Richard B.

    The English teaching profession must accept the fact that the new paradigm for composition involves microcomputers and word processors, and as such calls for a somewhat different set of skills on the part of both students and teachers. The "text editor" can lessen the effects of some physical and psychological constraints on students, allowing…

  8. Dynamic based damage detection in composite structures

    NASA Astrophysics Data System (ADS)

    Banerjee, Sauvik; Ricci, Fabrizio; Baid, Harsh; Mal, Ajit K.

    2009-03-01

    Advanced composites are being used increasingly in state-of-the-art aircraft and aerospace structures. In spite of their many advantages, composite materials are highly susceptible to hidden flaws that may occur at any time during the life cycle of a structure, and if undetected, may cause sudden and catastrophic failure of the entire structure. This paper is concerned with the detection and characterization of hidden defects in composite structures before they grow to a critical size. A methodology for automatic damage identification and localization is developed using a combination of vibration and wave propagation data. The structure is assumed to be instrumented with an array of actuators and sensors to excite and record its dynamic response, including vibration and wave propagation effects. A damage index, calculated from the measured dynamical response of the structure in a previous (reference) state and the current state, is introduced as a determinant of structural damage. The indices are used to identify low velocity impact damages in increasingly complex composite structural components. The potential application of the approach in developing health monitoring systems in defects-critical structures is indicated.

  9. Scaling up of manufacturing processes of recycled carpet based composites

    NASA Astrophysics Data System (ADS)

    Lakshminarayanan, Krishnan

    2011-12-01

    In this work, feasibility of recycling post-consumer carpets using a modified vacuum assisted resisted molding process into large-scale components was successfully demonstrated. The scale up also included the incorporation of nano-clay films in the carpet composites. It is expected that the films will enhance the ability of the composite to withstand environmental degradation and also serve as a fire retardant. Low-cost resins were used to fabricate the recycled carpet-based composites. The scale up in terms of process was achieved by manufacturing composites without a hot press and thereby saving additional equipment cost. Mechanical and physical properties were evaluated. Large-scale samples demonstrated mechanical properties that were different from results from small samples. Acoustic tests indicate good sound absorption of the carpet composite. Cost analysis of the composite material based on the cost of the raw materials and the manufacturing process has been presented.

  10. Cryotribology of diamond and graphite

    SciTech Connect

    Iwasa, Yukikazu; Ashaboglu, A.F.; Rabinowicz, E.R.

    1996-12-31

    An experimental study was carried out on the tribological behavior of materials of interest in cryogenic applications, focusing on diamond and graphite. Both natural diamond (referred in the text as diamond) and chemical-vapor-deposition (CVD) diamond (CVD-diamond) were used. The experiment was carried out using a pin-on-disk tribometer capable of operating at cryogenic temperatures, from 4.2 to 293 K. Two basic scenarios of testing were used: (1) frictional coefficient ({mu}) vs velocity (v) characteristics at constant temperatures; (2) {mu} vs temperature (T) behavior at fixed sliding speeds. For diamond/CVD-diamond, graphite/CVD-diamond, stainless steel/CVD-diamond pairs, {mu}`s are virtually velocity independent. For each of diamond/graphite, alumina/graphite, and graphite/graphite pairs, the {partial_derivative}{mu}/{partial_derivative}v characteristic is favorable, i.e., positive. For diamond/CVD-diamond and graphite/CVD-diamond pairs, {mu}`s are nearly temperature independent between in the range 77 - 293 K. Each {mu} vs T plot for pin materials sliding on graphite disks has a peak at a temperature in the range 100 - 200 K.

  11. Diamond Electronic Devices

    NASA Astrophysics Data System (ADS)

    Isberg, J.

    2010-11-01

    For high-power and high-voltage applications, silicon is by far the dominant semiconductor material. However, silicon has many limitations, e.g. a relatively low thermal conductivity, electric breakdown occurs at relatively low fields and the bandgap is 1.1 eV which effectively limits operation to temperatures below 175° C. Wide-bandgap materials, such as silicon carbide (SiC), gallium nitride (GaN) and diamond offer the potential to overcome both the temperature and power handling limitations of silicon. Diamond is the most extreme in this class of materials. By the fundamental material properties alone, diamond offers the largest benefits as a semiconductor material for power electronic applications. On the other hand, diamond has a problem with a large carrier activation energy of available dopants which necessitates specialised device concepts to allow room temperature (RT) operation. In addition, the role of common defects on the charge transport properties of diamond is poorly understood. Notwithstanding this, many proof-of-principle two-terminal and three-terminal devices have been made and tested. Two-terminal electronic diamond devices described in the literature include: p-n diodes, p-i-n diodes, various types of radiation detectors, Schottky diodes and photoconductive or electron beam triggered switches. Three terminal devices include e.g. MISFETs and JFETs. However, the development of diamond devices poses great challenges for the future. A particularly interesting way to overcome the doping problem, for which there has been some recent progress, is to make so-called delta doped (or pulse-doped) devices. Such devices utilise very thin (˜1 nm) doped layers in order to achieve high RT activation.

  12. Diamond Electronic Devices

    SciTech Connect

    Isberg, J.

    2010-11-01

    For high-power and high-voltage applications, silicon is by far the dominant semiconductor material. However, silicon has many limitations, e.g. a relatively low thermal conductivity, electric breakdown occurs at relatively low fields and the bandgap is 1.1 eV which effectively limits operation to temperatures below 175 deg.n C. Wide-bandgap materials, such as silicon carbide (SiC), gallium nitride (GaN) and diamond offer the potential to overcome both the temperature and power handling limitations of silicon. Diamond is the most extreme in this class of materials. By the fundamental material properties alone, diamond offers the largest benefits as a semiconductor material for power electronic applications. On the other hand, diamond has a problem with a large carrier activation energy of available dopants which necessitates specialised device concepts to allow room temperature (RT) operation. In addition, the role of common defects on the charge transport properties of diamond is poorly understood. Notwithstanding this, many proof-of-principle two-terminal and three-terminal devices have been made and tested. Two-terminal electronic diamond devices described in the literature include: p-n diodes, p-i-n diodes, various types of radiation detectors, Schottky diodes and photoconductive or electron beam triggered switches. Three terminal devices include e.g. MISFETs and JFETs. However, the development of diamond devices poses great challenges for the future. A particularly interesting way to overcome the doping problem, for which there has been some recent progress, is to make so-called delta doped (or pulse-doped) devices. Such devices utilise very thin ({approx}1 nm) doped layers in order to achieve high RT activation.

  13. Fabrication of tungsten wire reinforced nickel-base alloy composites

    NASA Technical Reports Server (NTRS)

    Brentnall, W. D.; Toth, I. J.

    1974-01-01

    Fabrication methods for tungsten fiber reinforced nickel-base superalloy composites were investigated. Three matrix alloys in pre-alloyed powder or rolled sheet form were evaluated in terms of fabricability into composite monotape and multi-ply forms. The utility of monotapes for fabricating more complex shapes was demonstrated. Preliminary 1093C (2000F) stress rupture tests indicated that efficient utilization of fiber strength was achieved in composites fabricated by diffusion bonding processes. The fabrication of thermal fatigue specimens is also described.

  14. Metal-ceramic composite development based on its modelling results

    NASA Astrophysics Data System (ADS)

    Dvilis, E. S.; Khasanov, O. L.; Khasanov, A. O.; Petyukevich, M. S.

    2016-02-01

    The modeling (and its experimental verification) of packing and deformation of the composites consisted of aluminum-magnesium alloy AMg6, B4C powder and W nano-powder has been performed. The powder compositions were determined using discrete element modeling of the composite particles packing based on the particle size distribution functions of real powders. The models of maximum mixture packing densities have been rendered.

  15. 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

  16. Surface Roughness, Microhardness, and Microleakage of a Silorane-Based Composite Resin after Immediate or Delayed Finishing/Polishing.

    PubMed

    Lins, Fernanda Carvalho Rezende; Ferreira, Raquel Conceição; Silveira, Rodrigo Richard; Pereira, Carolina Nemésio Barros; Moreira, Allyson Nogueira; Magalhães, Claudia Silami

    2016-01-01

    Objective. This study evaluated the effect of immediate or delayed finishing/polishing using different systems on the surface roughness, hardness, and microleakage of a silorane-based composite. Material and Methods. Specimens were made with silorane-based composite (Filtek P90, 3M ESPE) and assigned to the treatments: control (light-cured); aluminum oxide discs (Sof-Lex, 3M ESPE); diamond-impregnated silicone tips (Astropol, Ivoclar Vivadent); aluminum oxide-impregnated silicone tips (Enhance, Dentsply). Half of the specimens were finished/polished immediately and the rest after 7 days. Surface roughness (Ra, μm; n = 20) and Vickers microhardness (50 g; 45 s; n = 10) were measured. Cavities were prepared in bovine incisors and filled with Filtek P90. The fillings received immediate or delayed finishing/polishing (n = 10) and were subjected to dye penetration test (0.5% basic fuchsin, 24 h). Data were analyzed by ANOVA and Scheffe, Kruskal-Wallis, and Mann-Whitney tests (p < 0.05). Results. The finishing/polishing system significantly influenced roughness and microhardness (p < 0.0001). For enamel, microleakage was not affected by the finishing/polishing system (p = 0.309). For dentin, Sof-Lex discs and Astropol points promoted greater microleakage than Enhance points (p = 0.033). Conclusion. Considering roughness, microhardness, and microleakage together, immediate finishing/polishing of a silorane-based composite using aluminum oxide discs may be recommended. PMID:26977150

  17. Surface Roughness, Microhardness, and Microleakage of a Silorane-Based Composite Resin after Immediate or Delayed Finishing/Polishing

    PubMed Central

    Lins, Fernanda Carvalho Rezende; Ferreira, Raquel Conceição; Silveira, Rodrigo Richard; Pereira, Carolina Nemésio Barros; Moreira, Allyson Nogueira; Magalhães, Claudia Silami

    2016-01-01

    Objective. This study evaluated the effect of immediate or delayed finishing/polishing using different systems on the surface roughness, hardness, and microleakage of a silorane-based composite. Material and Methods. Specimens were made with silorane-based composite (Filtek P90, 3M ESPE) and assigned to the treatments: control (light-cured); aluminum oxide discs (Sof-Lex, 3M ESPE); diamond-impregnated silicone tips (Astropol, Ivoclar Vivadent); aluminum oxide-impregnated silicone tips (Enhance, Dentsply). Half of the specimens were finished/polished immediately and the rest after 7 days. Surface roughness (Ra, μm; n = 20) and Vickers microhardness (50 g; 45 s; n = 10) were measured. Cavities were prepared in bovine incisors and filled with Filtek P90. The fillings received immediate or delayed finishing/polishing (n = 10) and were subjected to dye penetration test (0.5% basic fuchsin, 24 h). Data were analyzed by ANOVA and Scheffe, Kruskal-Wallis, and Mann-Whitney tests (p < 0.05). Results. The finishing/polishing system significantly influenced roughness and microhardness (p < 0.0001). For enamel, microleakage was not affected by the finishing/polishing system (p = 0.309). For dentin, Sof-Lex discs and Astropol points promoted greater microleakage than Enhance points (p = 0.033). Conclusion. Considering roughness, microhardness, and microleakage together, immediate finishing/polishing of a silorane-based composite using aluminum oxide discs may be recommended. PMID:26977150

  18. Elastomeric composites based on carbon nanomaterials

    NASA Astrophysics Data System (ADS)

    Araby, Sherif; Meng, Qingshi; Zhang, Liqun; Zaman, Izzuddin; Majewski, Peter; Ma, Jun

    2015-03-01

    Carbon nanomaterials including carbon black (CB), carbon nanotubes (CNTs) and graphene have attracted increasingly more interest in academia due to their fascinating properties. These nanomaterials can significantly improve the mechanical, electrical, thermal, barrier, and flame retardant properties of elastomers. The improvements are dependent on the molecular nature of the matrix, the intrinsic property, geometry and dispersion of the fillers, and the interface between the matrix and the fillers. In this article, we briefly described the fabrication processes of elastomer composites, illuminated the importance of keeping fillers at nanoscale in matrices, and critically reviewed the recent development of the elastomeric composites by incorporating CB, CNTs, and graphene and its derivatives. Attention has been paid to the mechanical properties and electrical and thermal conductivity. Challenges and further research are discussed at the end of the article.

  19. The role of mantle ultrapotassic fluids in diamond formation

    PubMed Central

    Palyanov, Yuri N.; Shatsky, Vladislav S.; Sobolev, Nikolay V.; Sokol, Alexander G.

    2007-01-01

    Analysis of data on micro- and nano-inclusions in mantle-derived and metamorphic diamonds shows that, to a first approximation, diamond-forming medium can be considered as a specific ultrapotassic, carbonate/chloride/silicate/water fluid. In the present work, the processes and mechanisms of diamond crystallization were experimentally studied at 7.5 GPa, within the temperature range of 1,400–1,800°C, with different compositions of melts and fluids in the KCl/K2CO3/H2O/C system. It has been established that, at constant pressure, temperature, and run duration, the mechanisms of diamond nucleation, degree of graphite-to-diamond transformation, and formation of metastable graphite are governed chiefly by the composition of the fluids and melts. The experimental data suggest that the evolution of the composition of deep-seated ultrapotassic fluids/melts is a crucial factor of diamond formation in mantle and ultrahigh-pressure metamorphic processes. PMID:17379668

  20. The role of mantle ultrapotassic fluids in diamond formation.

    PubMed

    Palyanov, Yuri N; Shatsky, Vladislav S; Sobolev, Nikolay V; Sokol, Alexander G

    2007-05-29

    Analysis of data on micro- and nano-inclusions in mantle-derived and metamorphic diamonds shows that, to a first approximation, diamond-forming medium can be considered as a specific ultrapotassic, carbonate/chloride/silicate/water fluid. In the present work, the processes and mechanisms of diamond crystallization were experimentally studied at 7.5 GPa, within the temperature range of 1,400-1,800 degrees C, with different compositions of melts and fluids in the KCl/K(2)CO(3)/H(2)O/C system. It has been established that, at constant pressure, temperature, and run duration, the mechanisms of diamond nucleation, degree of graphite-to-diamond transformation, and formation of metastable graphite are governed chiefly by the composition of the fluids and melts. The experimental data suggest that the evolution of the composition of deep-seated ultrapotassic fluids/melts is a crucial factor of diamond formation in mantle and ultrahigh-pressure metamorphic processes. PMID:17379668

  1. A creep model for metallic composites based on matrix testing: Application to Kanthal composites

    NASA Technical Reports Server (NTRS)

    Binienda, W. K.; Robinson, D. N.; Arnold, S. M.; Bartolotta, Paul A.

    1990-01-01

    An anisotropic creep model is formulated for metallic composites with strong fibers and low to moderate fiber volume percent (less than 40 percent). The idealization admits no creep in the local fiber direction and assumes equal creep strength in longitudinal and transverse shear. Identification of the matrix behavior with that of the isotropic limit of the theory permits characterization of the composite through uniaxial creep tests on the matrix material. Constant and step-wise creep tests are required as a data base. The model provides an upper bound on the transverse creep strength of a composite having strong fibers embedded in a particular matrix material. Comparison of the measured transverse strength with the upper bound gives an assessment of the integrity of the composite. Application is made to a Kanthal composite, a model high-temperature composite system. Predictions are made of the creep response of fiber reinforced Kanthal tubes under interior pressure.

  2. 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

    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

  3. Synthesis of diamond on WC-Co substrates using a KrF excimer laser in combination with a combustion flame

    NASA Astrophysics Data System (ADS)

    Han, Y. X.; Ling, H.; Lu, Y. F.

