Development of Kawai-type multianvil technology using nano-polycrystalline diamond anvils

NASA Astrophysics Data System (ADS)

Irifune, T.; Kunimoto, T.

2016-12-01

Nano-polycrystalline diamond (NPD) developed at GRC, Ehime Univ., is known to be much harder than conventional sintered polycrystalline diamond (SD), and is potentially important as material for anvils for Kawai-type (6-8 type) multianvil apparatus (KMA), as well as for diamond anvil cell. We synthesized NPD rods with about 8 mm in both diameter and length using a 6000-ton press KMA (BOTCHAN-6000), which are cut by pulsed-laser to form cubes with 6 mm edge length and tested them as anvils for KMA. In situ X-ray observations were made to evaluate the produced pressures and sample images using the "6-6-8 assembly". A combination of semi-fired pyrophyllite gaskets and alumina ceramics pressure medium optimized for the NPD anvils with a truncation (TEL) of 1.0 mm yielded pressures up to 88 GPa at a press load of only 3.4 MN, which is nearly 60% higher than the pressure (56 GPa) reached using SD anvils with the identical cell assembly at the same press load. Moreover, the high X-ray transparency of NPD has enabled us to clearly see the sample image via the anvils, allowing diffraction measurements and observations of the sample shape even if the anvil gap becomes very small under such very high pressures. The use of NPD anvils should lead to new technology for mineral physics studies under the conditions of the Earth's lowermost mantle and possibly those of the core without scarifying the advantages of KMA over DAC.

Influence of Cobalt on the Adhesion Strength of Polycrystalline Diamond Coatings on WC-Co Hard Alloys

NASA Astrophysics Data System (ADS)

Linnik, S. A.; Gaidaichuk, A. V.; Okhotnikov, V. V.

2018-02-01

The influence of cobalt on the phase composition and adhesion strength of polycrystalline diamond coatings has been studied using scanning electron microscopy, Raman spectroscopy, and X-ray microanalysis. The coatings have been deposited on WC-Co hard alloy substrates in glow discharge plasma. It has been found that the catalytic amorphization of carbon only takes place during the direct synthesis of the diamond coating, when the cobalt vapor pressure over the substrate is high and the cobalt-related degradation of the synthesized diamond is absent.

Polycrystalline diamond RF MOSFET with MoO3 gate dielectric

NASA Astrophysics Data System (ADS)

Ren, Zeyang; Zhang, Jinfeng; Zhang, Jincheng; Zhang, Chunfu; Chen, Dazheng; Quan, Rudai; Yang, Jiayin; Lin, Zhiyu; Hao, Yue

2017-12-01

We report the radio frequency characteristics of the diamond metal-oxide-semiconductor field effect transistor with MoO3 gate dielectric for the first time. The device with 2-μm gate length was fabricated on high quality polycrystalline diamond. The maximum drain current of 150 mA/mm at VGS = -5 V and the maximum transconductance of 27 mS/mm were achieved. The extrinsic cutoff frequency of 1.2 GHz and the maximum oscillation frequency of 1.9 GHz have been measured. The moderate frequency characteristics are attributed to the moderate transconductance limited by the series resistance along the channel. We expect that the frequency characteristics of the device can be improved by increasing the magnitude of gm, or fundamentally decreasing the gate-controlled channel resistance and series resistance along the channel, and down-scaling the gate length.

Comparative investigation of smooth polycrystalline diamond films on dental burs by chemical vapor deposition

NASA Astrophysics Data System (ADS)

Sein, Htet; Ahmed, Waqar; Rego, Christopher; Jackson, Mark; Polini, Riccardo

2006-04-01

Depositions of hot filament chemical vapor-deposited diamond on cobalt-cemented tungsten carbide (WC-Co) rotary cutting dental burs are presented. Conventional dental tools made of sintered polycrystalline diamond have a number of problems associated with the heterogeneity of the crystallite, decreased cutting efficiency, and short life. A preferential (111) faceted diamond was obtained after 15 h of deposition at a growth rate of 1.1 µm/h. Diamond-coated WC-Co dental burs and conventional sintered burs are mainly used in turning, milling, and drilling operations for machining metal ceramic hard alloys such as CoCr, composite teeth, and aluminum alloy in the dental laboratory. The influence of structure, the mechanical characteristics of both diamond grains and hard alloys on the wear behavior, as well as the regimen of grinding on diamond wear are considered. Erosion wear properties are also investigated under air-sand erosion testing. After machining with excessive cutting performance, calculations can be made on flank and crater wear areas. Diamond-coated WC-Co dental burs offered significantly better erosion and wear resistance compared with uncoated WC-Co tools and sintered burs.

D.C. Arcjet Diamond Deposition

NASA Astrophysics Data System (ADS)

Russell, Derrek Andrew

1995-01-01

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

Single-crystal and polycrystalline diamond erosion studies in Pilot-PSI

NASA Astrophysics Data System (ADS)

Kogut, D.; Aussems, D.; Ning, N.; Bystrov, K.; Gicquel, A.; Achard, J.; Brinza, O.; Addab, Y.; Martin, C.; Pardanaud, C.; Khrapak, S.; Cartry, G.

2018-03-01

Diamond is a promising candidate for enhancing the negative-ion surface production in the ion sources for neutral injection in fusion reactors; hence evaluation of its reactivity towards hydrogen plasma is of high importance. Single crystal and polycrystalline diamond samples were exposed in Pilot-PSI with the D+ flux of (4‒7)·1024 m-2s-1 and the impact energy of 7-9 eV per deuteron at different surface temperatures; under such conditions physical sputtering is negligible, however chemical sputtering is important. Net chemical sputtering yield Y = 9.7·10-3 at/ion at 800 °C was precisely measured ex-situ using a protective platinum mask (5 × 10 × 2 μm) deposited beforehand on a single crystal followed by the post-mortem analysis using Transmission Electron Microscopy (TEM). The structural properties of the exposed diamond surface were analyzed by Raman spectroscopy and X-ray Photoelectron Spectroscopy (XPS). Gross chemical sputtering yields were determined in-situ by means of optical emission spectroscopy of the molecular CH A-X band for several surface temperatures. A bell-shaped dependence of the erosion yield versus temperature between 400 °C and 1200 °C was observed, with a maximum yield of ∼1.5·10-2 at/ion attained at 900 °C. The yields obtained for diamond are relatively high (0.5-1.5)·10-2 at/ion, comparable with those of graphite. XPS analysis shows amorphization of diamond surface within 1 nm depth, in a good agreement with molecular dynamics (MD) simulation. MD was also applied to study the hydrogen impact energy threshold for erosion of [100] diamond surface at different temperatures.

Laser beam machining of polycrystalline diamond for cutting tool manufacturing

NASA Astrophysics Data System (ADS)

Wyszyński, Dominik; Ostrowski, Robert; Zwolak, Marek; Bryk, Witold

2017-10-01

The paper concerns application of DPSS Nd: YAG 532nm pulse laser source for machining of polycrystalline WC based diamond inserts (PCD). The goal of the research was to determine optimal laser cutting parameters for cutting tool shaping. Basic criteria to reach the goal was cutting edge quality (minimalization of finishing operations), material removal rate (time and cost efficiency), choice of laser beam characteristics (polarization, power, focused beam diameter). The research was planned and realised and analysed according to design of experiment rules (DOE). The analysis of the cutting edge was prepared with use of Alicona Infinite Focus measurement system.

Thermal conductivity of ultrathin nano-crystalline diamond films determined by Raman thermography assisted by silicon nanowires

NASA Astrophysics Data System (ADS)

Anaya, Julian; Rossi, Stefano; Alomari, Mohammed; Kohn, Erhard; Tóth, Lajos; Pécz, Béla; Kuball, Martin

2015-06-01

The thermal transport in polycrystalline diamond films near its nucleation region is still not well understood. Here, a steady-state technique to determine the thermal transport within the nano-crystalline diamond present at their nucleation site has been demonstrated. Taking advantage of silicon nanowires as surface temperature nano-sensors, and using Raman Thermography, the in-plane and cross-plane components of the thermal conductivity of ultra-thin diamond layers and their thermal barrier to the Si substrate were determined. Both components of the thermal conductivity of the nano-crystalline diamond were found to be well below the values of polycrystalline bulk diamond, with a cross-plane thermal conductivity larger than the in-plane thermal conductivity. Also a depth dependence of the lateral thermal conductivity through the diamond layer was determined. The results impact the design and integration of diamond for thermal management of AlGaN/GaN high power transistors and also show the usefulness of the nanowires as accurate nano-thermometers.

Synchrotron X-ray Microdiffraction Analysis of Proton Irradiated Polycrystalline Diamond Films

NASA Technical Reports Server (NTRS)

Newton, R. I.; Davidson, J. L.; Ice, G. E.; Liu, W.

2004-01-01

X-ray microdiffraction is a non-destructive technique that allows for depth-resolved, strain measurements with sub-micron spatial resolution. These capabilities make this technique promising for understanding the mechanical properties of MicroElectroMechanical Systems (MEMS). This investigation examined the local strain induced by irradiating a polycrystalline diamond thin film with a dose of 2x10(exp 17) H(+)per square centimeter protons. Preliminary results indicate that a measurable strain, on the order of 10(exp -3), was introduced into the film near the End of Range (EOR) region of the protons.

Elastic properties of transparent nano-polycrystalline diamond measured by GHz-ultrasonic interferometry and resonant sphere methods

NASA Astrophysics Data System (ADS)

Chang, Yun-Yuan; Jacobsen, Steven D.; Kimura, Masaki; Irifune, Tetsuo; Ohno, Ichiro

2014-03-01

The sound velocities and elastic moduli of transparent nano-polycrystalline diamond (NPD) have been determined by GHz-ultrasonic interferometry on three different bulk samples, and by resonant spectroscopy on a spherically fabricated NPD sample. We employ a newly-developed optical contact micrometer to measure the thickness of ultrasonic samples to ±0.05 μm with a spatial resolution of ∼50 μm in the same position of the GHz-ultrasonic measurements, resulting in acoustic-wave sound velocity measurements with uncertainties of 0.005-0.02%. The isotropic and adiabatic bulk and shear moduli of NPD measured by GHz-ultrasonic interferometry are KS0 = 442.5 (±0.5) GPa and G0 = 532.4 (±0.5) GPa. By rotating the shear-wave polarization direction, we observe no transverse anisotropy in this NPD. Using resonant sphere spectroscopy, we obtain KS0 = 440.3 (±0.5) GPa and G0 = 532.7 (±0.4) GPa. For comparison, we also measured by GHz-ultrasonic interferometry the elastic constants of a natural single-crystal type-IA diamond with about one-half the experimental uncertainty of previous measurements. The resulting Voigt-Reuss-Hill averaged bulk and shear moduli of natural diamond are KS0 = 441.8 (±0.8) GPa and G0 = 532.6 (±0.5) GPa, demonstrating that the bulk-elastic properties of transparent NPD are equivalent to natural single-crystal diamond as calculated from polycrystalline averaging of its elastic constants.

Influence of coil current modulation on polycrystalline diamond film deposition by irradiation of Ar/CH4/H2 inductively coupled thermal plasmas

NASA Astrophysics Data System (ADS)

Betsuin, Toshiki; Tanaka, Yasunori; Arai, T.; Uesugi, Y.; Ishijima, T.

2018-03-01

This paper describes the application of an Ar/CH4/H2 inductively coupled thermal plasma with and without coil current modulation to synthesise diamond films. Induction thermal plasma with coil current modulation is referred to as modulated induction thermal plasma (M-ITP), while that without modulation is referred to as non-modulated ITP (NM-ITP). First, spectroscopic observations of NM-ITP and M-ITP with different modulation waveforms were made to estimate the composition in flux from the thermal plasma by measuring the time evolution in the spectral intensity from the species. Secondly, we studied polycrystalline diamond film deposition tests on a Si substrate, and we studied monocrystalline diamond film growth tests using the irradiation of NM-ITP and M-ITP. From these tests, diamond nucleation effects by M-ITP were found. Finally, following the irradiation results, we attempted to use a time-series irradiation of M-ITP and NM-ITP for polycrystalline diamond film deposition on a Si substrate. The results indicated that numerous larger diamond particles were deposited with a high population density on the Si substrate by time-series irradiation.

An All-Solid-State pH Sensor Employing Fluorine-Terminated Polycrystalline Boron-Doped Diamond as a pH-Insensitive Solution-Gate Field-Effect Transistor.

PubMed

Shintani, Yukihiro; Kobayashi, Mikinori; Kawarada, Hiroshi

2017-05-05

A fluorine-terminated polycrystalline boron-doped diamond surface is successfully employed as a pH-insensitive SGFET (solution-gate field-effect transistor) for an all-solid-state pH sensor. The fluorinated polycrystalline boron-doped diamond (BDD) channel possesses a pH-insensitivity of less than 3mV/pH compared with a pH-sensitive oxygenated channel. With differential FET (field-effect transistor) sensing, a sensitivity of 27 mv/pH was obtained in the pH range of 2-10; therefore, it demonstrated excellent performance for an all-solid-state pH sensor with a pH-sensitive oxygen-terminated polycrystalline BDD SGFET and a platinum quasi-reference electrode, respectively.

Fatigue and Fracture of Polycrystalline Silicon and Diamond MEMS at Room and Elevated Temperatures

DTIC Science & Technology

2006-12-01

amorphous diamond-like carbon (ta-C) and polycrystalline silicon ( polysilicon ) for microelectromechanical systems (MEMS). Polysilicon and ta-C test...toughness were obtained, many of them for the first time. Compared to polysilicon , ta-C was found to have superior mechanical properties: Its fracture...toughness and strength were 3.5 times and two times that of polysilicon , respectively. Its elastic modulus was 4.5 times that of polysilicon and its

Electromagnetic properties of polycrystalline diamond from 35 K to room temperature and microwave to terahertz frequencies

NASA Astrophysics Data System (ADS)

Floch, Jean-Michel Le; Bara, Romain; Hartnett, John G.; Tobar, Michael E.; Mouneyrac, David; Passerieux, Damien; Cros, Dominique; Krupka, Jerzy; Goy, Philippe; Caroopen, Sylvain

2011-05-01

Dielectric resonators are key components for many microwave and millimeter wave applications, including high-Q filters and frequency-determining elements for precision frequency synthesis. These often depend on the quality of the dielectric material. The commonly used material for building the best cryogenic microwave oscillators is sapphire. However, sapphire is becoming a limiting factor for higher frequency designs. It is, then, important to find new candidates that can fulfill the requirements for millimeter wave low noise oscillators at room and cryogenic temperatures. These clocks are used as a reference in many fields, such as modern telecommunication systems, radio astronomy (very-long-baseline interferometry), and precision measurements at the quantum limit. High resolution measurements were taken of the temperature-dependence of the electromagnetic properties of a polycrystalline diamond disk at temperatures between 35 and 330 K at microwave to submillimeter wave frequencies. The cryogenic measurements were made using a TE01δ dielectric mode resonator placed inside a vacuum chamber connected to a single-stage pulse-tube cryocooler. The high frequency characterization was performed at room temperature using a combination of a quasi-optical two-lens transmission setup, a Fabry-Perot cavity, and a whispering gallery mode resonator excited with waveguides. Our CVD diamond sample exhibits a decreasing loss tangent with increasing frequencies. We compare the results with well known crystals. This comparison makes it clear that polycrystalline diamond could be an important material for generating stable frequencies at millimeter waves.

Ion-beam-assisted etching of diamond

NASA Technical Reports Server (NTRS)

Efremow, N. N.; Geis, M. W.; Flanders, D. C.; Lincoln, G. A.; Economou, N. P.

1985-01-01

The high thermal conductivity, low RF loss, and inertness of diamond make it useful in traveling wave tubes operating in excess of 500 GHz. Such use requires the controlled etching of type IIA diamond to produce grating like structures tens of micrometers deep. Previous work on reactive ion etching with O2 gave etching rates on the order of 20 nm/min and poor etch selectivity between the masking material (Ni or Cr) and the diamond. An alternative approach which uses a Xe(+) beam and a reactive gas flux of NO2 in an ion-beam-assisted etching system is reported. An etching rate of 200 nm/min was obtained with an etching rate ratio of 20 between the diamond and an aluminum mask.

Diamond knife-assisted deep anterior lamellar keratoplasty to manage keratoconus.

PubMed

Vajpayee, Rasik B; Maharana, Prafulla K; Sharma, Namrata; Agarwal, Tushar; Jhanji, Vishal

2014-02-01

To evaluate the outcomes of a new surgical technique, diamond knife-assisted deep anterior lamellar keratoplasty (DALK), and compare its visual and refractive results with big-bubble DALK in cases of keratoconus. Tertiary eyecare hospital. Comparative case series. The visual and surgical outcomes of diamond knife-assisted DALK were compared with those of successful big-bubble DALK. Diamond knife-assisted DALK was performed in 19 eyes and big-bubble DALK, in 11 eyes. All surgeries were completed successfully. No intraoperative or postoperative complications occurred with diamond knife-assisted DALK. Six months after diamond knife-assisted DALK, the mean corrected distance visual acuity (CDVA) improved significantly from 1.87 logMAR ± 0.22 (SD) to 0.23 ± 0.06 logMAR, the mean keratometry improved from 65.99 ± 8.86 diopters (D) to 45.13 ± 1.16 D, and the mean keratometric cylinder improved from 7.99 ± 3.81 D to 2.87 ± 0.59 D (all P=.005). Postoperatively, the mean refractive astigmatism was 2.55 ± 0.49 D and the mean spherical equivalent was -1.97 ± 0.56 D. The mean logMAR CDVA (P = .06), postoperative keratometry (P=.64), refractive cylinder (P=.63), and endothelial cell loss (P=.11) were comparable between diamond knife-assisted DALK and big-bubble DALK. Diamond knife-assisted DALK was effective and predictable as a surgical technique for management of keratoconus cases. This technique has the potential to offer visual and refractive outcomes comparable to those of big-bubble DALK. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

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.

Nanostructured Diamond Device for Biomedical Applications.

PubMed

Fijalkowski, M; Karczemska, A; Lysko, J M; Zybala, R; KozaneckI, M; Filipczak, P; Ralchenko, V; Walock, M; Stanishevsky, A; Mitura, S

2015-02-01

Diamond is increasingly used in biomedical applications because of its unique properties such as the highest thermal conductivity, good optical properties, high electrical breakdown voltage as well as excellent biocompatibility and chemical resistance. Diamond has also been introduced as an excellent substrate to make the functional microchip structures for electrophoresis, which is the most popular separation technique for the determination of analytes. In this investigation, a diamond electrophoretic chip was manufactured by a replica method using a silicon mold. A polycrystalline 300 micron-thick diamond layer was grown by the microwave plasma-assisted CVD (MPCVD) technique onto a patterned silicon substrate followed by the removal of the substrate. The geometry of microstructure, chemical composition, thermal and optical properties of the resulting free-standing diamond electrophoretic microchip structure were examined by CLSM, SFE, UV-Vis, Raman, XRD and X-ray Photoelectron Spectroscopy, and by a modified laser flash method for thermal property measurements.

Nanopores creation in boron and nitrogen doped polycrystalline graphene: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Izadifar, Mohammadreza; Abadi, Rouzbeh; Nezhad Shirazi, Ali Hossein; Alajlan, Naif; Rabczuk, Timon

2018-05-01

In the present paper, molecular dynamic simulations have been conducted to investigate the nanopores creation on 10% of boron and nitrogen doped polycrystalline graphene by silicon and diamond nanoclusters. Two types of nanoclusters based on silicon and diamond are used to investigate their effect for the fabrication of nanopores. Therefore, three different diameter sizes of the clusters with five kinetic energies of 10, 50, 100, 300 and 500 eV/atom at four different locations in boron or nitrogen doped polycrystalline graphene nanosheets have been perused. We also study the effect of 3% and 6% of boron doped polycrystalline graphene with the best outcome from 10% of doping. Our results reveal that the diamond cluster with diameter of 2 and 2.5 nm fabricates the largest nanopore areas on boron and nitrogen doped polycrystalline graphene, respectively. Furthermore, the kinetic energies of 10 and 50 eV/atom can not fabricate nanopores in some cases for silicon and diamond clusters on boron doped polycrystalline graphene nanosheets. On the other hand, silicon and diamond clusters fabricate nanopores for all locations and all tested energies on nitrogen doped polycrystalline graphene. The area sizes of nanopores fabricated by silicon and diamond clusters with diameter of 2 and 2.5 nm are close to the actual area size of the related clusters for the kinetic energy of 300 eV/atom in all locations on boron doped polycrystalline graphene. The maximum area and the average maximum area of nanopores are fabricated by the kinetic energy of 500 eV/atom inside the grain boundary at the center of the nanosheet and in the corner of nanosheet with diameters of 2 and 3 nm for silicon and diamond clusters on boron and nitrogen doped polycrystalline graphene.

Research on electrodischarge drilling of polycrystalline diamond with increased gap voltage

NASA Astrophysics Data System (ADS)

Skoczypiec, Sebastian; Bizoń, Wojciech; Żyra, Agnieszka

2018-05-01

This paper presents an experimental investigation of the machining characteristics of polycrystalline diamond (PCD). Machining of PCD by conventional technologies is not an effective solution. Due to presence of cobalt this material can be machined by application of electrical discharges. On the other side, electrical conductivity of PCD is on the limit of electrodischarge machining (EDM) possibilities. Proposed paper reports experimental investigation on electrodischarge drilling of PCD samples. The test were carried out with application on of high-voltage (up to 550 V) pulse power unit for two kinds of dielectrics: carbon based (Exxsol D80) and de-ionized water. As output parameters machining accuracy (side gap), material removal rate were selected. Also, based on SEM photographs and energy dispersive X-ray spectroscopy (EDS) analysis, a qualitative evaluation of the obtained results was presented.

Deposition Of Cubic BN On Diamond Interlayers

NASA Technical Reports Server (NTRS)

Ong, Tiong P.; Shing, Yuh-Han

1994-01-01

Thin films of polycrystalline, pure, cubic boron nitride (c-BN) formed on various substrates, according to proposal, by chemical vapor deposition onto interlayers of polycrystalline diamond. Substrate materials include metals, semiconductors, and insulators. Typical substrates include metal-cutting tools: polycrystalline c-BN coats advantageous for cutting ferrous materials and for use in highly oxidizing environments-applications in which diamond coats tend to dissolve in iron or be oxidized, respectively.

First neutron spectroscopy measurements with a pixelated diamond detector at JET

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

Muraro, A., E-mail: muraro@ifp.cnr.it; Giacomelli, L.; Grosso, G.

2016-11-15

A prototype Single crystal Diamond Detector (SDD) was installed at the Joint European Torus (JET) in 2013 along an oblique line of sight and demonstrated the possibility to carry out neutron spectroscopy measurements with good energy resolution and detector stability in discharges heated by neutral beam injection and radio-frequency waves. Starting from these positive results, within the Vertical Neutron Spectrometer project of the Joint European Torus, we have developed a pixelated instrument consisting of a matrix of 12 independent SDDs, called the Diamond Vertical Neutron Spectrometer (DVNS), which boosts the detection efficiency of a single SDD by an order ofmore » magnitude. In this paper we describe the main features of the DVNS, including the detector design, energy resolution, and data acquisition system for on-line processing. Preliminary spectroscopy measurements of 2.5 MeV neutrons from the present deuterium plasma at JET are finally presented.« less

First neutron spectroscopy measurements with a pixelated diamond detector at JET.

PubMed

Muraro, A; Giacomelli, L; Nocente, M; Rebai, M; Rigamonti, D; Belli, F; Calvani, P; Figueiredo, J; Girolami, M; Gorini, G; Grosso, G; Murari, A; Popovichev, S; Trucchi, D M; Tardocchi, M

2016-11-01

A prototype Single crystal Diamond Detector (SDD) was installed at the Joint European Torus (JET) in 2013 along an oblique line of sight and demonstrated the possibility to carry out neutron spectroscopy measurements with good energy resolution and detector stability in discharges heated by neutral beam injection and radio-frequency waves. Starting from these positive results, within the Vertical Neutron Spectrometer project of the Joint European Torus, we have developed a pixelated instrument consisting of a matrix of 12 independent SDDs, called the Diamond Vertical Neutron Spectrometer (DVNS), which boosts the detection efficiency of a single SDD by an order of magnitude. In this paper we describe the main features of the DVNS, including the detector design, energy resolution, and data acquisition system for on-line processing. Preliminary spectroscopy measurements of 2.5 MeV neutrons from the present deuterium plasma at JET are finally presented.

Relationship Between Secondary-Electron Yield and Structure of Polycrystalline Diamond Prepared Under Different Methane Concentrations

NASA Astrophysics Data System (ADS)

Wei, Kongting; Wu, Shengli; Wei, Qiang; Zheng, Pu; Hu, Wenbo; Wang, Hongxing

2018-05-01

To understand the mechanism of electron transport and escape to vacuum of polycrystalline chemical-vapor-deposited diamond films prepared under different methane (CH4) concentrations, the secondary electron yield (SEY) δ as a function of primary electron (PE) energy E p has been investigated. The δ-E p curves exhibited different features for films synthesized under different CH4 concentrations, and the highest SEY was obtained when the CH4 concentration was 2%. A physical model was used to compute the key parameters of escape depth λ s and surface factor f 0·A s. The results indicated that λ s is closely related to the crystal quality of the diamond film, with diamond of high quality having larger λ s, while the surface factor f 0·A s is mainly determined by the surface morphology, which is associated with the surface roughness of the film. Using the above model, the SEY as a function of varying λ s and f 0·A s was also calculated; the results suggested that f 0·A s plays a key role in determining SEY for low-energy PEs, especially for energies < 500 eV, while the SEY is affected by both λ s and f 0·A s for high-energy PEs.

Removal of single point diamond-turning marks by abrasive jet polishing.

PubMed

Li, Z Z; Wang, J M; Peng, X Q; Ho, L T; Yin, Z Q; Li, S Y; Cheung, C F

2011-06-01

Single point diamond turning (SPDT) is highly controllable and versatile in producing axially symmetric forms, non-axially-symmetric forms, microstructured surfaces, and free forms. However, the fine SPDT marks left in the surface limit its performance, and they are difficult to reduce or eliminate. It is unpractical for traditional methods to remove the fine marks without destroying their forms, especially for the aspheres and free forms. This paper introduces abrasive jet polishing (AJP) for the posttreatment of diamond-turned surfaces to remove the periodic microstructures. Samples of diamond-turned electroless nickel plated plano mirror were used in the experiments. One sample with an original surface roughness of more than 400 nm decreased to 4 nm after two iterations abrasive jet polishing; the surface roughness of another sample went from 3.7 nm to 1.4 nm after polishing. The periodic signatures on both of the samples were removed entirely after polishing. Contrastive experimental research was carried out on electroless nickel mirror with magnetorheological finishing, computer controlled optical surfacing, and AJP. The experimental results indicate that AJP is more appropriate in removing the periodic SPDT marks. Also, a figure maintaining experiment was carried out with the AJP process; the uniform polishing process shows that the AJP process can remove the periodic turning marks without destroying the original form.

Channeling effect in polycrystalline deuterium-saturated CVD diamond target bombarded by deuterium ion beam

NASA Astrophysics Data System (ADS)

Bagulya, A. V.; Dalkarov, O. D.; Negodaev, M. A.; Rusetskii, A. S.; Chubenko, A. P.; Ralchenko, V. G.; Bolshakov, A. P.

2015-07-01

At the ion accelerator HELIS at LPI, the neutron yield is investigated in DD reactions within a strongly textured polycrystalline deuterium-saturated CVD diamond under irradiation by a deuterium ion beam with the energy of less than 30 keV. The measurements of the neutron flux in the beam direction are performed using a multichannel detector based on 3He counters, in dependence on the target angle, β, with respect to the beam axis. A significant anisotropy in the neutron yield is observed. At β = 0° the yield is higher by a factor of 3 as compared to that at β = ±45°. The possible reasons for the anisotropy, including ion channeling, are discussed.