    2007-02-01

    A KrF excimer laser was used in combination with a combustion flame to deposit diamond films on cemented tungsten carbide (WC-Co) substrates. The laser has a wavelength of 248 nm, a pulse width of 23 ns, a pulse energy range of 84~450 mJ, and a repetition rate up to 50 Hz. Using the combustion flame method, diamond films were deposited on the laser-processed WC-Co substrates for 10 min. The morphologies of the deposited diamond films were examined using a scanning electron microscopy (SEM). The composition and bonding structures in the deposited films were studied by energy dispersive X-ray analysis (EDX) and Raman spectroscopy, respectively. The film adhesion was characterized by scratching a razor across the films. It was found that C composition on WC-Co substrate surfaces was eliminated by the laser irradiation. As a consequence, diamond nucleation density decreased and diamond grains grew larger in the laser-processed areas. Based on the experimental results, a film growth mechanism at different deposition temperature ranges corresponding to pre-deposition laser-surface-treatment effects was proposed.

  4. Un Cours de composition francaise par ordinateur (A Computer-Based Course in French Composition).

    ERIC Educational Resources Information Center

    Landes, Anne; Kaplan, Alice

    1988-01-01

    The origins, organization, and methods of a Columbia University course offering computer-based instruction in French composition are outlined, and the progress of four individual students is described. (MSE)

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

  6. 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

    2016-01-01

    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

  7. 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

  8. The Diamond Makers

    NASA Astrophysics Data System (ADS)

    Hazen, Robert M.

    1999-08-01

    Since time immemorial, we have treasured diamonds for their exquisite beauty and unrivaled hardness. Yet, most of the earth's diamonds lie deep underground and totally unaccessible to us--if only we knew how to fabricate them! In The Diamond Makers Robert Hazen vividly recounts the very human desire to exceed nature and create a synthetic diamond. Spanning centuries of ground-breaking science, instances of bitter rivalry, cases of outright fraud and self-delusion, Hazen blends drama and science to reveal the extraordinary technological advances and devastating failures of the diamond industry. Along the way, readers will be introduced to the brilliant, often eccentric and controversial, pioneers of high-pressure research who have harnessed crushing pressures and scorching temperatures to transform almost any carbon-rich material, from road tar to peanut butter, into the most prized of all gems. Robert M. Hazen is the author of fifteen books, including the bestseller, Science Matters: Achieving Scientific Literacy, which he wrote with James Trefil. Dr. Hazen has won numerous awards for his research and scientific writing.

  9. Auger Spectroscopy of Hydrogenated Diamond Surfaces

    NASA Technical Reports Server (NTRS)

    Krainsky, I. L.; Asnin, V. M.; Petukhov, A. G.; Foygel, M.

    1997-01-01

    An energy shift and a change of the line shape of the carbon core-valence-valence Auger spectra are observed for diamond surfaces after their exposure to an electron beam, or annealing at temperatures higher then 950 C. The effect is studied for both natural diamond crystals and chemical-vapor-deposited diamond films. A theoretical model is proposed for Auger spectra of hydrogenated diamond surfaces. The observed changes of the carbon Auger line shape are shown to be related to the redistribution of the valence-band local density of states caused by the hydrogen desorption from the surface. One-electron calculation of Auger spectra of diamond surfaces with various hydrogen coverages are presented. They are based on self-consistent wave functions and matrix elements calculated in the framework of the local-density approximation and the self-consistent linear muffin-tin orbital method with static core-hole effects taken into account. The major features of experimental spectra are explained.

  10. Investigation of applications of diamond film

    NASA Astrophysics Data System (ADS)

    Jassowski, D. M.

    1989-11-01

    The unique properties of synthetic diamond prepared by chemical vapor deposition suggest potential aerospace applications of interest to the Air Force. The status of the rapidly developing technology of low-pressure diamond film synthesis has been determined by contacts with 76 research groups active in the field. Information on six synthetic techniques and a list of 112 active groups are included. Updated diamond film properties are presented based on the survey, literature data, and the measurements made in this program. Measurements were made of hydrogen diffusion resistance, hardness, thermal shock resistance, rupture strength, and propellant compatibility. A comprehensive screen of 200 potential Air Force applications is presented. These were reduced to a 4 high-value applications: bearing surfaces, barriers for hydrogen diffusion, barriers for propellant corrosion protection, and thermal protection for surfaces with localized high heat flux. Initial reports of unusually high tensile strength for diamond films cannot be supported by detailed analysis of test data, eliminating some structural applications. Technology development plans are presented for obtaining better properties data for demonstrating the application of diamond films to bearings.

  11. Ultradispersity of diamond at the nanoscale.

    PubMed

    Raty, Jean-Yves; Galli, Giulia

    2003-12-01

    Nanometre-sized diamond has been found in meteorites, protoplanetary nebulae and interstellar dusts, as well as in residues of detonation and in diamond films. Remarkably, the size distribution of diamond nanoparticles seems to be peaked around 2-5 nm, and to be largely independent of preparation conditions. We have carried out ab initio calculations of the stability of nanodiamond as a function of surface hydrogen coverage and of size. We have found that at about 3 nm, and for a broad range of pressures and temperatures, particles with bare, reconstructed surfaces become thermodynamically more stable than those with hydrogenated surfaces, thus preventing the formation of larger grains. Our findings provide an explanation of the size distribution of extraterrestrial and of terrestrial nanodiamond found in ultradispersed and ultracrystalline diamond films. They also provide an atomistic structural model of these films, based on the topology and structure of 2-3-nm dimond clusters consisting of a diamond core surrounded by a fullerene-like carbon network. PMID:14634641

  12. Comparative evaluation of CVD diamond technologies

    SciTech Connect

    Anthony, T.R.

    1993-01-01

    Chemical vapor deposition (CVD) of diamonds occurs from hydrogen-hydrocarbon gas mixtures in the presence of atomic hydrogen at subatmospheric pressures. Most CVD methods are based on different means of generating and transporting atomic hydrogen in a particular system. Evaluation of these different techniques involves their capital costs, material costs, energy costs, labor costs and the type and quality of diamond that they produce. Currently, there is no universal agreement on which is the best technique and technique selection has been largely driven by the professional background of the user as well as the particular application of interest. This article discusses the criteria for evaluating a process for low-pressure deposition of diamond. Next, a brief history of low-pressure diamond synthesis is reviewed. Several specific processes are addressed, including the hot filament process, hot filament electron-assisted chemical vapor deposition, and plasma generation of atomic hydrogen by glow discharge, microwave discharge, low pressure radio frequency discharge, high pressure DC discharge, high pressure microwave discharge jets, high pressure RF discharge, and high and low pressure flames. Other types of diamond deposition methods are also evaluated. 101 refs., 15 figs.

  13. Plasma and ion beam enhanced chemical vapour deposition of diamond and diamond-like carbon

    NASA Astrophysics Data System (ADS)

    Tang, Yongji

    WC-Co cutting tools are widely used in the machining industry. The application of diamond coatings on the surfaces of the tools would prolong the cutting lifetime and improves the manufacturing efficiency. However, direct chemical vapor deposition (CVD) of diamond coatings on WC-Co suffer from severe premature adhesion failure due to interfacial graphitization induced by the binder phase Co. In this research, a combination of hydrochloric acid (HCl) and hydrogen (H2) plasma pretreatments and a novel double interlayer of carbide forming element (CFE)/Al were developed to enhance diamond nucleation and adhesion. The results showed that both the pretreatments and interlayers were effective in forming continuous and adhesive nanocrystalline diamond coatings. The method is a promising replacement of the hazardous Murakami's regent currently used in WC-Co pretreatment with a more environmental friendly approach. Apart from coatings, diamond can be fabricated into other forms of nanostructures, such as nanotips. In this work, it was demonstrated that oriented diamond nanotip arrays can be fabricated by ion beam etching of as-grown CVD diamond. The orientation of diamond nanotips can be controlled by adjusting the direction of incident ion beam. This method overcomes the limits of other techniques in producing nanotip arrays on large areas with controlled orientation. Oriented diamond nano-tip arrays have been used to produce anisotropic frictional surface, which is successfully used in ultra-precision positioning systems. Diamond-like carbon (DLC) has many properties comparable to diamond. In this thesis, the preparation of alpha-C:H thin films by end-Hall (EH) ion source and the effects of ion energy and nitrogen doping on the microstructure and mechanical properties of the as-deposited thin films were investigated. The results have demonstrated that smooth and uniform alpha-C:H and alpha-C:H:N films with large area and reasonably high hardness and Young's modulus can be

  14. Trace element chemistry of peridotitic garnets in diamonds from the Premier (Cullinan) and Finsch kimberlites, South Africa: Contrasting styles of mantle metasomatism

    NASA Astrophysics Data System (ADS)

    Viljoen, K. S.; Harris, J. W.; Ivanic, T.; Richardson, S. H.; Gray, K.

    2014-11-01

    The purpose of this paper is to provide, discuss, and interpret a comprehensive set of geochemical data (involving major elements as well as Ni, Ti, Sr, Y, Zr, Nb, Hf and the rare earth elements) for peridotitic garnets in diamonds from Premier and Finsch, with a view on the nature of the metasomatic processes operating up to the time of diamond crystallisation, and the location of these two diamondiferous kimberlites within and outside the region of low seismic velocity in the Kaapvaal lithosphere. Trace element data were acquired using an ion microprobe, and a new method for the analysis of Ni in garnet by ion microprobe is presented. Peridotitic garnets in diamonds from the Premier mine are characterised by a significantly higher proportion of the lherzolite paragenesis relative to diamonds from other South African mines, such as Finsch, Venetia and De Beers Pool. Based on Ni-in-garnet thermometry, inclusion encapsulation temperatures of 1055 °C to 1669 °C are calculated for peridotitic garnets from Premier, with an average temperature of 1215 °C. Calculated temperatures for garnets from Finsch range from 1036 °C to 1167 °C, and are generally lower than for Premier, with an average of 1098 °C. The garnets in the diamonds from Premier and Finsch reflect contrasting styles of metasomatism associated with diamond crystallisation, with a low temperature fluid-type metasomatism prevalent in the case of the Paleoarchean diamonds from Finsch, and a higher temperature melt-related metasomatism occurring in the case of the Paleoproterozoic diamonds from Premier. The metasomatic agent accompanying diamond crystallisation at Finsch is effective at introducing Sr, the light rare earth elements, and some Zr into the lithosphere, but is ineffective at transporting much Ca, Ti, Y and heavy rare earth elements. In the case of Premier the metasomatic agent is highly effective at element transport, introducing e.g. Ca, Fe, Ti, Zr, Y and the rare earth elements. The location

  15. 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

  16. Making Diamond in the Laboratory

    ERIC Educational Resources Information Center

    Strong, Herbert

    1975-01-01

    Discusses the graphite to diamond transformation and a phase diagram for carbon. Describes high temperature-higher pressure experimental apparatus and growth of diamonds from seed crystals. Reviews properties of the diamond which suggest uses for the synthetic product. Illustrations with text. (GH)

  17. Diamond collecting in northern Colorado.

    USGS Publications Warehouse

    Collins, D.S.

    1982-01-01

    The discovery of numerous diamond-bearing kimberlite diatremes in the N Front Range of Colorado and Wyoming is of both scientific and economic interest. Species recovered from heavy-mineral concentrates include Cr-diopside, spinel, Mg-ilmenite, pyrope and diamond. A nodule tentatively identified as a graphite-diamond eclogite was also found. -G.W.R.

  18. Theory for a gas composition sensor based on acoustic properties

    NASA Technical Reports Server (NTRS)

    Phillips, Scott; Dain, Yefim; Lueptow, Richard M.

    2003-01-01

    Sound travelling through a gas propagates at different speeds and its intensity attenuates to different degrees depending upon the composition of the gas. Theoretically, a real-time gaseous composition sensor could be based on measuring the sound speed and the acoustic attenuation. To this end, the speed of sound was modelled using standard relations, and the acoustic attenuation was modelled using the theory for vibrational relaxation of gas molecules. The concept for a gas composition sensor is demonstrated theoretically for nitrogen-methane-water and hydrogen-oxygen-water mixtures. For a three-component gas mixture, the measured sound speed and acoustic attenuation each define separate lines in the composition plane of two of the gases. The intersection of the two lines defines the gas composition. It should also be possible to use the concept for mixtures of more than three components, if the nature of the gas composition is known to some extent.

  19. Theory for a gas composition sensor based on acoustic properties.

    PubMed

    Phillips, Scott; Dain, Yefim; Lueptow, Richard M

    2003-01-01

    Sound travelling through a gas propagates at different speeds and its intensity attenuates to different degrees depending upon the composition of the gas. Theoretically, a real-time gaseous composition sensor could be based on measuring the sound speed and the acoustic attenuation. To this end, the speed of sound was modelled using standard relations, and the acoustic attenuation was modelled using the theory for vibrational relaxation of gas molecules. The concept for a gas composition sensor is demonstrated theoretically for nitrogen-methane-water and hydrogen-oxygen-water mixtures. For a three-component gas mixture, the measured sound speed and acoustic attenuation each define separate lines in the composition plane of two of the gases. The intersection of the two lines defines the gas composition. It should also be possible to use the concept for mixtures of more than three components, if the nature of the gas composition is known to some extent. PMID:14552356

  20. Shape memory-based tunable resistivity of polymer composites

    NASA Astrophysics Data System (ADS)

    Luo, Hongsheng; Zhou, Xingdong; Ma, Yuanyuan; Yi, Guobin; Cheng, Xiaoling; Zhu, Yong; Zu, Xihong; Zhang, Nanjun; Huang, Binghao; Yu, Lifang

    2016-02-01

    A conductive composite in bi-layer structure was fabricated by embedding hybrid nanofillers, namely carbon nanotubes (CNTs) and silver nanoparticles (AgNPs), into a shape memory polyurethane (SMPU). The CNT/AgNP-SMPU composites exhibited a novel tunable conductivity which could be facially tailored in wide range via the compositions or a specifically designed thermo-mechanical shape memory programming. The morphologies of the conductive fillers and the composites were investigated by scanning electron microscope (SEM). The mechanical and thermal measurements were performed by tensile tests and differential scanning calorimetry (DSC). By virtue of a specifically explored shape memory programming, the composites were stretched and fixed into different temporary states. The electrical resistivity (Rs) varied accordingly, which was able to be stabilized along with the shape fixing. Theoretical prediction based upon the tunneling model was performed. The Rs-strain curves of the composites with different compositions were well fitted. Furthermore, the relative resistivity and the Gauge factor along with the elongation were calculated. The influence of the compositions on the strain-dependent Rs was disclosed. The findings provided a new avenue to tailor the conductivity of the polymeric nano-composites by combining the composition method and a thermo-mechanical programming, which may greatly benefit the application of intelligent polymers in flexible electronics and sensors fields.

  1. Tribological composition optimization of chromium-carbide-based solid lubricant coatings for foil gas bearings at temperatures to 650 C

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher

    1988-01-01

    The determination of the tribilogically optimum composition of chromium-carbide-based solid lubricant coatings using a foil gas bearing test apparatus is described. The coatings contain a wear resistant chromium carbide `base stock' with the lubricant additives silver and BaF2-CaF2 eutectic. The coating composition is optimized for air-lubricated foil gas bearings at temperatures ranging from 25 to 650 C. The various compositions were prepared by powder blending, then plasma sprayed onto Inconel 718 test journals and diamond ground to the desired coating thickness and surface finish. The journals were operated against preoxidized Ni-Cr alloy foils, and the test bearings were subjected to repeated start-stop cycles under a bearing unit of 14 kPa. Sliding contact between the coated journal and the smooth foil occurs during bearing start-up before lift-off or hydrodynamic lubrication by the air film and during bearing coast-down. The bearings were tested for 9000 start-stop cycles or until specimen reached a predetermined failure level.

  2. Design, Fabrication, Optical Testing, and Performance of Diamond Machined Aspheric Mirrors for Ground-Based Near-IR Astronomy

    NASA Technical Reports Server (NTRS)

    Ohl, Raymond G.; Mink, Ronald; Chambers, V. John; Connelly, Joseph A.; Mentzell, J. Eric; Tveekrem, June L.; Howard, Joseph M.; Preuss, Werner; Schroeder, Mechthild; Sohn, Alex; Krebs, Carolyn (Technical Monitor)

    2002-01-01

    Challenges in fabrication and testing have historically limited the choice of surfaces available for the design of reflective optical instruments. Spherical and conic mirrors are common, but, for future science instruments, more degrees of freedom are necessary to meet challenging performance and packaging requirements. These instruments will be composed of unusual aspheres located far off-axis with large spherical departure, and some designs will require asymmetric surface profiles. In particular, single-surface astigmatism correction in spectrographs necessitates a toroidal surface, which lacks an axis of rotational symmetry. We describe the design, fabrication, optical testing, and performance of three rotationally symmetric, off-axis, aspheric mirrors and one toroidal, off-axis, biconic camera mirror on aluminum substrates for the Infrared Multi-Object Spectrograph (IRMOS) instrument. IRMOS is a facility instrument for the Kitt Peak National Observatory's Mayall Telescope (3.8 m) and an engineering prototype for a possible design of the Next Generation Space Telescope/Multi-Object Spectrograph. The symmetric mirrors range in aperture from 94x86 mm to 286x269 mm and in f-number from 0.9 to 2.4. They are various off-axis, convex and concave, prolate and oblate ellipsoids. The concave biconic mirror has a 94x76 mm aperture, Rx=377 mm, kx=0.0778, Ry=407 mm, and ky=0.1265 and is decentered. by -2 mm in x and 227 mm in y. The mirrors have an aspect ratio of approximately 4:1. The surface error fabrication tolerances are less than 63.3 nm RMS figure error and less than 10 nm RMS microroughness. The mirrors are attached to the instrument bench via a semi-kinematic, integral flexure mount. We describe mirror design, diamond machining, the results of figure testing using computer-generated holograms, and imaging and scattered light modeling and performance.

  3. Composition-based prediction of dielectric properties of foods.

    PubMed

    Sun, E; Datta, A; Lobo, S

    1995-01-01

    Prediction of accurate dielectric property data from fundamental principles for systems as complex as foods has not been possible. Simple prediction models based on easily measurable composition data can serve many useful purposes. Literature dielectric data on foods and their composition were statistically correlated. Dielectric data on salt solutions were measured to explain some of the results. When composition data were not available, standard handbook compositions were used. Inclusion of all types of foods (meats, fruits, and vegetables) inhibited any useful correlation with composition. Based on a smaller data set of meats, both dielectric constant and loss increased with water and salt content. Dielectric constant generally decreased with temperature whereas dielectric loss decreased with temperature at lower salt concentrations and increased with temperature at higher salt concentrations. PMID:8600277

  4. Towards magnetic imaging of neurons using NV diamond

    NASA Astrophysics Data System (ADS)

    Barry, John; Turner, Matthew; Glenn, David; Song, Yuyu; Walsworth, Ronald

    2015-05-01

    Magnetic field imaging based on optically detected magnetic resonances (ODMR) in NV diamond offers an unmatched combination of sensitivity, resolution and field-of-view. For certain biological applications NV diamond imaging is particularly useful; in contrast to traditional fluorescent markers, NV diamond imaging is label-free and does not suffer from bleaching. Additionally the solid-state nature of NV diamond imaging allows for various fast modulation techniques to be employed to increase the signal-to-noise ratio. Here we present progress towards creating an NV diamond imager with sensitivity and resolution appropriate for imaging neural activity within a living neural network. When integrating over our detector, we demonstrate a DC magnetic field sensitivity of better than 50 pT/Hz1/2, which we demonstrate is suitable for detecting the action potentials in invertebrate giants axons.

  5. Physical and Mechanical Properties of Composites and Light Alloys Reinforced with Detonation Nanodiamonds

    NASA Astrophysics Data System (ADS)

    Sakovich, G. V.; Vorozhtsov, S. A.; Vorozhtsov, A. B.; Potekaev, A. I.; Kulkov, S. N.

    2016-07-01

    The influence of introduction of particles of detonation-synthesized nanodiamonds into composites and aluminum-base light alloys on their physical and mechanical properties is analyzed. The data on microstructure and physical and mechanical properties of composites and cast aluminum alloys reinforced with diamond nanoparticles are presented. The introduction of nanoparticles is shown to result in a significant improvement of the material properties.

  6. Phenomenological effets of tantalum incorporation into diamond films: Experimental and first principle studies

    NASA Astrophysics Data System (ADS)

    Ullah, Mahtab; Rana, Anwar Manzoor; Ahmad, E.; Raza, Rizwan; Hussain, Fayyaz; Hussain, Akhtar; Iqbal, Muhammad

    2016-09-01

    Tantalum (Ta) incorporated diamond films are synthesized on silicon substrate by chemical vapor deposition under gas mixture of CH4 + H2. Characterizations of the resulting films indicate that morphology and resistivity of as-grown diamond films are significantly influenced by the process parameters and the amount of tantalum incorporated in the diamond films. XRD plots reveal that diamond films are composed of TaC along with diamond for higher concentration of tantalum and Ta2C phases for lower concentration of tantalum. EDS spectra confirms the existence of tantalum in the diamond films. Resistivity measurements illustrate a sudden fall of about two orders of magnitude by the addition of tantalum in the diamond films. Band structure of Ta-incorporated diamond has been investigated based on density functional theory (DFT) using VASP code. Band structure calculations lead to the semiconducting behavior of Ta-incorporated diamond films because of the creation of defects states inside the band gap extending towards conduction band minimum. Present DFT results support experimental trend of resistivity that with the incorporation of tantalum into diamond lattice causes a decrease in the resistivity of diamond films so that tantalum-incorporated diamond films behave like a good semiconductor.

  7. Diamond Measuring Machine

    SciTech Connect

    Krstulic, J.F.

    2000-01-27

    The fundamental goal of this project was to develop additional capabilities to the diamond measuring prototype, work out technical difficulties associated with the original device, and perform automated measurements which are accurate and repeatable. For this project, FM and T was responsible for the overall system design, edge extraction, and defect extraction and identification. AccuGem provided a lab and computer equipment in Lawrence, 3D modeling, industry expertise, and sets of diamonds for testing. The system executive software which controls stone positioning, lighting, focusing, report generation, and data acquisition was written in Microsoft Visual Basic 6, while data analysis and modeling were compiled in C/C++ DLLs. All scanning parameters and extracted data are stored in a central database and available for automated analysis and reporting. The Phase 1 study showed that data can be extracted and measured from diamond scans, but most of the information had to be manually extracted. In this Phase 2 project, all data required for geometric modeling and defect identification were automatically extracted and passed to a 3D modeling module for analysis. Algorithms were developed which automatically adjusted both light levels and stone focus positioning for each diamond-under-test. After a diamond is analyzed and measurements are completed, a report is printed for the customer which shows carat weight, summarizes stone geometry information, lists defects and their size, displays a picture of the diamond, and shows a plot of defects on a top view drawing of the stone. Initial emphasis of defect extraction was on identification of feathers, pinpoints, and crystals. Defects were plotted color-coded by industry standards for inclusions (red), blemishes (green), and unknown defects (blue). Diamonds with a wide variety of cut quality, size, and number of defects were tested in the machine. Edge extraction, defect extraction, and modeling code were tested for

  8. 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.

  9. Dosimetry with diamond detectors

    NASA Astrophysics Data System (ADS)

    Gervino, G.; Marino, C.; Silvestri, F.; Lavagno, A.; Truc, F.

    2010-05-01

    In this paper we present the dosimetry analysis in terms of stability and repeatability of the signal and dose rate dependence of a synthetic single crystal diamond grown by Chemical Vapor Deposition (CVD) technique. The measurements carried out by 5 MeV X-ray photons beam show very promising results, even if the dose rate detector response points out that the charge trapping centers distribution is not uniform inside the crystal volume. This handicap that affects the detectors performances, must be ascribed to the growing process. Synthetic single crystal diamonds could be a valuable alternative to air ionization chambers for quality beam control and for intensity modulated radiation therapy beams dosimetry.

  10. Identification of /sup 13/C depleted mantle carbon in diamonds from the Roberts Victor Kimberlite, South Africa

    SciTech Connect

    Deines, P.

    1985-01-01

    The Roberts Victor Kimberlite is known for the abundance of eclogite xenoliths, some of which show an unusual depletion in /sup 18/O. The question whether the observed oxygen isotope variations can be related to carbon isotopic composition variations has been investigated. Peridotite-suite diamons (X = -5.4 per thousand vs. PDB, s = +/-0.9 per thousand, n = 65) and sulfide containing diamonds (X = -4.9, s = +/-0.9, n = 20) do not differ in their /sup 13/C content. For these samples, delta/sup 13/C is not related to diamond shape, color, minerals occluded, or the inclusion chemistry. Eclogite suite diamonds (11) can be subdivided into two groups, GI and GII, based on delta/sup 13/C : GI = (X = -15.4, s = +/-0.4, n = 8); GII = (X = -5.9, s = +/-0.4, n = 3). The composition of the gt and cpx inclusions of the two groups is distinct; e.g. cpx of GI is significantly depleted in SiO/sub 2/, MgO, and CaO, and significantly enriched in Al/sub 2/O/sub 3/, FeO and MnO, compared to cpx of GII. Comparison of the chemical composition of the inclusions in E-type diamonds with those of eclogite xenoliths showing /sup 18/O depletion suggests that /sup 13/C and /sup 18/O depletion are not likely to be related. Evaluation of compositional trends of gt and cpx in eclogite xenoliths indicates that GI and GII are not related by a single fractionation event, but represent products from different reservoirs. Equilibration conditions deduced from coexisting gt and cpx demonstrate that GI diamonds come from larger depths than eclogite xenoliths and by inference GII diamonds. The high FeO and MnO content of a gt inclusion in cpx of an eclogite xenolith is used to argue for the existence of two separate events responsible for the formation of GI and GII diamonds.

  11. Heat-resistance of composite electrochemical coatings based on nickel

    SciTech Connect

    Pokmurskii, V.I.; Dalisov, V.B.; Guslienko, Y.A.; Mardarevich, R.S.

    1986-02-01

    The authors study the features of oxidation and determine the temperature limits in the application of carbon steels with composite electrochemical coatings based on the Ni-B system. Coatings based on the Ni-B system deposited on carbon steels can operate for a long time at temperatures up to 750 degrees C. Above this temperature, they begin to decompose and oxidize strongly owing to the instability of nickel borides. A reliable functioning of a composite coating of the composition is possible in the absence of unreacted boron in it.

  12. 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.

  13. Influence of composition gradients on weld metal creep behavior: An analysis based on laminate composites

    SciTech Connect

    Choi, I.

    1989-01-01

    The effects of weld metal microsegregation, as altered by post-weld heat treatments, on both low and high temperatures tensile properties were investigated on Monel alloy 400. Flat, all weld metal, tensile specimens were machined from single pass GTA welds and were heat treated in vacuum in the range of 600 C to 1000 C to produce samples with different composition gradients. Short-time tensile tests were run at room temperature and elevated temperature. Long-time constant load creep tests were performed at 500 C. The room temperature mechanical properties of the as-welded specimen and heat treated specimens were similar and thus unaffected by variations in composition gradients. In contrast, at high temperatures the steady state creep rates decreased, rupture strains increased, and rupture lives decreases with increases in heat treatment temperature, that is, with decreases in the amplitudes of composition gradients. The deformation behavior of solidified dendritic structure was modeled based on results obtained on laminate composites of nickel and copper. The laminates, prepared by roll bonding, were annealed to produce controlled composition gradients with dimensions equivalent to those observed in the weld metal. The steady state creep rates of laminate composites decreased with increases in heat treatment time, that is, with decreases in the amplitudes of composition gradients. To rationalize the creep properties of each component in laminate composites, nickel-copper solid solutions having systematic compositional variations were prepared and tested under the same conditions as the laminate composites. The creep rates of nickel-copper solid solutions showed a minimum with nickel composition.

  14. Ferromagnets based on diamond-like semiconductors GaSb, InSb, Ge, and Si supersaturated with manganese or iron impurities during laser-plasma deposition

    SciTech Connect

    Demidov, E. S. Podol'skii, V. V.; Lesnikov, V. P.; Sapozhnikov, M. V.; Druzhnov, D. M.; Gusev, S. N.; Gribkov, B. A.; Filatov, D. O.; Stepanova, Yu. S.; Levchuk, S. A.

    2008-01-15

    Properties of thin (30-100 nm) layers of diluted magnetic semiconductors based on diamond-like compounds III-V (InSb and GaSb) and elemental semiconductors Ge and Si doped with 3d impurities of manganese and iron up to 15% were measured and discussed. The layers were grown by laser-plasma deposition onto heated single-crystal gallium arsenide or sapphire substrates. The ferromagnetism of layers with the Curie temperature up to 500 K appeared in observations of the ferromagnetic resonance, anomalous Hall effect, and magneto-optic Kerr effect. The carrier mobility of diluted magnetic semiconductors is a hundred times larger than that of the previously known highest temperature magnetic semiconductors, i.e., copper and chromium chalcogenides. The difference between changes in the magnetization with temperature in diluted semiconductors based on III-V, Ge, and Si was discussed. A complex structure of the ferromagnetic resonance spectrum in Si:Mn/GaAs was observed. The results of magnetic-force microscopy showed a weak correlation between the surface relief and magnetic inhomogeneity, which suggests that the ferromagnetism is caused by the 3d-impurity solid solution, rather than ferromagnetic phase inclusions.

  15. Measurements and Diagnostics of Diamond Films and Coatings

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Wu, Richard L. C.

    1999-01-01

    The commercial potential of chemical-vapor-deposited (CVD) diamond films has been established and a number of applications have been identified through university, industry, and government research studies. This paper discusses the methodologies used for property measurement and diagnostic of CVD diamond films and coatings. Measurement and diagnostic techniques studied include scanning electron microscopy, transmission electron microscopy, atomic force microscopy, stylus profilometry, x-ray diffraction, electron diffraction, Raman spectroscopy, Rutherford backscattering, elastic recoil spectroscopy, and friction examination. Each measurement and diagnostic technique provides unique information. A combination of techniques can provide the technical information required to understand the quality and properties of CVD diamond films, which are important to their application in specific component systems and environments. In this study the combination of measurement and diagnostic techniques was successfully applied to correlate deposition parameters and resultant diamond film composition, crystallinity, grain size, surface roughness, and coefficient of friction.

  16. Repulsive effects of hydrophobic diamond thin films on biomolecule detection

    NASA Astrophysics Data System (ADS)

    Ruslinda, A. Rahim; Ishiyama, Y.; Penmatsa, V.; Ibori, S.; Kawarada, H.

    2015-02-01

    The repulsive effect of hydrophobic diamond thin film on biomolecule detection, such as single-nucleotide polymorphisms and human immunodeficiency virus type 1 trans-activator of transcription peptide protein detection, was investigated using a mixture of a fluorine-, amine-, and hydrogen-terminated diamond surfaces. These chemical modifications lead to the formation of a surface that effectively resists the nonspecific adsorption of proteins and other biomolecules. The effect of fluorine plasma treatment on elemental composition was also investigated via X-ray photoelectron spectroscopy (XPS). XPS results revealed a fluorocarbon layer on the diamond thin films. The contact angle measurement results indicated that the fluorine-treated diamond thin films were highly hydrophobic with a surface energy value of ∼25 mN/m.