The Flowfield Characteristics of a Mach 2 Diamond Jet

NASA Technical Reports Server (NTRS)

Washington, Donnell; Alvi, Farrukh S.; Krothapalli, Anjanevulu

1997-01-01

The potential for using a novel diamond-shaped nozzle which may allow for superior mixing characteristics of supersonic jets without significant thrust losses is explored. The results of flow visualization and pressure measurements indicate the presence of distinct structures in the shear layers, not normally observed in shear layers of axisymmetric and rectangular jets. As characteristics of these features suggests that they are a manifestation of significant streamwise vorticity in the shear layers. Despite the distinct nature of the flowfield structure of the present shear layer, the global growth rates of this shear layer were found to be very similar to its two-dimensional and axisymmetric counterparts. These and other observations suggest that the presence of streamwise vorticity may not play a significant role in the global development of a compressible shear layer.

Selective deposition of polycrystalline diamond films using photolithography with addition of nanodiamonds as nucleation centers

NASA Astrophysics Data System (ADS)

Okhotnikov, V. V.; Linnik, S. A.; Gaidaichuk, A. V.; Shashev, D. V.; Nazarova, G. Yu; Yurchenko, V. I.

2016-02-01

A new method of selective deposition of polycrystalline diamond has been developed and studied. The diamond coatings with a complex, predetermined geometry and resolution up to 5 μm were obtained. A high density of polycrystallites in the coating area was reached (up to 32·107 pcs/cm2). The uniformity of the film reached 100%, and the degree of the surface contamination by parasitic crystals did not exceed 2%. The technology was based on the application of the standard photolithography with an addition of nanodiamond suspension into the photoresist that provided the creation of the centers of further nucleation in the areas which require further overgrowth. The films were deposited onto monocrystalline silicon substrates using the method of “hot filaments” in the CVD reactor. The properties of the coating and the impact of the nanodiamond suspension concentration in the photoresist were also studied. The potential use of the given method includes a high resolution, technological efficiency, and low labor costs compared to the standard methods (laser treatment, chemical etching in aggressive environments,).

Status of the R&D activity on diamond particle detectors

NASA Astrophysics Data System (ADS)

Adam, W.; Bellini, B.; Berdermann, E.; Bergonzo, P.; de Boer, W.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; D'Angelo, P.; Dabrowski, W.; Delpierre, P.; Doroshenko, J.; Dulinski, W.; van Eijk, B.; Fallou, A.; Fischer, P.; Fizzotti, F.; Furetta, C.; Gan, K. K.; Ghodbane, N.; Grigoriev, E.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kaplon, J.; Karl, C.; Kass, R.; Keil, M.; Knöpfle, K. T.; Koeth, T.; Krammer, M.; Logiudice, A.; Lu, R.; mac Lynne, L.; Manfredotti, C.; Marshall, R. D.; Meier, D.; Menichelli, D.; Meuser, S.; Mishina, M.; Moroni, L.; Noomen, J.; Oh, A.; Perera, L.; Pernicka, M.; Polesello, P.; Potenza, R.; Riester, J. L.; Roe, S.; Rudge, A.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Sutera, C.; Trischuk, W.; Tromson, D.; Tuve, C.; Weilhammer, P.; Wermes, N.; Wetstein, M.; Zeuner, W.; Zoeller, M.; RD42 Collaboration

2003-09-01

Chemical Vapor Deposited (CVD) polycrystalline diamond has been proposed as a radiation-hard alternative to silicon in the extreme radiation levels occurring close to the interaction region of the Large Hadron Collider. Due to an intense research effort, reliable high-quality polycrystalline CVD diamond detectors, with up to 270 μm charge collection distance and good spatial uniformity, are now available. The most recent progress on the diamond quality, on the development of diamond trackers and on radiation hardness studies are presented and discussed.

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

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

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

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

Diamond detectors for high energy physics experiments

NASA Astrophysics Data System (ADS)

Bäni, L.; Alexopoulos, A.; Artuso, M.; Bachmair, F.; Bartosik, M.; Beacham, J.; Beck, H.; Bellini, V.; Belyaev, V.; Bentele, B.; Berdermann, E.; Bergonzo, P.; Bes, A.; Brom, J.-M.; Bruzzi, M.; Cerv, M.; Chiodini, G.; Chren, D.; Cindro, V.; Claus, G.; Collot, J.; Cumalat, J.; Dabrowski, A.; D'Alessandro, R.; Dauvergne, D.; de Boer, W.; Dorfer, C.; Dünser, M.; Eremin, V.; Eusebi, R.; Forcolin, G.; Forneris, J.; Frais-Kölbl, H.; Gallin-Martel, L.; Gallin-Martel, M. L.; Gan, K. K.; Gastal, M.; Giroletti, C.; Goffe, M.; Goldstein, J.; Golubev, A.; Gorišek, A.; Grigoriev, E.; Grosse-Knetter, J.; Grummer, A.; Gui, B.; Guthoff, M.; Haughton, I.; Hiti, B.; Hits, D.; Hoeferkamp, M.; Hofmann, T.; Hosslet, J.; Hostachy, J.-Y.; Hügging, F.; Hutton, C.; Jansen, H.; Janssen, J.; Kagan, H.; Kanxheri, K.; Kasieczka, G.; Kass, R.; Kassel, F.; Kis, M.; Konovalov, V.; Kramberger, G.; Kuleshov, S.; Lacoste, A.; Lagomarsino, S.; Lo Giudice, A.; Lukosi, E.; Maazouzi, C.; Mandic, I.; Mathieu, C.; Menichelli, M.; Mikuž, M.; Morozzi, A.; Moss, J.; Mountain, R.; Murphy, S.; Muškinja, M.; Oh, A.; Oliviero, P.; Passeri, D.; Pernegger, H.; Perrino, R.; Picollo, F.; Pomorski, M.; Potenza, R.; Quadt, A.; Re, A.; Reichmann, M.; Riley, G.; Roe, S.; Sanz, D.; Scaringella, M.; Schaefer, D.; Schmidt, C. J.; Schnetzer, S.; Sciortino, S.; Scorzoni, A.; Seidel, S.; Servoli, L.; Smith, S.; Sopko, B.; Sopko, V.; Spagnolo, S.; Spanier, S.; Stenson, K.; Stone, R.; Sutera, C.; Tannenwald, B.; Taylor, A.; Traeger, M.; Tromson, D.; Trischuk, W.; Tuve, C.; Uplegger, L.; Velthuis, J.; Venturi, N.; Vittone, E.; Wagner, S.; Wallny, R.; Wang, J. C.; Weingarten, J.; Weiss, C.; Wengler, T.; Wermes, N.; Yamouni, M.; Zavrtanik, M.

2018-01-01

Beam test results of the radiation tolerance study of chemical vapour deposition (CVD) diamond against different particle species and energies is presented. We also present beam test results on the independence of signal size on incident particle rate in charged particle detectors based on un-irradiated and irradiated poly-crystalline CVD diamond over a range of particle fluxes from 2 kHz/cm2 to 10 MHz/cm2. The pulse height of the sensors was measured with readout electronics with a peaking time of 6 ns. In addition functionality of poly-crystalline CVD diamond 3D devices was demonstrated in beam tests and 3D diamond detectors are shown to be a promising technology for applications in future high luminosity experiments.

Catalytic aided electrical discharge machining of polycrystalline diamond - parameter analysis of finishing condition

NASA Astrophysics Data System (ADS)

Haikal Ahmad, M. A.; Zulafif Rahim, M.; Fauzi, M. F. Mohd; Abdullah, Aslam; Omar, Z.; Ding, Songlin; Ismail, A. E.; Rasidi Ibrahim, M.

2018-01-01

Polycrystalline diamond (PCD) is regarded as among the hardest material in the world. Electrical Discharge Machining (EDM) typically used to machine this material because of its non-contact process nature. This investigation was purposely done to compare the EDM performances of PCD when using normal electrode of copper (Cu) and newly proposed graphitization catalyst electrode of copper nickel (CuNi). Two level full factorial design of experiment with 4 center points technique was used to study the influence of main and interaction effects of the machining parameter namely; pulse-on, pulse-off, sparking current, and electrode materials (categorical factor). The paper shows interesting discovery in which the newly proposed electrode presented positive impact to the machining performance. With the same machining parameters of finishing, CuNi delivered more than 100% better in Ra and MRR than ordinary Cu electrode.

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

NASA Astrophysics Data System (ADS)

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

2018-03-01

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

Growth of oriented polycrystalline α-HgI 2 films by ultrasonic-wave-assisted physical vapor deposition

NASA Astrophysics Data System (ADS)

Yang, Weiguang; Nie, Lei; Li, Dongmei; Wang, Yali; Zhou, Jie; Ma, Lei; Wang, Zhenhua; Shi, Weimin

2011-06-01

Polycrystalline α-HgI 2 thick films have been grown on ITO-coated glass substrates using ultrasonic-wave-assisted vapor phase deposition (UWAVPD) with the different source temperatures and ultrasonic frequencies. The influence of the assisted ultrasonic wave and source temperature on the structural and electrical properties of the polycrystalline α-HgI 2 films is investigated. It is found that the assisted ultrasonic wave plays an important role in the improvement of the structural and electrical properties. An uniformly oriented polycrystalline α-HgI 2 film with clear facets and narrow size distribution can be obtained at the source temperature of 80 °C under the assistance of 59 KHz ultrasonic frequency with the ultrasonic power of 200 W, which has the lowest value of ρ=2.2×10 12 Ω cm for E-field parallel to c-axis, approaching to that of high quality α-HgI 2 single crystals (4.0×10 12 Ω cm).

All diamond self-aligned thin film transistor

DOEpatents

Gerbi, Jennifer [Champaign, IL

2008-07-01

A substantially all diamond transistor with an electrically insulating substrate, an electrically conductive diamond layer on the substrate, and a source and a drain contact on the electrically conductive diamond layer. An electrically insulating diamond layer is in contact with the electrically conductive diamond layer, and a gate contact is on the electrically insulating diamond layer. The diamond layers may be homoepitaxial, polycrystalline, nanocrystalline or ultrananocrystalline in various combinations.A method of making a substantially all diamond self-aligned gate transistor is disclosed in which seeding and patterning can be avoided or minimized, if desired.

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

NASA Astrophysics Data System (ADS)

Gorla, Sai Prasanth

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

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

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

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

2017-09-08

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

Role of deuterium desorption kinetics on the thermionic emission properties of polycrystalline diamond films with respect to kinetic isotope effects

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

Paxton, W. F., E-mail: william.f.paxton@vanderbilt.edu; Howell, M.; Kang, W. P.

2014-06-21

The desorption kinetics of deuterium from polycrystalline chemical vapor deposited diamond films were characterized by monitoring the isothermal thermionic emission current behavior. The reaction was observed to follow a first-order trend as evidenced by the decay rate of the thermionic emission current over time which is in agreement with previously reported studies. However, an Arrhenius plot of the reaction rates at each tested temperature did not exhibit the typical linear behavior which appears to contradict past observations of the hydrogen (or deuterium) desorption reaction from diamond. This observed deviation from linearity, specifically at lower temperatures, has been attributed to non-classicalmore » processes. Though no known previous studies reported similar deviations, a reanalysis of the data obtained in the present study was performed to account for tunneling which appeared to add merit to this hypothesis. Additional investigations were performed by reevaluating previously reported data involving the desorption of hydrogen (as opposed to deuterium) from diamond which further indicated this reaction to be dominated by tunneling at the temperatures tested in this study (<775 °C). An activation energy of 3.19 eV and a pre-exponential constant of 2.3 × 10{sup 12} s{sup −1} were determined for the desorption reaction of deuterium from diamond which is in agreement with previously reported studies.« less

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Measurement of optical absorption in polycrystalline CVD diamond plates by the phase photothermal method at a wavelength of 10.6 μm

NASA Astrophysics Data System (ADS)

Luk'yanov, A. Yu; Ral'chenko, Viktor G.; Khomich, A. V.; Serdtsev, E. V.; Volkov, P. V.; Savel'ev, A. V.; Konov, Vitalii I.

2008-12-01

A highly-efficient phase photothermal method is developed for quantitative measurements of the small optical absorption coefficient in thin plates made of highly transparent materials in which bulk losses significantly exceed surface losses. The bulk absorption coefficient at 10.6 μm is estimated in polycrystalline diamond plates grown from the vapour phase (a CVD diamond). The results are compared with those for natural and synthetic diamond single crystals and with the concentrations of nitrogen and hydrogen impurities. The absorption coefficient of the best samples of the CVD diamond did not exceed 0.06 cm-1, which, taking into account the high thermal conductivity of the CVD diamond (1800-2200 W mK-1 at room temperature), makes this material attractive for fabricating output windows of high-power CO2 lasers, especially for manufacturing large-size optics.

Note: Evaluation of microfracture strength of diamond materials using nano-polycrystalline diamond spherical indenter

NASA Astrophysics Data System (ADS)

Sumiya, H.; Hamaki, K.; Harano, K.

2018-05-01

Ultra-hard and high-strength spherical indenters with high precision and sphericity were successfully prepared from nanopolycrystalline diamond (NPD) synthesized by direct conversion sintering from graphite under high pressure and high temperature. It was shown that highly accurate and stable microfracture strength tests can be performed on various super-hard diamond materials by using the NPD spherical indenters. It was also verified that this technique enables quantitative evaluation of the strength characteristics of single crystal diamonds and NPDs which have been quite difficult to evaluate.

Crystal-face-selective adsorption of Au nanoparticles onto polycrystalline diamond surfaces.

PubMed

Kondo, Takeshi; Aoshima, Shinsuke; Hirata, Kousuke; Honda, Kensuke; Einaga, Yasuaki; Fujishima, Akira; Kawai, Takeshi

2008-07-15

Crystal-face-selective adsorption of Au nanoparticles (AuNPs) was achieved on polycrystalline boron-doped diamond (BDD) surface via the self-assembly method combined with a UV/ozone treatment. To the best of our knowledge, this is the first report of crystal-face-selective adsorption on an inorganic solid surface. Hydrogen-plasma-treated BDD samples and those followed by UV/ozone treatment for 2 min or longer showed almost no adsorption of AuNP after immersion in the AuNP solution prepared by the citrate reduction method. However, the samples treated by UV/ozone for 10 s showed AuNP adsorption on their (111) facets selectively after the immersion. Moreover, the sample treated with UV/ozone for 40-60 s showed AuNP adsorption on the whole surface. These results indicate that the AuNP adsorption behavior can be controlled by UV/ozone treatment time. This phenomenon was highly reproducible and was applied to a two-step adsorption method, where AuNPs from different batches were adsorbed on the (111) and (100) surface in this order. Our findings may be of great value for the fabrication of advanced nanoparticle-based functional materials via bottom-up approaches with simple macroscale procedures.

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.

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.

Nanosecond formation of diamond and lonsdaleite by shock compression of graphite.

PubMed

Kraus, D; Ravasio, A; Gauthier, M; Gericke, D O; Vorberger, J; Frydrych, S; Helfrich, J; Fletcher, L B; Schaumann, G; Nagler, B; Barbrel, B; Bachmann, B; Gamboa, E J; Göde, S; Granados, E; Gregori, G; Lee, H J; Neumayer, P; Schumaker, W; Döppner, T; Falcone, R W; Glenzer, S H; Roth, M

2016-03-14

The shock-induced transition from graphite to diamond has been of great scientific and technological interest since the discovery of microscopic diamonds in remnants of explosively driven graphite. Furthermore, shock synthesis of diamond and lonsdaleite, a speculative hexagonal carbon polymorph with unique hardness, is expected to happen during violent meteor impacts. Here, we show unprecedented in situ X-ray diffraction measurements of diamond formation on nanosecond timescales by shock compression of pyrolytic as well as polycrystalline graphite to pressures from 19 GPa up to 228 GPa. While we observe the transition to diamond starting at 50 GPa for both pyrolytic and polycrystalline graphite, we also record the direct formation of lonsdaleite above 170 GPa for pyrolytic samples only. Our experiment provides new insights into the processes of the shock-induced transition from graphite to diamond and uniquely resolves the dynamics that explain the main natural occurrence of the lonsdaleite crystal structure being close to meteor impact sites.

Nanosecond formation of diamond and lonsdaleite by shock compression of graphite

PubMed Central

Kraus, D.; Ravasio, A.; Gauthier, M.; Gericke, D. O.; Vorberger, J.; Frydrych, S.; Helfrich, J.; Fletcher, L. B.; Schaumann, G.; Nagler, B.; Barbrel, B.; Bachmann, B.; Gamboa, E. J.; Göde, S.; Granados, E.; Gregori, G.; Lee, H. J.; Neumayer, P.; Schumaker, W.; Döppner, T.; Falcone, R. W.; Glenzer, S. H.; Roth, M.

2016-01-01

The shock-induced transition from graphite to diamond has been of great scientific and technological interest since the discovery of microscopic diamonds in remnants of explosively driven graphite. Furthermore, shock synthesis of diamond and lonsdaleite, a speculative hexagonal carbon polymorph with unique hardness, is expected to happen during violent meteor impacts. Here, we show unprecedented in situ X-ray diffraction measurements of diamond formation on nanosecond timescales by shock compression of pyrolytic as well as polycrystalline graphite to pressures from 19 GPa up to 228 GPa. While we observe the transition to diamond starting at 50 GPa for both pyrolytic and polycrystalline graphite, we also record the direct formation of lonsdaleite above 170 GPa for pyrolytic samples only. Our experiment provides new insights into the processes of the shock-induced transition from graphite to diamond and uniquely resolves the dynamics that explain the main natural occurrence of the lonsdaleite crystal structure being close to meteor impact sites. PMID:26972122

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

NASA Astrophysics Data System (ADS)

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

2016-05-01

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

Development of a water-jet assisted laser paint removal process

NASA Astrophysics Data System (ADS)

Madhukar, Yuvraj K.; Mullick, Suvradip; Nath, Ashish K.

2013-12-01

The laser paint removal process usually leaves behind traces of combustion product i.e. ashes on the surface. An additional post-processing such as light-brushing or wiping by some mechanical means is required to remove the residual ash. In order to strip out the paint completely from the surface in a single step, a water-jet assisted laser paint removal process has been investigated. The 1.07 μm wavelength of Yb-fiber laser radiation has low absorption in water; therefore a high power fiber laser was used in the experiment. The laser beam was delivered on the paint-surface along with a water jet to remove the paint and residual ashes effectively. The specific energy, defined as the laser energy required removing a unit volume of paint was found to be marginally more than that for the gas-jet assisted laser paint removal process. However, complete paint removal was achieved with the water-jet assist only. The relatively higher specific energy in case of water-jet assist is mainly due to the scattering of laser beam in the turbulent flow of water-jet.

Quartz Crystal Micro-Balance Gas Sensor with Ink-Jet Printed Nano-Diamond Sensitive Layer

NASA Astrophysics Data System (ADS)

Kulha, Pavel; Kroutil, Jiří; Laposa, Alexandr; Procházka, Václav; Husák, Miroslav

2016-01-01

the paper presents fabrication and characterization of a Quartz Crystal Microbalance based gas sensor with a diamond powder sensitive layer deposited using the ink-jet printing technique. The sensor was exposed to a low concentration of ammonia, acetone vapors and different levels of humidity. Impedance characteristics close to the natural resonant frequency of 10 MHz were examined. The sensor exhibits significant shifts in serial resonant frequency under different gas environments.

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.

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

NASA Astrophysics Data System (ADS)

Jackson, M. J.; Ahmed, W.

2005-10-01

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

Method to fabricate micro and nano diamond devices

DOEpatents

Morales, Alfredo M.; Anderson, Richard J.; Yang, Nancy Y. C.; Skinner, Jack L.; Rye, Michael J.

2017-04-11

A method including forming a diamond material on the surface of a substrate; forming a first contact and a separate second contact; and patterning the diamond material to form a nanowire between the first contact and the second contact. An apparatus including a first contact and a separate second contact on a substrate; and a nanowire including a single crystalline or polycrystalline diamond material on the substrate and connected to each of the first contact and the second contact.

Method to fabricate micro and nano diamond devices

DOEpatents

Morales, Alfredo M; Anderson, Richard J; Yang, Nancy Y. C.; Skinner, Jack L; Rye, Michael J

2014-10-07

A method including forming a diamond material on the surface of a substrate; forming a first contact and a separate second contact; and patterning the diamond material to form a nanowire between the first contact and the second contact. An apparatus including a first contact and a separate second contact on a substrate; and a nanowire including a single crystalline or polycrystalline diamond material on the substrate and connected to each of the first contact and the second contact.

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

NASA Technical Reports Server (NTRS)

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

1994-01-01

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

Role of high microwave power on growth and microstructure of thick nanocrystalline diamond films: A comparison with large grain polycrystalline diamond films

NASA Astrophysics Data System (ADS)

Tang, C. J.; Fernandes, A. J. S.; Girão, A. V.; Pereira, S.; Shi, Fa-Nian; Soares, M. R.; Costa, F.; Neves, A. J.; Pinto, J. L.

2014-03-01

In this work, we study the growth habit of nanocrystalline diamond (NCD) films by exploring the very high power regime, up to 4 kW, in a 5 kW microwave plasma chemical vapour deposition (MPCVD) reactor, through addition of a small amount of nitrogen and oxygen (0.24%) into 4% CH4 in H2 plasma. The coupled effect of high microwave power and substrate temperature on NCD growth behaviour is systematically investigated by varying only power, while fixing the remaining operating parameters. When the power increases from 2 kW to 4 kW, resulting also in rise of the Si substrate temperature higher than 150 °C, the diamond films obtained maintain the NCD habit, while the growth rate increases significantly. The highest growth rate of 4.6 μm/h is achieved for the film grown at 4 kW, which represents a growth rate enhancement of about 15 times compared with that obtained when using 2 kW power. Possible factors responsible for such remarkable growth rate enhancement of the NCD films are discussed. The evolution of NCD growth characteristics such as morphology, microstructure and texture is studied by growing thick films and comparing it with that of large grain polycrystalline (PCD) films. One important characteristic of the NCD films obtained, in contrast to PCD films, is that irrespective of deposition time (i.e. film thickness), their grain size and surface roughness remain in the nanometer range throughout the growth. Finally, based on our present and previous experimental results, a potential parameter window is established for fast growth of NCD films under high power conditions.

Equilibrium, chemical kinetic, and transport limitations to diamond growth

NASA Astrophysics Data System (ADS)

Evans, Edward Anthony

the conclusion that diamond growth, in current hot-filament and microwave assisted CVD processes, is occurring in a partial equilibrium environment in which diffusion of atomic hydrogen controls the overall diamond growth rate. The initial stages of diamond growth on non-diamond substrates correspond to carburization, nucleation and growth. When polycrystalline or single crystal diamond is used as a substrate, the carburization and nucleation stages are not observed and growth begins immediately. The nucleation rate depends sensitively on the radiative heat transfer to the substrate. Adding ozone to the hot-filament CVD charge increases the production of carbon monoxide and carbon dioxide; this increase is observed with or without the filament being activated. A consistent effect on the diamond growth rate was not observed when ozone was added to the hot-filament reactor.

Growth of diamond by RF plasma-assisted chemical vapor deposition

NASA Technical Reports Server (NTRS)

Meyer, Duane E.; Ianno, Natale J.; Woollam, John A.; Swartzlander, A. B.; Nelson, A. J.

1988-01-01

A system has been designed and constructed to produce diamond particles by inductively coupled radio-frequency, plasma-assisted chemical vapor deposition. This is a low-pressure, low-temperature process used in an attempt to deposit diamond on substrates of glass, quartz, silicon, nickel, and boron nitride. Several deposition parameters have been varied including substrate temperature, gas concentration, gas pressure, total gas flow rate, RF input power, and deposition time. Analytical methods employed to determine composition and structure of the deposits include scanning electron microscopy, absorption spectroscopy, scanning Auger microprobe spectroscopy, and Raman spectroscopy. Analysis indicates that particles having a thin graphite surface, as well as diamond particles with no surface coatings, have been deposited. Deposits on quartz have exhibited optical bandgaps as high as 4.5 eV. Scanning electron microscopy analysis shows that particles are deposited on a pedestal which Auger spectroscopy indicates to be graphite. This is a phenomenon that has not been previously reported in the literature.

Confined compressive strength analysis can improve PDC bit selection. [Polycrystalline Diamond Compact

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

Fabain, R.T.

1994-05-16

A rock strength analysis program, through intensive log analysis, can quantify rock hardness in terms of confined compressive strength to identify intervals suited for drilling with polycrystalline diamond compact (PDC) bits. Additionally, knowing the confined compressive strength helps determine the optimum PDC bit for the intervals. Computing rock strength as confined compressive strength can more accurately characterize a rock's actual hardness downhole than other methods. the information can be used to improve bit selections and to help adjust drilling parameters to reduce drilling costs. Empirical data compiled from numerous field strength analyses have provided a guide to selecting PDC drillmore » bits. A computer analysis program has been developed to aid in PDC bit selection. The program more accurately defines rock hardness in terms of confined strength, which approximates the in situ rock hardness downhole. Unconfined compressive strength is rock hardness at atmospheric pressure. The program uses sonic and gamma ray logs as well as numerous input data from mud logs. Within the range of lithologies for which the program is valid, rock hardness can be determine with improved accuracy. The program's output is typically graphed in a log format displaying raw data traces from well logs, computer-interpreted lithology, the calculated values of confined compressive strength, and various optional rock mechanic outputs.« less

New developments in CVD diamond for detector applications

NASA Astrophysics Data System (ADS)

Adam, W.; Berdermann, E.; Bergonzo, P.; de Boer, W.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; D'Angelo, P.; Dabrowski, W.; Delpierre, P.; Dulinski, W.; Doroshenko, J.; van Eijk, B.; Fallou, A.; Fischer, P.; Fizzotti, F.; Furetta, C.; Gan, K. K.; Ghodbane, N.; Grigoriev, E.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kaplon, J.; Kass, R.; Keil, M.; Knoepfle, K. T.; Koeth, T.; Krammer, M.; Logiudice, A.; Lu, R.; Mac Lynne, L.; Manfredotti, C.; Meier, D.; Menichelli, D.; Meuser, S.; Mishina, M.; Moroni, L.; Noomen, J.; Oh, A.; Pernicka, M.; Perera, L.; Potenza, R.; Riester, J. L.; Roe, S.; Rudge, A.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Sutera, C.; Trischuk, W.; Tromson, D.; Tuve, C.; Vincenzo, B.; Weilhammer, P.; Wermes, N.; Wetstein, M.; Zeuner, W.; Zoeller, M.

Chemical Vapor Deposition (CVD) diamond has been discussed extensively as an alternative sensor material for use very close to the interaction region of the LHC and other machines where extreme radiation conditions exist. During the last seven years the RD42 collaboration has developed diamond detectors and tested them with LHC electronics towards the end of creating a device usable by experiments. The most recent results of this work are presented. Recently, a new form of CVD diamond has been developed: single crystal CVD diamond which resolves many of the issues associated with poly-crystalline CVD material. The first tests of this material are also presented.

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

NASA Astrophysics Data System (ADS)

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

2018-05-01

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

Thermally induced alkylation of diamond.

PubMed

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

2010-12-21

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

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.

Near-ultraviolet micro-Raman study of diamond grown on GaN

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

Nazari, M., E-mail: m-n79@txstate.edu; Hancock, B. L.; Anderson, J.

2016-01-18

Ultraviolet (UV) micro-Raman measurements are reported of diamond grown on GaN using chemical vapor deposition. UV excitation permits simultaneous investigation of the diamond (D) and disordered carbon (DC) comprising the polycrystalline layer. From line scans of a cross-section along the diamond growth direction, the DC component of the diamond layer is found to be highest near the GaN-on-diamond interface and diminish with characteristic length scale of ∼3.5 μm. Transmission electron microscopy (TEM) of the diamond near the interface confirms the presence of DC. Combined micro-Raman and TEM are used to develop an optical method for estimating the DC volume fraction.