  17. CVD diamond layers for electrochemistry

    NASA Astrophysics Data System (ADS)

    Kowalska, M.; Fabisiak, K.; Wrzyszczyński, A.; Banaszak, A.; Szybowicz, M.; Paprocki, K.; Bała, W.; Bylicki, F.

    2014-09-01

    Diamond electrodes of different morphologies and qualities were manufactured by hot filament chemical deposition (HF CVD) techniques by changing the parameters of diamond growth process. The estimation of diamond quality and identification of different carbon phases was performed by Raman spectroscopy measurements. The effect of diamond quality and amorphous carbon phase content on the electrochemical response of an obtained diamond electrode in 0.5 M H2SO4 as supporting electrolyte was investigated by cyclic voltammetry with [Fe(CN)6]4-/3- as a redox probe. The kinetic parameters such as catalytic reaction rate constant k0 and electron transfer coefficient α were determined. The obtained results show that the analytical performance of undoped diamond electrodes can be implemented just by the change of diamond layers quality.

  18. Hydrophobic composition based on mixed-molecular weight polyethylene

    NASA Astrophysics Data System (ADS)

    Gorlenko, Nikolay; Debelova, Natalya; Sarkisov, Yuriy; Volokitin, Gennadiy; Zavyalova, Elena; Lapova, Tatyana

    2016-01-01

    The paper presents investigations of compositions based on low and high molecular weight polyethylene so as to synthesize a hydrophobic composition for moisture protection of timber. X-ray phase analysis and measurements of the tear-off force of hydrophobic coating needed to apply to the timber surface and the limiting wetting angle are carried out to detect the hydrophobic, adhesive, electrophysical, and physicochemical properties of compositions. Kinetic dependencies are given for moisture absorption of timber specimens. It is shown that the preliminary formation of the texture by the surface patterning or its treatment with low-temperature plasma with the following protective coating results in the improvement of hydrophobic properties of the suggested compositions. These compositions can be used in the capacity of water repellents to protect building materials from moisture including restoration works.

  19. Dynamic Mechanical Behavior of Boron Carbide Based Composites

    NASA Astrophysics Data System (ADS)

    Hayun, S.; Frage, N.; Dariel, M. P.; Zaretsky, E.

    2007-12-01

    The dynamic response of two boron carbide-based composites was studied in planar impact experiments (impact velocities 100-1000 m/sec) using a 25 mm gas gun. The composites were fabricated by infiltration of compacted B4C and partially sintered B4C preforms by molten Si. In the course of the infiltration process, the liquid silicon reacts with the B4C phase resulting in the formation of the SiC and B12(B,C,Si)3 phases along with some residual silicon present in the infiltrated composites. The velocities of the sample-PMMA window interface were monitored continuously by VISAR. The composites display a relatively high HEL (12-14 GPa) and spall strength (about 1 GPa) values. Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) were used to characterize the fracture surface. The correlation between the microstructure of the infiltrated composites and their dynamic response is discussed.

  20. Aluminum-Based Cast In Situ Composites: A Review

    NASA Astrophysics Data System (ADS)

    Pramod, S. L.; Bakshi, Srinivasa R.; Murty, B. S.

    2015-06-01

    In situ composites are a class of composite materials in which the reinforcement is formed within the matrix by reaction during the processing. In situ method of composite synthesis has been widely followed by researchers because of several advantages over conventional stir casting such as fine particle size, clean interface, and good wettability of the reinforcement with the matrix and homogeneous distribution of the reinforcement compared to other processes. Besides this, in situ processing of composites by casting route is also economical and amenable for large scale production as compared to other methods such as powder metallurgy and spray forming. Commonly used reinforcements for Al and its alloys which can be produced in situ are Al2O3, AlN, TiB2, TiC, ZrB2, and Mg2Si. The aim of this paper is to review the current research and development in aluminum-based in situ composites by casting route.

  1. Maghemite based silicone composite for arterial embolization hyperthermia.

    PubMed

    Smolkova, Ilona S; Kazantseva, Natalia E; Makoveckaya, Kira N; Smolka, Petr; Saha, Petr; Granov, Anatoly M

    2015-03-01

    Maghemite nanoparticle based silicone composite for application in arterial embolization hyperthermia is developed. It possesses embolization ability, high heating efficiency in alternating magnetic fields and radiopaque property. The initial components of the composite are selected so that the material stays liquid for 20min, providing the opportunity for transcatheter transportation and filling of the tumour vascular system. After this induction period the viscosity increases rapidly and soft embolus is formed which is able to occlude the tumour blood vessels. The composite is thermally stable up to 225°C, displays rubber-elastic properties and has a thermal expansion coefficient higher than that of blood. Maghemite nanoparticles uniformly distributed in the composite provide its rapid heating (tens of °Cmin(-1)) due to Neel magnetization relaxation. Required X-ray contrast of composite is achieved by addition of potassium iodide. PMID:25579966

  2. Carbonado: natural polycrystalline diamond.

    PubMed

    Trueb, L F; De Wys, E C

    1969-08-22

    Carbonados are porous aggregates of mostly xenomorphic diamond crystallites ranging in diameter from a fraction of a micron to over 20 microns. Crystalline inclusions (up to 3 percent) occur in the pores of the crystallites and consist mainly of orthoclase and small amounts of other igneous, metamorphic, and secondary minerals. PMID:17742270

  3. 'Diamond' in 3-D

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This 3-D, microscopic imager mosaic of a target area on a rock called 'Diamond Jenness' was taken after NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool for a second time.

    Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

    On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

    The image mosaic is about 6 centimeters (2.4 inches) across.

  4. Diamond is on budget

    NASA Astrophysics Data System (ADS)

    Materlik, Gerhard

    2008-02-01

    Your editorial last month, entitled "The £80m black hole" (January p15), was accompanied by a picture of the Diamond Light Source, which some readers may have interpreted as being responsible for the current shortfall in funding for the Science and Technology Facilities Council (STFC). This implication is totally inaccurate and misleading.

  5. ELECTRON AMPLIFICATION IN DIAMOND.

    SciTech Connect

    SMEDLEY, J.; BEN-ZVI, I.; BURRILL, A.; CHANG, X.; GRIMES, J.; RAO, T.; SEGALOV, Z.; WU, Q.

    2006-07-10

    We report on recent progress toward development of secondary emission ''amplifiers'' for photocathodes. Secondary emission gain of over 300 has been achieved in transmission mode and emission mode for a variety of diamond samples. Techniques of sample preparation, including hydrogenation to achieve negative electron affinity (NEA), have been adapted to this application.

  6. DIAMOND AMPLIFIED PHOTOCATHODES.

    SciTech Connect

    SMEDLEY,J.; BEN-ZVI, I.; BOHON, J.; CHANG, X.; GROVER, R.; ISAKOVIC, A.; RAO, T.; WU, Q.

    2007-11-26

    High-average-current linear electron accelerators require photoinjectors capable of delivering tens to hundreds of mA average current, with peak currents of hundreds of amps. Standard photocathodes face significant challenges in meeting these requirements, and often have short operational lifetimes in an accelerator environment. We report on recent progress toward development of secondary emission amplifiers for photocathodes, which are intended to increase the achievable average current while protecting the cathode from the accelerator. The amplifier is a thin diamond wafer which converts energetic (few keV) primary electrons into hundreds of electron-hole pairs via secondary electron emission. The electrons drift through the diamond under an external bias and are emitted into vacuum via a hydrogen-terminated surface with negative electron affinity (NEA). Secondary emission gain of over 200 has been achieved. Two methods of patterning diamond, laser ablation and reactive-ion etching (RIE), are being developed to produce the required geometry. A variety of diagnostic techniques, including FTIR, SEM and AFM, have been used to characterize the diamonds.

  7. CVD diamond - fundamental phenomena

    SciTech Connect

    Yarbrough, W.A.

    1993-01-01

    This compilation of figures and diagrams addresses the basic physical processes involved in the chemical vapor deposition of diamond. Different methods of deposition are illustrated. For each method, observations are made of the prominent advantages and disadvantages of the technique. Chemical mechanisms of nucleation are introduced.

  8. Multiplying Electrons With Diamond

    NASA Technical Reports Server (NTRS)

    2003-01-01

    As researchers in the Space Communications Division of NASA s Glenn Research Center in 1992, Dr. Gerald Mearini, Dr. Isay Krainsky, and Dr. James Dayton made a secondary electron emission discovery that became the foundation for Mearini s company, GENVAC AeroSpace Corporation. Even after Mearini departed Glenn, then known as Lewis Research Center, his contact with NASA remained strong as he was awarded Small Business Innovation Research (SBIR) contracts to further develop his work. Mearini s work for NASA began with the investigation of diamond as a material for the suppression of secondary electron emissions. The results of his research were the opposite of what was expected diamond proved to be an excellent emitter rather than absorber. Mearini, Krainsky, and Dayton discovered that laboratory-grown diamond films can produce up to 45 electrons from a single incident electron. Having built an electron multiplier prototype at NASA, Mearini decided to start his own company to develop diamond structures usable in electron beam devices.

  9. Alpha particle response study of polycrstalline diamond radiation detector

    NASA Astrophysics Data System (ADS)

    Kumar, Amit; Topkar, Anita

    2016-05-01

    Chemical vapor deposition has opened the possibility to grow high purity synthetic diamond at relatively low cost. This has opened up uses of diamond based detectors for wide range of applications. These detectors are most suitable for harsh environments where standard semiconductor detectors cannot work. In this paper, we present the fabrication details and performance study of polycrystalline diamond based radiation detector. Effect of different operating parameters such as bias voltage and shaping time for charge collection on the performance of detector has been studied.

  10. Temperature dependent simulation of diamond depleted Schottky PIN diodes

    NASA Astrophysics Data System (ADS)

    Hathwar, Raghuraj; Dutta, Maitreya; Koeck, Franz A. M.; Nemanich, Robert J.; Chowdhury, Srabanti; Goodnick, Stephen M.

    2016-06-01

    Diamond is considered as an ideal material for high field and high power devices due to its high breakdown field, high lightly doped carrier mobility, and high thermal conductivity. The modeling and simulation of diamond devices are therefore important to predict the performances of diamond based devices. In this context, we use Silvaco® Atlas, a drift-diffusion based commercial software, to model diamond based power devices. The models used in Atlas were modified to account for both variable range and nearest neighbor hopping transport in the impurity bands associated with high activation energies for boron doped and phosphorus doped diamond. The models were fit to experimentally reported resistivity data over a wide range of doping concentrations and temperatures. We compare to recent data on depleted diamond Schottky PIN diodes demonstrating low turn-on voltages and high reverse breakdown voltages, which could be useful for high power rectifying applications due to the low turn-on voltage enabling high forward current densities. Three dimensional simulations of the depleted Schottky PIN diamond devices were performed and the results are verified with experimental data at different operating temperatures

  11. Protein-based composites and biomaterials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    World industrialization has generated substantial quantities of petroleum-based plastics over many years, which are not biodegradable or compostable, and are permanently residing on land, in landfills, or in the oceans, as environmental pollution. Recently, total or partially degradable materials ha...

  12. Microstructure and properties of pitch-based carbon composites

    PubMed

    Blanco; Santamaria; Bermejo; Bonhomme; Menendez

    1999-11-01

    Pitches prepared in the laboratory by thermal treatment and air-blowing of a commercial coal-tar pitch were used as matrix precursors of carbon composites using granular petroleum coke, foundry coke, amorphous graphite and anthracite. Pitches were characterized by standard procedures (elemental analysis, softening point, solubility tests and carbon yield) and light microscopy (mesophase content). Pitch pyrolysis behaviour was monitored by thermogravimetric analysis and from the optical texture of cokes. Pitch wettability to the different carbons, at different temperatures, was also studied. Experimental conditions selected for the preparation of composites were based on pitch composition and properties. The main microstructural features of composites were determined by light microscopy and scanning electron microscopy. Composite properties were described in terms of their density, porosity and compressive strength, and related to composite microstructure and the characteristics of the precursors. Thermal treatment and air-blowing of pitch improved carbon composite structure and properties. The lowest porosities and best mechanical properties were observed in those composites obtained with the thermally treated pitches combined with foundry coke and anthracite. PMID:10540274

  13. Some functional properties of composite material based on scrap tires

    NASA Astrophysics Data System (ADS)

    Plesuma, Renate; Malers, Laimonis

    2013-09-01

    The utilization of scrap tires still obtains a remarkable importance from the aspect of unloading the environment from non-degradable waste [1]. One of the most prospective ways for scrap tires reuse is a production of composite materials [2] This research must be considered as a continuation of previous investigations [3, 4]. It is devoted to the clarification of some functional properties, which are considered important for the view of practical applications, of the composite material. Some functional properties of the material were investigated, for instance, the compressive stress at different extent of deformation of sample (till 67% of initial thickness) (LVS EN 826) [5] and the resistance to UV radiation (modified method based on LVS EN 14836) [6]. Experiments were realized on the purposefully selected samples. The results were evaluated in the correlation with potential changes of Shore C hardness (Shore scale, ISO 7619-1, ISO 868) [7, 8]. The results showed noticeable resistance of the composite material against the mechanical influence and ultraviolet (UV) radiation. The correlation with the composition of the material, activity of binder, definite technological parameters, and the conditions supported during the production, were determined. It was estimated that selected properties and characteristics of the material are strongly dependent from the composition and technological parameters used in production of the composite material, and from the size of rubber crumb. Obtained results show possibility to attain desirable changes in the composite material properties by changing both the composition and technological parameters of examined material.

  14. Technological Aspects of Forming the Surface Microrelief of Low-Wear Coatings after Electro-Diamond Grinding

    NASA Astrophysics Data System (ADS)

    Burov, V. G.; Yanpolskiy, V. V.; Rakhimyanov, K. Kh

    2016-04-01

    The results of electro-diamond grinding of coatings based on the WC25 powder material are presented in the paper. It is shown that after electro-diamond grinding of the WC25 coating, an obtained magnitude (Ra=2.02µm) of surface roughness doesn’t meet the qualifying standards to parts surface working in wear-out conditions. The forming of the obtained microrelief is probably connected to the features of electrochemical dissolution of the WC25 coating material in the electrolyte being used. Based on the polarization studies, it is revealed that the electrochemical dissolution character of the indicated coating in the water solution of 10%NaNO3 is determined by the dissolution character of cobalt (Co) component. The intensive cobalt (Co) dissolution during the electro-diamond grinding of the WC25 coating leads to the tungsten carbide chipping by the grinding disk particles that increases the roughness. One of the way to improve the surface quality of low-wear coatings after electro-diamond grinding is an introduction of an additional step in a technological process, carrying out with the switched off source of technological current. For realization of the process according to this scheme a technological dimension chain is made which takes into consideration the dissolution value of the most active coating composition element while the calculating of the operating dimensions of a detail.

  15. 31 CFR 592.310 - Rough diamond.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Rough diamond. 592.310 Section 592.310... ASSETS CONTROL, DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means any diamond that is unworked or simply sawn,...

  16. 31 CFR 592.310 - Rough diamond.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance:Treasury 3 2012-07-01 2012-07-01 false Rough diamond. 592.310 Section 592.310... ASSETS CONTROL, DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means any diamond that is unworked or simply sawn,...

  17. 31 CFR 592.310 - Rough diamond.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false Rough diamond. 592.310 Section 592.310... ASSETS CONTROL, DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means any diamond that is unworked or simply sawn,...

  18. 31 CFR 592.310 - Rough diamond.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Rough diamond. 592.310 Section 592.310... ASSETS CONTROL, DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means any diamond that is unworked or simply sawn,...

  19. 31 CFR 592.310 - Rough diamond.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Rough diamond. 592.310 Section 592... FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY ROUGH DIAMONDS CONTROL REGULATIONS General Definitions § 592.310 Rough diamond. The term rough diamond means any diamond that is unworked or simply...

  20. Properties of recycled polypropylene based composites incorporating treated hardwood sawdust

    NASA Astrophysics Data System (ADS)

    Shulga, Galia; Jaunslavietis, Jevgenijs; Ozolins, Jurijs; Neiberte, Brigita; Verovkins, Anrijs; Vitolina, Sanita; Shakels, Vadims

    2016-05-01

    The effect of different treatment of hardwood sawdust under mild conditions on contact angles, adhesion energy and water sorption was studied. A comparison of these indices for the hardwood treated sawdust and the composites filled with them was performed. The treatment promoted the compatibility between the recycled polypropylene and the hardwood filler. The inclusion of the lignin-based compatibiliser in the composite, containing the ammoxidised wood filler, essentially improved its mechanical properties.

  1. Fractal dimension and surface topography on the diamond deposition of seeded WC-Co substrates

    NASA Astrophysics Data System (ADS)

    Chou, C.-C.; Lin, H.-H.

    2010-04-01

    Diamond thin films were deposited on WC-Co substrates by hot filament chemical vapor deposition to improve the tribological performance. The influence of the substrate surface topography was found to play an important role during the nucleation stage and the later growth rate as well. In this study, we systematically investigated the relation between substrate surface irregularity, which was evaluated by fractal dimension as well as statistical roughness parameters and the quality of the later deposited diamond film. Preseeding processes, in diamond acetone suspensions with two particle diameters, by supersonic vibrator were also implemented to investigate the effect of particular size on diamond nucleation. The original surfaces were measured with a stylus profiler and contact-mode atomic force microscopy. The diamond deposited substrates were examined by scanning electron microscopy, x-ray diffractometry, Raman spectroscopy, and Rockwell-C indentation to study substrate topography, crystalline structure of the coating, the composition of diamond films, and adhesion between deposited layers and substrates, respectively. The synergetic influence of the substrate's fractal dimension and the particular size of pre-seeding diamond suspension were studied and addressed. The deposited film of a WC-Co substrate with higher surface fractal dimension (>2.50), preseeded by fine diamond suspension (4-12 nm particle size) in advance, has a high diamond-rich composition and adhesion strength.

  2. Redox-freezing and nucleation of diamond via magnetite formation in the Earth's mantle.

    PubMed

    Jacob, Dorrit E; Piazolo, Sandra; Schreiber, Anja; Trimby, Patrick

    2016-01-01

    Diamonds and their inclusions are unique probes into the deep Earth, tracking the deep carbon cycle to >800 km. Understanding the mechanisms of carbon mobilization and freezing is a prerequisite for quantifying the fluxes of carbon in the deep Earth. Here we show direct evidence for the formation of diamond by redox reactions involving FeNi sulfides. Transmission Kikuchi Diffraction identifies an arrested redox reaction from pyrrhotite to magnetite included in diamond. The magnetite corona shows coherent epitaxy with relict pyrrhotite and diamond, indicating that diamond nucleated on magnetite. Furthermore, structures inherited from h-Fe3O4 define a phase transformation at depths of 320-330 km, the base of the Kaapvaal lithosphere. The oxidation of pyrrhotite to magnetite is an important trigger of diamond precipitation in the upper mantle, explaining the presence of these phases in diamonds. PMID:27327434

  3. Redox-freezing and nucleation of diamond via magnetite formation in the Earth's mantle

    NASA Astrophysics Data System (ADS)

    Jacob, Dorrit E.; Piazolo, Sandra; Schreiber, Anja; Trimby, Patrick

    2016-06-01

    Diamonds and their inclusions are unique probes into the deep Earth, tracking the deep carbon cycle to >800 km. Understanding the mechanisms of carbon mobilization and freezing is a prerequisite for quantifying the fluxes of carbon in the deep Earth. Here we show direct evidence for the formation of diamond by redox reactions involving FeNi sulfides. Transmission Kikuchi Diffraction identifies an arrested redox reaction from pyrrhotite to magnetite included in diamond. The magnetite corona shows coherent epitaxy with relict pyrrhotite and diamond, indicating that diamond nucleated on magnetite. Furthermore, structures inherited from h-Fe3O4 define a phase transformation at depths of 320-330 km, the base of the Kaapvaal lithosphere. The oxidation of pyrrhotite to magnetite is an important trigger of diamond precipitation in the upper mantle, explaining the presence of these phases in diamonds.

  4. Nucleation mechanism for the direct graphite-to-diamond phase transition.

    PubMed

    Khaliullin, Rustam Z; Eshet, Hagai; Kühne, Thomas D; Behler, Jörg; Parrinello, Michele

    2011-09-01

    Graphite and diamond have comparable free energies, yet forming diamond from graphite in the absence of a catalyst requires pressures that are significantly higher than those at equilibrium coexistence. At lower temperatures, the formation of the metastable hexagonal polymorph of diamond is favoured instead of the more stable cubic diamond. These phenomena cannot be explained by the concerted mechanism suggested in previous theoretical studies. Using an ab initio quality neural-network potential, we carried out a large-scale study of the graphite-to-diamond transition assuming that it occurs through nucleation. The nucleation mechanism accounts for the observed phenomenology and reveals its microscopic origins. We demonstrate that the large lattice distortions that accompany the formation of diamond nuclei inhibit the phase transition at low pressure, and direct it towards the hexagonal diamond phase at higher pressure. The proposed nucleation mechanism should improve our understanding of structural transformations in a wide range of carbon-based materials. PMID:21785417

  5. Raman investigation of diamond films

    SciTech Connect

    Feng, Li-Ming

    1993-12-31

    Extensive Raman investigations were conducted on a wide range of diamond films whose structures were dilineated by optical and confocal microscopy. The Raman Spectra from one extreme of this range indicates a very intense 1331 cm{sup {minus}1} line diagnostic of bulk crystalline diamond. Microscopy of the corresponding film shows the presence of many large true diamond crystallite. The 1331 cm{sup {minus}1} Raman line at the other extreme of the range, however, is virtually absent. It is replaced, at this extreme, by a very broad Raman contour whose maxima occur near 1355 cm{sup {minus}1} and 1575 cm{sup {minus}1}. Optical microscopy now reveals a complete lack of diamond crystallites. The ratio of the integrated Raman intensity of the 1331 cm{sup {minus}1} diamond line to the integral of the entire broad contour extending from {approx}1200 cm{sup {minus}1} to 1800 cm{sup {minus}1}, with maxima near 1355 cm{sup {minus}1} and 1575 cm{sup {minus}1}, was determined. This ratio rises with increasing diamond crystallite size, and it decreases as true diamond crystallites are replaced by diamond-like, but amorphous, hard carbon, which produces the broad Raman contour. The measured intensity ratio was analyzed in terms of a differential equation related to phonon coupling. The increase of the intensity ratio of the 1331 cm{sup {minus}1} diagnostic diamond peak is due to phono-phonon coupling between the diamond crystallites, as the concentration of the amorphous diamond-like carbon decreases. Confocal microscopy indicates many amorphous-like regions interspersed between diamond crystallites which account for the intensity loss, and agree with the Raman intensity measurements. These Raman measurements crystallinity versus amorphous hard-carbon character of thin diamond film.

  6. Diamond Turning Of Infra-Red Components

    NASA Astrophysics Data System (ADS)

    Hodgson, B.; Lettington, A. H.; Stillwell, P. F. T. C.

    1986-05-01

    Single point diamond machining of infra-red optical components such as aluminium mirrors, germanium lenses and zinc sulphide domes is potentially the most cost effective method for their manufacture since components may be machined from the blanks to a high surface finish, requiring no subsequent polishing, in a few minutes. Machines for the production of flat surfaces are well established. Diamond turning lathes for curved surfaces however require a high capital investment which can be justified only for research purposes or high volume production. The present paper describes the development of a low cost production machine based on a Bryant Symons diamond turning lathe which is able to machine spherical components to the required form and finish. It employs two horizontal spindles one for the workpiece the other for the tool. The machined radius of curvature is set by the alignment of the axes and the radius of the tool motion, as in conventional generation. The diamond tool is always normal to the workpiece and does not need to be accurately profiled. There are two variants of this basic machine. For machining hemispherical domes the axes are at right angles while for lenses with positive or negative curvature these axes are adjustable. An aspherical machine is under development, based on the all mechanical spherical machine, but in which a ± 2 mm aspherecity may be imposed on the best fit sphere by moving the work spindle under numerical control.

  7. Potassium in clinopyroxene inclusions from diamonds.

    PubMed

    Harlow, G E; Veblen, D R

    1991-02-01

    Analytical transmission electron microscopy, electron microprobe analyses, and singlecrystal x-ray diffraction data support the conclusion that high potassium contents, up to 1.5 weight percent K(2)O, of some diopside and omphacite inclusions from diamonds represent valid clinopyroxene compositions with K in solid solution. This conclusion contradicts the traditional view of pyroxene crystal chemistry, which holds that K is too large to be incorporated in the pyroxene structure. These diopside and omphacite inclusions have a high degree of crystal perfection and anomalously large unit-cell volumes, and a defect-free structure is observed in K-bearing regions when imaged by transmission electron microscopy. These observations imply that clinopyroxene can be a significant host for K in the mantle and that some clinopyroxene inclusions and their diamond hosts may have grown in a highly K-enriched environment. PMID:17741381

  8. Isotopic homojunction band engineering from diamond.

    PubMed

    Watanabe, H; Nebel, C E; Shikata, S

    2009-06-12

    Confinement of charge carriers in semiconductors by quantum wells is usually accomplished with layers that vary in elemental composition, such as aluminum gallium arsenide and gallium arsenide. We fabricated diamond superlattices by creating multilayer structures of isotopically pure carbon isotopes carbon-12 (12C) and carbon-13 (13C), which confine electrons by a difference in band-gap energy of 17 millielectron volts. Cathodoluminescence experiments performed at 80 kelvin showed that excitonic recombination in the higher-energy band of 13C vanishes in favor of increased recombination in the lower-energy 12C material. Carrier confinement was achieved in diamond superlattices made up of both thinner (30 nanometers) and thicker (up to 350 nanometers) layers. PMID:19520955

  9. Modification of diamond growth chemistry and surface properties by fluorine addition

    NASA Astrophysics Data System (ADS)

    Fox, Ciaran Avram

    Interest in the interactions of halogens with diamond surfaces has arisen recently following reports of diamond chemical vapor deposition (CVD) at low substrate temperatures (<500sp°C) and spontaneous nucleation when fluorine precursors were added to the growth process. This study concerns the effect of adding halogenated precursors to the conventional microwave plasma-assisted CVD growth process from theoretical and experimental perspectives. A comparison of the kinetics of hydrogen and fluorine interactions with diamond indicates that fluorine addition should enable low temperature growth of diamond films, if hydrogen abstraction kinetics limit low temperature diamond growth. To test this hypothesis, CFsb4/Hsb2, CHsb3F/Hsb2, and CHsb4/Hsb2 precursor gas mixtures were used to grow diamond films in the 600-900sp°C temperature range. Growth rates and activation energies were measured and found to be essentially independent of fluorine addition. To understand this result, molecular beam mass spectroscopy was used to determine the gas composition near the diamond surface during growth. Surprisingly, this technique revealed the absence of any active fluorine radicals. Consequently, diamond films were grown from atomic hydrogen and CHsb3 radicals using each of the aforementioned precursors, thereby yielding similar growth activation energies. These growth results indicate that the experimental conditions must be substantially modified to transport both atomic fluorine and atomic hydrogen to the diamond surface during growth. Although simultaneous transport of atomic fluorine and atomic hydrogen to the diamond surface proved difficult due to consumption by gas-phase reactions, fluorination of diamond surfaces following growth was possible using plasma techniques. Such a fluorination treatment greatly enhanced the reactivity of diamond surfaces with cesium, ultimately enabling the bonding of cesium with carbon on diamond. The enhanced field emission characteristics

  10. Growth of Diamond from a Carbonaceous Hydrous Silicate Melt: An Experimental Study

    NASA Astrophysics Data System (ADS)

    Fagan, A. J.; Luth, R. W.

    2007-12-01

    Diamond was grown in a hydrous halide-bearing silicate system at pressures and temperatures near those at which natural peridotitic diamonds form (1000-1300° C, 5-7 GPa) in the Earth' s upper mantle. The mechanisms by which diamonds are made within the earth is still unresolved, and many authors have suggested possible media from which diamonds precipitate; examples include mantle carbonates, sulphides and silicates (1-3). To date, little work has been conducted on silicate melts and the effect of mantle catalysts on diamond formation. This study used a hydrous silicate melt (HSM) to attempt to precipitate diamond. The primary experimental system was MgO-SiO2-C-H2O, with subsystems to document the addition of alkali halides (KCl and NaCl). Previous studies have concluded that alkali halides have a catalytic effect on diamond formation reactions and observed halides in inclusions in natural diamonds. Diamond was successfully grown on seed crystals at temperatures of 1400-1500° C and pressures of 6-7 GPa, in 3-4 hours. No spontaneous nucleation of diamond was observed during these experiments. No diamond growth was observed in experiments at < 1400° C and 6 GPa to date. The addition of KCl to the HSM system allowed diamond to form 200° C lower than the previously published minimum temperature of over 1600° C (3). The effect of NaCl and other catalysts are still under investigation. The starting compositions contain ~ 20.6wt% structural H2O. At run conditions, a hydrous melt coexisted with olivine and orthropyroxene, with the halides either dissolved in the melt or forming a separate brine. This study demonstrates that hydrous silicate melts, especially containing alkali halides, are a viable medium for diamond growth in the Earth' s upper mantle. 1) Arima et al, 2002; 2) Gunn & Luth, 2006; 3) Pal' yanov et al, 2007

  11. Three-dimensional graphene-based composites for energy applications

    NASA Astrophysics Data System (ADS)

    Mao, Shun; Lu, Ganhua; Chen, Junhong

    2015-04-01

    Three-dimensional (3D) graphene-based composites have drawn increasing attention for energy applications due to their unique structures and properties. By combining the merits of 3D graphene (3DG), e.g., a porous and interconnected network, a high electrical conductivity, a large accessible surface area, and excellent mechanical strength and thermal stability, with the high chemical/electrochemical activities of active materials, 3DG-based composites show great promise as high-performance electrode materials in various energy devices. This article reviews recent progress in 3DG-based composites and their applications in energy storage/conversion devices, i.e., supercapacitors, lithium-ion batteries, dye-sensitized solar cells, and fuel cells.

  12. A physically-based abrasive wear model for composite materials

    SciTech Connect

    Lee, Gun Y.; Dharan, C.K.H.; Ritchie, Robert O.

    2001-05-01

    A simple physically-based model for the abrasive wear of composite materials is presented based on the mechanics and mechanisms associated with sliding wear in soft (ductile) matrix composites containing hard (brittle) reinforcement particles. The model is based on the assumption that any portion of the reinforcement that is removed as wear debris cannot contribute to the wear resistance of the matrix material. The size of this non-contributing portion of the reinforcement is estimated by modeling the three primary wear mechanisms, specifically plowing, interfacial cracking and particle removal. Critical variables describing the role of the reinforcement, such as its relative size and the nature of the matrix/reinforcement interface, are characterized by a single contribution coefficient, C. Predictions are compared with the results of experimental two-body (pin-on drum) abrasive wear tests performed on a model aluminum particulate-reinforced epoxy matrix composite material.