Thermal diffusivity of diamond nanowires studied by laser assisted atom probe tomography

NASA Astrophysics Data System (ADS)

Arnoldi, L.; Spies, M.; Houard, J.; Blum, I.; Etienne, A.; Ismagilov, R.; Obraztsov, A.; Vella, A.

2018-04-01

The thermal properties of single-crystal diamond nanowires (NWs) have been calculated from first principles but have never been measured experimentally. Taking advantage of the sharp geometry of samples analyzed in a laser assisted atom probe, this technique is used to measure the thermal diffusivity of a single NW at low temperature (<300 K). The obtained value is in good agreement with the ab-initio calculations and confirms that thermal diffusivity in nanoscale samples is lower than in bulk samples. The results impact the design and integration of diamond NWs and nanoneedles in nanoscale devices for heat dissipation.

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

DOE PAGES

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

2016-07-04

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

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

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

Berman, Diana; Deshmukh, Sanket; Narayanan, Badri

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

Diamond- cBN alloy: A universal cutting material

DOE PAGES

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

2015-09-08

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

Diamond-cBN alloy: A universal cutting material

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

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

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

Diamond- cBN alloy: A universal cutting material

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

Wang, Pei; He, Duanwei; Wang, Liping

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

A thermal-sensitive device fabricated with diamond film and a planar microelectrode

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

Changzhi Gu; Zengsun Jin; Xianyi Lu

1995-12-31

Polycrystalline diamond film were deposited by means of the hot filament CVD technique (HFCVD) onto a planar interdigital Ti microelectrode arrays, and forming a thermal-sensitive device, The resistor changes of diamond film caused by temperature are shown to be sensitive, reproducible, rapid and stable thermal-sensitive device. The characteristics of thermal-sensitive for this device was study. Functionalized diamond film deposited onto planar microelectrode arrays can easily detect temperature from 20{degrees}C to 700{degrees}C.

Surgical energy device using steam jet for robotic assisted surgery.

PubMed

Yoshiki, Hitoshi; Tadano, Kotaro; Ban, Daisuke; Ohuchi, Katsuhiro; Tanabe, Minoru; Kawashima, Kenji

2015-01-01

In robotic assisted surgery, the carbonization and the adherence of coagulated tissues caused by surgical energy devices are problems. We propose a surgical energy device using a steam jet to solve the problems. The device applies a steam jet and performs coagulation and hemostasis. The exposed tissue is heated quickly with latent heat of the steam. The carbonization and the adherence of the tissue can be avoided. We prototyped a steam jet coagulator to prove the concept. The coagulator was mounted on the laparoscopic surgical robot. The effectiveness of the coagulation and hemostasis using steam was confirmed by the in vitro experiment on the chicken's liver and the in vivo experiments on the pig's spleen under the robotic assisted laparoscopic environment.

Development of a jet pump-assisted arterial heat pipe

NASA Technical Reports Server (NTRS)

Bienert, W. B.; Ducao, A. S.; Trimmer, D. S.

1977-01-01

The development of a jet pump assisted arterial heat pipe is described. The concept utilizes a built-in capillary driven jet pump to remove vapor and gas from the artery and to prime it. The continuous pumping action also prevents depriming during operation of the heat pipe. The concept is applicable to fixed conductance and gas loaded variable conductance heat pipes. A theoretical model for the jet pump assisted arterial heat pipe is presented. The model was used to design a prototype for laboratory demonstration. The 1.2 m long heat pipe was designed to transport 500 watts and to prime at an adverse elevation of up to 1.3 cm. The test results were in good agreement with the theoretical predictions. The heat pipe carried as much as 540 watts and was able to prime up to 1.9 cm. Introduction of a considerable amount of noncondensible gas had no adverse effect on the priming capability.

An investigation on co-axial water-jet assisted fiber laser cutting of metal sheets

NASA Astrophysics Data System (ADS)

Madhukar, Yuvraj K.; Mullick, Suvradip; Nath, Ashish K.

2016-02-01

Water assisted laser cutting has received significant attention in recent times with assurance of many advantages than conventional gas assisted laser cutting. A comparative study between co-axial water-jet and gas-jet assisted laser cutting of thin sheets of mild steel (MS) and titanium (Ti) by fiber laser is presented. Fiber laser (1.07 μm wavelength) was utilised because of its low absorption in water. The cut quality was evaluated in terms of average kerf, projected dross height, heat affected zone (HAZ) and cut surface roughness. It was observed that a broad range process parameter could produce consistent cut quality in MS. However, oxygen assisted cutting could produce better quality only with optimised parameters at high laser power and high cutting speed. In Ti cutting the water-jet assisted laser cutting performed better over the entire range of process parameters compared with gas assisted cutting. The specific energy, defined as the amount of laser energy required to remove unit volume of material was found more in case of water-jet assisted laser cutting process. It is mainly due to various losses associated with water assisted laser processing such as absorption of laser energy in water and scattering at the interaction zone.

Temperature characteristics of SAW resonators on Sc0.26Al0.74N/polycrystalline diamond heterostructures

NASA Astrophysics Data System (ADS)

Sinusía Lozano, M.; Chen, Z.; Williams, Oliver A.; Iriarte, G. F.

2018-07-01

Surface acoustic wave (SAW) resonators have been fabricated on a 2 μm scandium aluminium nitride (ScAlN) film deposited by means of pulsed-DC reactive magnetron sputtering on a 5.8 μm polycrystalline diamond substrate. Thin film characterization comprised of the assessment of the thin film texture by means of x-ray diffraction (XRD) measurements, reporting highly c-axis oriented ScAlN thin films with a full width at half maximum (FWHM) of the ω-θ scans below 2°. Compositional and piezoelectric analyses of the thin films synthesized with the sputtering parameters used in this work, namely a sputtering power of 700 W and a synthesis pressure of 0.53 Pa, have reported a thin film composition of Sc0.26Al0.74N together with a piezoelectric d33 constant of ‑11 pC/N. Finally, a SAW resonator has been characterized using a vector network analyser (VNA) under various substrate temperature conditions with two iterations. The resulting temperature coefficient of frequency (TCF) values show a highly linear behaviour within two temperature ranges, namely from 20 K to room temperature (300 K) (‑12.5 ppm/K) as well as from 300 K up to 450 K (‑34.6 ppm/K).

Single Crystal Diamond Needle as Point Electron Source.

PubMed

Kleshch, Victor I; Purcell, Stephen T; Obraztsov, Alexander N

2016-10-12

Diamond has been considered to be one of the most attractive materials for cold-cathode applications during past two decades. However, its real application is hampered by the necessity to provide appropriate amount and transport of electrons to emitter surface which is usually achieved by using nanometer size or highly defective crystallites having much lower physical characteristics than the ideal diamond. Here, for the first time the use of single crystal diamond emitter with high aspect ratio as a point electron source is reported. Single crystal diamond needles were obtained by selective oxidation of polycrystalline diamond films produced by plasma enhanced chemical vapor deposition. Field emission currents and total electron energy distributions were measured for individual diamond needles as functions of extraction voltage and temperature. The needles demonstrate current saturation phenomenon and sensitivity of emission to temperature. The analysis of the voltage drops measured via electron energy analyzer shows that the conduction is provided by the surface of the diamond needles and is governed by Poole-Frenkel transport mechanism with characteristic trap energy of 0.2-0.3 eV. The temperature-sensitive FE characteristics of the diamond needles are of great interest for production of the point electron beam sources and sensors for vacuum electronics.

Single Crystal Diamond Needle as Point Electron Source

PubMed Central

Kleshch, Victor I.; Purcell, Stephen T.; Obraztsov, Alexander N.

2016-01-01

Diamond has been considered to be one of the most attractive materials for cold-cathode applications during past two decades. However, its real application is hampered by the necessity to provide appropriate amount and transport of electrons to emitter surface which is usually achieved by using nanometer size or highly defective crystallites having much lower physical characteristics than the ideal diamond. Here, for the first time the use of single crystal diamond emitter with high aspect ratio as a point electron source is reported. Single crystal diamond needles were obtained by selective oxidation of polycrystalline diamond films produced by plasma enhanced chemical vapor deposition. Field emission currents and total electron energy distributions were measured for individual diamond needles as functions of extraction voltage and temperature. The needles demonstrate current saturation phenomenon and sensitivity of emission to temperature. The analysis of the voltage drops measured via electron energy analyzer shows that the conduction is provided by the surface of the diamond needles and is governed by Poole-Frenkel transport mechanism with characteristic trap energy of 0.2–0.3 eV. The temperature-sensitive FE characteristics of the diamond needles are of great interest for production of the point electron beam sources and sensors for vacuum electronics. PMID:27731379

Single Crystal Diamond Needle as Point Electron Source

NASA Astrophysics Data System (ADS)

Kleshch, Victor I.; Purcell, Stephen T.; Obraztsov, Alexander N.

2016-10-01

Diamond has been considered to be one of the most attractive materials for cold-cathode applications during past two decades. However, its real application is hampered by the necessity to provide appropriate amount and transport of electrons to emitter surface which is usually achieved by using nanometer size or highly defective crystallites having much lower physical characteristics than the ideal diamond. Here, for the first time the use of single crystal diamond emitter with high aspect ratio as a point electron source is reported. Single crystal diamond needles were obtained by selective oxidation of polycrystalline diamond films produced by plasma enhanced chemical vapor deposition. Field emission currents and total electron energy distributions were measured for individual diamond needles as functions of extraction voltage and temperature. The needles demonstrate current saturation phenomenon and sensitivity of emission to temperature. The analysis of the voltage drops measured via electron energy analyzer shows that the conduction is provided by the surface of the diamond needles and is governed by Poole-Frenkel transport mechanism with characteristic trap energy of 0.2-0.3 eV. The temperature-sensitive FE characteristics of the diamond needles are of great interest for production of the point electron beam sources and sensors for vacuum electronics.

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

NASA Astrophysics Data System (ADS)

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

2007-03-01

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

Growth, characterization and device development in monocrystalline diamond films

NASA Astrophysics Data System (ADS)

Davis, R. F.; Glass, J. T.; Nemanich, R. J.; Bozeman, S. P.; Sowers, A. T.

1995-06-01

Experimental and theoretical studies concerned with interface interactions of diamond with Si, Ni, and Ni3Si substrates have been conducted. Oriented diamond films deposited on (100) Si were characterized by polar Raman, polar x-ray diffraction (XRD), and cross-sectional high resolution transmission electron microscopy (HRTEM). These sutides showed that the diamond(100)/Si(100) interface adopted the 3:2-match arrangement rather than a 45 deg rotation. Extended Hueckel tight-binding (EHTB) electronic structure calculations for a model system revealed that the interface interaction favors the 3:2-match arrangement. Growth on polycrystalline Ni3Si resulted in oriented diamond particles; under the same growth conditions, graphite was formed on the nickel substrate. Our EHTB electronic structure calculations showed that the (111) and (100) surfaces of Ni3Si have a strong preference for diamond nucleation over graphite nucleation, but this was not the case for the (111) and (100) surfaces of Ni.

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

NASA Technical Reports Server (NTRS)

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

2000-01-01

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

Zero bias thermally stimulated currents in synthetic diamond

NASA Astrophysics Data System (ADS)

Mori, R.; Miglio, S.; Bruzzi, M.; Bogani, F.; De Sio, A.; Pace, E.

2009-06-01

Zero bias thermally stimulated currents (ZBTSCs) have been observed in single crystal high pressure high temperature (HPHT) and polycrystalline chemical vapor deposited (pCVD) diamond films. The ZBTSC technique is characterized by an increased sensitivity with respect to a standard TSC analysis. Due to the absence of the thermally activated background current, new TSC peaks have been observed in both HPHT and pCVD diamond films, related to shallow activation energies usually obscured by the emission of the dominant impurities. The ZBTSC peaks are explained in terms of defect discharge in the nonequilibrium potential distribution created by a nonuniform traps filling at the metal-diamond junctions. The electric field due to the charged defects has been estimated in a quasizero bias TSC experiment by applying an external bias.

Nanosecond formation of diamond and lonsdaleite by shock compression of graphite

DOE PAGES

Kraus, D.; Ravasio, A.; Gauthier, M.; ...

2016-03-14

The shock-induced transition from graphite to diamond has been of great scientific and technological interest since the discovery of microscopic diamonds in remnants of explosively driven graphite. Furthermore, shock synthesis of diamond and lonsdaleite, a speculative hexagonal carbon polymorph with unique hardness, is expected to happen during violent meteor impacts. Here, we show unprecedented in situ X-ray diffraction measurements of diamond formation on nanosecond timescales by shock compression of pyrolytic as well as polycrystalline graphite to pressures from 19 GPa up to 228 GPa. While we observe the transition to diamond starting at 50 GPa for both pyrolytic and polycrystallinemore » graphite, we also record the direct formation of lonsdaleite above 170 GPa for pyrolytic samples only. In conclusion, our experiment provides new insights into the processes of the shock-induced transition from graphite to diamond and uniquely resolves the dynamics that explain the main natural occurrence of the lonsdaleite crystal structure being close to meteor impact sites.« less

Controllable synthesizing DLC nano structures as a super hydrophobic layer on cotton fabric using a low-cost ethanol electrospray-assisted atmospheric plasma jet.

PubMed

Sohbatzadeh, F; Eshghabadi, M; Mohsenpour, T

2018-06-29

The surface modification of cotton samples was carried out using a liquid (ethanol) electrospray-assisted atmospheric pressure plasma jet. X-ray photoelectron spectroscopy (XPS) and Raman analysis confirmed the successful deposition of diamond like carbon (DLC) nano structures on the cotton surface. The super hydrophobic state of the samples was probed by contact angle measurements. The water repellency of the layers was tuned by controlling the voltage applied to the electrospray electrode. An investigation of the morphological and chemical structures of the samples by field emission scanning microscopy, atomic force microscopy (AFM) and XPS indicated that the physical shape, distribution and amorphization of the DLC structures were successfully adjusted and improved by applying a voltage to the electrospray electrode. Finally wash durability of the best sample was tested for 35 cycles. In this work, the use of a well-developed atmospheric pressure plasma jet for DLC nano structures deposition can enable a promising environmentally friendly and low-cost approach for modifying cotton fabrics for super water-repellent fabric applications.

Controllable synthesizing DLC nano structures as a super hydrophobic layer on cotton fabric using a low-cost ethanol electrospray-assisted atmospheric plasma jet

NASA Astrophysics Data System (ADS)

Sohbatzadeh, F.; Eshghabadi, M.; Mohsenpour, T.

2018-06-01

The surface modification of cotton samples was carried out using a liquid (ethanol) electrospray-assisted atmospheric pressure plasma jet. X-ray photoelectron spectroscopy (XPS) and Raman analysis confirmed the successful deposition of diamond like carbon (DLC) nano structures on the cotton surface. The super hydrophobic state of the samples was probed by contact angle measurements. The water repellency of the layers was tuned by controlling the voltage applied to the electrospray electrode. An investigation of the morphological and chemical structures of the samples by field emission scanning microscopy, atomic force microscopy (AFM) and XPS indicated that the physical shape, distribution and amorphization of the DLC structures were successfully adjusted and improved by applying a voltage to the electrospray electrode. Finally wash durability of the best sample was tested for 35 cycles. In this work, the use of a well-developed atmospheric pressure plasma jet for DLC nano structures deposition can enable a promising environmentally friendly and low-cost approach for modifying cotton fabrics for super water-repellent fabric applications.

Plasma-assisted conversion of solid hydrocarbon to diamond

DOEpatents

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

1996-01-01

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

Diagnostic Techniques Used to Study Chemical-Vapor-Deposited Diamond Films

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

2000-01-01

The advantages and utility of chemical-vapor-deposited (CVD) diamond as an industrial ceramic can only be realized if the price and quality are right. Until recently, this technology was of interest only to the academic and basic research community. However, interest has grown because of advances made by leading CVD diamond suppliers: 1) Reduction of the cost of CVD polycrystalline diamond deposition below $5/carat ($8/sq cm); 2) Installation of production capacity; 3) Epitaxial growth of CVD single-crystal diamond. Thus, CVD diamond applications and business are an industrial reality. At present, CVD diamond is produced in the form of coatings or wafers. CVD diamond film technology offers a broader technological potential than do natural and high-pressure synthetic diamonds because size, geometry, and eventually cost will not be as limiting. Now that they are cost effective, diamond coatings - with their extreme properties - can be used in a variety of applications. Diamond coatings can improve many of the surface properties of engineering substrate materials, including erosion, corrosion, and wear resistance. Examples of actual and potential applications, from microelectromechanical systems to the wear parts of diamond coatings and related superhard coatings are described. For example, diamond coatings can be used as a chemical and mechanical barrier for the space shuttles check valves, particularly on the guide pins and seat assemblies.

A large area diamond-based beam tagging hodoscope for ion therapy monitoring

NASA Astrophysics Data System (ADS)

Gallin-Martel, M.-L.; Abbassi, L.; Bes, A.; Bosson, G.; Collot, J.; Crozes, T.; Curtoni, S.; Dauvergne, D.; De Nolf, W.; Fontana, M.; Gallin-Martel, L.; Hostachy, J.-Y.; Krimmer, J.; Lacoste, A.; Marcatili, S.; Morse, J.; Motte, J.-F.; Muraz, J.-F.; Rarbi, F. E.; Rossetto, O.; Salomé, M.; Testa, É.; Vuiart, R.; Yamouni, M.

2018-01-01

The MoniDiam project is part of the French national collaboration CLaRyS (Contrôle en Ligne de l'hAdronthérapie par RaYonnements Secondaires) for on-line monitoring of hadron therapy. It relies on the imaging of nuclear reaction products that is related to the ion range. The goal here is to provide large area beam detectors with a high detection efficiency for carbon or proton beams giving time and position measurement at 100 MHz count rates (beam tagging hodoscope). High radiation hardness and intrinsic electronic properties make diamonds reliable and very fast detectors with a good signal to noise ratio. Commercial Chemical Vapor Deposited (CVD) poly-crystalline, heteroepitaxial and monocrystalline diamonds were studied. Their applicability as a particle detector was investigated using α and β radioactive sources, 95 MeV/u carbon ion beams at GANIL and 8.5 keV X-ray photon bunches from ESRF. This facility offers the unique capability of providing a focused ( 1 μm) beam in bunches of 100 ps duration, with an almost uniform energy deposition in the irradiated detector volume, therefore mimicking the interaction of single ions. A signal rise time resolution ranging from 20 to 90 ps rms and an energy resolution of 7 to 9% were measured using diamonds with aluminum disk shaped surface metallization. This enabled us to conclude that polycrystalline CVD diamond detectors are good candidates for our beam tagging hodoscope development. Recently, double-side stripped metallized diamonds were tested using the XBIC (X Rays Beam Induced Current) set-up of the ID21 beamline at ESRF which permits us to evaluate the capability of diamond to be used as position sensitive detector. The final detector will consist in a mosaic arrangement of double-side stripped diamond sensors read out by a dedicated fast-integrated electronics of several hundreds of channels.

Diamond-Based Supercapacitors: Realization and Properties.

PubMed

Gao, Fang; Nebel, Christoph E

2016-10-26

In this Spotlight on Applications, we describe our recent progress on the fabrication of surface-enlarged boron-doped polycrystalline diamond electrodes, and evaluate their performance in supercapacitor applications. We begin with a discussion of the fabrication methods of porous diamond materials. The diamond surface enlargement starts with a top-down plasma etching method. Although the extra surface area provided by surface roughening or nanostructuring provides good outcome for sensing applications, a capacitance value <1 mF cm -2 or a surface-enlargement factor <100 fail to meet the requirement of a practical supercapacitor. Driven by the need for large surface areas, we recently focused on the tempated-growth method. We worked on both supported and free-standing porous diamond materials to enhance the areal capacitance to the "mF cm -2 " range. With our newly developed free-standing diamond paper, areal capacitance can be multiplied by stacking multilayers of the electrode material. Finally, considering the fact that there is no real diamond-based supercapacitor device up to now, we fabricated the first prototype pouch-cell device based on the free-standing diamond paper to evaluate its performance. The results reveal that the diamond paper is suitable for operation in high potential windows (up to 2.5 V) in aqueous electrolyte with a capacitance of 0.688 mF cm -2 per layer of paper (or 0.645 F g -1 ). Impedance spectroscopy revealed that the operation frequency of the device exceeds 30 Hz. Because of the large potential window and the ability to work at high frequency, the specific power of the device reached 1 × 10 5 W kg -1 . In the end, we made estimations on the future target performance of diamond supercapacitors based on the existing information.

Grafting odorant binding proteins on diamond bio-MEMS.

PubMed

Manai, R; Scorsone, E; Rousseau, L; Ghassemi, F; Possas Abreu, M; Lissorgues, G; Tremillon, N; Ginisty, H; Arnault, J-C; Tuccori, E; Bernabei, M; Cali, K; Persaud, K C; Bergonzo, P

2014-10-15

Odorant binding proteins (OBPs) are small soluble proteins found in olfactory systems that are capable of binding several types of odorant molecules. Cantilevers based on polycrystalline diamond surfaces are very promising as chemical transducers. Here two methods were investigated for chemically grafting porcine OBPs on polycrystalline diamond surfaces for biosensor development. The first approach resulted in random orientation of the immobilized proteins over the surface. The second approach based on complexing a histidine-tag located on the protein with nickel allowed control of the proteins' orientation. Evidence confirming protein grafting was obtained using electrochemical impedance spectroscopy, fluorescence imaging and X-ray photoelectron spectroscopy. The chemical sensing performances of these OBP modified transducers were assessed. The second grafting method led to typically 20% more sensitive sensors, as a result of better access of ligands to the proteins active sites and also perhaps a better yield of protein immobilization. This new grafting method appears to be highly promising for further investigation of the ligand binding properties of OBPs in general and for the development of arrays of non-specific biosensors for artificial olfaction applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Materials Research Society Symposium Proceedings on Diamond, SiC and Nitride Wide Bandgap Semiconductors Held at San Francisco, California on 4-8 April 1994. Volume 339.

DTIC Science & Technology

1994-04-08

demonstrated that there existed no graphite phase at the surface of the as-deposited and 02 plasma treated polycrystalline diamond films. W 3- uO 2.5...diamond, highly ordered pyrolitic graphite ( HOPG ), and an amorphous carbon surface created by 1 keV ion bombardment of diamond. The diamond surface was...Library of Congress Cataloging in Publication Data Materials Research Society. Meeting (1994 : San Francisco, Calif.). Symposium D. Diamond, SiC and nitride

Thin film diamond temperature sensor array for harsh aerospace environment

NASA Technical Reports Server (NTRS)

Aslam, M.; Masood, A.; Fredricks, R. J.; Tamor, M. A.

1992-01-01

The feasibility of using polycrystalline CVD diamond films as temperature sensors in harsh aerospace environment associated with hypersonic flights was tested using patterned diamond resistors, fabricated on flat or curved oxidized Si surfaces, as temperature sensors at temperatures between 20 and 1000 C. In this temperature range, the measured resistance was found to vary over 3 orders of magnitude and the temperature coefficient of resistance to change from 0.017/K to 0.003/K. After an annealing treatment, the resistance change was reproducible within 1 percent on the entire temperature range for short measuring times.

Tool wear mechanisms in turning titanium-aluminum-vanadium using tungsten carbide and polycrystalline diamond inserts

NASA Astrophysics Data System (ADS)

Schrock, David James

The objective of this work is to identify some of the tool wear mechanisms at the material level for the machining of titanium and to provide some understanding of these mechanisms for use in physics based tool wear models. Turning experiments were conducted at cutting speeds of 61m/min, 91m/min, and 122m/min on Ti-6Al-4V, an alloy of titanium, using two different grades of tungsten carbide cutting inserts and one grade of polycrystalline diamond inserts. Three-dimensional wear data and two-dimensional wear profiles of the rake face were generated using Confocal Laser Scanning Microscopy to quantify the tool wear mechanisms. Additionally, the microstructure of the deformed work material (chip) and un-deformed parent material (work piece) were studied using Orientation Imaging Microscopy (OIM). Observations from tool wear studies on the PCD inserts revealed the presence of two fundamentally different wear mechanisms operating at the different cutting speeds. Microstructural analyses of the chip and the work material showed phase dependent tool wear mechanisms for machining titanium. There is a high likelihood of phase change occurring in the work material during machining, with a transformation from the alpha phase to the beta phase. The observed dramatic increase in wear is attributed to a combination of increased diffusivity in the beta phase of the titanium alloy in conjunction with a higher degree of recrystallization of the prior beta phase upon cooling. Results of other observations such as the influence of carbide grain size on tool wear are also discussed.

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

NASA Astrophysics Data System (ADS)

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

2016-10-01

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

Boron-doped diamond electrode: synthesis, characterization, functionalization and analytical applications.

PubMed

Luong, John H T; Male, Keith B; Glennon, Jeremy D

2009-10-01

In recent years, conductive diamond electrodes for electrochemical applications have been a major focus of research and development. The impetus behind such endeavors could be attributed to their wide potential window, low background current, chemical inertness, and mechanical durability. Several analytes can be oxidized by conducting diamond compared to other carbon-based materials before the breakdown of water in aqueous electrolytes. This is important for detecting and/or identifying species in solution since oxygen and hydrogen evolution do not interfere with the analysis. Thus, conductive diamond electrodes take electrochemical detection into new areas and extend their usefulness to analytes which are not feasible with conventional electrode materials. Different types of diamond electrodes, polycrystalline, microcrystalline, nanocrystalline and ultrananocrystalline, have been synthesized and characterized. Of particular interest is the synthesis of boron-doped diamond (BDD) films by chemical vapor deposition on various substrates. In the tetrahedral diamond lattice, each carbon atom is covalently bonded to its neighbors forming an extremely robust crystalline structure. Some carbon atoms in the lattice are substituted with boron to provide electrical conductivity. Modification strategies of doped diamond electrodes with metallic nanoparticles and/or electropolymerized films are of importance to impart novel characteristics or to improve the performance of diamond electrodes. Biofunctionalization of diamond films is also feasible to foster several useful bioanalytical applications. A plethora of opportunities for nanoscale analytical devices based on conducting diamond is anticipated in the very near future.

Secondary Electron Emission Spectroscopy of Diamond Surfaces

NASA Technical Reports Server (NTRS)

Krainsky, Isay L.; Asnin, Vladimir M.; Petukhov, Andre G.

1999-01-01

This report presents the results of the secondary electron emission spectroscopy study of hydrogenated diamond surfaces for single crystals and chemical vapor-deposited polycrystalline films. One-electron calculations of Auger spectra of diamond surfaces having various hydrogen coverages are presented, the major features of the experimental spectra are explained, and a theoretical model for Auger spectra of hydrogenated diamond surfaces is proposed. An energy shift and a change in the line shape of the carbon core-valence-valence (KVV) Auger spectra were observed for diamond surfaces after exposure to an electron beam or by annealing at temperatures higher than 950 C. This change is related to the redistribution of the valence-band local density of states caused by hydrogen desorption from the surface. A strong negative electron affinity (NEA) effect, which appeared as a large, narrow peak in the low-energy portion of the spectrum of the secondary electron energy distribution, was also observed on the diamond surfaces. A fine structure in this peak, which was found for the first time, reflected the energy structure of the bottom of the conduction band. Further, the breakup of the bulk excitons at the surface during secondary electron emission was attributed to one of the features of this structure. The study demonstrated that the NEA type depends on the extent of hydrogen coverage of the diamond surface, changing from the true type for the completely hydrogenated surface to the effective type for the partially hydrogenated surface.

Calculation of Debye-Scherrer diffraction patterns from highly stressed polycrystalline materials

DOE PAGES

MacDonald, M. J.; Vorberger, J.; Gamboa, E. J.; ...