  13. Predicting mortality based on body composition analysis.

    PubMed Central

    Tellado, J M; Garcia-Sabrido, J L; Hanley, J A; Shizgal, H M; Christou, N V

    1989-01-01

    The role of the Nae/Ke ratio (the ratio of exchangeable sodium to exchangeable potassium) was examined as a nutritional marker in surgical patients in relation to anthropometrical and biochemical indexes by its ability to identify patients at risk for mortality after hospitalization. In 73 patients with sepsis and malnutrition (Training Group, Madrid) the following were determined: percentage of recent weight loss, triceps skin fold, midarm muscle circumference, serum albumin, serum transferrin, delayed hypersensitivity skin test response, total lymphocytes, and Nae/Ke ratio by multiple isotope dilution. The predictive power of Nae/Ke ratio was so strong (F = 105.1; p less than 0.00001) that it displaced anthropometric, biochemical, and immunologic variables from the linear equation derived from stepwise discriminant analysis using hospital mortality as the dependent variable. A theoretical curve of expected deaths was developed, based on an equation obtained by logistic regression analysis: Pr/death/ = 1/(1 + e[11.8-5.2 Nae/Ke]). Pre- and post-test probabilities on that curve allowed us to determine two cut-off values, Nae/Ke ratios of 1.5 and 2.5, which were markers for nonrisk and mortality, respectively. The model was tested in a heterogeneous data base of surgical patients (n = 417) in another hospital (Validation Group, Montreal). For patients exhibiting an abnormal Nae/Ke ratio (greater than 1.2) and a greater than 10% of probability of death, 54 deaths were expected and 53 observed (X2 = 1.8 NS). Two tests confirmed the basic agreement between the model and its performance, a G statistic of -0.704 and the area beneath the "receiver-operating-characteristic" (ROC) curve (Az = 0.904 + 0.0516 for the Madrid group vs. Az = 0.915 + 0.0349 for the Montreal group, NS). It was concluded from this analysis that, compared with the usual anthropometric measurements, the Nae/Ke ratio, if available, is the best method for identifying malnourished patients at risk of

  14. Compressive elastic modulus of natural fiber based binary composites

    NASA Astrophysics Data System (ADS)

    Widayani, Susanah, Y.; Utami, L. S.; Khotimah, S. N.; Viridi, S.

    2012-06-01

    The composites made of bamboo apus fiber - epoxy resin and charcoal - tapioca starch with several compositions have been synthesized. Bamboo fiber powder as the rest of cutting process was refined and filtered by mesh 40 before used. Epoxy resin 1021A and hardener 1021B has been used as resin. The synthesis of epoxy resin-based composites was carried out via simple mixing method by adding adequate 70% ethanol solution before drying. The 100 mesh-filtered dry charcoal was mixed with tapioca mixture before it was pressed and dried to produce briquette composites. To study the compressive elastic modulus of the composites, pressure tests using Mark 10 Pressure Test Machine have been carried out. It was found that all the composites show maximum compressive elastic modulus at certain component compositions. The maximum elastic modulus for bamboo fiber-epoxy resin, charcoal - epoxy resin and charcoal-tapioca starch were observed at 52.9%, 56.3%, and 25.0% of mass fraction of bamboo fiber, charcoal and tapioca starch, respectively.

  15. Composition optimization of chromium carbide based solid lubricant coatings for foil gas bearings at temperatures to 650 C

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher

    1987-01-01

    A test program to determine the optimum composition of chromium carbide based solid lubricant coatings for compliant gas bearings is described. The friction and wear properties of the coatings are evaluated using a foil gas bearing test apparatus. The various coatings were prepared by powder blending, then plasma sprayed onto Inconel 718 test journals and diamond ground to the desired coating thickness and surface finish. The journals were operated against preoxidized nickel-chromium alloy foils. The test bearings were subjected to repeated start/stop cycles under a 14 kPa (2 psi) bearing unit load. The bearings were tested for 9000 start/stop cycles or until the specimen wear reached a predetermined failure level. In general, the addition of silver and eutectic to the chromium carbide base stock significantly reduced foil wear and increased journal coating wear. The optimum coating composition, PS212 (70 wt% metal bonded Cr3C2, 15 wt% Ag, 15% BaF2/CaF2 eutectic), reduced foil wear by a factor of two and displayed coating wear well within acceptable limits. The load capacity of the bearing using the plasma-sprayed coating prior to and after a run-in period was ascertained and compared to polished Inconel 718 specimens.

  16. Diamond Morphology: Link to Metasomatic Events in the Mantle or Record of Evolution of Kimberlitic Fluid?

    NASA Astrophysics Data System (ADS)

    Fedortchouk, Y.

    2009-05-01

    Morphology and surface features on diamonds show tremendous variation even within a single kimberlite body reflecting a complex history of growth and dissolution. But does the diamond surface record the conditions in the several mantle sources sampled by the rising kimberlite magma, or evolution of the fluid system in the kimberlite magma itself? To address this question I revised morphological classification of diamonds from several kimberlite pipes from EKATI Mine property, N.W.T., Canada. The novelty of the approach, compared to the existing classifications, is in utilizing a random but large dataset of diamond dissolution experiments accumulated by several researchers including myself. These experiments have shown that similar forms (e.g. trigon etch pits) can be produced in a variety of conditions and environments, whereas their shape and size would depend on the reactant. Similarly, different types of resorption features always form together and can be used for deriving the composition of oxidizing fluid. The proposed classification method is focused on relating various types of diamond surfaces to the composition and conditions of oxidizing media. The study uses parcels of micro-and macro-diamonds (total of 125 carats) from Misery, Grizzly, Leslie and Koala kimberlites, EKATI Mine property, Northwest Territories, Canada. Only octahedron and hexoctahedron diamonds were selected (total ~600 stones). Diamond surfaces were studied using an optical and Field- Emission Scanning Electron Microscope to define resorption elements - simple surface features. These elements were identified for each of the three categories: 1) present on octahedral faces (well-preserved diamonds), 2) present on hexoctahedral faces (rounded resorbed diamonds), and 3) frosting (micro-features). Consistent associations of several elements define Resorption Types of diamonds, which form during a single oxidizing event. We further relate these types to the composition of the C-H-O + chlorides

  17. Investigation of transferred-electron oscillations in diamond

    NASA Astrophysics Data System (ADS)

    Suntornwipat, N.; Majdi, S.; Gabrysch, M.; Isberg, J.

    2016-05-01

    The recent discovery of Negative Differential Mobility (NDM) in intrinsic single-crystalline diamond enables the development of devices for high frequency applications. The Transferred-Electron Oscillator (TEO) is one example of such devices that uses the benefit of NDM to generate continuous oscillations. This paper presents theoretical investigations of a diamond TEO in the temperature range of 110 to 140 K where NDM has been observed. Our simulations map out the parameter space in which transferred-electron oscillations are expected to occur for a specific device geometry. The results are promising and indicate that it is possible to fabricate diamond based TEO devices.

  18. Tetraethyl orthosilicate-based glass composition and method

    DOEpatents

    Wicks, George G.; Livingston, Ronald R.; Baylor, Lewis C.; Whitaker, Michael J.; O'Rourke, Patrick E.

    1997-01-01

    A tetraethyl orthosilicate-based, sol-gel glass composition with additives selected for various applications. The composition is made by mixing ethanol, water, and tetraethyl orthosilicate, adjusting the pH into the acid range, and aging the mixture at room temperature. The additives, such as an optical indicator, filler, or catalyst, are then added to the mixture to form the composition which can be applied to a substrate before curing. If the additive is an indicator, the light-absorbing characteristics of which vary upon contact with a particular analyte, the indicator can be applied to a lens, optical fiber, reagant strip, or flow cell for use in chemical analysis. Alternatively, an additive such as alumina particles is blended into the mixture to form a filler composition for patching cracks in metal, glass, or ceramic piping.

  19. Photo-excited terahertz switch based on composite metamaterial structure

    NASA Astrophysics Data System (ADS)

    Wang, Guocui; Zhang, Jianna; Zhang, Bo; He, Ting; He, Yanan; Shen, Jingling

    2016-09-01

    A photo-excited terahertz switch based on a composite metamaterial structure was designed by integration of photoconductive silicon into the gaps of split-ring resonators. The conductivity of the silicon that was used to fill the gaps in the split-ring resonators was tuned dynamically as a function of the incident pump power using laser excitation, leading to a change in the composite metamaterial structure's properties. We studied the transmission characteristics of the composite metamaterial structure for various silicon conductivities, and the results indicated that this type of composite metamaterial structure could be used as a resonance frequency tunable terahertz metamaterial switch. We also designed other structures by filling different gaps with silicon, and proved that these structures could be used as terahertz metamaterial switches can change the working mode from a single frequency to multiple frequencies.

  20. Properties of lightweight cement-based composites containing waste polypropylene

    NASA Astrophysics Data System (ADS)

    Záleská, Martina; Pavlíková, Milena; Pavlík, Zbyšek

    2016-07-01

    Improvement of buildings thermal stability represents an increasingly important trend of the construction industry. This work aims to study the possible use of two types of waste polypropylene (PP) for the development of lightweight cement-based composites with enhanced thermal insulation function. Crushed PP waste originating from the PP tubes production is used for the partial replacement of silica sand by 10, 20, 30, 40 and 50 mass%, whereas a reference mixture without plastic waste is studied as well. First, basic physical and thermal properties of granular PP random copolymer (PPR) and glass fiber reinforced PP (PPGF) aggregate are studied. For the developed composite mixtures, basic physical, mechanical, heat transport and storage properties are accessed. The obtained results show that the composites with incorporated PP aggregate exhibit an improved thermal insulation properties and acceptable mechanical resistivity. This new composite materials with enhanced thermal insulation function are found to be promising materials for buildings subsoil or floor structures.

  1. Tetraethyl orthosilicate-based glass composition and method

    DOEpatents

    Wicks, G.G.; Livingston, R.R.; Baylor, L.C.; Whitaker, M.J.; O`Rourke, P.E.

    1997-06-10

    A tetraethyl orthosilicate-based, sol-gel glass composition with additives selected for various applications is described. The composition is made by mixing ethanol, water, and tetraethyl orthosilicate, adjusting the pH into the acid range, and aging the mixture at room temperature. The additives, such as an optical indicator, filler, or catalyst, are then added to the mixture to form the composition which can be applied to a substrate before curing. If the additive is an indicator, the light-absorbing characteristics of which vary upon contact with a particular analyte, the indicator can be applied to a lens, optical fiber, reagent strip, or flow cell for use in chemical analysis. Alternatively, an additive such as alumina particles is blended into the mixture to form a filler composition for patching cracks in metal, glass, or ceramic piping. 12 figs.

  2. Kinetics of diamond-silicon reaction under high pressure-high temperature conditions

    NASA Astrophysics Data System (ADS)

    Pantea, Cristian

    In this dissertation work, the kinetics of the reaction between diamond and silicon at high pressure-high temperature conditions was investigated. This study was motivated by the extremely limited amount of information related to the kinetics of the reaction in diamond-silicon carbide composites formation. It was found that the reaction between diamond and melted silicon and the subsequent silicon carbide formation is a two-stage process. The initial stage is a result of direct reaction of melted silicon with carbon atoms from the diamond surface, the phase boundary reaction. Further growth of SiC is much more complicated and when the outer surfaces of diamond crystals are covered with the silicon carbide layer it involves diffusion of carbon and silicon atoms through the SiC layer. The reaction takes place differently for the two regions of stability of carbon. In the graphite-stable region, the reaction between diamond and melted silicon is associated with the diamond-to-graphite phase transition, while in the diamond-stable region there is no intermediary step for the reaction. The data obtained at HPHT were fitted by the Avrami-Erofeev equation. It was found that the reaction is isotropic, the beta-SiC grown on different faces of the diamond crystals showing the same reaction rate, and that the controlling mechanism for the reaction is the diffusion. In the graphite-stable region the activation energy, 402 kJ/mol is slightly higher than in the diamond-stable region, 260 kJ/mol, as the reaction between diamond and melted silicon is associated with the diamond-to-graphite phase transition, which has higher activation energy. In the diamond-stable region, the calculated activation energy is higher for micron size diamond powders (≈260 kJ/mol), while for nanocrystalline diamond powders a lower value of 170 kJ/mol was obtained. This effect was attributed to nanocrystalline structure and strained bonds within grain boundaries in SiC formed from nanosize diamond

  3. High pressure synthesis of novel, zeolite based nano-composite materials

    NASA Astrophysics Data System (ADS)

    Santoro, Mario

    2013-06-01

    Meso/micro-porous solids such as zeolites are complex materials exhibiting an impressive range of applications, including molecular sieve, gas storage, catalysis, electronics and photonics. We used these materials, particularly non catalytic zeolites in an entirely different fashion. In fact, we performed high pressure (0.5-30 GPa) chemical reactions of simple molecules on a sub-nanometer scale in the channels of a pure SiO2 zeolite, silicalite to obtain unique nano-composite materials with drastically modified physical and chemical properties. Our material investigations are based on a combination of X-ray diffraction and optical spectroscopy techniques in the diamond anvil cell. I will first briefly show how silicalite can be easily filled by simple molecules such as Ar, CO2 and C2H4 among others from the fluid phase at high pressures, and how this efficient filling removes the well known pressure induced amorphization of the silica framework (Haines et al., JACS 2010). I will then present on a silicon carbonate crystalline phase synthesized by reacting silicalite and molecular CO2 that fills the nano-pores, at 18-26 GPa and 600-980 K; after the synthesis the compound is temperature quenched and it results to be slightly metastable at room conditions (Santoro et al., PNAS 2011). On the other hand, a stable at room condition spectacular crystalline nano-composite is obtained by photo-polymerizing ethylene at 0.5-1.5 GPa under UV (351-364 nm) irradiation in the channels of silicalite (Santoro et al., Nat. Commun, in press 2013). For this composite we obtained a structure with single polyethylene chains adapting very well to the confining channels, which results in significant increases in bulk modulus and density, and the thermal expansion coefficient changes sign from negative to positive with respect to the original silicalite host. Mechanical properties may thus be tuned by varying the amount of polymerized ethylene. We then think our findings could allow the

  4. Genetics Home Reference: Diamond-Blackfan anemia

    MedlinePlus

    ... Home Health Conditions Diamond-Blackfan anemia Diamond-Blackfan anemia Enable Javascript to view the expand/collapse boxes. ... PDF Open All Close All Description Diamond-Blackfan anemia is a disorder of the bone marrow . The ...

  5. Nanocrystalline diamond for medicine

    NASA Astrophysics Data System (ADS)

    Mitura, Stanislaw

    1997-06-01

    The unique properties of thin amorphous diamond layers make them perspective candidates for producing advanced micro- electronic devices, coatings for cutting tools and optics. Moreover, due to the highest bicompatibility of carbon resulting from the presence of this element in human body, it appears to be a potential biomaterial. Until present the amorphous diamond has found industrial applications in some areas. One of the applications of the carbon layers are coatings for medical implants. The studies of carbon films as coatings for implants in surgery were aimed on the investigations of biological resistance of implants, histopathological investigations on laboratory animals, tests of corrosion resistance, measurements of mechanical properties and a breakdown test in Tyrod solution. The current state of published work in the subject is reviewed in the paper together with a discussion concerning classification of this material.

  6. 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.

  7. Twinning of cubic diamond explains reported nanodiamond polymorphs.

    PubMed

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

    2015-01-01

    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 (<121> 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. PMID:26671288

  8. Twinning of cubic diamond explains reported nanodiamond polymorphs

    PubMed Central

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

    2015-01-01

    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. PMID:26671288

  9. Polycrystalline-Diamond MEMS Biosensors Including Neural Microelectrode-Arrays.

    PubMed

    Varney, Michael W; Aslam, Dean M; Janoudi, Abed; Chan, Ho-Yin; Wang, Donna H

    2011-01-01

    Diamond is a material of interest due to its unique combination of properties, including its chemical inertness and biocompatibility. Polycrystalline diamond (poly-C) has been used in experimental biosensors that utilize electrochemical methods and antigen-antibody binding for the detection of biological molecules. Boron-doped poly-C electrodes have been found to be very advantageous for electrochemical applications due to their large potential window, low background current and noise, and low detection limits (as low as 500 fM). The biocompatibility of poly-C is found to be comparable, or superior to, other materials commonly used for implants, such as titanium and 316 stainless steel. We have developed a diamond-based, neural microelectrode-array (MEA), due to the desirability of poly-C as a biosensor. These diamond probes have been used for in vivo electrical recording and in vitro electrochemical detection. Poly-C electrodes have been used for electrical recording of neural activity. In vitro studies indicate that the diamond probe can detect norepinephrine at a 5 nM level. We propose a combination of diamond micro-machining and surface functionalization for manufacturing diamond pathogen-microsensors. PMID:25586924

  10. Polycrystalline-Diamond MEMS Biosensors Including Neural Microelectrode-Arrays

    PubMed Central

    Varney, Michael W.; Aslam, Dean M.; Janoudi, Abed; Chan, Ho-Yin; Wang, Donna H.

    2011-01-01

    Diamond is a material of interest due to its unique combination of properties, including its chemical inertness and biocompatibility. Polycrystalline diamond (poly-C) has been used in experimental biosensors that utilize electrochemical methods and antigen-antibody binding for the detection of biological molecules. Boron-doped poly-C electrodes have been found to be very advantageous for electrochemical applications due to their large potential window, low background current and noise, and low detection limits (as low as 500 fM). The biocompatibility of poly-C is found to be comparable, or superior to, other materials commonly used for implants, such as titanium and 316 stainless steel. We have developed a diamond-based, neural microelectrode-array (MEA), due to the desirability of poly-C as a biosensor. These diamond probes have been used for in vivo electrical recording and in vitro electrochemical detection. Poly-C electrodes have been used for electrical recording of neural activity. In vitro studies indicate that the diamond probe can detect norepinephrine at a 5 nM level. We propose a combination of diamond micro-machining and surface functionalization for manufacturing diamond pathogen-microsensors. PMID:25586924

  11. Hexagonal diamonds in meteorites: implications.

    PubMed

    Hanneman, R E; Strong, H M; Bundy, F P

    1967-02-24

    A new polymorph of carbon, hexagonal diamond, has been discovered in the Canyon Diablo and Goalpara meteorites. This phase had been synthesized recently under specific high-pressure conditions in the laboratory. Our results: provide strong evidence that diamonds found in these meteorites were produced by intense shock pressures acting on crystalline graphite inclusions present within the meteorite before impact, rather than by disintegration of larger, statically grown diamonds, as some theories propose. PMID:17830485

  12. Diamond films for laser hardening

    NASA Technical Reports Server (NTRS)

    Albin, S.; Watkins, L.; Ravi, K.; Yokota, S.

    1989-01-01

    Laser-damage experiments were performed on free-standing polycrystalline diamond films prepared by plasma-enhanced CVD. The high laser-induced stress resistance found for this material makes it useful for thin-film coatings for laser optics. Results for diamond-coated silicon substrates demonstrate the enhanced damage threshold imparted by diamond thin-film coatings to materials susceptible to laser damage.

  13. Conversion of fullerenes to diamond

    DOEpatents

    Gruen, Dieter M.

    1993-01-01

    A method of forming synthetic diamond on a substrate is disclosed. The method involves providing a substrate surface covered with a fullerene or diamond coating, positioning a fullerene in an ionization source, creating a fullerene vapor, ionizing fullerene molecules, accelerating the fullerene ions to energies above 250 eV to form a fullerene ion beam, impinging the fullerene ion beam on the substrate surface and continuing these steps to obtain a diamond thickness on the substrate.

  14. Conversion of fullerenes to diamond

    DOEpatents

    Gruen, Dieter M.

    1994-01-01

    A method of forming synthetic diamond on a substrate. The method involves providing a substrate surface covered with a fullerene or diamond coating, positioning a fullerene in an ionization source, creating a fullerene vapor, ionizing fullerene molecules, accelerating the fullerene ions to energies above 250 eV to form a fullerene ion beam, impinging the fullerene ion beam on the substrate surface and continuing these steps to obtain a diamond film thickness on the substrate.

  15. Diamond turning of glass

    SciTech Connect

    Blackley, W.S.; Scattergood, R.O.

    1988-12-01

    A new research initiative will be undertaken to investigate the critical cutting depth concepts for single point diamond turning of brittle, amorphous materials. Inorganic glasses and a brittle, thermoset polymer (organic glass) are the principal candidate materials. Interrupted cutting tests similar to those done in earlier research are Ge and Si crystals will be made to obtain critical depth values as a function of machining parameters. The results will provide systematic data with which to assess machining performance on glasses and amorphous materials

  16. DIAMOND SECONDARY EMITTER

    SciTech Connect

    BEN-ZVI, I.; RAO, T.; BURRILL, A.; CHANG, X.; GRIMES, J.; RANK, J.; SEGALOV, Z.; SMEDLEY, J.

    2005-10-09

    We present the design and experimental progress on the diamond secondary emitter as an electron source for high average power injectors. The design criteria for average currents up to 1 A and charge up to 20 nC are established. Secondary Electron Yield (SEY) exceeding 200 in transmission mode and 50 in emission mode have been measured. Preliminary results on the design and fabrication of the self contained capsule with primary electron source and secondary electron emitter will also be presented.

  17. DIAMOND PEAK WILDERNESS, OREGON.

    USGS Publications Warehouse

    Sherrod, David R.; Moyle, Phillip R.

    1984-01-01

    No metallic mineral resources were identified during a mineral survey of the Diamond Peak Wilderness in Oregon. Cinder cones within the wilderness contain substantial cinder resources, but similar deposits that are more accessible occur outside the wilderness. The area could have geothermal resources, but available data are insufficient to evaluate their potential. Several deep holes could be drilled in areas of the High Cascades outside the wilderness, from which extrapolations of the geothermal potential of the several Cascade wilderness could be made.

  18. Application of diamond films to electric propulsion: Low energy sputter yield measurement and MPD plasma assisted chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Blandino, John Joseph

    One application of chemically vapor deposited (CVD) diamond films under evaluation at the Jet Propulsion Laboratory is the coating of ion thruster electrodes subject to sputter erosion from xenon ions. Sputter yields were measured for polycrystalline diamond, single crystal diamond, a carbon-carbon composite, and molybdenum subject to xenon ion bombardment. The tests were performed using a 3 cm Kaufman ion source to produce incident ions with energy in the range of 150--750 eV and a profilometry-based technique to measure the amount of sputtered material. The yields increased monotonically with energy with values ranging from 0.16 atoms/ion at 150 eV to 0.80 at 750 eV for the molybdenum and 0.06 to 0.14 for the carbon-carbon. At 150 eV the yield for both diamond samples was 0.07 and at 7 50 eV, 0.19 and 0.17 for the CVD and single crystal diamond respectively. In terms of erosion rate, this translates into a factor of 7--12 lower erosion rate for diamond compared to molybdenum and at least a factor of 1.5 compared to carbon-carbon. In addition, an experimental investigation of an electromagnetic (magnetoplasmadynamic or MPD) plasma source for diamond CVD was undertaken using gas mixtures of methane, hydrogen and argon. Numerous trials were conducted using methane to hydrogen mixture ratios of 1.5--3.5 percent by volume, four different methane injector configurations, and substrate biasing at potentials of 25--75 V positive with respect to facility ground. These tests were performed at discharge currents of 700--950 A at approximately 18 V (12--17 kW). Crystalline films were produced with growth rates of 0.8 to 6.3 microns/hr. X-ray diffraction spectroscopy was used to identify at least one unambiguous diamond peak in each sample. The films all exhibited poor Raman spectra with no well defined peak at 1332 cm-1 and a broad background possibly due to high background levels of nitrogen, defects, and metal vapor contamination. Finally, the potential benefits of the MPD

  19. DIAMONDS: a new Bayesian nested sampling tool

    NASA Astrophysics Data System (ADS)

    Corsaro, Enrico; De Ridder, Joris

    2015-09-01

    In the context of high-quality asteroseismic data provided by the NASA Kepler Mission, we developed a new code, termed DIAMONDS (high-DImensional And multi-MOdal NesteD Sampling), for fast Bayesian parameter estimation and model comparison by means of the Nested Sampling Monte Carlo (NSMC) algorithm, an efficient and powerful method very suitable for high-dimensional problems (like the peak bagging analysis of solar-like oscillations) and multi-modal problems (i.e. problems that show multiple solutions). We applied the code to the peak bagging analysis of solar-like oscillations observed in a challenging F-type star. By means of DIAMONDS one is able to detect the different backgrounds in the power spectrum of the star (e.g. stellar granulation and faculae activity) and to understand whether one or two oscillation peaks can be identified or not. In addition, we demonstrate a novel approach to peak bagging based on multi-modality, which is able to reduce significantly the number of free parameters involved in the peak bagging model. This novel approach is therefore of great interest for possible future automatization of the entire analysis technique. Software package available at the DIAMONDS code website: http://https://fys.kuleuven.be/ster/Software/Diamonds/.

  20. Microcrystalline diamonds in the oceanic lithosphere and their nature

    NASA Astrophysics Data System (ADS)

    Galimov, E. M.; Sevastyanov, V. S.; Karpov, G. A.; Shilobreeva, S. N.; Maksimov, A. P.

    2016-07-01

    The carbon isotope composition of microdiamonds found in products of the Tolbachik Volcano eruption, Kamchatka (porous lavas and ash), was studied. The isotope composition of microdiamonds (with an average value of δ13C =-25.05‰) is close to that of microsized carbon particles in lavas (from-28.9 to-25.3‰). The general peculiarities of the diamond-forming environment include (1) no evidence for high pressure in the medium; (2) a reduced environment; and (3) mineralogical evidence for the presence of a fluid. The geochemical data characterizing the type of diamonds studied allow us to suggest that they were formed in accordance with the mechanism of diamond synthesis during cavitation in a rapidly migrating fluid, which was suggested by E.M. Galimov.

  1. Origins of Majoritic Inclusions in Diamond

    NASA Astrophysics Data System (ADS)

    Kiseeva, K.; Wood, B. J.; Ghosh, S. K.; Stachel, T.

    2015-12-01

    Mineral inclusions in diamonds are the only available samples from the transition zone and the lower mantle. The dominant type of inclusions for the range of transition zone (410-660 km) pressures is majoritic garnet, a high-pressure Si-rich tetragonal garnet which crystallises when pyroxene breaks down and dissolves in the garnet structure. Two majoritic garnet endmembers: Na2MgSi5O12 and Mg4Si4O12 can be distinguished for eclogitic and peridotitic parageneses, respectively. In our recent study [1] we used these idealised substitutions to show that the majority of majoritic garnets reported in the literature belong to neither eclogitic nor peridotitic lithologies and rather crystallised from a wide range of intermediate compositions, referred to as pyroxenites [1]. Here we elaborate on the origin and composition of the pyroxenite lithology. According to Si geobarometry most majoritic garnet inclusions formed at mantle transition zone pressures, predominantly within the stability field of clinopyroxene + garnet. Using experimental partition coefficients for Na, Al, Mg and Fe between garnet and clinopyroxene, we have calculated the compositions of clinopyroxene in equilibrium with majoritic garnet, which allows us to estimate the locus of possible bulk rock compositions. These lie in the field of upper mantle pyroxenites as defined by Hirschmann and Stolper [2]. We also find that occasional clinopyroxene inclusions in diamond actually coexisting with majoritic garnet inclusions are all close in composition to those predicted by our study. Additionally, we show experimentally that the pyroxenite-diamond association is probably a consequence of the interaction between basaltic and peridotitic compositions in the presence of carbonate melt and that layering of pyroxenites is a natural consequence of this interaction. Reduction of carbonate to carbon at high pressures is responsible for the genetic connection between pyroxenite and diamond and the abundance of

  2. DIAMOND AMPLIFIER FOR PHOTOCATHODES.

    SciTech Connect

    RAO,T.; BEN-ZVI,I.; BURRILL,A.; CHANG,X.; HULBERT,S.; JOHNSON,P.D.; KEWISCH,J.

    2004-06-21

    We report a new approach to the generation of high-current, high-brightness electron beams. Primary electrons are produced by a photocathode (or other means) and are accelerated to a few thousand electron-volts, then strike a specially prepared diamond window. The large Secondary Electron Yield (SEY) provides a multiplication of the number of electrons by about two orders of magnitude. The secondary electrons drift through the diamond under an electric field and emerge into the accelerating proper of the ''gun'' through a Negative Electron Affinity surface of the diamond. The advantages of the new approach include the following: (1) Reduction of the number of primary electrons by the large SEY, i.e. a very low laser power in a photocathode producing the primaries. (2) Low thermal emittance due to the NEA surface and the rapid thermalization of the electrons. (3) Protection of the cathode from possible contamination from the gun, allowing the use of large quantum efficiency but sensitive cathodes. (4) Protection of the gun from possible contamination by the cathode, allowing the use of superconducting gun cavities. (5) Production of high average currents, up to ampere class. (6) Encapsulated design, making the ''load-lock'' systems unnecessary. This paper presents the criteria that need to be taken into account in designing the amplifier.

  3. Conversion of fullerenes to diamonds

    DOEpatents

    Gruen, Dieter M.

    1995-01-01

    A method of forming synthetic diamond or diamond-like films on a substrate surface. The method involves the steps of providing a vapor selected from the group of fullerene molecules or an inert gas/fullerene molecule mixture, providing energy to the fullerene molecules consisting of carbon-carbon bonds, the energized fullerene molecules breaking down to form fragments of fullerene molecules including C.sub.2 molecules and depositing the energized fullerene molecules with C.sub.2 fragments onto the substrate with farther fragmentation occurring and forming a thickness of diamond or diamond-like films on the substrate surface.

  4. 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

  5. A physically based model for stress sensing using magnetostrictive composites

    NASA Astrophysics Data System (ADS)

    Yoffe, Alexander; Weber, Yarden; Shilo, Doron

    2015-12-01

    Magnetostrictive composites are of considerable interest for real-time remote force sensing and structural health monitoring. In this paper, we introduce a new procedure for modeling the magnetic field induced by an external load applied on an epoxy-based composite material filled with Terfenol-D particles. This model is based on an assumed sequence of physical processes that occur at the microscopic scale, and it includes both domain switching and magnetization rotation. The modeling procedure is demonstrated on a problem relevant for load sensing applications in which the magnetostrictive composite is subjected to a uniaxial compression. Comparison of the calculated and experimental results strengthens the validity of the assumed sequence of physical processes and provides valuable insights important for application developments.

  6. Annealing dependence of diamond-metal Schottky barrier heights probed by hard x-ray photoelectron spectroscopy

    SciTech Connect

    Gaowei, M.; Muller, E. M.; Rumaiz, A. K.; Weiland, C.; Cockayne, E.; Woicik, J. C.; Jordan-Sweet, J.; Smedley, J.

    2012-05-14

    Hard x-ray photoelectron spectroscopy was applied to investigate the diamond-metal Schottky barrier heights for several metals and diamond surface terminations. The position of the diamond valence-band maximum was determined by theoretically calculating the diamond density of states and applying cross section corrections. The diamond-platinum Schottky barrier height was lowered by 0.2 eV after thermal annealing, indicating annealing may increase carrier injection in diamond devices leading to photoconductive gain. The platinum contacts on oxygen-terminated diamond was found to provide a higher Schottky barrier and therefore a better blocking contact than that of the silver contact in diamond-based electronic devices.