2016-06-07

Calculations of Debye-Scherrer diffraction patterns from polycrystalline materials have typically been done in the limit of small deviatoric stresses. Although these methods are well suited for experiments conducted near hydrostatic conditions, more robust models are required to diagnose the large strain anisotropies present in dynamic compression experiments. A method to predict Debye-Scherrer diffraction patterns for arbitrary strains has been presented in the Voigt (iso-strain) limit. Here, we present a method to calculate Debye-Scherrer diffraction patterns from highly stressed polycrystalline samples in the Reuss (iso-stress) limit. This analysis uses elastic constants to calculate lattice strains for all initial crystallite orientations, enablingmore » elastic anisotropy and sample texture effects to be modeled directly. Furthermore, the effects of probing geometry, deviatoric stresses, and sample texture are demonstrated and compared to Voigt limit predictions. An example of shock-compressed polycrystalline diamond is presented to illustrate how this model can be applied and demonstrates the importance of including material strength when interpreting diffraction in dynamic compression experiments.« less

Calculation of Debye-Scherrer diffraction patterns from highly stressed polycrystalline materials

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

MacDonald, M. J., E-mail: macdonm@umich.edu; SLAC National Accelerator Laboratory, Menlo Park, California 94025; Vorberger, J.

2016-06-07

Calculations of Debye-Scherrer diffraction patterns from polycrystalline materials have typically been done in the limit of small deviatoric stresses. Although these methods are well suited for experiments conducted near hydrostatic conditions, more robust models are required to diagnose the large strain anisotropies present in dynamic compression experiments. A method to predict Debye-Scherrer diffraction patterns for arbitrary strains has been presented in the Voigt (iso-strain) limit [Higginbotham, J. Appl. Phys. 115, 174906 (2014)]. Here, we present a method to calculate Debye-Scherrer diffraction patterns from highly stressed polycrystalline samples in the Reuss (iso-stress) limit. This analysis uses elastic constants to calculate latticemore » strains for all initial crystallite orientations, enabling elastic anisotropy and sample texture effects to be modeled directly. The effects of probing geometry, deviatoric stresses, and sample texture are demonstrated and compared to Voigt limit predictions. An example of shock-compressed polycrystalline diamond is presented to illustrate how this model can be applied and demonstrates the importance of including material strength when interpreting diffraction in dynamic compression experiments.« less

Nitrogen doping, optical characterization, and electron emission study of diamond

NASA Astrophysics Data System (ADS)

Park, Minseo

bombardment. Field emission measurements were performed in-situ with an electron beam induced current (EBIC) probe inside the chamber of the scanning electron microscope. It was found that amorphous sp2 carbon is produced as the diamond is sputtered by the Ar ion beam. The field emission turn-on field was also significantly lowered after sharpening, which, it is speculated, is caused by field enhancement due to a change in geometry and/or structural changes (such as amorphization of crystalline diamond into graphitic or amorphous sp2 carbon) by Ar ion irradiation. Secondary electron emission patterning of single crystal diamond surfaces with hydrogen and oxygen plasma treatments was demonstrated. Hydrogen plasma treated regions were much brighter than the oxygen terminated regions. Results of atomic force microscopy confirmed that the observed contrast is not topographical. Several other possible negative electron affinity (or low positive electron affinity) materials such as chemical vapor deposited (CVD) diamond, aluminum nitride and tetrahedrally bonded amorphous carbon [tx a-C 1-x] were also investigated. Faint image contrast (patterning) was also observed from polycrystalline CVD diamond, single crystal aluminum nitride films, and polycrystalline aluminum nitride films; however, no contrast at all was obtained from tetrahedrally bonded amorphous carbon [tx a-C1-x] films.

Nitrogen-vacancy-assisted magnetometry of paramagnetic centers in an individual diamond nanocrystal.

PubMed

Laraoui, Abdelghani; Hodges, Jonathan S; Meriles, Carlos A

2012-07-11

Semiconductor nanoparticles host a number of paramagnetic point defects and impurities, many of them adjacent to the surface, whose response to external stimuli could help probe the complex dynamics of the particle and its local, nanoscale environment. Here, we use optically detected magnetic resonance in a nitrogen-vacancy (NV) center within an individual diamond nanocrystal to investigate the composition and spin dynamics of the particle-hosted spin bath. For the present sample, a ∼45 nm diamond crystal, NV-assisted dark-spin spectroscopy reveals the presence of nitrogen donors and a second, yet-unidentified class of paramagnetic centers. Both groups share a common spin lifetime considerably shorter than that observed for the NV spin, suggesting some form of spatial clustering, possibly on the nanoparticle surface. Using double spin resonance and dynamical decoupling, we also demonstrate control of the combined NV center-spin bath dynamics and attain NV coherence lifetimes comparable to those reported for bulk, Type Ib samples. Extensions based on the experiments presented herein hold promise for applications in nanoscale magnetic sensing, biomedical labeling, and imaging.

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Selective metallisation of diamonds with the aid of laser radiation

NASA Astrophysics Data System (ADS)

Shafeev, Georgii A.; Pimenov, S. M.; Lubnin, Evgenii N.; Smolin, A. A.; Konov, Vitalii I.; Laptev, V. A.

1995-02-01

An experimental investigation was made of laser activation of diamond surfaces (single crystals and polycrystalline diamond films) prior to electroless before catalytic deposition of metals from solutions. The activation was carried out by a copper vapour laser or a KrF excimer laser in two ways: decomposition of a thin film of palladium acetylacetonate and local laser stimulated modification of the diamond surface by laser evaporation. An ohmic contact (Cu or Ni) with an adhesive strength of 3 N mm-2 was formed and the spatial resolution achieved was 10 μm.

Non-Markovianity-assisted high-fidelity Deutsch-Jozsa algorithm in diamond

NASA Astrophysics Data System (ADS)

Dong, Yang; Zheng, Yu; Li, Shen; Li, Cong-Cong; Chen, Xiang-Dong; Guo, Guang-Can; Sun, Fang-Wen

2018-01-01

The memory effects in non-Markovian quantum dynamics can induce the revival of quantum coherence, which is believed to provide important physical resources for quantum information processing (QIP). However, no real quantum algorithms have been demonstrated with the help of such memory effects. Here, we experimentally implemented a non-Markovianity-assisted high-fidelity refined Deutsch-Jozsa algorithm (RDJA) with a solid spin in diamond. The memory effects can induce pronounced non-monotonic variations in the RDJA results, which were confirmed to follow a non-Markovian quantum process by measuring the non-Markovianity of the spin system. By applying the memory effects as physical resources with the assistance of dynamical decoupling, the probability of success of RDJA was elevated above 97% in the open quantum system. This study not only demonstrates that the non-Markovianity is an important physical resource but also presents a feasible way to employ this physical resource. It will stimulate the application of the memory effects in non-Markovian quantum dynamics to improve the performance of practical QIP.

Evaluation of a 3D diamond detector for medical radiation dosimetry

NASA Astrophysics Data System (ADS)

Kanxheri, K.; Servoli, L.; Oh, A.; Munoz Sanchez, F.; Forcolin, G. T.; Murphy, S. A.; Aitkenhead, A.; Moore, C. J.; Morozzi, A.; Passeri, D.; Bellini, M.; Corsi, C.; Lagomarsino, S.; Sciortino, S.

2017-01-01

Synthetic diamond has several properties that are particularly suited to applications in medical radiation dosimetry. It is tissue equivalent, not toxic and shows a high resistance to radiation damage, low leakage current and stability of response. It is an electrical insulator, robust and realizable in small size; due to these features there are several examples of diamond devices, mainly planar single-crystalline chemical vapor depositation (sCVD) diamond, used for relative dose measurement in photon beams. Thanks to a new emerging technology, diamond devices with 3-dimensional structures are produced by using laser pulses to create graphitic paths in the diamond bulk. The necessary bias voltage to operate such detector decreases considerably while the signal response and radiation resistance increase. In order to evaluate the suitability of this new technology for measuring the dose delivered by radiotherapy beams in oncology a 3D polycrystalline (pCVD) diamond detector designed for single charged particle detection has been tested and the photon beam profile has been studied. The good linearity and high sensitivity to the dose observed in the 3D diamond, opens the way to the possibility of realizing a finely segmented device with the potential for dose distribution measurement in a single exposure for small field dosimetry that nowadays is still extremely challenging.

Selection of the most influential factors on the water-jet assisted underwater laser process by adaptive neuro-fuzzy technique

NASA Astrophysics Data System (ADS)

Nikolić, Vlastimir; Petković, Dalibor; Lazov, Lyubomir; Milovančević, Miloš

2016-07-01

Water-jet assisted underwater laser cutting has shown some advantages as it produces much less turbulence, gas bubble and aerosols, resulting in a more gentle process. However, this process has relatively low efficiency due to different losses in water. It is important to determine which parameters are the most important for the process. In this investigation was analyzed the water-jet assisted underwater laser cutting parameters forecasting based on the different parameters. The method of ANFIS (adaptive neuro fuzzy inference system) was applied to the data in order to select the most influential factors for water-jet assisted underwater laser cutting parameters forecasting. Three inputs are considered: laser power, cutting speed and water-jet speed. The ANFIS process for variable selection was also implemented in order to detect the predominant factors affecting the forecasting of the water-jet assisted underwater laser cutting parameters. According to the results the combination of laser power cutting speed forms the most influential combination foe the prediction of water-jet assisted underwater laser cutting parameters. The best prediction was observed for the bottom kerf-width (R2 = 0.9653). The worst prediction was observed for dross area per unit length (R2 = 0.6804). According to the results, a greater improvement in estimation accuracy can be achieved by removing the unnecessary parameter.

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

Conversion of fullerenes to diamond

DOEpatents

Gruen, Dieter M.

1994-01-01

A method of forming synthetic hydrogen defect free diamond or diamond like films on a substrate. The method involves providing vapor containing fullerene molecules with or without an inert gas, providing a device to impart energy to the fullerene molecules, fragmenting at least in part some of the fullerene molecules in the vapor or energizing the molecules to incipient fragmentation, ionizing the fullerene molecules, impinging ionized fullerene molecules on the substrate to assist in causing fullerene fragmentation to obtain a thickness of diamond on the substrate.

Highly oriented diamond films on Si: growth, characterization, and devices

NASA Astrophysics Data System (ADS)

Stoner, Brian R.; Malta, D. M.; Tessmer, A. J.; Holmes, J.; Dreifus, David L.; Glass, R. C.; Sowers, A.; Nemanich, Robert J.

1994-04-01

Highly oriented, (100) textured diamond films have been grown on single-crystal Si substrates via microwave plasma enhanced chemical vapor deposition. A multistep deposition process including bias-enhanced nucleation and textured growth was used to obtain smooth films consisting of epitaxial grains with only low-angle grain boundaries. Boron-doped layers were selectively deposited onto the surface of these oriented films and temperature-dependent Hall effect measurements indicated a 3 to 5 times improvement in hole mobility over polycrystalline films grown under similar conditions. Room temperature hole mobilities between 135 and 278 cm2/V-s were measured for the highly oriented samples as compared to 2 to 50 cm2/V-s for typical polycrystalline films. Grain size effects and a comparison between the transport properties of polycrystalline, highly oriented and homoepitaxial films will be discussed. Metal-oxide- semiconductor field-effect transistors were then fabricated on the highly oriented films and exhibited saturation and pinch-off of the channel current.

Unexpected pressure induced ductileness tuning in sulfur doped polycrystalline nickel metal

NASA Astrophysics Data System (ADS)

Guo, Cheng; Yang, Yan; Tan, Liuxi; Lei, Jialin; Guo, Shengmin; Chen, Bin; Yan, Jinyuan; Yang, Shizhong

2018-02-01

The sulfur induced embrittlement of polycrystalline nickel (Ni) metal has been a long-standing mystery. It is suggested that sulfur impurity makes ductile Ni metal brittle in many industry applications due to various mechanisms, such as impurity segregation and disorder-induced melting etc. Here we report an observation that the most ductile measurement occurs at a critical sulfur doping concentration, 14 at.% at pressure from 14 GPa up to 29 GPa through texture evolution analysis. The synchrotron-based high pressure texturing measurements using radial diamond anvil cell (rDAC) X-ray diffraction (XRD) techniques reveal that the activities of slip systems in the polycrystalline nickel metal are affected by sulfur impurities and external pressures, giving rise to the changes in the plastic deformation of the nickel metal. Dislocation dynamics (DD) simulation on dislocation density and velocity further confirms the pressure induced ductilization changes in S doped Ni metal. This observation and simulation suggests that the ductilization of the doped polycrystalline nickel metal can be optimized by engineering the sulfur concentration under pressure, shedding a light on tuning the mechanical properties of this material for better high pressure applications.

Status of Reconstruction of Fragmented Diamond-on-Silicon Collector From Genesis Spacecraft Solar Wind Concentrator

NASA Technical Reports Server (NTRS)

Rodriquez, Melissa C.; Calaway, M. C.; McNamara, K. M.; Hittle, J. D.

2009-01-01

In addition to passive solar wind collector surfaces, the Genesis Discovery Mission science canister had on board an electrostatic concave mirror for concentrating the solar wind ions, known as the concentrator . The 30-mm-radius collector focal point (the target) was comprised of 4 quadrants: two of single crystal SiC, one of polycrystalline 13C diamond and one of diamond-like-carbon (DLC) on a silicon substrate. [DLC-on-silicon is also sometimes referenced as Diamond-on-silicon, DOS.] Three of target quadrants survived the hard landing intact, but the DLC-on-silicon quadrant fractured into numerous pieces (Fig. 1). This abstract reports the status of identifying the DLC target fragments and reconstructing their original orientation.

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.

Rhenium Alloys as Ductile Substrates for Diamond Thin-Film Electrodes.

PubMed

Halpern, Jeffrey M; Martin, Heidi B

2014-02-01

Molybdenum-rhenium (Mo/Re) and tungsten-rhenium (W/Re) alloys were investigated as substrates for thin-film, polycrystalline boron-doped diamond electrodes. Traditional, carbide-forming metal substrates adhere strongly to diamond but lose their ductility during exposure to the high-temperature (1000°C) diamond, chemical vapor deposition environment. Boron-doped semi-metallic diamond was selectively deposited for up to 20 hours on one end of Mo/Re (47.5/52.5 wt.%) and W/Re (75/25 wt.%) alloy wires. Conformal diamond films on the alloys displayed grain sizes and Raman signatures similar to films grown on tungsten; in all cases, the morphology and Raman spectra were consistent with well-faceted, microcrystalline diamond with minimal sp 2 carbon content. Cyclic voltammograms of dopamine in phosphate-buffered saline (PBS) showed the wide window and low baseline current of high-quality diamond electrodes. In addition, the films showed consistently well-defined, dopamine electrochemical redox activity. The Mo/Re substrate regions that were uncoated but still exposed to the diamond-growth environment remained substantially more flexible than tungsten in a bend-to-fracture rotation test, bending to the test maximum of 90° and not fracturing. The W/Re substrates fractured after a 27° bend, and the tungsten fractured after a 21° bend. Brittle, transgranular cleavage fracture surfaces were observed for tungsten and W/Re. A tension-induced fracture of the Mo/Re after the prior bend test showed a dimple fracture with a visible ductile core. Overall, the Mo/Re and W/Re alloys were suitable substrates for diamond growth. The Mo/Re alloy remained significantly more ductile than traditional tungsten substrates after diamond growth, and thus may be an attractive metal substrate for more ductile, thin-film diamond electrodes.

Rhenium Alloys as Ductile Substrates for Diamond Thin-Film Electrodes

PubMed Central

Halpern, Jeffrey M.; Martin, Heidi B.

2014-01-01

Molybdenum-rhenium (Mo/Re) and tungsten-rhenium (W/Re) alloys were investigated as substrates for thin-film, polycrystalline boron-doped diamond electrodes. Traditional, carbide-forming metal substrates adhere strongly to diamond but lose their ductility during exposure to the high-temperature (1000°C) diamond, chemical vapor deposition environment. Boron-doped semi-metallic diamond was selectively deposited for up to 20 hours on one end of Mo/Re (47.5/52.5 wt.%) and W/Re (75/25 wt.%) alloy wires. Conformal diamond films on the alloys displayed grain sizes and Raman signatures similar to films grown on tungsten; in all cases, the morphology and Raman spectra were consistent with well-faceted, microcrystalline diamond with minimal sp2 carbon content. Cyclic voltammograms of dopamine in phosphate-buffered saline (PBS) showed the wide window and low baseline current of high-quality diamond electrodes. In addition, the films showed consistently well-defined, dopamine electrochemical redox activity. The Mo/Re substrate regions that were uncoated but still exposed to the diamond-growth environment remained substantially more flexible than tungsten in a bend-to-fracture rotation test, bending to the test maximum of 90° and not fracturing. The W/Re substrates fractured after a 27° bend, and the tungsten fractured after a 21° bend. Brittle, transgranular cleavage fracture surfaces were observed for tungsten and W/Re. A tension-induced fracture of the Mo/Re after the prior bend test showed a dimple fracture with a visible ductile core. Overall, the Mo/Re and W/Re alloys were suitable substrates for diamond growth. The Mo/Re alloy remained significantly more ductile than traditional tungsten substrates after diamond growth, and thus may be an attractive metal substrate for more ductile, thin-film diamond electrodes. PMID:25404788

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

NASA Astrophysics Data System (ADS)

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

2015-11-01

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

Hybrid quantum gates between flying photon and diamond nitrogen-vacancy centers assisted by optical microcavities

PubMed Central

Wei, Hai-Rui; Lu Long, Gui

2015-01-01

Hybrid quantum gates hold great promise for quantum information processing since they preserve the advantages of different quantum systems. Here we present compact quantum circuits to deterministically implement controlled-NOT, Toffoli, and Fredkin gates between a flying photon qubit and diamond nitrogen-vacancy (NV) centers assisted by microcavities. The target qubits of these universal quantum gates are encoded on the spins of the electrons associated with the diamond NV centers and they have long coherence time for storing information, and the control qubit is encoded on the polarizations of the flying photon and can be easily manipulated. Our quantum circuits are compact, economic, and simple. Moreover, they do not require additional qubits. The complexity of our schemes for universal three-qubit gates is much reduced, compared to the synthesis with two-qubit entangling gates. These schemes have high fidelities and efficiencies, and they are feasible in experiment. PMID:26271899

Comparison of silicon, nickel, and nickel silicide (Ni 3Si) as substrates for epitaxial diamond growth

NASA Astrophysics Data System (ADS)

Tucker, D. A.; Seo, D.-K.; Whangbo, M.-H.; Sivazlian, F. R.; Stoner, B. R.; Bozeman, S. P.; Sowers, A. T.; Nemanich, R. J.; Glass, J. T.

1995-07-01

We carried out experimental and theoretical studies aimed at probing interface interactions of diamond with Si, Ni, and Ni 3Si substrates. Oriented diamond films deposited on (100) silicon were characterized by polar Raman, polar XRD, and cross-sectional HRTEM. These studies show that the diamond-(100)/Si(100) interface does not adopt the 45°-rotation but the 3 : 2-match arrangement. Our extended Hückel tight-binding (EHTB) electronic structure calculations for a model system show that the interface interaction favors the 3 : 2-match arrangement. Growth on polycrystalline Ni 3Si resulted in oriented diamond particles while, under the same growth conditions, largely graphite was formed on the nickel substrate. Our EHTB electronic structure calculations for model systems show that the (111) and (100) surfaces of Ni 3Si have a strong preference for diamond-nucleation over graphite-nucleation, but this is not the case for the (111) and (100) surfaces of Ni.

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

Effect of absorbing coating on ablation of diamond by IR laser pulses

NASA Astrophysics Data System (ADS)

Kononenko, T. V.; Pivovarov, P. A.; Khomich, A. A.; Khmel'nitskii, R. A.; Konov, V. I.

2018-03-01

We study the possibility of increasing the efficiency and quality of laser ablation microprocessing of diamond by preliminary forming an absorbing layer on its surface. The laser pulses having a duration of 1 ps and 10 ns at a wavelength of 1030 nm irradiate the polycrystalline diamond surface coated by a thin layer of titanium or graphite. We analyse the dynamics of the growth of the crater depth as a function of the number of pulses and the change in optical transmission of the ablated surface. It is found that under irradiation by picosecond pulses the preliminary graphitisation allows one to avoid the laser-induced damage of the internal diamond volume until the appearance of a self-maintained graphitised layer. The absorbing coating (both graphite and titanium) much stronger affects ablation by nanosecond pulses, since it reduces the ablation threshold by more than an order of magnitude and allows full elimination of a laser-induced damage of deep regions of diamond and uncontrolled explosive ablation in the nearsurface layer.

Polycrystalline indium phosphide on silicon by indium assisted growth in hydride vapor phase epitaxy

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

Metaferia, Wondwosen; Sun, Yan-Ting, E-mail: yasun@kth.se; Lourdudoss, Sebastian

2014-07-21

Polycrystalline InP was grown on Si(001) and Si(111) substrates by using indium (In) metal as a starting material in hydride vapor phase epitaxy (HVPE) reactor. In metal was deposited on silicon substrates by thermal evaporation technique. The deposited In resulted in islands of different size and was found to be polycrystalline in nature. Different growth experiments of growing InP were performed, and the growth mechanism was investigated. Atomic force microscopy and scanning electron microscopy for morphological investigation, Scanning Auger microscopy for surface and compositional analyses, powder X-ray diffraction for crystallinity, and micro photoluminescence for optical quality assessment were conducted. Itmore » is shown that the growth starts first by phosphidisation of the In islands to InP followed by subsequent selective deposition of InP in HVPE regardless of the Si substrate orientation. Polycrystalline InP of large grain size is achieved and the growth rate as high as 21 μm/h is obtained on both substrates. Sulfur doping of the polycrystalline InP was investigated by growing alternating layers of sulfur doped and unintentionally doped InP for equal interval of time. These layers could be delineated by stain etching showing that enough amount of sulfur can be incorporated. Grains of large lateral dimension up to 3 μm polycrystalline InP on Si with good morphological and optical quality is obtained. The process is generic and it can also be applied for the growth of other polycrystalline III–V semiconductor layers on low cost and flexible substrates for solar cell applications.« less

Investigation of 3D diamond detector dosimetric characteristics

NASA Astrophysics Data System (ADS)

Kanxheri, K.; Alunni Solestizi, L.; Biasini, M.; Caprai, M.; Dipilato, A. C.; Iacco, M.; Ionica, M.; Lagomarsino, S.; Menichelli, M.; Morozzi, A.; Passeri, D.; Sciortino, S.; Talamonti, C.; Zucchetti, C.; Servoli, L.

2018-06-01

Recently, a polycrystalline chemical vapor deposited (pCVD) 3D diamond detector with graphitic in bulk electrodes, fabricated using a pulsed laser technique has been evaluated for photon beam radiation dosimetry during in-air exposure. The same 3D diamond detector, has now been investigated to evaluate its performance under clinically relevant conditions putting the detector inside a Polymethylmethacrylate (PMMA) phantom, to obtain higher precision dosimetric measurements. The detector leakage current was of the order of ± 25 pA or less for bias voltages up to ‑100 V. The 3D detector was tested for time stability and repeatability showing excellent performance with less than 0.6% signal variation. It also showed a linear response for low dose rates with a deviation from linearity of 2%. It was also possible to verify the detector response as a function of the depth in PMMA up to 18 cm.

Chromatographic performance of synthetic polycrystalline diamond as a stationary phase in normal phase high performance liquid chromatography.

PubMed

Peristyy, Anton; Paull, Brett; Nesterenko, Pavel N

2015-04-24

The chromatographic properties of high pressure high temperature synthesised diamond (HPHT) are investigated in normal phase mode of high performance liquid chromatography. Purified nonporous irregular shape particles of average particles size 1.2 μm and specific surface area 5.1 m(2) g(-1) were used for packing 100×4.6 mm ID or 50×4.6 mm ID stainless steel columns. The retention behaviour of several classes of compounds including alkyl benzenes, polyaromatic hydrocarbons (PAH), alkylphenylketones, phenols, aromatic acids and bases were studied using n-hexane-2-propanol mixtures as mobile phase. The results are compared with those observed for microdispersed sintered detonation nanodiamond (MSDN) and porous graphitic carbon (PGC). HPHT diamond revealed distinctive separation selectivity, which is orthogonal to that observed for porous graphitic carbon; while selectivities of HPHT diamond and microdispersed sintered detonation nanodiamonds are similar. Owing to non-porous particle nature, columns packed with high pressure high temperature diamond exhibited excellent mass transfer and produce separations with maximum column efficiency of 128,200 theoretical plates per meter. Copyright © 2015 Elsevier B.V. All rights reserved.

Fabrication and characterization of an all-diamond tubular flow microelectrode for electroanalysis.

PubMed

Hutton, Laura A; Vidotti, Marcio; Iacobini, James G; Kelly, Chris; Newton, Mark E; Unwin, Patrick R; Macpherson, Julie V

2011-07-15

The development of the first all-diamond hydrodynamic flow device for electroanalytical applications is described. Here alternate layers of intrinsic (insulating), conducting (heavily boron doped), and intrinsic polycrystalline diamond are grown to create a sandwich structure. By laser cutting a hole through the material, it is possible to produce a tubular flow ring electrode of a characteristic length defined by the thickness of the conducting layer (for these studies ∼90 μm). The inside of the tube can be polished to 17 ± 10 nm surface roughness using a diamond impregnanted wire resulting in a coplanar, smooth, all-diamond surface. The steady-state limiting current versus volume flow rate characteristics for the one electron oxidation of FcTMA(+) are in agreement with those expected for laminar flow in a tubular electrode geometry. For dopamine detection, it is shown that the combination of the reduced fouling properties of boron doped diamond, coupled with the flow geometry design where the products of electrolysis are washed away downstream of the electrode, completely eradicates fouling during electrolysis. This paves the way for incorporation of this flow design into online electroanalytical detection systems. Finally, the all diamond tubular flow electrode system described here provides a platform for future developments including the development of ultrathin ring electrodes, multiple apertures for increased current response, and multiple, individually addressable ring electrodes incorporated into the same flow tube.

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

DOE PAGES

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

2015-11-02

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

Surface roughness analysis after laser assisted machining of hard to cut materials

NASA Astrophysics Data System (ADS)

Przestacki, D.; Jankowiak, M.

2014-03-01

Metal matrix composites and Si3N4 ceramics are very attractive materials for various industry applications due to extremely high hardness and abrasive wear resistance. However because of these features they are problematic for the conventional turning process. The machining on a classic lathe still requires special polycrystalline diamond (PCD) or cubic boron nitride (CBN) cutting inserts which are very expensive. In the paper an experimental surface roughness analysis of laser assisted machining (LAM) for two tapes of hard-to-cut materials was presented. In LAM, the surface of work piece is heated directly by a laser beam in order to facilitate, the decohesion of material. Surface analysis concentrates on the influence of laser assisted machining on the surface quality of the silicon nitride ceramic Si3N4 and metal matrix composite (MMC). The effect of the laser assisted machining was compared to the conventional machining. The machining parameters influence on surface roughness parameters was also investigated. The 3D surface topographies were measured using optical surface profiler. The analysis of power spectrum density (PSD) roughness profile were analyzed.

Cliftonite: A proposed origin, and its bearing on the origin of diamonds in meteorites

USGS Publications Warehouse

Brett, R.; Higgins, G.T.

1969-01-01

Cliftonite, a polycrystalline aggregate of graphite with spherulitic structure and cubic morphology, is known in 14 meteorites. Some workers have considered it to be a pseudomorph after diamond, and have used the proposed diamond ancestry as evidence of a meteoritic parent body of at least lunar dimensions. Careful examination of meteoritic samples indicates that cliftonite forms by precipitation within kamacite. We have also demonstrated that graphite with cubic morphology may be synthesized in a Fe-Ni-C alloy annealed in a vacuum. We therefore suggest that a high pressure origin is unnecessary for meteorities which contain cliftonite, and that these meteorities were formed at low pressures. This conclusion is in agreement with other recent evidence. We also suggest that recently discovered cubes and cubo-octahedra of lonsdaleite in the Canyon Diablo meteorite are pseudomorphs after cliftonite, not diamond, as has previously been suggested. ?? 1969.