  7. Additives for cement compositions based on modified peat

    NASA Astrophysics Data System (ADS)

    Kopanitsa, Natalya; Sarkisov, Yurij; Gorshkova, Aleksandra; Demyanenko, Olga

    2016-01-01

    High quality competitive dry building mixes require modifying additives for various purposes to be included in their composition. There is insufficient amount of quality additives having stable properties for controlling the properties of cement compositions produced in Russia. Using of foreign modifying additives leads to significant increasing of the final cost of the product. The cost of imported modifiers in the composition of the dry building mixes can be up to 90% of the material cost, depending on the composition complexity. Thus, the problem of import substitution becomes relevant, especially in recent years, due to difficult economic situation. The article discusses the possibility of using local raw materials as a basis for obtaining dry building mixtures components. The properties of organo-mineral additives for cement compositions based on thermally modified peat raw materials are studied. Studies of the structure and composition of the additives are carried out by physicochemical research methods: electron microscopy and X-ray analysis. Results of experimental research showed that the peat additives contribute to improving of cement-sand mortar strength and hydrophysical properties.

  8. Durability-based design criteria for an automotive structural composite

    SciTech Connect

    Corum, J.M.; Battiste, R.L.; Brinkman, C.R.; Ren, W.; Ruggles, M.B.; Yahr, G.T.

    1998-11-01

    Before composite structures can be widely used in automotive applications, their long-term durability must be assured. The Durability of Lightweight Composite Structures Project at Oak Ridge National Laboratory was established by the US Department of Energy to help provide that assurance. The project is closely coordinated with the Automotive Composites Consortium. The experimentally-based, durability-driven design criteria described in this paper are the result of the initial project thrust. The criteria address a single reference composite, which is an SRIM (Structural Reaction Injection Molded) polyurethane, reinforced with continuous strand, swirl-mat E-glass fibers. The durability issues addressed include the effects of cyclic and sustained loadings, temperature, automotive fluid environments, and low-energy impacts (e.g., tool drops and roadway kickups) on strength, stiffness, and deformation. The criteria provide design analysis guidance, a multiaxial strength criterion, time-independent and time-dependent allowable stresses, rules for cyclic loading, and damage tolerance design guidance. Environmental degradation factors and the degrading effects of prior loadings are included. Efforts are currently underway to validate the criteria by application to a second random-glass-fiber composite. Carbon-fiber composites are also being addressed.

  9. Tracing the Source of Borneo's Cempaka Diamond Deposit

    NASA Astrophysics Data System (ADS)

    White, L. T.; Graham, I.; Armstrong, R. A.; Hall, R.

    2014-12-01

    Several gem quality diamond deposits are found in paleo-alluvial deposits across Borneo. The source of the diamonds and their origin are enigmatic. They could have formed in Borneo and be derived from local sources, or they could be related to diamond deposits in NW Australia, and carried with the Southwest Borneo Block after it rifted from Australia in the Late Jurassic. We collected U-Pb isotopic data from detrital zircons from the Cempaka alluvial diamond deposit in southeast Borneo. Two thirds of the zircons that were dated crystallized between 75 Ma and 110 Ma. The other third are Triassic or older (223 Ma, 314-319 Ma, 353-367 Ma, 402-414 Ma, 474 Ma, 521 Ma, 549 Ma, 1135-1176 Ma, 1535 Ma, 2716 Ma). All of the Cretaceous zircons are angular, euhedral grains with minor evidence of mechanical abrasion. Considering their age and morphology they were likely derived from the nearby Schwaner Granites. The Triassic and older grains are rounded to semi-rounded and were likely derived from Australia before Borneo rifted from Gondwana. Some of the zircons have ages that resemble those of the Merlin and Argyle diamond deposits of Australia. The diamonds themselves have delicate resorption features and overgrowths that would potentially be destroyed with prolonged transport. Geochemical data collected from the diamonds implies they were associated with lamproite intrusions. Deep seismic lines and zircons from igneous rocks suggest SE Borneo, the East Java Sea and East Java are largely underlain by thick lithosphere rifted from NW Australia. Based on several lines of evidence, we propose that diamond-bearing lamproites intruded before rifting of SW Borneo from Australia, or after collision with Sundaland of SW Borneo and the East Java-West Sulawesi Blocks during the Cretaceous. Exposure of the source after the Late Cretaceous led to diamond accumulation in river systems that flowed from the Schwaner Mountains.

  10. A Composition Curriculum Based on James Britton's Theories.

    ERIC Educational Resources Information Center

    Monahan, Brian D.; Zelner, Jane

    In 1979, the Yonkers Public School district (New York) launched a project to design and implement secondary school language arts curriculum guides with an emphasis on written composition. A theoretical framework was developed, based on the work of James Britton and the philosophy of the Bay Area Writing Project (BAWP). Britton's work provided the…

  11. Thermoformed protein based composites in presence of organic acids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    World industrialization has generated substantial quantities of petroleum-based plastics over many years, which are non biodegradable. There is a growing demand for the use of renewable agricultural sources to develop eco-friendly biobased composites. Agriculture-sourced proteins and starches are b...

  12. Novel amine-based presursor compounds and composite membranes thereof

    DOEpatents

    Lee, Eric K. L.; Tuttle, Mark E.

    1989-01-01

    Novel amine-based precursor compounds comprising the condensation products of dialkylenetriamine and alpha, beta-unsaturated acid halides are disclosed, as well as composite membranes containing such compounds, the membranes being useful in RO-type processes for desalination and the removal of low molecular weight organic compounds such as phenols and carboxylic acids.

  13. Automated geospatial Web Services composition based on geodata quality requirements

    NASA Astrophysics Data System (ADS)

    Cruz, Sérgio A. B.; Monteiro, Antonio M. V.; Santos, Rafael

    2012-10-01

    Service-Oriented Architecture and Web Services technologies improve the performance of activities involved in geospatial analysis with a distributed computing architecture. However, the design of the geospatial analysis process on this platform, by combining component Web Services, presents some open issues. The automated construction of these compositions represents an important research topic. Some approaches to solving this problem are based on AI planning methods coupled with semantic service descriptions. This work presents a new approach using AI planning methods to improve the robustness of the produced geospatial Web Services composition. For this purpose, we use semantic descriptions of geospatial data quality requirements in a rule-based form. These rules allow the semantic annotation of geospatial data and, coupled with the conditional planning method, this approach represents more precisely the situations of nonconformities with geodata quality that may occur during the execution of the Web Service composition. The service compositions produced by this method are more robust, thus improving process reliability when working with a composition of chained geospatial Web Services.

  14. Colloidal-based additive manufacturing of bio-inspired composites

    NASA Astrophysics Data System (ADS)

    Studart, Andre R.

    Composite materials in nature exhibit heterogeneous architectures that are tuned to fulfill the functional demands of the surrounding environment. Examples range from the cellulose-based organic structure of plants to highly mineralized collagen-based skeletal parts like bone and teeth. Because they are often utilized to combine opposing properties such as strength and low-density or stiffness and wear resistance, the heterogeneous architecture of natural materials can potentially address several of the technical limitations of artificial homogeneous composites. However, current man-made manufacturing technologies do not allow for the level of composition and fiber orientation control found in natural heterogeneous systems. In this talk, I will present two additive manufacturing technologies recently developed in our group to build composites with exquisite architectures only rivaled by structures made by living organisms in nature. Since the proposed techniques utilize colloidal suspensions as feedstock, understanding the physics underlying the stability, assembly and rheology of the printing inks is key to predict and control the architecture of manufactured parts. Our results will show that additive manufacturing routes offer a new exciting pathway for the fabrication of biologically-inspired composite materials with unprecedented architectures and functionalities.

  15. MoSi2-Base Hybrid Composites from Aeroengine Applications

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G.

    2000-01-01

    Addition of about 30 to 50 vol % of Si3N4 particulate to MoSi2 improved low temperature accelerated oxidation resistance by forming a Si2ON2 protective scale and thereby eliminated catastrophic 'pest failure'. The Si3N4 addition also improved the high temperature creep strength by nearly five orders of magnitude, doubled the room temperature toughness, and significantly lowered the CTE of the MoSi2 which eliminated matrix cracking in SCS-6 reinforced composites even after thermal cycling. The SCS-6 fiber reinforcement improved the room temperature fracture toughness by seven times and impact resistance by five times. The composite exhibited this excellent strength and toughness improvement up to 1673 K. More recently, tape casting was adopted as the preferred processing of MoSi2-base composites due to improved fiber spacing, ability to use small diameter fibers, and for lower cost. Good strength and toughness values were also obtained with fine diameter Hi-Nicalon tow fibers. These hybrid composites remain competitive with ceramic matrix composites as a replacement for Ni-base superalloys in aircraft engine applications.

  16. Heating of thermoplastic-based unidirectional composite prepregs

    SciTech Connect

    Wang, X.; Weber, M.E.; Charrier, J.M. )

    1989-04-01

    Thermoplastic-based prepregs offer a potential for faster manufacture of composite products than with thermoset-based prepregs. The winding or controlled placement of thermoplastic-based prepreg tapes requires the rapid heating of the moving tape, just prior to its contact with the substrate on the mandrel. In the case of complex shapes, geometrical constraints and significant variations in tape speeds in the course of manufacture, make it particularly desirable to be able to model the heating process. A mathematical model and its experimental verification for convection/conduction heat transfer to and through either a homogeneous thermoplastic material, or thermoplastic-based unidirectional composites featuring glass, aramid and carbon fibers, is discussed. 12 refs.

  17. A novel paper-based device coupled with a silver nanoparticle-modified boron-doped diamond electrode for cholesterol detection.

    PubMed

    Nantaphol, Siriwan; Chailapakul, Orawon; Siangproh, Weena

    2015-09-01

    A novel paper-based analytical device (PAD) coupled with a silver nanoparticle-modified boron-doped diamond (AgNP/BDD) electrode was first developed as a cholesterol sensor. The AgNP/BDD electrode was used as working electrode after modification by AgNPs using an electrodeposition method. Wax printing was used to define the hydrophilic and hydrophobic areas on filter paper, and then counter and reference electrodes were fabricated on the hydrophilic area by screen-printing in house. For the amperometric detection, cholesterol and cholesterol oxidase (ChOx) were directly drop-cast onto the hydrophilic area, and H2O2 produced from the enzymatic reaction was monitored. The fabricated device demonstrated a good linearity (0.39 mg dL(-1) to 270.69 mg dL(-1)), low detection limit (0.25 mg dL(-1)), and high sensitivity (49.61 μA mM(-1) cm(-2)). The precision value for ten replicates was 3.76% RSD for 1 mM H2O2. In addition, this biosensor exhibited very high selectivity for cholesterol detection and excellent recoveries for bovine serum analysis (in the range of 99.6-100.8%). The results showed that this new sensing platform will be an alternative tool for cholesterol detection in routine diagnosis and offers the advantages of low sample/reagent consumption, low cost, portability, and short analysis time. PMID:26388372

  18. Effects of electrical conductivity of substrate materials on microstructure of diamond-like carbon films prepared by bipolar-type plasma based ion implantation

    NASA Astrophysics Data System (ADS)

    Nakao, S.; Sonoda, T.

    2013-03-01

    Diamond-like carbon (DLC) films are prepared by a bipolar-type plasma based ion implantation, and the structural differences between DLC films deposited on different electrical conductive substrates, i.e., conductive Si wafers and insulating glass plates are examined by Raman spectroscopy and x-ray photo emission spectroscopy (XPS). In the Raman measurements, graphite (G) and disorder (D) peaks are observed for both samples. However, the additional photo luminescence is overlapped on the spectra in the case of on-glass sample. To elucidate the structural difference, the intensity ratio of D to G peak (I(D)/I(G)), G peak position and full width at half maximum (FWHM) are obtained by curve fitting using Gaussian function and linear baseline. It is found that the I(D)/I(G) is lower, G peak position is higher and FWHM of G peak is narrower for on-glass sample than for on-Si sample. According to Robertson [1], lower I(D)/I(G) seems more sp3 C-C bonding in amount for on-glass sample. In contrast, higher G peak position and narrower FWHM of G peak suggest less sp3 C-C bonding in amount for on-glass sample. The results of XPS analysis with C1s spectra reveal that sp3 ratio, i.e., the intensity ratio of sp3/(sp3+sp2) is smaller for on-glass sample than for on-Si sample. The inconsistency of the trend between I(D)/I(G) and other parameters (G peak position and FWHM of G peak) might be caused by the overlap of photo luminescence signal on Raman spectrum as to on-glass sample. From these results, it is considered that sp3 C-C bonding is reduced in amount when using insulating substrate in comparison with conductive substrate.

  19. Online, efficient and precision laser profiling of bronze-bonded diamond grinding wheels based on a single-layer deep-cutting intermittent feeding method

    NASA Astrophysics Data System (ADS)

    Deng, Hui; Chen, Genyu; He, Jie; Zhou, Cong; Du, Han; Wang, Yanyi

    2016-06-01

    In this study, an online, efficient and precision laser profiling approach that is based on a single-layer deep-cutting intermittent feeding method is described. The effects of the laser cutting depth and the track-overlap ratio of the laser cutting on the efficiency, precision and quality of laser profiling were investigated. Experiments on the online profiling of bronze-bonded diamond grinding wheels were performed using a pulsed fiber laser. The results demonstrate that an increase in the laser cutting depth caused an increase in the material removal efficiency during the laser profiling process. However, the maximum laser profiling efficiency was only achieved when the laser cutting depth was equivalent to the initial surface contour error of the grinding wheel. In addition, the selection of relatively high track-overlap ratios of laser cutting for the profiling of grinding wheels was beneficial with respect to the increase in the precision of laser profiling, whereas the efficiency and quality of the laser profiling were not affected by the change in the track-overlap ratio. After optimized process parameters were employed for online laser profiling, the circular run-out error and the parallelism error of the grinding wheel surface decreased from 83.1 μm and 324.6 μm to 11.3 μm and 3.5 μm, respectively. The surface contour precision of the grinding wheel significantly improved. The highest surface contour precision for grinding wheels of the same type that can be theoretically achieved after laser profiling is completely dependent on the peak power density of the laser. The higher the laser peak power density is, the higher the surface contour precision of the grinding wheel after profiling.

  20. Effect of cyclic loading on microleakage of silorane based composite compared with low shrinkage methacrylate-based composites

    PubMed Central

    Kermanshah, Hamid; Yasini, Esmail; Hoseinifar, Razieh

    2016-01-01

    Background: There are many concerns regarding the marginal seal of composite restorations, especially when composite restorations are subjected to cyclic loading. The aim of this study was to evaluate the effect of cyclic loading on the microleakage of silorane based composite compared with low shrinkage methacrylate-based composites in class V cavities. Materials and Methods: In this in vitro study, class V cavities were prepared on the facial and lingual surfaces of 48 human premolars (96 cavities). The teeth were randomly divided into four groups of 12 teeth (24 cavities) each and restored as follows: Group 1 (Siloran System Adhesive + Filtek P90), Group 2 (All Bond SE + Aelite LS Posterior), Group 3 (Futurabond NR + Grandio), and Group 4 (G-Bond + Kalore-GC). All the specimens were thermocycled for 2000 cycles (5-55°C) and then half of the specimens from each group, were Load cycled. All teeth were immersed in 0.5% basic fuchsine dye, sectioned, and observed under a stereomicroscope. Data were analyzed using Wilcoxon test, Kruskal–Wallis, and Mann–Whitney U-tests. P < 0.05 was considered as significant. Results: In both unloaded and loaded groups, no statistically significant differences were observed among four composites at the occlusal margin, but a significant difference in gingival microleakage was found between Aelite and silorane. Occlusal and gingival microleakage was not affected by cyclic loading in none of the four restorative materials. Conclusion: Silorane did not provide better marginal seal than the low shrinkage methacrylate-based composites (except Aelite). In addition, cyclic loading did not affect the marginal microleakage of evaluated composite restorations. PMID:27274348