Electrical conductivity enhancement by boron-doping in diamond using first principle calculations

NASA Astrophysics Data System (ADS)

Ullah, Mahtab; Ahmed, Ejaz; Hussain, Fayyaz; Rana, Anwar Manzoor; Raza, Rizwan

2015-04-01

Boron doping in diamond plays a vital role in enhancing electrical conductivity of diamond by making it a semiconductor, a conductor or even a superconductor. To elucidate this fact, partial and total density of states has been determined as a function of B-content in diamond. Moreover, the orbital charge distributions, B-C bond lengths and their population have been studied for B-doping in pristine diamond thin films by applying density functional theory (DFT). These parameters have been found to be influenced by the addition of different percentages of boron atoms in diamond. The electronic density of states, B-C bond situations as well as variations in electrical conductivities of diamond films with different boron content and determination of some relationship between these parameters were the basic tasks of this study. Diamond with high boron concentration (∼5.88% B-atoms) showed maximum splitting of energy bands (caused by acceptor impurity states) at the Fermi level which resulted in the enhancement of electron/ion conductivities. Because B atoms either substitute carbon atoms and/or assemble at grain boundaries (interstitial sites) inducing impurity levels close to the top of the valence band. At very high B-concentration, impurity states combine to form an impurity band which accesses the top of the valence band yielding metal like conductivity. Moreover, bond length and charge distributions are found to decrease with increase in boron percentage in diamond. It is noted that charge distribution decreased from +1.89 to -1.90 eV whereas bond length reduced by 0.04 Å with increasing boron content in diamond films. These theoretical results support our earlier experimental findings on B-doped diamond polycrystalline films which depict that the addition of boron atoms to diamond films gives a sudden fall in resistivity even up to 105 Ω cm making it a good semiconductor for its applications in electrical devices.

Friction and wear of plasma-deposited diamond films

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa; Wu, Richard L. C.; Garscadden, Alan; Barnes, Paul N.; Jackson, Howard E.

1993-01-01

Reciprocating sliding friction experiments in humid air and in dry nitrogen and unidirectional sliding friction experiments in ultrahigh vacuum were conducted with a natural diamond pin in contact with microwave-plasma-deposited diamond films. Diamond films with a surface roughness (R rms) ranging from 15 to 160 nm were produced by microwave-plasma-assisted chemical vapor deposition. In humid air and in dry nitrogen, abrasion occurred when the diamond pin made grooves in the surfaces of diamond films, and thus the initial coefficients of friction increased with increasing initial surface roughness. The equilibrium coefficients of friction were independent of the initial surface roughness of the diamond films. In vacuum the friction for diamond films contacting a diamond pin arose primarily from adhesion between the sliding surfaces. In these cases, the initial and equilibrium coefficients of friction were independent of the initial surface roughness of the diamond films. The equilibrium coefficients of friction were 0.02 to 0.04 in humid air and in dry nitrogen, but 1.5 to 1.8 in vacuum. The wear factor of the diamond films depended on the initial surface roughness, regardless of environment; it increased with increasing initial surface roughness. The wear factors were considerably higher in vacuum than in humid air and in dry nitrogen.

Mechanism-Based FE Simulation of Tool Wear in Diamond Drilling of SiCp/Al Composites.

PubMed

Xiang, Junfeng; Pang, Siqin; Xie, Lijing; Gao, Feinong; Hu, Xin; Yi, Jie; Hu, Fang

2018-02-07

The aim of this work is to analyze the micro mechanisms underlying the wear of macroscale tools during diamond machining of SiC p /Al6063 composites and to develop the mechanism-based diamond wear model in relation to the dominant wear behaviors. During drilling, high volume fraction SiC p /Al6063 composites containing Cu, the dominant wear mechanisms of diamond tool involve thermodynamically activated physicochemical wear due to diamond-graphite transformation catalyzed by Cu in air atmosphere and mechanically driven abrasive wear due to high-frequency scrape of hard SiC reinforcement on tool surface. An analytical diamond wear model, coupling Usui abrasive wear model and Arrhenius extended graphitization wear model was proposed and implemented through a user-defined subroutine for tool wear estimates. Tool wear estimate in diamond drilling of SiC p /Al6063 composites was achieved by incorporating the combined abrasive-chemical tool wear subroutine into the coupled thermomechanical FE model of 3D drilling. The developed drilling FE model for reproducing diamond tool wear was validated for feasibility and reliability by comparing numerically simulated tool wear morphology and experimentally observed results after drilling a hole using brazed polycrystalline diamond (PCD) and chemical vapor deposition (CVD) diamond coated tools. A fairly good agreement of experimental and simulated results in cutting forces, chip and tool wear morphologies demonstrates that the developed 3D drilling FE model, combined with a subroutine for diamond tool wear estimate can provide a more accurate analysis not only in cutting forces and chip shape but also in tool wear behavior during drilling SiC p /Al6063 composites. Once validated and calibrated, the developed diamond tool wear model in conjunction with other machining FE models can be easily extended to the investigation of tool wear evolution with various diamond tool geometries and other machining processes in cutting different

Mechanism-Based FE Simulation of Tool Wear in Diamond Drilling of SiCp/Al Composites

PubMed Central

Xiang, Junfeng; Pang, Siqin; Xie, Lijing; Gao, Feinong; Hu, Xin; Yi, Jie; Hu, Fang

2018-01-01

The aim of this work is to analyze the micro mechanisms underlying the wear of macroscale tools during diamond machining of SiCp/Al6063 composites and to develop the mechanism-based diamond wear model in relation to the dominant wear behaviors. During drilling, high volume fraction SiCp/Al6063 composites containing Cu, the dominant wear mechanisms of diamond tool involve thermodynamically activated physicochemical wear due to diamond-graphite transformation catalyzed by Cu in air atmosphere and mechanically driven abrasive wear due to high-frequency scrape of hard SiC reinforcement on tool surface. An analytical diamond wear model, coupling Usui abrasive wear model and Arrhenius extended graphitization wear model was proposed and implemented through a user-defined subroutine for tool wear estimates. Tool wear estimate in diamond drilling of SiCp/Al6063 composites was achieved by incorporating the combined abrasive-chemical tool wear subroutine into the coupled thermomechanical FE model of 3D drilling. The developed drilling FE model for reproducing diamond tool wear was validated for feasibility and reliability by comparing numerically simulated tool wear morphology and experimentally observed results after drilling a hole using brazed polycrystalline diamond (PCD) and chemical vapor deposition (CVD) diamond coated tools. A fairly good agreement of experimental and simulated results in cutting forces, chip and tool wear morphologies demonstrates that the developed 3D drilling FE model, combined with a subroutine for diamond tool wear estimate can provide a more accurate analysis not only in cutting forces and chip shape but also in tool wear behavior during drilling SiCp/Al6063 composites. Once validated and calibrated, the developed diamond tool wear model in conjunction with other machining FE models can be easily extended to the investigation of tool wear evolution with various diamond tool geometries and other machining processes in cutting different workpiece

Electrochemically assisted deposition of hydroxyapatite on Ti6Al4V substrates covered by CVD diamond films - Coating characterization and first cell biological results.

PubMed

Strąkowska, Paulina; Beutner, René; Gnyba, Marcin; Zielinski, Andrzej; Scharnweber, Dieter

2016-02-01

Although titanium and its alloys are widely used as implant material for orthopedic and dental applications they show only limited corrosion stability and osseointegration in different cases. The aim of the presented research was to develop and characterize a novel surface modification system from a thin diamond base layer and a hydroxyapatite (HAp) top coating deposited on the alloy Ti6Al4V widely used for implants in contact with bone. This coating system is expected to improve both the long-term corrosion behavior and the biocompatibility and bioactivity of respective surfaces. The diamond base films were obtained by Microwave Plasma Assisted Chemical Vapor Deposition (MW-PACVD); the HAp coatings were formed in aqueous solutions by electrochemically assisted deposition (ECAD) at varying polarization parameters. Scanning electron microscopy (SEM), Raman microscopy, and electrical conductivity measurements were applied to characterize the generated surface states; the calcium phosphate coatings were additionally chemically analyzed for their composition. The biological properties of the coating system were assessed using hMSC cells analyzing for cell adhesion, proliferation, and osteogenic differentiation. Varying MW-PACVD process conditions resulted in composite coatings containing microcrystalline diamond (MCD/Ti-C), nanocrystalline diamond (NCD), and boron-doped nanocrystalline diamond (B-NCD) with the NCD coatings being dense and homogeneous and the B-NCD coatings showing increased electrical conductivity. The ECAD process resulted in calcium phosphate coatings from stoichiometric and non-stoichiometric HAp. The deposition of HAp on the B-NCD films run at lower cathodic potentials and resulted both in the highest coating mass and the most homogenous appearance. Initial cell biological investigations showed an improved cell adhesion in the order B-NCD>HAp/B-NCD>uncoated substrate. Cell proliferation was improved for both investigated coatings whereas ALP

Jet pump assisted artery

NASA Technical Reports Server (NTRS)

1975-01-01

A procedure for priming an arterial heat pump is reported; the procedure also has a means for maintaining the pump in a primed state. This concept utilizes a capillary driven jet pump to create the necessary suction to fill the artery. Basically, the jet pump consists of a venturi or nozzle-diffuser type constriction in the vapor passage. The throat of this venturi is connected to the artery. Thus vapor, gas, liquid, or a combination of the above is pumped continuously out of the artery. As a result, the artery is always filled with liquid and an adequate supply of working fluid is provided to the evaporator of the heat pipe.

Characterization of diamond thin films and related materials

NASA Astrophysics Data System (ADS)

McKindra, Travis Kyle

Thin carbon films including sputtered deposited graphite and CO 2 laser-assisted combustion-flame deposited graphite and diamond thin films were characterized using optical and electron microscopy, X-ray diffraction and micro-Raman spectroscopy. Amorphous carbon thin films were deposited by DC magnetron sputtering using Ar/O2 gases. The film morphology changed with the oxygen content. The deposition rate decreased as the amount of oxygen increased due to oxygen reacting with the growing film. The use of oxygen in the working gas enhanced the crystalline nature of the films. Graphite was deposited on WC substrates by a CO2 laser-assisted O2/C2H2 combustion-flame method. Two distinct microstructural areas were observed; an inner core of dense material surrounded by an outer shell of lamellar-like material. The deposits were crystalline regardless of the laser power and deposition times of a few minutes. Diamond films were deposited by a CO2 laser-assisted O 2/C2H2/C2H4 combustion-flame method with the laser focused parallel to the substrate surface. The laser enhanced diamond growth was most pronounced when deposited with a 10.532 microm CO2 laser wavelength tuned to the CH2-wagging vibrational mode of the C2H4 molecule. Nucleation of diamond thin films deposited with and without using a CO 2 laser-assisted combustion-flame process was investigated. With no laser there was nucleation of a sub-layer of grains followed by irregular grain growth. An untuned laser wavelength yielded nucleation of a sub-layer then columnar grain growth. The 10.532 microm tuned laser wavelength caused growth of columnar grains.

Grating-assisted coupling to nanophotonic circuits in microcrystalline diamond thin films.

PubMed

Rath, Patrik; Khasminskaya, Svetlana; Nebel, Christoph; Wild, Christoph; Pernice, Wolfram Hp

2013-01-01

Synthetic diamond films can be prepared on a waferscale by using chemical vapour deposition (CVD) on suitable substrates such as silicon or silicon dioxide. While such films find a wealth of applications in thermal management, in X-ray and terahertz window design, and in gyrotron tubes and microwave transmission lines, their use for nanoscale optical components remains largely unexplored. Here we demonstrate that CVD diamond provides a high-quality template for realizing nanophotonic integrated optical circuits. Using efficient grating coupling devices prepared from partially etched diamond thin films, we investigate millimetre-sized optical circuits and achieve single-mode waveguiding at telecoms wavelengths. Our results pave the way towards broadband optical applications for sensing in harsh environments and visible photonic devices.

Dose Enhancement near Metal Interfaces in Synthetic Diamond Based X-ray Dosimeters

NASA Astrophysics Data System (ADS)

Alamoudi, Dalal

Diamond is an attractive material for medical dosimetry due to its radiation hardness, fast response, chemical resilience, small sensitive volume, high spatial resolution, near-tissue equivalence, and energy and dose rate independence. These properties make diamond a promising material for medical dosimetry compared to other semiconductor detector materials and wider radiation detection applications. This study is focused on one of the important factors to consider in the radiation detector; the influence of dose enhancement on the photocurrent performance at metallic interfaces in synthetic diamond radiation dosimeters with carbon based electrodes as a function of bias voltages. Monte Carlo (MC) simulations with BEAMnrc code were carried out to simulate the dose enhancement factor (DEF) and compared against the equivalent photocurrent ratio from experimental investigation. MC simulations show that the sensitive region for the absorbed dose distribution covers a few micrometers distances from the interface. Experimentally, two single crystal (SC) and one polycrystalline (PC) samples with carbon based electrodes were used. The samples were each mounted inside a tissue equivalent encapsulation design in order to minimize fluence perturbations. Copper, Gold and Lead have been investigated experimentally as generators of photoelectrons using 50 kVp and 100 kVp X-rays relevant for medical dosimetry. The results show enhancement in the detectors' photocurrent performance when different metals are butted up to the diamond detector. The variation in the photocurrent ratio measurements depends on the type of diamond samples, their electrode fabrication and the applied bias voltages indicating that the dose enhancement from diamond-metal interface modifies the electronic performance of the detector.

High-pressure-assisted synthesis of high-volume ZnGeP2 polycrystalline

NASA Astrophysics Data System (ADS)

Huang, Changbao; Wu, Haixin; Xiao, Ruichun; Chen, Shijing; Ma, Jiaren

2018-06-01

The pnictide and chalcogenide semiconductors are promising materials for the applications in the field of photoelectric. High-purity and high-volume polycrystalline required in the real-world applications is hard to be synthesized due to the high vapor pressure of phosphorus and sulfur components at high temperature. A new high-pressure-resisted method was used to investigate the synthesis of the nonlinear-optical semiconductor ZnGeP2. The high-purity ZnGeP2 polycrystalline material of approximately 500 g was synthesized in one run, which enables the preparation of nominally stoichiometric material. Since increasing internal pressure resistance of quartz crucible and reducing the reaction space, the high-pressure-resisted method can be used to rapidly synthesize other pnictide and chalcogenide semiconductors and control the components ratio.

Ink jet assisted metallization for low cost flat plate solar cells

NASA Technical Reports Server (NTRS)

Teng, K. F.; Vest, R. W.

1987-01-01

Computer-controlled ink-jet-assisted metallization of the front surface of solar cells with metalorganic silver inks offers a maskless alternative method to conventional photolithography and screen printing. This method can provide low cost, fine resolution, reduced process complexity, avoidance of degradation of the p-n junction by firing at lower temperature, and uniform line film on rough surface of solar cells. The metallization process involves belt furnace firing and thermal spiking. With multilayer ink jet printing and firing, solar cells of about 5-6 percent efficiency without antireflection (AR) coating can be produced. With a titanium thin-film underlayer as an adhesion promoter, solar cells of average efficiency 8.08 percent without AR coating can be obtained. This efficiency value is approximately equal to that of thin-film solar cells of the same lot. Problems with regard to lower inorganic content of the inks and contact resistance are noted.

Enantiomerically enriched, polycrystalline molecular sieves

DOE PAGES

Brand, Stephen K.; Schmidt, Joel E.; Deem, Michael W.; ...

2017-05-01

Zeolite and zeolite-like molecular sieves are being used in a large number of applications such as adsorption and catalysis. Achievement of the long-standing goal of creating a chiral, polycrystalline molecular sieve with bulk enantioenrichment would enable these materials to perform enantioselective functions. Here, we report the synthesis of enantiomerically enriched samples of a molecular sieve. For this study, enantiopure organic structure directing agents are designed with the assistance of computational methods and used to synthesize enantioenriched, polycrystalline molecular sieve samples of either enantiomer. Computational results correctly predicted which enantiomer is obtained, and enantiomeric enrichment is proven by high-resolution transmission electronmore » microscopy. The enantioenriched and racemic samples of the molecular sieves are tested as adsorbents and heterogeneous catalysts. The enantioenriched molecular sieves show enantioselectivity for the ring opening reaction of epoxides and enantioselective adsorption of 2-butanol (the R enantiomer of the molecular sieve shows opposite and approximately equal enantioselectivity compared with the S enantiomer of the molecular sieve, whereas the racemic sample of the molecular sieve shows no enantioselectivity).« less

Enantiomerically enriched, polycrystalline molecular sieves

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

Brand, Stephen K.; Schmidt, Joel E.; Deem, Michael W.

Zeolite and zeolite-like molecular sieves are being used in a large number of applications such as adsorption and catalysis. Achievement of the long-standing goal of creating a chiral, polycrystalline molecular sieve with bulk enantioenrichment would enable these materials to perform enantioselective functions. Here, we report the synthesis of enantiomerically enriched samples of a molecular sieve. For this study, enantiopure organic structure directing agents are designed with the assistance of computational methods and used to synthesize enantioenriched, polycrystalline molecular sieve samples of either enantiomer. Computational results correctly predicted which enantiomer is obtained, and enantiomeric enrichment is proven by high-resolution transmission electronmore » microscopy. The enantioenriched and racemic samples of the molecular sieves are tested as adsorbents and heterogeneous catalysts. The enantioenriched molecular sieves show enantioselectivity for the ring opening reaction of epoxides and enantioselective adsorption of 2-butanol (the R enantiomer of the molecular sieve shows opposite and approximately equal enantioselectivity compared with the S enantiomer of the molecular sieve, whereas the racemic sample of the molecular sieve shows no enantioselectivity).« less

Growth of high quality AlN films on CVD diamond by RF reactive magnetron sputtering

NASA Astrophysics Data System (ADS)

Chen, Liang-xian; Liu, Hao; Liu, Sheng; Li, Cheng-ming; Wang, Yi-chao; An, Kang; Hua, Chen-yi; Liu, Jin-long; Wei, Jun-jun; Hei, Li-fu; Lv, Fan-xiu

2018-02-01

A highly oriented AlN layer has been successfully grown along the c-axis on a polycrystalline chemical vapor deposited (CVD) diamond by RF reactive magnetron sputtering. Structural, morphological and mechanical properties of the heterostructure were investigated by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), Nano-indentation and Four-probe meter. A compact AlN film was demonstrated on the diamond layer, showing columnar grains and a low surface roughness of 1.4 nm. TEM results revealed a sharp AlN/diamond interface, which was characterized by the presence of a distinct 10 nm thick buffer layer resulting from the initial AlN growth stage. The FWHM of AlN (002) diffraction peak and its rocking curve are as low as 0.41° and 3.35° respectively, indicating a highly preferred orientation along the c-axis. AlN sputtered films deposited on glass substrates show a higher bulk resistivity (up to 3 × 1012 Ω cm), compared to AlN films deposited on diamond (∼1010 Ω cm). Finally, the film hardness and Young's modulus of AlN films on diamond are 25.8 GPa and 489.5 GPa, respectively.

Gas-phase kinetics during diamond growth: CH4 as-growth species

NASA Astrophysics Data System (ADS)

Harris, Stephen J.

1989-04-01

We have used a one-dimensional kinetic analysis to model the gas-phase chemistry that occurred during the diamond growth experiments of Chauhan, Angus, and Gardner [J. Appl. Phys. 47, 4746 (1976)]. In those experiments the weight of diamond seed crystals heated by lamps in a CH4/H2 environment was monitored by a microbalance. No filament or electric discharge was present. Our analysis shows that diamond growth occurred in this system by direct reaction of CH4 on the diamond surface. C2H2 and CH3, which have been proposed as diamond growth species, played no significant role there, although our results do not address their possible contributions in other systems such as filament- or plasma-assisted diamond growth.

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.

Radiation Halos, a Rare Microstructure in Diamonds From the Central African Republic

NASA Astrophysics Data System (ADS)

Vicenzi, E. P.; Heaney, P. J.; Snyder, K.; Armstrong, L.

2002-05-01

The geochemical characterization of bulk diamonds and associated inclusions as a tool for determining provenance carries significant inherent limitations. Isotopic and trace element signatures are imparted within the mantle during diamond growth; hence, discriminating crystals from a particular region on the Earth's surface on this basis is difficult at best, and impossible (using current technologies) in many cases. In contrast, rare diamond characteristics may provide a partial solution for recognizing stones from a limited number of localities. Here we discuss an analysis of radiation halos in alluvially deposited polycrystalline diamonds (carbonados) from the Central African Republic (CAR). Large amounts of implanted Xe and Kr, as well as isotopic ratios of those elements consistent with fission, in carbonado strongly suggest that diamond crystallization took place in the presence of significant quantities of uranium [1]. Such ionizing radiation ultimately results in the loss of periodicity of the diamond structure. Crystallographically damaged areas produce fewer photons in cathodoluminescence microscopy, and therefore, the metamict regions resulting from point source radiation in diamond can be visualized on the scale of ~1-25 micrometers [2]. Because intermediate daughter products in the decay chain release alpha particles at differing energies, a ``bull's eye'' pattern is produced in 2-D by the point source radiation. Radiation haloes have been previously observed in carbonados and are thought to result from U deposition associated with fluids following diamond formation [3,4]. We have made a series of measurements of the apparent diameter of the largest circle within a damage halo. By comparing the statistical distribution of this dimension to the distribution expected for a series of circles resulting from random sectioning of mono-sized spheres, one can estimate whether the radiation resulted from one or more fluid pulses widely separated in time

Further development and application of polycrystalline metal whiskers

NASA Technical Reports Server (NTRS)

Schladitz, H. J.

1979-01-01

High strength metal whiskers have a larger versatile field of application than monocrystalline whiskers. Although polycrystalline metal whiskers can be used for composites, preferably by extrusion in thermoplastics or by infiltration of resins or metals into whisker networks, the chief application at present may be the production and various use of whisker networks. Such networks can be produced up to high degrees of porosity and besides high mechanical strength, they have high inside surfaces and high electric conductivity. There are for instance, applications concerning construction of electrodes for batteries and fuel cells, catalysts and also new heat-exchanger material, capable of preparing fuel oil and gasoline in order to assist a high-efficiency combustion. The technical application of polycrystalline metal whiskers require their modification as well as the construction of a pilot production unit.

Effects of Surface Treatments on Secondary Electron Emission from CVD Diamond Films

NASA Technical Reports Server (NTRS)

Mearini, G. T.; Krainsky, I. L.; Dayton, J. A., Jr.; Zorman, Christian; Wang, Yaxin; Lamouri, A.

1995-01-01

Secondary electron emission (SEE) properties of polycrystalline diamond films grown by chemical vapor deposition (CVD) were measured. The total secondary yield (sigma) from as-grown samples was observed to be as high as 20 at room temperature and 48 while heating at 700 K in vacuum. Electron-beam-activated, alkali-terminated diamond films have shown stable values of sigma as high as 60 when coated with CsI and similarly high values when coated with other alkali halides. Diamond coated with BaF2 had a stable sigma of 6, but no enhancement of the SEE properties was observed with coatings of Ti or Au. Hydrogen was identified to give rise to this effect in as-grown films. However, electron beam exposure led to a reduction in sigma values as low as 2. Exposure to a molecular hydrogen environment restored sigma to its original value after degradation, and enabled stable secondary emission during electron beam exposure. Atomic hydrogen and hydrogen plasma treatments were performed on diamond/Mo samples in an attempt to increase the near-surface hydrogen concentration which might lead to increased stability in the secondary emission. Raman scattering analysis, scanning electron microscopy, and Auger electron spectroscopy (AES) confirmed that hydrogen plasma and atomic hydrogen treatments improved the quality of the CVD diamond significantly. Elastic recoil detection (ERD) showed that heating as-grown diamond targets to 7OO K, which was correlated with an increase in sigma, removed contaminants from the surface but did not drive hydrogen from the diamond bulk. ERD showed that the hydrogen plasma treatment produced an increase in the hydrogen concentration in the near-surface region which did not decrease while heating in vacuum at 700 K, but no improvement in the SEE properties was observed.

Diamond deposition in a hot-filament reactor using different hydrocarbon precursor gases

NASA Astrophysics Data System (ADS)

May, P. W.; Everitt, N. M.; Trevor, C. G.; Ashfold, M. N. R.; Rosser, K. N.

1993-07-01

A hot-filament reactor was used to deposit polycrystalline diamond films upon single-crystal Si substrates using hydrocarbon/H 2 gas mixtures. We studied the effect upon the deposition process and resulting film properties by varying the hydrocarbon gas from C 1H x to C 4H x alkanes. This was done maintaining a constant carbon-to-hydrogen ratio, but using a substantially lower-than- normal filament temperature (1500°C) in order to highlight differences in activation barriers and in the chemistry of the diamond-forming step. It was found that with increasing hydrocarbon chain length the deposition rate decreased, from a value of about 0.4 μm h -1 for methane/H 2 mixtures to less than 0.07 μm h -1 for butane/H 2. This was accompanied by an increase in the relative proportion of amorphous carbon to diamond present in the films. After one hour deposition the diamond grain size remained constant at about 20 nm, irrespective of the precursor gas. The measured Knoop hardness of the films also decreased when using process gases other than methane. We also studied the effect of changing the bond order in C 2H x precursor gases (ethane, ethene, ethyne) but found that this had no effect on either the deposition rate or the film quality.

Waferscale nanophotonic circuits made from diamond-on-insulator substrates.

PubMed

Rath, P; Gruhler, N; Khasminskaya, S; Nebel, C; Wild, C; Pernice, W H P

2013-05-06

Wide bandgap dielectrics are attractive materials for the fabrication of photonic devices because they allow broadband optical operation and do not suffer from free-carrier absorption. Here we show that polycrystalline diamond thin films deposited by chemical vapor deposition provide a promising platform for the realization of large scale integrated photonic circuits. We present a full suite of photonic components required for the investigation of on-chip devices, including input grating couplers, millimeter long nanophotonic waveguides and microcavities. In microring resonators we measure loaded optical quality factors up to 11,000. Corresponding propagation loss of 5 dB/mm is also confirmed by measuring transmission through long waveguides.

Breast Augmentation by Water-Jet Assisted Autologous Fat Grafting: A Report of 300 Operations.

PubMed

Muench, Daniel P

2016-04-01

Background  The BEAULI -method (Breast Augmentation by Lipotransfer) is available for extraction and processing of large transplantable fat quantities. The aim of this work is to describe the surgical technique precisely and reproducibly and to provide an overview of the autologous fat transfer based on surgical experience. Method  The author performed 300 autologous fat transplantations on 254 women between September 3, 2010, and May 13, 2015. Patients desiring moderate volume increase, fuller and firmer breasts, as well as an optimization of the silhouette, ideally with the concurrent desire of the correction of unwanted fat deposits, were selected. The fat was extracted via water-jet assisted liposuction (Body-jet, Human Med AG, Schwerin, Germany), and the fat cells were subsequently separated with the Lipocollector ® (Human Med AG, Schwerin, Germany). Results  The results were assessed with a control exam and photo comparison and were based on the responses on a questionnaire. Overall, 35.9% of the patients defined the result as very good, 38.6% as good, 22.4% as satisfactory, and 3.1% as poor. Conclusion  This study shows that the autologous fat cell transplantation into the female breast via water-jet assisted liposuction achieves a moderate and harmoniously appearing breast volume enlargement as well as contour improvement. Further studies with more cases and longer observation periods over several years could contribute to improving the method of the autologous fat transfer regarding the grow-in rate, efficiency, and safety.

Distribution and origin of diamonds in Brazil: An overview

NASA Astrophysics Data System (ADS)

Svisero, Darcy P.

1995-12-01

Brazil was the first western country to produce diamonds from the washing of alluvial deposits found in central Minas Gerais in the early 1700s. For a century the country remained the world's greatest producer, losing its position only after the discovery of the Kimberley field in South Africa. Currently there are placer deposits (garimpos) scattered throughout the majority of the states with official production averaging 1,000,000 ct/y. Mechanized exploitation using modern dredges has succeeded in only two distinct localities: along the Jequitinhonha River (Diamantina) and at the Fazenda Camargo (Mato Grosso). Large diamonds of several hundred carats have been found periodically in the area of the municipalities of Abaeté and Coromandel in western Minas Gerais State. Carbonado, a polycrystalline variety of diamond, was intensively mined in several localities of the Chapada Diamantina in central Bahia State, mainly in the second half of the last century. Kimberlite-type rocks, on the other hand, were discovered only in the late 1960s, first in the Coromandel area in Minas Gerais and later in Goiás, Mato Grosso, Rondônia and Piauí States. Little is yet known about these intrusions, mainly because the discoveries have been made by foreign companies operating in the country. Detailed studies reported during the Kimberlite Conference of Araxá in 1991 revealed that some intrusions of the Coromandel area have mineralogical and petrographical characteristics, as well as major chemical element compositions, similar to worldwide kimberlites. However, their isotopic signatures in terms of Sr and Nd are intermediate between Groups I and II kimberlites of South Africa. As to mineral inclusions, Brazilian diamonds contain the common phases of olivine, garnets, pyroxenes, sulphides and oxides as observed in diamonds elsewhere. Furthermore, diamonds from the São Luis River in northern Mato Grosso contain, in addition to garnet and pyroxene, periclase, ferripericlase, w

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.

Water Jetting

NASA Technical Reports Server (NTRS)

1985-01-01

Hi-Tech Inc., a company which manufactures water jetting equipment, needed a high pressure rotating swivel, but found that available hardware for the system was unsatisfactory. They were assisted by Marshall, which had developed water jetting technology to clean the Space Shuttles. The result was a completely automatic water jetting system which cuts rock and granite and removes concrete. Labor costs have been reduced; dust is suppressed and production has been increased.

Self-Lubricating, Wear-Resistant Diamond Films Developed for Use in Vacuum Environment

NASA Technical Reports Server (NTRS)

1996-01-01

Diamond's outstanding properties--extreme hardness, chemical and thermal inertness, and high strength and rigidity--make it an ideal material for many tribological applications, such as the bearings, valves, and engine parts in the harsh environment found in internal-combustion engines, jet engines, and space propulsion systems. It has been demonstrated that chemical-vapor-deposited diamond films have low coefficients of friction (on the order of 0.01) and low wear rates (less than 10(sup -7) mm (sup 3/N-m)) both in humid air and dry nitrogen but that they have both high coefficients of friction (greater than 0.4) and high wear rates (on the order of 1(sup -4) mm sup 3/N-m)) in vacuum. It is clear that surface modifications that provide acceptable levels of friction and wear properties will be necessary before diamond films can be used for tribological applications in a space-like, vacuum environment. Previously, it was found that coatings of amorphous, non-diamond carbon can provide low friction in vacuum. Therefore, to reduce the friction and wear of diamond film in vacuum, carbon ions were implanted in an attempt to form a surface layer of amorphous carbon phases on the diamond films.

An all-diamond, hermetic electrical feedthrough array for a retinal prosthesis.

PubMed

Ganesan, Kumaravelu; Garrett, David J; Ahnood, Arman; Shivdasani, Mohit N; Tong, Wei; Turnley, Ann M; Fox, Kate; Meffin, Hamish; Prawer, Steven

2014-01-01

The interface between medical implants and the human nervous system is rapidly becoming more and more complex. This rise in complexity is driving the need for increasing numbers of densely packed electrical feedthrough to carry signals to and from implanted devices. This is particularly crucial in the field of neural prosthesis where high resolution stimulating or recording arrays near peripheral nerves or in the brain could dramatically improve the performance of these devices. Here we describe a flexible strategy for implementing high density, high count arrays of hermetic electrical feedthroughs by forming conducting nitrogen doped nanocrystalline diamond channels within an insulating polycrystalline diamond substrate. A unique feature of these arrays is that the feedthroughs can themselves be used as stimulating electrodes for neural tissue. Our particular application is such a feedthrough, designed as a component of a retinal implant to restore vision to the blind. The hermeticity of the feedthroughs means that the array can also form part of an implantable capsule which can interface directly with internal electronic chips. The hermeticity of the array is demonstrated by helium leak tests and electrical and electrochemical characterisation of the feedthroughs is described. The nitrogen doped nanocrystalline diamond forming the electrical feedthroughs is shown to be non-cyctotoxic. New fabrication strategies, such as the one described here, combined with the exceptional biostability of diamond can be exploited to generate a range of biomedical implants that last for the lifetime of the user without fear of degradation.

Direct integration of polycrystalline graphene into light emitting diodes by plasma-assisted metal-catalyst-free synthesis.

PubMed

Kim, Yong Seung; Joo, Kisu; Jerng, Sahng-Kyoon; Lee, Jae Hong; Moon, Daeyoung; Kim, Jonghak; Yoon, Euijoon; Chun, Seung-Hyun

2014-03-25

The integration of graphene into devices is a challenging task because the preparation of a graphene-based device usually includes graphene growth on a metal surface at elevated temperatures (∼1000 °C) and a complicated postgrowth transfer process of graphene from the metal catalyst. Here we report a direct integration approach for incorporating polycrystalline graphene into light emitting diodes (LEDs) at low temperature by plasma-assisted metal-catalyst-free synthesis. Thermal degradation of the active layer in LEDs is negligible at our growth temperature, and LEDs could be fabricated without a transfer process. Moreover, in situ ohmic contact formation is observed between DG and p-GaN resulting from carbon diffusion into the p-GaN surface during the growth process. As a result, the contact resistance is reduced and the electrical properties of directly integrated LEDs outperform those of LEDs with transferred graphene electrodes. This relatively simple method of graphene integration will be easily adoptable in the industrialization of graphene-based devices.

Physical and Tribological Characteristics of Ion-Implanted Diamond Films

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Heidger, S.; Korenyi-Both, A. L.; Jayne, D. T.; Herrera-Fierro, P.; Shogrin, B.; Wilbur, P. J.; Wu, R. L. C.; Garscadden, A.; Barnes, P. N.

1994-01-01

Unidirectional sliding friction experiments were conducted with a natural, polished diamond pin in contact with both as-deposited and carbon-ion-implanted diamond films in ultrahigh vacuum. Diamond films were deposited on silicon, silicon carbide, and silicon nitride by microwave-plasma-assisted chemical vapor deposition. The as-deposited diamond films were impacted with carbon ions at an accelerating energy of 60 keV and a current density of 50 micron A/cm(exp 2) for approximately 6 min, resulting in a dose of 1.2 x 10(exp 17) carbon ions/cm(exp 2). The results indicate that the carbon ion implantation produced a thin surface layer of amorphous, nondiamond carbon. The nondiamond carbon greatly decreased both friction and wear of the diamond films. The coefficients of friction for the carbon-ion-implanted, fine-grain diamond films were less than 0.1, factors of 20 to 30 lower than those for the as-deposited, fine-grain diamond films. The coefficients of friction for the carbon-ion-implanted, coarse-grain diamond films were approximately 0.35, a factor of five lower than those for the as-deposited, coarse-grain diamond films. The wear rates for the carbon-ion-implanted, diamond films were on the order of 10(exp -6) mm(exp 3)/Nm, factors of 30 to 80 lower than that for the as-deposited diamond films, regardless of grain size. The friction of the carbon-ion-implanted diamond films was greatly reduced because the amorphous, nondiamond carbon, which had a low shear strength, was restricted to the surface layers (less than 0.1 micron thick) and because the underlying diamond materials retained their high hardness. In conclusion, the carbon-ion-implanted, fine-grain diamond films can be used effectively as wear resistant, self-lubricating coatings for ceramics, such as silicon nitride and silicon carbide, in ultrahigh vacuum.

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

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

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

2015-07-15

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

Synthesis of silane and silicon in a non-equilibrium plasma jet

NASA Technical Reports Server (NTRS)

Calcote, H. F.; Felder, W.

1977-01-01

The feasibility of using a non-equilibrium hydrogen plasma jet as a chemical synthesis tool was investigated. Four possible processes were identified for further study: (1) production of polycrystalline silicon photovoltaic surfaces, (2) production of SiHCl3 from SiCl4, (3) production of SiH4 from SiHCl3, and (4) purification of SiCl4 by metal impurity nucleation. The most striking result was the recognition that the strongly adhering silicon films, amorphous or polycrystalline, produced in our studies could be the basis for preparing a photovoltaic surface directly; this process has potential advantages over other vapor deposition processes.

The effect of dose enhancement near metal interfaces on synthetic diamond based X-ray dosimeters

NASA Astrophysics Data System (ADS)

Alamoudi, D.; Lohstroh, A.; Albarakaty, H.

2017-11-01

This study investigates the effects of dose enhancement on the photocurrent performance at metallic interfaces in synthetic diamond detectors based X-ray dosimeters as a function of bias voltages. Monte Carlo (MC) simulations with the BEAMnrc code were carried out to simulate the dose enhancement factor (DEF) and compared against the equivalent photocurrent ratio from experimental investigations. The MC simulation results show that the sensitive region for the absorbed dose distribution covers a few micrometers distances from the interface. Experimentally, two single crystals (SC) and one polycrystalline (PC) synthetic diamond samples were fabricated into detectors with carbon based electrodes by boron and carbon ion implantation. Subsequently; the samples were each mounted inside a tissue equivalent encapsulation to minimize unintended fluence perturbation. Dose enhancement was generated by placing copper, lead or gold near the active volume of the detectors using 50 kVp and 100 kVp X-rays relevant for medical dosimetry. The results show enhancement in the detectors' photocurrent performance when different metals are butted up to the diamond bulk as expected. The variation in the photocurrent measurement depends on the type of diamond samples, their electrodes' fabrication and the applied bias voltages indicating that the dose enhancement near the detector may modify their electronic performance.

Monocrystalline CVD-diamond optics for high-power laser applications

NASA Astrophysics Data System (ADS)

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

2016-03-01

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

Unusual Cathodoluminescence in Diamonds: Evidence for Metamorphism or a Source Characteristic

NASA Astrophysics Data System (ADS)

Bruce, L. F.; Longo, M.; Kopylova, M.; Ryder, J.

2009-05-01

Cathodoluminescence (CL) is a useful means of diamond "fingerprinting". CL-active cratonic macrodiamonds usually cathodoluminesce blue or yellow, and always exhibit prominent wide CL emittance peaks at 430-450 nm and 480-490 nm. Exceptions to this norm are diamond suites recently discovered in the Archean rocks metamorphosed in the greenschist facies. These macrodiamonds cathodoluminesce red, orange and yellow, and invariably exhibit the most prominent CL peak at 520 nm. The diamond suites with the unusual CL are derived from two different locations within the Michipicoten Greenstone Belt (Southern Superior craton), near the town of Wawa (Ontario). One suite is extracted from the 2.68-2.74 Ga polymict volcanic breccias and lamprophyres and the other suite - from the 2.68 Ga sedimentary conglomerates grading into overlying sandstones of the Dore assemblage. The diamondiferous conglomerates are found in an area 8 km south of the breccias and 12 km northeast of Wawa. CL emittance of macrodiamonds (> 0.5 mm) extracted from the breccias consists of a broad band at 520 nm, a sharp peak at 575.5 nm, and several lines at 550-670 nm. The conglomerate macrodiamonds mostly show a dominant peak at 520 nm, whereas corresponding microdiamonds exhibit two peaks at about 576 and 600 nm. None of the diamonds show a maximum peak at 420 nm. Polycrystalline stones from conglomerates show distinct CL spectra and colours for all intergrown crystals in the same diamond. The relative abundances of the CL colors of the conglomerate diamonds are orange-red (46%), yellow (28%), orange-green (10%), green (6%), and non-uniform colors (10%). These colours are more diverse than mostly orange CL colours in the breccia diamonds; this results from a larger variety of positions and intensity of CL peaks in the conglomerate diamonds. We propose two models for explaining the presence of the 520 nm CL peak in the breccia and conglomerate diamonds in Wawa. The first model suggests metamorphism as the

Laser-Assisted Field Evaporation and Three-Dimensional Atom-by-Atom Mapping of Diamond Isotopic Homojunctions.

PubMed

Mukherjee, Samik; Watanabe, Hideyuki; Isheim, Dieter; Seidman, David N; Moutanabbir, Oussama

2016-02-10

It addition to its high evaporation field, diamond is also known for its limited photoabsorption, strong covalent bonding, and wide bandgap. These characteristics have been thought for long to also complicate the field evaporation of diamond and make its control hardly achievable on the atomistic-level. Herein, we demonstrate that the unique behavior of nanoscale diamond and its interaction with pulsed laser lead to a controlled field evaporation thus enabling three-dimensional atom-by-atom mapping of diamond (12)C/(13)C homojunctions. We also show that one key element in this process is to operate the pulsed laser at high energy without letting the dc bias increase out of bounds for diamond nanotip to withstand. Herein, the role of the dc bias in evaporation of diamond is essentially to generate free charge carriers within the nanotip via impact ionization. The mobile free charges screen the internal electric field, eventually creating a hole rich surface where the pulsed laser is effectively absorbed leading to an increase in the nanotip surface temperature. The effect of this temperature on the uncertainty in the time-of-flight of an ion, the diffusion of atoms on the surface of the nanotip, is also discussed. In addition to paving the way toward a precise manipulation of isotopes in diamond-based nanoscale and quantum structures, this result also elucidates some of the basic properties of dielectric nanostructures under high electric field.

Jet pump assisted arterial heat pipe

NASA Technical Reports Server (NTRS)

Bienert, W. B.; Ducao, A. S.; Trimmer, D. S.

1978-01-01

This paper discusses the concept of an arterial heat pipe with a capillary driven jet pump. The jet pump generates a suction which pumps vapor and noncondensible gas from the artery. The suction also forces liquid into the artery and maintains it in a primed condition. A theoretical model was developed which predicts the existence of two stable ranges. Up to a certain tilt the artery will prime by itself once a heat load is applied to the heat pipe. At higher tilts, the jet pump can maintain the artery in a primed condition but self-priming is not possible. A prototype heat pipe was tested which self-primed up to a tilt of 1.9 cm, with a heat load of 500 watts. The heat pipe continued to prime reliably when operated as a VCHP, i.e., after a large amount of noncondensible gas was introduced.

Microstructural Characterisation and Wear Behaviour of Diamond Composite Materials

PubMed Central

Boland, James N.; Li, Xing S.

2010-01-01

Since the initial research leading to the production of diamond composite materials, there have been several important developments leading to significant improvements in the properties of these superhard composite materials. Apart from the fact that diamonds, whether originating from natural resources or synthesised commercially, are the hardest and most wear-resistant materials commonly available, there are other mechanical properties that limit their industrial application. These include the low fracture toughness and low impact strength of diamond. By incorporating a range of binder phases into the sintering production process of these composites, these critically important properties have been radically improved. These new composites can withstand much higher operating temperatures without markedly reducing their strength and wear resistance. Further innovative steps are now being made to improve the properties of diamond composites by reducing grain and particle sizes into the nano range. This review will cover recent developments in diamond composite materials with special emphasis on microstructural characterisation. The results of such studies should assist in the design of new, innovative diamond tools as well as leading to radical improvements in the productivity of cutting, drilling and sawing operations in the exploration, mining, civil construction and manufacturing industries.

Facile MALDI-MS analysis of neutral glycans in NaOH-doped matrixes: microwave-assisted deglycosylation and one-step purification with diamond nanoparticles.

PubMed

Tzeng, Yan-Kai; Chang, Cheng-Chun; Huang, Chien-Ning; Wu, Chih-Che; Han, Chau-Chung; Chang, Huan-Cheng

2008-09-01

A streamlined protocol has been developed to accelerate, simplify, and enhance matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) of neutral underivatized glycans released from glycoproteins. It involved microwave-assisted enzymatic digestion and release of glycans, followed by rapid removal of proteins and peptides with carboxylated/oxidized diamond nanoparticles, and finally treating the analytes with NaOH before mixing them with acidic matrix (such as 2,5-dihydroxybenzoic acid) to suppress the formation of both peptide and potassiated oligosaccharide ions in MS analysis. The advantages of this protocol were demonstrated with MALDI-TOF-MS of N-linked glycans released from ovalbumin and ribonuclease B.

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.

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.

Tribological properties of CVD diamond coated ceramic surfaces

NASA Astrophysics Data System (ADS)

Abreu, Cristiano Simoes de

Recent developments in chemical vapour deposited (CVD) diamond coatings have attracted considerable interest and a host of new applications, each more challenging than the others. This increased attention results from the fact that CVD diamond lms retain to a large extent the outstanding physical and chemical properties of natural single crystal diamond such as extreme hardness, chemical inertness and high corrosion resistance, optical transparency and high thermal conductivity. Diamond features also surprisingly low friction and high wear resistance in unlubricated sliding contacts. Moreover, as opposed to natural diamond where the friction and wear behaviour is highly dependent on crystal orientation, polycrystalline CVD diamond lms supersede the monocrystalline variety due to isotropic tribological properties and possibility of coating complex shapes. Several materials have been tested and more or less successfully used as substrates for CVD diamond coatings. Nonetheless, satisfactory adherence of diamond coatings lms is often only attainable by the use of interlayers, in order to compensate for the large interfacial thermal expansion mismatch between the coating and substrate, which represent an additional processing step and added costs. A promising route will consist in using substrate materials with a low thermal expansion mismatch relative to that of diamond and, therefore, enhanced 1m adhesion. Among these, the ceramic silicon nitride (Si3N4) arises as a serious candidate. As a general rule, available literature regarding the tribological performance of CVD diamond coated Si3N4 lms is scarce, and the few available tribological data only deals with low applied loads. That being said, the correct tribological assessment of CVD diamond coated Si3N4 lms under more realistic sliding conditions, reproducing the stresses found in applications fields such as the fluid handling and metalworking industry, as well as in emerging biotribological areas, is on the

Shear Deformation of Fe Polycrystals in the Rotational Diamond Anvil Cell

NASA Astrophysics Data System (ADS)

Merkel, S.; Lincot, A.; Nisr, C.; Hanfland, M.; Zerr, A.

2014-12-01

For many years, experiments are being developed for performing deformation experiments under lower mantle conditions. They include methods such as the Deformation-DIA (Wang et al, 2003) or radial x-ray diffraction in the diamond anvil cell (Merkel et al, 2002). However, the strain applied to the sample is typically limited to about 40%. This can be an issue for studying effects of large deformation or, for the case of diamond anvil cells, applying actual plastic strain at megabar pressures. The issue can be solved using apparatus such as the Rotational-Drickamer (RDA) (e.g. Yamazaki and Karato, 2001). However, the RDA offers limited diffraction access to the sample and operating pressures do not reach those of the lower mantle.In this abstract, we investigate the potential applications of the rotational diamond anvil cell (Rot-DAC) for such studies. 300 K experiments in the Rot-DAC have been performed up to pressures exceeding 50 GPa (e.g. Serebryanaya et al, 1995) with studies focusing on the effect of shear on solid-solid phase transformation pressures. The authors did not investigate the possibility of using the Rot-DAC for studying rheological properties.Here, a sample of polycrystalline Fe is submitted to shear deformation in the Rot-DAC at pressures up to 20 GPa. Synchrotron X-ray diffraction and Rietveld refinements are then used to study the texture and stress state at multiple locations in the sample. The study shows that the Rot-DAC is efficient at producing deformation textures in a polycrystalline aggregate but that care should be taken in ensuring that the sample is actually undergoing plastic deformation and not solid rotation. Stresses, on the other hand, are difficult to extract from the x-ray diffraction data because of lack of understanding of stress distributions in the deforming aggregate.S. Merkel, H. R. Wenk, J. Shu, G. Shen, P. Gillet, H. K. Mao and R. J. Hemley, J. Geophys. Res., 107, 2271 (2002)N. Serebryanaya, V. Blank and V. Ivdenko, Phys

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.

Supersonic Injection of Aerated Liquid Jet

NASA Astrophysics Data System (ADS)

Choudhari, Abhijit; Sallam, Khaled

2016-11-01

A computational study of the exit flow of an aerated two-dimensional jet from an under-expanded supersonic nozzle is presented. The liquid sheet is operating within the annular flow regime and the study is motivated by the application of supersonic nozzles in air-breathing propulsion systems, e.g. scramjet engines, ramjet engines and afterburners. The simulation was conducted using VOF model and SST k- ω turbulence model. The test conditions included: jet exit of 1 mm and mass flow rate of 1.8 kg/s. The results show that air reaches transonic condition at the injector exit due to the Fanno flow effects in the injector passage. The aerated liquid jet is alternately expanded by Prandtl-Meyer expansion fan and compressed by oblique shock waves due to the difference between the back (chamber) pressure and the flow pressure. The process then repeats itself and shock (Mach) diamonds are formed at downstream of injector exit similar to those typical of exhaust plumes of propulsion system. The present results, however, indicate that the flow field of supersonic aerated liquid jet is different from supersonic gas jets due to the effects of water evaporation from the liquid sheet. The contours of the Mach number, static pressure of both cases are compared to the theory of gas dynamics.

Formation of X-ray emitting stationary shocks in magnetized protostellar jets

NASA Astrophysics Data System (ADS)

Ustamujic, S.; Orlando, S.; Bonito, R.; Miceli, M.; Gómez de Castro, A. I.; López-Santiago, J.

2016-12-01

Context. X-ray observations of protostellar jets show evidence of strong shocks heating the plasma up to temperatures of a few million degrees. In some cases, the shocked features appear to be stationary. They are interpreted as shock diamonds. Aims: We investigate the physics that guides the formation of X-ray emitting stationary shocks in protostellar jets; the role of the magnetic field in determining the location, stability, and detectability in X-rays of these shocks; and the physical properties of the shocked plasma. Methods: We performed a set of 2.5-dimensional magnetohydrodynamic numerical simulations that modelled supersonic jets ramming into a magnetized medium and explored different configurations of the magnetic field. The model takes into account the most relevant physical effects, namely thermal conduction and radiative losses. We compared the model results with observations, via the emission measure and the X-ray luminosity synthesized from the simulations. Results: Our model explains the formation of X-ray emitting stationary shocks in a natural way. The magnetic field collimates the plasma at the base of the jet and forms a magnetic nozzle there. After an initial transient, the nozzle leads to the formation of a shock diamond at its exit which is stationary over the time covered by the simulations ( 40-60 yr; comparable with timescales of the observations). The shock generates a point-like X-ray source located close to the base of the jet with luminosity comparable with that inferred from X-ray observations of protostellar jets. For the range of parameters explored, the evolution of the post-shock plasma is dominated by the radiative cooling, whereas the thermal conduction slightly affects the structure of the shock. A movie is available at http://www.aanda.org

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.

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.

Diamond Heat-Spreader for Submillimeter-Wave Frequency Multipliers

NASA Technical Reports Server (NTRS)

Lin, Robert H.; Schlecht, Erich T.; Chattopadhyay, Goutam; Gill, John J.; Mehdi, Imran; Siegel, Peter H.; Ward, John S.; Lee, Choonsup; Thomas, Bertrand C.; Maestrini, Alain

2010-01-01

The planar GaAs Shottky diode frequency multiplier is a critical technology for the local oscillator (LO) for submillimeter- wave heterodyne receivers due to low mass, tenability, long lifetime, and room-temperature operation. The use of a W-band (75-100 GHz) power amplifier followed by a frequency multiplier is the most common for submillimeter-wave sources. Its greatest challenge is to provide enough input power to the LO for instruments onboard future planetary missions. Recently, JPL produced 800 mW at 92.5 GHz by combining four MMICs in parallel in a balanced configuration. As more power at W-band is available to the multipliers, their power-handling capability be comes more important. High operating temperatures can lead to degradation of conversion efficiency or catastrophic failure. The goal of this innovation is to reduce the thermal resistance by attaching diamond film as a heat-spreader on the backside of multipliers to improve their power-handling capability. Polycrystalline diamond is deposited by hot-filament chemical vapor deposition (CVD). This diamond film acts as a heat-spreader to both the existing 250- and 300-GHz triplers, and has a high thermal conductivity (1,000-1,200 W/mK). It is approximately 2.5 times greater than copper (401 W/mK) and 20 times greater than GaAs (46 W/mK). It is an electrical insulator (resistivity approx. equals 10(exp 15) Ohms-cm), and has a low relative dielectric constant of 5.7. Diamond heat-spreaders reduce by at least 200 C at 250 mW of input power, compared to the tripler without diamond, according to thermal simulation. This superior thermal management provides a 100-percent increase in power-handling capability. For example, with this innovation, 40-mW output power has been achieved from a 250-GHz tripler at 350-mW input power, while the previous triplers, without diamond, suffered catastrophic failures. This breakthrough provides a stepping-stone for frequency multipliers-based LO up to 3 THz. The future work

Diamond-Coated Carbon Nanotubes for Efficient Field Emission

NASA Technical Reports Server (NTRS)

Dimitrijevic, Stevan; Withers, James C.

2005-01-01

Field-emission cathodes containing arrays of carbon nanotubes coated with diamond or diamondlike carbon (DLC) are undergoing development. Multiwalled carbon nanotubes have been shown to perform well as electron field emitters. The idea underlying the present development is that by coating carbon nanotubes with wideband- gap materials like diamond or DLC, one could reduce effective work functions, thereby reducing threshold electric-field levels for field emission of electrons and, hence, improving cathode performance. To demonstrate feasibility, experimental cathodes were fabricated by (1) covering metal bases with carbon nanotubes bound to the bases by an electrically conductive binder and (2) coating the nanotubes, variously, with diamond or DLC by plasma-assisted chemical vapor deposition. In tests, the threshold electric-field levels for emission of electrons were reduced by as much as 40 percent, relative to those of uncoated- nanotube cathodes. Coating with diamond or DLC could also make field emission-cathodes operate more stably by helping to prevent evaporation of carbon from nanotubes in the event of overheating of the cathodes. Cathodes of this type are expected to be useful principally as electron sources for cathode-ray tubes and flat-panel displays.

Scanning tunneling microscopy studies of diamond films and optoelectronic materials

NASA Technical Reports Server (NTRS)

Perez, Jose M.

1993-01-01

In this report, we report on progress achieved from 12/1/92 to 10/1/93 under the grant entitled 'Scanning Tunneling Microscopy Studies of Diamond Films and Optoelectronic Materials'. We have set-up a chemical vapor deposition (CVD) diamond film growth system and a Raman spectroscopy system to study the nucleation and growth of diamond films with atomic resolution using scanning tunneling microscopy (STM). A unique feature of the diamond film growth system is that diamond films can be transferred directly to the ultrahigh vacuum (UHV) chamber of a scanning tunneling microscope without contaminating the films by exposure to air. The University of North Texas (UNT) provided $20,000 this year as matching funds for the NASA grant to purchase the diamond growth system. In addition, UNT provided a Coherent Innova 90S Argon ion laser, a Spex 1404 double spectrometer, and a Newport optical table costing $90,000 to set-up the Raman spectroscopy system. The CVD diamond growth system and Raman spectroscopy system will be used to grow and characterize diamond films with atomic resolution using STM as described in our proposal. One full-time graduate student and one full-time undergraduate student are supported under this grant. In addition, several graduate and undergraduate students were supported during the summer to assist in setting-up the diamond growth and Raman spectroscopy systems. We have obtained research results concerning STM of the structural and electronic properties of CVD grown diamond films, and STM and scanning tunneling spectroscopy of carbon nanotubes. In collaboration with the transmission electron microscopy (TEM) group at UNT, we have also obtained results concerning the optoelectronic material siloxene. These results were published in refereed scientific journals, submitted for publication, and presented as invited and contributed talks at scientific conferences.

Microwave-Assisted Cross-Polarization of Nuclear Spin Ensembles from Optically Pumped Nitrogen-Vacancy Centers in Diamond.

PubMed

Shagieva, F; Zaiser, S; Neumann, P; Dasari, D B R; Stöhr, R; Denisenko, A; Reuter, R; Meriles, C A; Wrachtrup, J

2018-06-13

The ability to optically initialize the electronic spin of the nitrogen-vacancy (NV) center in diamond has long been considered a valuable resource to enhance the polarization of neighboring nuclei, but efficient polarization transfer to spin species outside the diamond crystal has proven challenging. Here we demonstrate variable-magnetic-field, microwave-enabled cross-polarization from the NV electronic spin to protons in a model viscous fluid in contact with the diamond surface. Further, slight changes in the cross-relaxation rate as a function of the wait time between successive repetitions of the transfer protocol suggest slower molecular dynamics near the diamond surface compared to that in bulk. This observation is consistent with present models of the microscopic structure of a fluid and can be exploited to estimate the diffusion coefficient near a solid-liquid interface, of importance in colloid science.

Lateral overgrowth of diamond film on stripes patterned Ir/HPHT-diamond substrate

NASA Astrophysics Data System (ADS)

Wang, Yan-Feng; Chang, Xiaohui; Liu, Zhangcheng; Liu, Zongchen; Fu, Jiao; Zhao, Dan; Shao, Guoqing; Wang, Juan; Zhang, Shaopeng; Liang, Yan; Zhu, Tianfei; Wang, Wei; Wang, Hong-Xing

2018-05-01

Epitaxial lateral overgrowth (ELO) of diamond films on patterned Ir/(0 0 1)HPHT-diamond substrates have been carried out by microwave plasma CVD system. Ir/(0 0 1)HPHT-diamond substrates are fabricated by photolithographic and magnetron sputtering technique. The morphology of the as grown ELO diamond film is characterized by optical microscopy and scanning electronic microscopy. The quality and stress of the ELO diamond film are investigated by surface etching pit density and micro-Raman spectroscopy. Two ultraviolet photodetectors are fabricated on ELO diamond area and non-ELO diamond area prepared on same substrate, and that one on ELO diamond area indicates better photoelectric properties. All results indicate quality of ELO diamond film is improved.

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.

Nanoscale deformation and fracture mechanics of polycrystalline silicon and diamond-like carbon for MEMS by the AFM/DIC method

NASA Astrophysics Data System (ADS)

Cho, Sung Woo

A method for nanoscale experimental mechanics was developed to address problems in deformation and fracture of micron-scale components in Microelectromechanical Systems (MEMS). Specifically, the effective and local, elastic and fracture behavior of polycrystalline silicon (polysilicon) and tetrahedral amorphous diamond-like carbon (ta-C) were studied using freestanding thin films subject to uniaxial tension. In this method, direct measurements of local deformations were derived from Atomic Force Microscopy (AFM) images in specimen areas varying between 1x2 mum2 and 15x15 mum2 using Digital Image Correlation (DIC) to extract displacements and strains with spatial resolution of 1-2 nm. The effective elastic modulus and Poisson's ratio of polysilicon and ta-C from the Sandia National Laboratories (SUMMiT) were 155 +/- 6 GPa and 0.22 +/- 0.02, and 759 +/- 22 GPa and 0.17 +/- 0.03, respectively. Similarly, the elastic modulus and Poisson's ratio of polysilicon fabricated at MCNC via the Multi-User MEMS Processes (MUMPs) with <110> texture were 164 +/- 7 GPa and 0.22 +/- 0.02, respectively. A second problem studied using the AFM/DIC method was the fracture of polysilicon in the presence of atomically sharp cracks. The effective (macroscopic) Mode-I critical stress intensity factor for polysilicon from different MUMPs runs was 1.00 +/- 0.1 MPa√m, where 0.1 MPa√m was the standard deviation, attributed to local cleavage anisotropy and grain boundary toughening. The variation in the effective critical stress intensity factor and the subcritical crack growth of polysilicon that was spatially recorded and quantified for the first time were the result of the spatial variation of the 4 local stress intensity factor at the crack tip that controlled crack initiation and thus, the overall fracture process. The AFM/DIC method was also applied to determine the minimum size of a polysilicon domain whose effective mechanical behavior could be described by the isotropic elastic

High-efficiency treatment of PTA wastewater using a biogas jet assisted anaerobic fluidized bed reactor.

PubMed

Zhang, Wei; Feng, Yangyang; Chen, Yingwen; Li, Peiwen; Zhu, Shemin; Shen, Shubao

2018-02-05

In this paper, a new type of biogas jet assisted anaerobic fluidized bed reactor loaded with a polypropylene carrier has been proposed. There was a clear improvement in the fluidized state due to the biogas assisted input when the gas/water ratio was set at 1:3 with a suitable carrier loading of 60%. When the circulating water flow is 30 L/min assisted with biogas 10 L/min, the mixing time shortens from 26 to 18 s. The performance of anaerobic biodegradation on wastewater treatment was improved largely. The chemical oxygen demand (COD) and terepthallic acid removal efficiencies were at 85.4% and 84%, respectively, at hydraulic retention time of 20 h, even when the influent COD concentration was as high as 4224 mg/L. In addition, plenty of microorganisms, attached to the carriers and assumed to be the reason behind the organic biodegradation efficiency of the proposed system, were observed using scanning electron microscopy.

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.

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

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

dislocations. The understanding of the critical processes that are involved in CVD diamond growth are becoming clearer. Two papers in this issue model it on a microscopic scale [11, 12], and a further two explore the practical techniques [13, 14] in order to lead to improvement in deposition techniques. Diamond is emerging as an engineering material [3] with its cost no longer regarded as prohibitive even for some large-scale uses, such as the fusion reactor first wall. It is striking how few useful dopants can be put into diamond in a controlled way. The studies reported here, whether theory or experiment, concentrate on phosphorus [14] as the donor, and demonstrate that boron (although deep in semiconductor terms,) can act as the acceptor [3] in practical devices. Other impurities, with deeper levels, such as nitrogen [15], with the muon as an honorary hydrogen [16], are studied in depth. Here, many of the characterization techniques developed over several decades have been brought to bear, to attempt to quantify impurities and defects and ultimately assist in improving the crystal quality [17, 18, 15]. However, further, more novel techniques such as reflection anisotropy spectroscopy [19] and luminescence lifetime mapping [20] have been introduced to diamond in this issue, and one can see how such techniques might play a crucial role in areas such as systems for quantum information processing. The presence and migration of radiation damage defects [21, 22], vacancies and interstitials, and vacancy clusters can dramatically influence the exploitable properties of diamond [23, 24]. It is now apparent that charge traps not only impact on electrical properties, but also on the colour of diamond and that thermo-chromic and photo-chromic effects are more common than previously thought [25, 23]. Combinations, like the negatively charged nitrogen-vacancy centre, have proved impressive in quantum information studies [26]. But diamond has yet to benefit from the sort of dopant

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.

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

NASA Astrophysics Data System (ADS)

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

2002-09-01

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

Layer Protecting the Surface of Zirconium Used in Nuclear Reactors.

PubMed

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

2016-01-01

Zirconium alloys have very useful properties for nuclear facilities applications having low absorption cross-section of thermal electrons, high ductility, hardness and corrosion resistance. However, there is also a significant disadvantage: it reacts with water steam and during this (oxidative) reaction it releases hydrogen gas, which partly diffuses into the alloy forming zirconium hydrides. A new strategy for surface protection of zirconium alloys against undesirable oxidation in nuclear reactors by polycrystalline diamond film has been patented- Czech patent 305059: Layer protecting the surface of zirconium alloys used in nuclear reactors and PCT patent: Layer for protecting surface of zirconium alloys (Patent Number: WO2015039636-A1). The zirconium alloy surface was covered by polycrystalline diamond layer grown in plasma enhanced chemical vapor deposition apparatus with linear antenna delivery system. Substantial progress in the description and understanding of the polycrystalline diamond/ zirconium alloys interface and material properties under standard and nuclear reactors conditions (irradiation, hot steam oxidation experiments and heating-quenching cycles) was made. In addition, process technology for the deposition of protective polycrystalline diamond films onto the surface of zirconium alloys was optimized. Zircaloy2 nuclear fuel pins were covered by 300 nm thick protective polycrystalline diamond layer (PCD) using plasma enhanced chemical vapor deposition apparatus with linear antenna delivery system. The polycrystalline diamond layer protects the zirconium alloy surface against undesirable oxidation and consolidates its chemical stability while preserving its functionality. PCD covered Zircaloy2 and standard Zircaloy2 pins were for 30 min. oxidized in 1100°C hot steam. Under these conditions α phase of zirconium changes to β phase (more opened for oxygen/hydrogen diffusion). PCD anticorrosion protection of Zircaloy nuclear fuel assemblies can

Systematic study of polycrystalline flow during tension test of sheet 304 austenitic stainless steel at room temperature

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

Muñoz-Andrade, Juan D., E-mail: jdma@correo.azc.uam.mx

2013-12-16

By systematic study the mapping of polycrystalline flow of sheet 304 austenitic stainless steel (ASS) during tension test at constant crosshead velocity at room temperature was obtained. The main results establish that the trajectory of crystals in the polycrystalline spatially extended system (PCSES), during irreversible deformation process obey a hyperbolic motion. Where, the ratio between the expansion velocity of the field and the velocity of the field source is not constant and the field lines of such trajectory of crystals become curved, this accelerated motion is called a hyperbolic motion. Such behavior is assisted by dislocations dynamics and self-accommodation processmore » between crystals in the PCSES. Furthermore, by applying the quantum mechanics and relativistic model proposed by Muñoz-Andrade, the activation energy for polycrystalline flow during the tension test of 304 ASS was calculated for each instant in a global form. In conclusion was established that the mapping of the polycrystalline flow is fundamental to describe in an integral way the phenomenology and mechanics of irreversible deformation processes.« less

Systematic study of polycrystalline flow during tension test of sheet 304 austenitic stainless steel at room temperature

NASA Astrophysics Data System (ADS)

Muñoz-Andrade, Juan D.

2013-12-01

By systematic study the mapping of polycrystalline flow of sheet 304 austenitic stainless steel (ASS) during tension test at constant crosshead velocity at room temperature was obtained. The main results establish that the trajectory of crystals in the polycrystalline spatially extended system (PCSES), during irreversible deformation process obey a hyperbolic motion. Where, the ratio between the expansion velocity of the field and the velocity of the field source is not constant and the field lines of such trajectory of crystals become curved, this accelerated motion is called a hyperbolic motion. Such behavior is assisted by dislocations dynamics and self-accommodation process between crystals in the PCSES. Furthermore, by applying the quantum mechanics and relativistic model proposed by Muñoz-Andrade, the activation energy for polycrystalline flow during the tension test of 304 ASS was calculated for each instant in a global form. In conclusion was established that the mapping of the polycrystalline flow is fundamental to describe in an integral way the phenomenology and mechanics of irreversible deformation processes.

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

PubMed

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

2014-06-24

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

Nanocrystalline diamond coatings for mechanical seals applications.

PubMed

Santos, J A; Neto, V F; Ruch, D; Grácio, J

2012-08-01

A mechanical seal is a type of seal used in rotating equipment, such as pumps and compressors. It consists of a mechanism that assists the connection of the rotating shaft to the housings of the equipments, preventing leakage or avoiding contamination. A common cause of failure of these devices is end face wear out, thus the use of a hard, smooth and wear resistant coating such as nanocrystalline diamond would be of great importance to improve their working performance and increase their lifetime. In this paper, different diamond coatings were deposited by the HFCVD process, using different deposition conditions. Additionally, the as-grown films were characterized for, quality, morphology and microstructure using scanning electron microscopy (SEM) and Raman spectroscopy. The topography and the roughness of the films were characterized by atomic force microscopy (AFM).

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.

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

A diamond active target for the PADME experiment

NASA Astrophysics Data System (ADS)

Chiodini, G.

2017-02-01

The PADME (Positron Annihilation into Dark Mediator Experiment) collaboration searches for dark photons produced in the annihilation e++e-→γ+A' of accelerated positrons with atomic electrons of a fixed target at the Beam Test Facility of Laboratori Nazionali di Frascati. The apparatus can detect dark photons decaying into visible A'→e+e- and invisible A'→χχ channels, where χ's are particles of a secluded sector weakly interacting and therefore undetected. In order to improve the missing mass resolution and to measure the beam flux, PADME has an active target able to reconstruct the beam spot position and the bunch multiplicity. In this work the active target is described, which is made of a detector grade polycrystalline synthetic diamond with strip electrodes on both surfaces. The electrodes segmentation allows to measure the beam profile along X and Y and evaluate the average beam position bunch per bunch. The results of beam tests for the first two diamond detector prototypes are shown. One of them holds innovative graphitic electrodes built with a custom process developed in the laboratory, and the other one with commercially available traditional Cr-Au electrodes. The front-end electronics used in the test beam is discussed and the performance observed is presented. Finally, the final design of the target to be realized at the beginning of 2017 to be ready for data taking in 2018 is illustrated.

Superconductivity in diamond.

PubMed

Ekimov, E A; Sidorov, V A; Bauer, E D; Mel'nik, N N; Curro, N J; Thompson, J D; Stishov, S M

2004-04-01

Diamond is an electrical insulator well known for its exceptional hardness. It also conducts heat even more effectively than copper, and can withstand very high electric fields. With these physical properties, diamond is attractive for electronic applications, particularly when charge carriers are introduced (by chemical doping) into the system. Boron has one less electron than carbon and, because of its small atomic radius, boron is relatively easily incorporated into diamond; as boron acts as a charge acceptor, the resulting diamond is effectively hole-doped. Here we report the discovery of superconductivity in boron-doped diamond synthesized at high pressure (nearly 100,000 atmospheres) and temperature (2,500-2,800 K). Electrical resistivity, magnetic susceptibility, specific heat and field-dependent resistance measurements show that boron-doped diamond is a bulk, type-II superconductor below the superconducting transition temperature T(c) approximately 4 K; superconductivity survives in a magnetic field up to Hc2(0) > or = 3.5 T. The discovery of superconductivity in diamond-structured carbon suggests that Si and Ge, which also form in the diamond structure, may similarly exhibit superconductivity under the appropriate conditions.

Process Research On Polycrystalline Silicon Material (PROPSM)

NASA Technical Reports Server (NTRS)

Culik, J. S.; Wohlgemuth, J. H.

1982-01-01

Performance limiting mechanisms in polycrystalline silicon are investigated by fabricating a matrix of solar cells of various thicknesses from polycrystalline silicon wafers of several bulk resistivities. The analysis of the results for the entire matrix indicates that bulk recombination is the dominant factor limiting the short circuit current in large grain (greater than 1 to 2 mm diameter) polycrystalline silicon, the same mechanism that limits the short circuit current in single crystal silicon. An experiment to investigate the limiting mechanisms of open circuit voltage and fill factor for large grain polycrystalline silicon is designed. Two process sequences to fabricate small cells are investigated.

Diamond For Optical Material

NASA Astrophysics Data System (ADS)

Clay, Robert D.; Clay, John P.

1984-12-01

Clay Engineering Inc. currently has a proposal before DARPA to manufacture large optical quality diamond for use as optical material. The manufactured diamond will be approximately 100 mm in diameter by 100 mm long. The cost of producing the diamond is expected to be three dollars per carat. It is expected that total impurities of a few parts per billion can readily be obtained. A study of diamond is a study of the effects of impurities. The elements boron and nitrogen can replace carbon atoms in the lattice structure, making diamond a "P" or "N" type semiconductor. Diamonds which are not semiconductors are classified as type IIa. The presence of B or N in the lattice causes diamond to photoconduct in ultraviolet light. All type I and III) and most type IIa diamonds photoconduct. The manufactured diamond will not photoconduct and will have an electrical resistivity greater than 1018 ohm*m. All non-lattice impurities are in the form of inclusions which dramatically affect the mechanical properties of diamond. High purity diamond has a coefficient of absorption of order 10-3 cm-1 at wavelengths of 8 to 12 micro metres, which makes it useful for infrared applications. It also has a low coefficient of absorption at wavelengths greater than 12 micro metres. For missile and aircraft applications, diamond is relatively immune to erosion or pitting damage by sand and rain. Diamond will readily withstand the stagnation temperature of Mach 3 flight and will go to Mach 4.8 with an anti-reflective coating to protect it from oxygen attack. Diamond is highly resistant to thermal shock, which makes it valuable for high energy laser applications. Using R = St (1-)) k/Ea as a measure of thermal shock resistance, diamond is 107 w/m vs "sapphire" and Zerodur at 104 and fused quartz at 1.45x103. Diamond does not perform well in the 2.5-7.5 micro metres and less than 0.4 micro metres wavelengths. Intense beams of less than 0.4 micro metres energy can create color centers in diamond

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

PubMed

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

2014-06-11

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

Grinding With Diamond Burs and Hydrothermal Aging of a Y-TZP Material: Effect on the Material Surface Characteristics and Bacterial Adhesion.

PubMed

Dutra, Dam; Pereira, Gkr; Kantorski, K Z; Exterkate, Ram; Kleverlaan, C J; Valandro, L F; Zanatta, F B

The aim of this study was to evaluate the effect of grinding with diamond burs and low-temperature aging on the material surface characteristics and bacteria adhesion on a yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) surface. Y-TZP specimens were made from presintered blocks, sintered as recommended by the manufacturer, and assigned into six groups according to two factors-grinding (three levels: as sintered, grinding with extra-fine diamond bur [25-μm grit], and grinding with coarse diamond bur [181-μm grit]) and hydrothermal aging-to promote low-temperature degradation (two levels: presence/absence). Phase transformation (X-ray diffractometer), surface roughness, micromorphological patterns (atomic force microscopy), and contact angle (goniometer) were analyzed. Bacterial adhesion (colony-forming units [CFU]/biofilm) was quantified using an in vitro polymicrobial biofilm model. Both the surface treatment and hydrothermal aging promoted an increase in m-phase content. Roughness values increased as a function of increasing bur grit sizes. Grinding with a coarse diamond bur resulted in significantly lower values of contact angle (p<0.05) when compared with the extra-fine and control groups, while there were no differences (p<0.05) after hydrothermal aging simulation. The CFU/biofilm results showed that neither the surface treatment nor hydrothermal aging simulation significantly affected the bacteria adherence (p>0.05). Grinding with diamond burs and hydrothermal aging modified the Y-TZP surface properties; however, these properties had no effect on the amount of bacteria adhesion on the material surface.

Diamond/diamond-like carbon coated nanotube structures for efficient electron field emission

NASA Technical Reports Server (NTRS)

Dimitrijevic, Steven (Inventor); Withers, James C. (Inventor); Loutfy, Raouf O. (Inventor)

2005-01-01

The present invention is directed to a nanotube coated with diamond or diamond-like carbon, a field emitter cathode comprising same, and a field emitter comprising the cathode. It is also directed to a method of preventing the evaporation of carbon from a field emitter comprising a cathode comprised of nanotubes by coating the nanotube with diamond or diamond-like carbon. In another aspect, the present invention is directed to a method of preventing the evaporation of carbon from an electron field emitter comprising a cathode comprised of nanotubes, which method comprises coating the nanotubes with diamond or diamond-like carbon.

Plastic deformation of polycrystalline MgO up to 1250 K and 65 GPa

NASA Astrophysics Data System (ADS)

Merkel, S.; Liermann, H.; Miyagi, L. M.; Wenk, H.

2009-12-01

Understanding the development of lattice preferred orientations (LPO) in polycrystals is critical to constrain the anisotropy and dynamics of the Earth mantle. Until recently, it was not possible to study LPO under high pressure and high temperature. The introduction of the deformation-DIA (D-DIA) and radial diffraction experiments in the diamond anvil cell (DAC) have extended the range of pressures and temperatures that can be accessed. However, the pressure range accessible in the D-DIA remains limited (up to 19 GPa, 1) and LPO measurements in the DAC have been performed at 300 K (2). Recently, we have designed a new DAC that can be used to study LPO in polycrystalline samples up to temperatures of 1300 K and pressures of 65 GPa (3). In this study, we use this new device for the study of MgO up to 65 GPa and 1250 K. Four samples of polycrystalline MgO were deformed in the DAC at constant temperature: 300, 600, 900, and 1250 K. At each temperature, we study the development of stress and LPO as the sample is compressed between ambient and high pressures (up to 65 GPa). In all cases, we collect diffraction data in a radial geometry that can be used to extract lattice strains and LPO in the sample. A comparison of the LPO measured in the experiment and results of visco-plastic self-consistent models can be used to extract information about the active deformation mechanisms in the sample (2). Similarly, the measured lattice strains can be compared to results of an elasto-plastic self-consistent model to extract information on average stress, stress distribution among grains, and active deformation in the sample (4). Details of the measurements along with the LPO measured in the experiments will be presented. We will also discuss the implication of those results for our understanding of the behavior of MgO in the deep mantle. 1- N. Nishiyama, Y. Wang, M. L. Rivers, S. R. Sutton, D. Cookson, Rheology of e-iron up to 19 GPa and 600 K in the D-DIA, Geophys. Res. Lett., 34

Processing of crack-free high density polycrystalline LiTaO3 ceramics

DOE PAGES

Chen, Ching-Fong; Brennecka, Geoff L.; King, Graham; ...

2016-11-04

Our work achieved high density (99.9%) polycrystalline LiTaO 3. The keys to the high density without cracking were the use of LiF-assisted densification to maintain fine grain size as well as the presence of secondary lithium aluminate phases as grain growth inhibitors. The average grain size of the hot pressed polycrystalline LiTaO 3 is less than 5 μm, limiting residual stresses caused by the anisotropic thermal expansion. Dilatometry results clearly indicate liquid phase sintering via the added LiF sintering aid. Efficient liquid phase sintering allows densification during low temperature hot pressing. Electron microscopy confirmed the high-density microstructure. Furthermore, Rietveld analysismore » of neutron diffraction data revealed the presence of LiAlO 2 and LiAl 5O 8 minority phases and negligible substitutional defect incorporation in LiTaO 3.« less

The Diamond Window with Boron-Doped Layers for the Output of Microwave Radiation at High Peak and Average Power Levels

NASA Astrophysics Data System (ADS)

Ivanov, O. A.; Kuzikov, S. V.; Vikharev, A. A.; Vikharev, A. L.; Lobaev, M. A.

2017-10-01

We propose a novel design of the barrier window for the output of microwave radiation at high peak and average power levels. A window based on a plate of polycrystalline CVD diamond with thin (nanometer-thick) boron-doped layers with increased conductivity is considered. Such a window, which retains the low radiation loss due to the small total thickness of the conductive layers and the high thermal conductivity inherent in diamond, prevents accumulation of a static charge on its surface, on the one hand, and allows one to produce a static electric field on the surface of the doped layer, which impedes the development of a multipactor discharge, on the other hand. In this case, a high level of the power of the transmitted radiation and a large passband width are ensured by choosing the configuration of the field in the form of a traveling wave inside the window.

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.

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

PubMed

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

2018-04-27

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

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.

Recrystallization of polycrystalline silicon

NASA Technical Reports Server (NTRS)

Lall, C.; Kulkarni, S. B.; Graham, C. D., Jr.; Pope, D. P.

1981-01-01

Optical metallography is used to investigate the recrystallization properties of polycrystalline semiconductor-grade silicon. It is found that polycrystalline silicon recrystallizes at 1380 C in relatively short times, provided that the prior deformation is greater than 30%. For a prior deformation of about 40%, the recrystallization process is essentially complete in about 30 minutes. Silicon recrystallizes at a substantially slower rate than metals at equivalent homologous temperatures. The recrystallized grain size is insensitive to the amount of prestrain for strains in the range of 10-50%.

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.

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.

Silicon solar cell performance deposited by diamond like carbon thin film ;Atomic oxygen effects;

NASA Astrophysics Data System (ADS)

Aghaei, Abbas Ail; Eshaghi, Akbar; Karami, Esmaeil

2017-09-01

In this research, a diamond-like carbon thin film was deposited on p-type polycrystalline silicon solar cell via plasma-enhanced chemical vapor deposition method by using methane and hydrogen gases. The effect of atomic oxygen on the functioning of silicon coated DLC thin film and silicon was investigated. Raman spectroscopy, field emission scanning electron microscopy, atomic force microscopy and attenuated total reflection-Fourier transform infrared spectroscopy were used to characterize the structure and morphology of the DLC thin film. Photocurrent-voltage characteristics of the silicon solar cell were carried out using a solar simulator. The results showed that atomic oxygen exposure induced the including oxidation, structural changes, cross-linking reactions and bond breaking of the DLC film; thus reducing the optical properties. The photocurrent-voltage characteristics showed that although the properties of the fabricated thin film were decreased after being exposed to destructive rays, when compared with solar cell without any coating, it could protect it in atomic oxygen condition enhancing solar cell efficiency up to 12%. Thus, it can be said that diamond-like carbon thin layer protect the solar cell against atomic oxygen exposure.

Optimizing Dense Plasma Focus Neutron Yields With Fast Gas Jets

NASA Astrophysics Data System (ADS)

McMahon, Matthew; Stein, Elizabeth; Higginson, Drew; Kueny, Christopher; Link, Anthony; Schmidt, Andrea

2017-10-01

We report a study using the particle-in-cell code LSP to perform fully kinetic simulations modeling dense plasma focus (DPF) devices with high density gas jets on axis. The high-density jets are modeled in the large-eddy Navier-Stokes code CharlesX, which is suitable for modeling both sub-sonic and supersonic gas flow. The gas pattern, which is essentially static on z-pinch time scales, is imported from CharlesX to LSP for neutron yield predictions. Fast gas puffs allow for more mass on axis while maintaining the optimal pressure for the DPF. As the density of a subsonic jet increases relative to the background fill, we find the neutron yield increases, as does the variability in the neutron yield. Introducing perturbations in the jet density via super-sonic flow (also known as Mach diamonds) allow for consistent seeding of the m =0 instability leading to more consistent ion acceleration and higher neutron yields with less variability. Jets with higher on axis density are found to have the greatest yield. The optimal jet configuration and the necessary jet conditions for increasing neutron yield and reducing yield variability are explored. Simulations of realistic jet profiles are performed and compared to the ideal scenario. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and supported by the Laboratory Directed Research and Development Program (15-ERD-034) at LLNL.

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.

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.

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

DOEpatents

Gruen, Dieter M [Downers Grove, IL

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.

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

NASA Astrophysics Data System (ADS)

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

2017-04-01

In the same way that melt inclusions in phenocrysts have expanded our idea of melt formation and evolution in basalts, studying fluids trapped in diamonds is providing important new constraints on the nature of diamond-forming fluids. Fibrous and cloudy diamonds trap a high but variable density of fluid inclusions and so have been extensively studied using major and trace element compositions. In contrast, constraining the nature of the diamond-forming fluid for high purity gem-quality diamonds has been restricted by the rarity of available high quality trace element data. This is due to the extremely low concentrations of impurities that gem diamonds contain - often in the ppt range. The recent discovery of fluids in gem diamonds showing similar major element chemistry to fluid-rich diamonds suggest that many diamonds may share a common spectrum of parental fluids. Here we test this idea further. Recent advances in analytical techniques, in particular the development of the "off-line" laser ablation pre-concentration approach, have allowed fully quantitative trace element data to be recovered from "fluid-poor", high quality gem diamonds. We present trace element data for gem diamonds from a variety of locations from Canada, S. Africa and Russia, containing either silicate or sulphide inclusions to examine possible paragenetic or genetic differences between fluids. REE abundance in the "gem" diamonds vary from 0.1 to 0.0001 x chondrite. To a first order, we observe the same spectrum of trace element compositions in the gem diamonds as that seen in fluid-rich "fibrous" diamonds, supporting a common origin for the fluids. REE patterns range from extremely flat (Ce/Yb)n 2.5 to 5 (commonly in sulphide-bearing diamonds) to >70, the latter having significantly greater inter-element HFSE/LILE fractionation. In general, the fluids from the sulphide-bearing diamonds are less REE-enriched than the silicate-bearing diamonds, but the ranges overlap significantly. The very

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

NASA Astrophysics Data System (ADS)

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

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

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

NASA Astrophysics Data System (ADS)

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

2001-08-01

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

A methodological toolkit for field assessments of artisanally mined alluvial diamond deposits

USGS Publications Warehouse

Chirico, Peter G.; Malpeli, Katherine C.

2014-01-01

This toolkit provides a standardized checklist of critical issues relevant to artisanal mining-related field research. An integrated sociophysical geographic approach to collecting data at artisanal mine sites is outlined. The implementation and results of a multistakeholder approach to data collection, carried out in the assessment of Guinea’s artisanally mined diamond deposits, also are summarized. This toolkit, based on recent and successful field campaigns in West Africa, has been developed as a reference document to assist other government agencies or organizations in collecting the data necessary for artisanal diamond mining or similar natural resource assessments.

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.

Thermally stable diamond brazing

DOEpatents

Radtke, Robert P [Kingwood, TX

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.

Multilayered micro/nanocrystalline CVD diamond coatings for biotribology =

NASA Astrophysics Data System (ADS)

Salgueiredo, Ermelinda da Conceicao Portela

In the present work multilayered micro/nanocrystalline (MCD/NCD) diamond coatings were developed by Hot Filament Chemical Vapour Deposition (HFCVD). The aim was to minimize the surface roughness with a top NCD layer, to maximize adhesion onto the Si3N4 ceramic substrates with a starting MCD coating and to improve the mechanical resistance by the presence of MCD/NCD interfaces in these composite coatings. This set of features assures high wear resistance and low friction coefficients which, combined to diamond biocompatibility, set this material as ideal for biotribological applications. The deposition parameters of MCD were optimized using the Taguchi method, and two varieties of NCD were used: NCD-1, grown in a methane rich gas phase, and NCD-2 where a third gas, Argon, was added to the gas mixture. The best combination of surface pre-treatments in the Si3N4 substrates is obtained by polishing the substrates with a 15 mum diamond slurry, further dry etching with CF4 plasma for 10 minutes and final ultrasonic seeding in a diamond powder suspension in ethanol for 1 hour. The interfaces of the multilayered CVD diamond films were characterized with high detail using HRTEM, STEM-EDX and EELS. The results show that at the transition from MCD to NCD a thin precursor graphitic film is formed. On the contrary, the transition of the NCD to MCD grade is free of carbon structures other than diamond, as a result of the richer atomic hydrogen content and of the higher substrate temperature for MCD deposition. At those transitions, WC nanoparticles were found due to contamination from the filament, being also present at the first interface of the MCD layer with the silicon nitride substrate. In order to study the adhesion and mechanical resistance of the diamond coatings, indentation and particle jet blasting tests were conducted, as well as tribological experiments with homologous pairs. Indentation tests proved the superior behaviour of the multilayered coatings that attained

The aeroacoustics of supersonic jets

NASA Technical Reports Server (NTRS)

Morris, Philip J.; McLaughlin, Dennis K.

1995-01-01

This research project was a joint experimental/computational study of noise in supersonic jets. The experiments were performed in a low to moderate Reynolds number anechoic supersonic jet facility. Computations have focused on the modeling of the effect of an external shroud on the generation and radiation of jet noise. This report summarizes the results of the research program in the form of the Masters and Doctoral theses of those students who obtained their degrees with the assistance of this research grant. In addition, the presentations and publications made by the principal investigators and the research students is appended.

Diamond heteroepitaxial lateral overgrowth

DOE PAGES

Tang, Y. -H.; Bi, B.; Golding, B.

2015-02-24

A method of diamond heteroepitaxial lateral overgrowth is demonstrated which utilizes a photolithographic metal mask to pattern a thin (001) epitaxial diamond surface. Significant structural improvement was found, with a threading dislocation density reduced by two orders of magnitude at the top surface of a thick overgrown diamond layer. In the initial stage of overgrowth, a reduction of diamond Raman linewidth in the overgrown area was also realized. Thermally-induced stress and internal stress were determined by Raman spectroscopy of adhering and delaminated diamond films. As a result, the internal stress is found to decrease as sample thickness increases.

Effect of air-abrasion regimens and fine diamond bur grinding on flexural strength, Weibull modulus and phase transformation of zirconium dioxide.

PubMed

Michida, Silvia Masae de Araújo; Kimpara, Estevão Tomomitsu; dos Santos, Claudinei; Souza, Rodrigo Othavio Assunção; Bottino, Marco Antonio; Özcan, Mutlu

2015-10-16

This study evaluated the effect of air abrasion and polishing regimens on the flexural strength of yttrium stabilized polycrystalline tetragonal zirconia (Y-TZP). From Y-TZP blocks (InCeram 2000 YZ Cubes; Vita Zahnfabrik, Bad Säckingen, Germany) 120 bars (25 mm × 4 mm × 1.2 mm) were obtained according to ISO 6872:2008 and randomly divided into 4 groups: Group C: (control) without surface treatment (n = 30); Group APA: Air abrasion with aluminum oxide (44 µm) (n = 30); Group SC: Silica-coating (CoJet, 30 µm) (n = 30); Group FD: Fine diamond bur (n = 30). Subsequently, all specimens were subjected to 4-point bending test (in distilled water at 37 °C) in a universal testing machine (EMIC DL 1000; São José dos Pinhais, Paraná, Brazil); cross-head speed: 0.5 mm/min). The characteristic strength (σ0) of each specimen was obtained from the flexural strength test and evaluated using Weibull analysis. X-ray diffraction analysis was utilized to quantity the monoclinic phase. The surface topography of specimens was analyzed using 3D optical profilometer and scanning electron microscopy (SEM) after surface conditioning methods. The flexural strength data (σ4p) were statistically analyzed by 1-way ANOVA, Tukey test (α = 0.05) and Weibull (m = modulus, σ0 = characteristic strength) were calculated. The mean ± standard deviations (MPa) of the groups were as follows: C: 1196.2 ± 284.2a; APA: 1369.7 ± 272.3a; SC: 1207.1 ± 229.7a and FD: 874.4 ± 365.4b. The values (m) and (σ0) were as follows: C: 4.5 and 1308.12; APA: 5.9 and 1477.88; SC: 6.0 and 1300.28; and FD: 2.6 and 985.901, respectively. Air particle abrasion with neither silica nor alumina showed significant difference compared to the control group but grinding with fine diamond bur impaired the flexural strength of the zirconia tested.

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

NASA Astrophysics Data System (ADS)

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

2004-09-01

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

3D Textural and Geochemical Analyses on Carbonado Diamond: Insights from Pores and the Minerals within Them

NASA Astrophysics Data System (ADS)

Eckley, S. A.; Ketcham, R. A.

2017-12-01

Carbonado is an enigmatic variety of polycrystalline diamond found only in placer deposits and Proterozoic metaconglomerates in Brazil and the Central African Republic with unknown primary origin. These highly porous black nodules possess a narrow range of isotopically light carbon (δ13C -31 to -24 ‰), a primarily crustal inclusion suite unusually enriched in REEs and actinides filling the pore spaces, a crystallization age from 2.6 to 3.8 Ga, and other atypical features which have led to a variety of formation theories from extra-solar to deep mantle. We have completed the first multi-sample 3D textural analysis on nine carbonados using high resolution X-ray CT (XCT), with follow-up geochemical work. We have documented a variety of textures in both pore structure and mineralogy within pores. All pore textures feature a preferred orientation. Spatial coherence in pore fillings in some specimens suggest that secondary minerals formed by in-situ breakdown of primary inclusion phases. This, combined with the presence of pseudomorphs, support the hypothesis that elements comprising the secondary minerals within the pore spaces are actually primary. SEM-EDS analysis of one carbonado's exterior revealed the presence of zircon; XCT analysis of the complete volume indicates zircon is present only on the exterior of that specimen, but may be interior to others. Anticipated follow-up work will include LA-ICP-MS U-Pb dating and REE analysis of the zircon, and step-leaching and ICP analysis of some specimens. Periodic XCT imaging will allow us to trace leaching progress and effectiveness. To provide further context for our observed pore fabrics, we also analyzed a framesite, a less porous polycrystalline diamond found in kimberlites thought to crystallize shortly before eruption. Both diamond varieties have bladed/elongated pores forming a foliation with a moderate lineation. The similarity in fabrics suggests a similar process could have formed both carbonados and

Chemical-Vapor-Deposited Diamond Film

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1999-01-01

This chapter describes the nature of clean and contaminated diamond surfaces, Chemical-vapor-deposited (CVD) diamond film deposition technology, analytical techniques and the results of research on CVD diamond films, and the general properties of CVD diamond films. Further, it describes the friction and wear properties of CVD diamond films in the atmosphere, in a controlled nitrogen environment, and in an ultra-high-vacuum environment.

Orapa Diamond Mine, Botswana

NASA Image and Video Library

2015-11-16

This image from NASA Terra spacecraft shows the Orapa diamond mine, the world largest diamond mine by area. The mine is located in Botswana. It is the oldest of four mines operated by the same company, having begun operations in 1971. Orapa is an open pit style of mine, located on two kimberlite pipes. Currently, the Orapa mine annually produces approximately 11 million carats (2200 kg) of diamonds. The Letlhakane diamond mine is also an open pit construction. In 2003, the Letlhakane mine produced 1.06 million carats of diamonds. The Damtshaa diamond mine is the newest of four mines, located on top of four distinct kimberlite pipes of varying ore grade. The mine is forecast to produce about 5 million carats of diamond over the projected 31 year life of the mine. The image was acquired October 5, 2014, covers an area of 28 by 45 km, and is located at 21.3 degrees south, 25.4 degrees east. http://photojournal.jpl.nasa.gov/catalog/PIA20104

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

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

Kang, Qiping; He, Xinbo, E-mail: xb_he@163.com; Ren, Shubin

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}more » 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.« less

Coupling modes between liquid/gas coaxial jets and transverse acoustic waves

NASA Astrophysics Data System (ADS)

Helland, Chad; Hilliker, Cullen; Forliti, David; University of St. Thomas Team

2017-11-01

The interactions between shear flows and acoustic disturbances plays a very important role in many propulsion and energy applications. Liquid jets, either independent or air assisted, respond to acoustic disturbances in a manner that alters the primary and secondary atomization processes. The current study focused on the response of an air-assisted liquid jet to disturbances associated with a transverse acoustic wave. The jet is placed in the pressure node (velocity antinode) region of the resonant mode shape. It has been shown in previous studies, under certain conditions, that the acoustic forces can cause the jet flow to distort and atomize. Both liquid and coaxial gas/ liquid jet flows have been shown to distort via acoustic forces. The purpose of the current study is to understand the predictive characteristics that cause the distortion behaviors of a liquid and coaxial jet flow, and how a how a coaxial flow affects the behavior.

Modelling heat conduction in polycrystalline hexagonal boron-nitride films

PubMed Central

Mortazavi, Bohayra; Pereira, Luiz Felipe C.; Jiang, Jin-Wu; Rabczuk, Timon

2015-01-01

We conducted extensive molecular dynamics simulations to investigate the thermal conductivity of polycrystalline hexagonal boron-nitride (h-BN) films. To this aim, we constructed large atomistic models of polycrystalline h-BN sheets with random and uniform grain configuration. By performing equilibrium molecular dynamics (EMD) simulations, we investigated the influence of the average grain size on the thermal conductivity of polycrystalline h-BN films at various temperatures. Using the EMD results, we constructed finite element models of polycrystalline h-BN sheets to probe the thermal conductivity of samples with larger grain sizes. Our multiscale investigations not only provide a general viewpoint regarding the heat conduction in h-BN films but also propose that polycrystalline h-BN sheets present high thermal conductivity comparable to monocrystalline sheets. PMID:26286820

Cold plasma decontamination using flexible jet arrays

NASA Astrophysics Data System (ADS)

Konesky, Gregory

2010-04-01

Arrays of atmospheric discharge cold plasma jets have been used to decontaminate surfaces of a wide range of microorganisms quickly, yet not damage that surface. Its effectiveness in decomposing simulated chemical warfare agents has also been demonstrated, and may also find use in assisting in the cleanup of radiological weapons. Large area jet arrays, with short dwell times, are necessary for practical applications. Realistic situations will also require jet arrays that are flexible to adapt to contoured or irregular surfaces. Various large area jet array prototypes, both planar and flexible, are described, as is the application to atmospheric decontamination.

Homoepitaxial Boron Doped Diamond Anvils as Heating Elements in a Diamond Anvil Cell

NASA Astrophysics Data System (ADS)

Montgomery, Jeffrey; Samudrala, Gopi; Smith, Spencer; Tsoi, Georgiy; Vohra, Yogesh; Weir, Samuel

2013-03-01

Recent advances in designer-diamond technology have allowed for the use of electrically and thermally conducting homoepitaxially-grown layers of boron-doped diamond (grown at 1200 °C with a 2% mixture of CH4 in H, resulting in extremely high doping levels ~ 1020/cm3) to be used as heating elements in a diamond anvil cell (DAC). These diamonds allow for precise control of the temperature inside of the diamond anvil itself, particularly when coupled with a cryostat. Furthermore, the unmatched thermally conducting nature of diamond ensures that no significant lateral gradient in temperature occurs across the culet area. Since a thermocouple can easily be attached anywhere on the diamond surface, we can also measure diamond temperatures directly. With two such heaters, one can raise sample temperatures uniformly, or with any desired gradient along the pressure axis while preserving optical access. In our continuing set of benchmark experiments, we use two newly created matching heater anvils with 500 μm culets to analyze the various fluorescence emission lines of ruby microspheres, which show more complicated behavior than traditional ruby chips. We also report on the temperature dependence of the high-pressure Raman modes of paracetamol (C8H9NO2) up to 20 GPa.

Process Research on Polycrystalline Silicon Material (PROPSM)

NASA Technical Reports Server (NTRS)

Culik, J. S.

1983-01-01

The performance limiting mechanisms in large grain (greater than 1-2 mm in diameter) polycrystalline silicon was investigated by measuring the illuminated current voltage (I-V) characteristics of the minicell wafer set. The average short circuit current on different wafers is 3 to 14 percent lower than that of single crystal Czochralski silicon. The scatter was typically less than 3 percent. The average open circuit voltage is 20 to 60 mV less than that of single crystal silicon. The scatter in the open circuit voltage of most of the polycrystalline silicon wafers was 15 to 20 mV, although two wafers had significantly greater scatter than this value. The fill factor of both polycrystalline and single crystal silicon cells was typically in the range of 60 to 70 percent; however several polycrystalline silicon wafers have fill factor averages which are somewhat lower and have a significantly larger degree of scatter.

Photovoltaic Cell Having A P-Type Polycrystalline Layer With Large Crystals

DOEpatents

Albright, Scot P.; Chamberlin, Rhodes R.

1996-03-26

A photovoltaic cell has an n-type polycrystalline layer and a p-type polycrystalline layer adjoining the n-type polycrystalline layer to form a photovoltaic junction. The p-type polycrystalline layer comprises a substantially planar layer portion having relatively large crystals adjoining the n-type polycrystalline layer. The planar layer portion includes oxidized impurities which contribute to obtainment of p-type electrical properties in the planar layer portion.

Surface structure of micro-diamond from ultrahigh-pressure felsic granulite, Bohemian Massif: AFM study of growth and resorption phenomena

NASA Astrophysics Data System (ADS)

Kotková, J.; Klapetek, P.

2012-04-01

Morphology, associated phases and retrogression phenomena of in-situ microdiamonds formed at extreme pressures in ultrahigh-pressure metamorphic terranes represent excellent tools to study character of diamond-forming media at great depths. Well-preserved microdiamonds discovered recently along with coesite in ultrahigh-pressure granulites of the north Bohemian crystalline basement, European Variscan belt (Kotková et al., 2011), provide unique material for such investigations. The diamonds are enclosed in major granulite phases, i.e. garnet both in felsic and intermediate lithologies and in kyanite in the felsic sample, as well as in zircon. Transmitted and reflected light microscopy of the felsic granulite sample, with peak mineral assemblage garnet, kyanite, feldspar and quartz, revealed presence of numerous, 5-20 μm-sized, perfectly preserved diamond crystals enclosed in kyanite grains. In contrast, diamonds within garnet are rare, can reach up to 30 μm in size, and graphite rims as well as polycrystalline graphite aggregates possibly representing complete diamond retrogression are common. We applied atomic force microscopy to study in-situ crystal morphology and surface microtopographic features, representing clues to the conditions and mechanisms of crystal formation as well as diamond resorption and retrogression. Both diamond enclosed in garnet and in kyanite of the felsic granulite occur exclusively as single crystals. The crystals have octahedral crystal shapes with straight but rounded edges and rounded corners. Concentric triangular terraces delimiting a flat triangular table on crystal scale and small micron-sized negatively oriented downward-pointing trigons developed on the octahedron crystal faces. Higher magnification reveals presence of discontinuous elongate hillocks oriented parallel to the octahedron face edge with positively oriented trigons. We suggest that the large-scale triangular terraces represent growth features. In contrast, the

Probing Growth-Induced Anisotropic Thermal Transport in High-Quality CVD Diamond Membranes by Multifrequency and Multiple-Spot-Size Time-Domain Thermoreflectance.

PubMed

Cheng, Zhe; Bougher, Thomas; Bai, Tingyu; Wang, Steven Y; Li, Chao; Yates, Luke; Foley, Brian M; Goorsky, Mark; Cola, Baratunde A; Faili, Firooz; Graham, Samuel

2018-02-07

understanding of thermal conductivity inhomogeneity in high-quality CVD polycrystalline diamond that is important for applications in the thermal management of high-power electronics.

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.

Absolute age Determinations on Diamond by Radioisotopic Methods: NOT the way to Accurately Identify Diamond Provenance

NASA Astrophysics Data System (ADS)

Shirey, S. B.

2002-05-01

Gem-quality diamond contains such low abundances of parent-daughter radionuclides that dating the diamond lattice directly by isotopic measurements has been and will be impossible. Absolute ages on diamonds typically are obtained through measurements of their syngenetic mineral inclusions: Rb-Sr in garnet; Sm-Nd in garnet and pyroxene; Re-Os and U-Th-Pb in sulfide; K-Ar in pyroxene; and U-Pb in zircon. The application of the first two isotope schemes in the list requires putting together many inclusions from many diamonds whereas the latter isotope schemes permit ages on single diamonds. The key limitations on the application of these decay pairs are the availability and size of the inclusions, the abundance levels of the radionuclides, and instrumental sensitivity. Practical complications of radioisotope dating of inclusions are fatal to the application of the technique for diamond provenance. In all mines, the ratio of gem-quality diamonds to stones with datable inclusions is very high. Thus there is no way to date the valuable, marketable stones that are part of the conflict diamond problem, just their rare, flawed cousins. Each analysis destroys the diamond host plus the inclusion and can only be carried out in research labs by highly trained scientists. Thus, these methods can not be automated or applied to the bulk of diamond production. The geological problems with age dating are equally fatal to its application to diamond provenance. From the geological perspective, for age determination to work as a tool for diamond provenance studies, diamond ages would have to be specific to particular kimberlites or kimberlite fields and different between fields. The southern African Kaapvaal-Zimbabwe Craton and Limpopo Mobile Belt is the only cratonic region where age determinations have been applied on a large enough scale to a number of kimberlites to illustrate the geological problems in age measurements for diamond provenance. However, this southern African example

Diamonds in an Archean greenstone belt: Diamond suites in unconventional rocks of Wawa, Northern Ontario (Canada)

NASA Astrophysics Data System (ADS)

Kopylova, Maya; Bruce, Loryn; Ryder, John

2010-05-01

Diamonds typically are found on Archean cratons entrained by younger Phanerozoic kimberlites. In contrast, Wawa diamonds are hosted in "unconventional", non-kimberlitic rocks that formed contemporaneously with the mafic and sedimentary rocks of the Archean Michipicoten Greenstone Belt (MGB). We studied two diamond suites that occur within the 2.9-2.7 Ga greenschist facies rocks of MGB located in the southwest portion of the Superior Craton (E. Canada). The first diamond suite henceforth referred to as the Wawa breccia diamonds (384 stones), are hosted in the 2618-2744 Ma calc-alkaline lamprophyres and volcaniclastic breccias, contemporaneous with pillow basalts and felsic volcanics of MGB. The second suite, the Wawa conglomerate diamonds (80 crystals), are hosted in the 2697-2700 Ma poorly sorted sedimentary polymictic conglomerate which is interpreted as a proximal alluvial fan debris flow in a fan-delta environment. The majority of the diamonds was found within the matrix of the conglomerate. The diamondiferous breccia occurs 20 km north of the town of Wawa, whereas the conglomerate is found 12 km northeast of Wawa. Diamonds from the 2 occurrences were characterized and described for provenance studies. Both the breccia and conglomerate diamonds show similar crystal habits, with the predominance of octahedral single crystals and ~ 10% of cubes. The conglomerate diamonds are significantly less resorbed (no resorbtion in 43% of the stones) than the breccia diamonds (8% non-resorbed stones). In both suites, only 21-24% show high degrees of resorption. The majority of crystals in both suites are colourless, with some yellow, brown and grey stones. Conglomerate diamonds had a wider variety of colours that were not seen in the breccia diamonds, including green and pink. The breccia diamonds contain 0-740 ppm N and show two modes of N aggregation at 0-30 and 60-95%. Among the breccia diamonds, Type IaA stones comprise 17%, whereas IaAB stones make up 49% of the

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

NASA Technical Reports Server (NTRS)

1990-01-01

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

Improvements in the Formation of Boron-Doped Diamond Coatings on Platinum Wires Using the Novel Nucleation Process (NNP)

PubMed Central

Fhaner, Mathew; Zhao, Hong; Bian, Xiaochun; Galligan, James J.; Swain, Greg M.

2010-01-01

In order to increase the initial nucleation density for the growth of boron-doped diamond on platinum wires, we employed the novel nucleation process (NNP) originally developed by Rotter et al. and discussed by others [1–3]. This pretreatment method involves (i) the initial formation of a thin carbon layer over the substrate followed by (ii) ultrasonic seeding of this “soft” carbon layer with nanoscale particles of diamond. This two-step pretreatment is followed by the deposition of boron-doped diamond by microwave plasma-assisted CVD. Both the diamond seed particles and sites on the carbon layer itself function as the initial nucleation zones for diamond growth from an H2-rich source gas mixture. We report herein on the characterization of the pre-growth carbon layer formed on Pt as well as boron-doped films grown for 2, 4 and 6 h post NNP pretreatment. Results from scanning electron microscopy, Raman spectroscopy and electrochemical studies are reported. The NNP method increases the initial nucleation density on Pt and leads to the formation of a continuous diamond film in a shorter deposition time than is typical for wires pretreated by conventional ultrasonic seeding. The results indicate that the pregrowth layer itself consists of nanoscopic domains of diamond and functions well to enhance the initial nucleation of diamond without any diamond powder seeding. PMID:21617759

Laser patterning of diamond films

NASA Astrophysics Data System (ADS)

Narayan, J.; Chen, X.

1992-04-01

Selective deposition and fine-scale patterning of hot filament deposited diamond films by the use of pulsed laser irradiation on silicon and copper substrates are reported. The substrates were abraded with diamond and alumina powders before hot-filament chemical vapor deposition. A drastic enhancement in diamond nucleation (using hot-filament chemical vapor deposition) was observed on specimens treated with diamond powder, whereas enhancement on specimens pretreated with alumina powder was relatively insignificant. It is found that the seeding of diamond crystals was substantially reduced by pulsed laser annealing/melting which removes the plastic damage as well as the seed crystals introduced by diamond powder pretreatment. The selective deposition or fine-scale patterning of diamond films was achieved either by a shadow masking or by scanning a focused laser beam to generate desired patterns. The nucleation can also be enhanced by laser deposition of thin films, such as diamond-like carbon and tungsten carbide (WC), and selective deposition and patterning achieved by controlled removal or deposition of the above films.

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, cleaved...

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, cleaved...

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 sawn...

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, cleaved...

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, cleaved...

Electrically conductive diamond electrodes

DOEpatents

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

2009-05-19

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

Diamonds in detonation soot

NASA Technical Reports Server (NTRS)

Greiner, N. Roy; Phillips, Dave; Johnson, J. D.; Volk, Fred

1990-01-01

Diamonds 4 to 7 nm in diameter have been identified and partially isolated from soot formed in detonations of carbon-forming composite explosives. The morphology of the soot has been examined by transmission electron microscopy (TEM), and the identity of the diamond has been established by the electron diffraction pattern of the TEM samples and by the X-ray diffraction (XRD) pattern of the isolated solid. Graphite is also present in the form of ribbons of turbostatic structure with a thickness of 2 to 4 nm. A fraction, about 25 percent of the soot by weight, was recovered from the crude soot after oxidation of the graphite with fuming perchloric acid. This fraction showed a distinct XRD pattern of diamond and the diffuse band of amorphous carbon. The IR spectrum of these diamonds closely matches that of diamonds recovered from meteorites (Lewis et al., 1987), perhaps indicating similar surface properties after the oxidation. If these diamonds are produced in the detonation itself or during the initial expansion, they exhibit a phenomenal crystal growth rate (5 nm/0.00001 s equal 1.8 m/hr) in a medium with a very low hydrogen/carbon ratio. Because the diamonds will be carried along with the expanding gases, they will be accelerated to velocities approaching 8 km/s.

Ion Microscopy on Diamond

NASA Astrophysics Data System (ADS)

Manfredotti, Claudio

Because of its physical properties (strong radiation hardness, wide energy gap with a consequent extremely low dark current, very large electron and hole mobility) diamond is a very good candidate for nuclear particle detection, particularly in harsh environments or in conditions of strong radiation damage. Being commonly polycrystalline, diamond samples obtained by chemical vapour deposition (CVD) are not homogeneous, not only from the morphological point of view, but also from the electronic one. As a consequence, as it was indicated quite early starting from 1995, charge collection properties such as charge collection efficiency (cce) are not uniform, but they are depending on the site hit by incoming particle. Moreover, these properties are influenced by previous irradiations which are used in order to improve them and, finally, they are also dependent on the thickness of the sample, since the electronic non uniformity extends also in depth by affecting the profile of the electrical field from top to bottom electrode of the nuclear detector in the standard "sandwich" arrangement. By the use of focussed ion beams, it is possible to investigate these non uniformities by the aid of techniques like IBIC (Ion Beam Induced Charge) and IBIL (Ion Beam Induced Luminescence) with a space resolution of the order of 1 m. This relatively new kind of microscopy, which is called "ion microscopy", is capable not only to give 2D maps of cce, which can be quite precisely compared with morphological images obtained by Scanning Electron Microscopy (generally the grains display a much better cce than intergrain regions), but also to give the electric field profile from one electrode to the other one in a "lateral" arrangement of the ion beam. IBIL, by supplying 2D maps of luminescence intensity at different wavelength, can give information about the presence of specific radiative recombination centers and their distribution in the material. Finally, a new technique called XBIC (X

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.

Developments in FTIR spectroscopy of diamonds and better constraints on diamond thermal histories

NASA Astrophysics Data System (ADS)

Kohn, Simon; Speich, Laura; Smith, Christopher; Bulanova, Galina

2017-04-01

Fourier Transform Infrared (FTIR) spectroscopy is a commonly-used technique for investigating diamonds. It gives the most useful information if spatially-resolved measurements are used [1]. In this contribution we discuss the best way to acquire and present FTIR data from diamonds, using examples from Murowa (Zimbabwe), Argyle (Australia) and Machado River (Brazil). Examples of FTIR core-to-rim line scans, maps with high spatial resolution and maps with high spectral resolution that are fitted to extract the spatial variation of different nitrogen and hydrogen defects are presented. Model mantle residence temperatures are calculated from the concentration of A and B nitrogen-containing defects in the diamonds using known times of annealing in the mantle. A new, two-stage thermal annealing model is presented that better constrains the thermal history of the diamond and that of the mantle lithosphere in which the diamond resided. The effect of heterogeneity within the analysed FTIR volume is quantitatively assessed and errors in model temperatures that can be introduced by studying whole diamonds instead of thin plates are discussed. The kinetics of platelet growth and degradation will be discussed and the potential for two separate, kinetically-controlled defect reactions to be used to constrain a full thermal history of the diamond will be assessed. [1] Kohn, S.C., Speich, L., Smith, C.B. and Bulanova, G.P., 2016. FTIR thermochronometry of natural diamonds: A closer look. Lithos, 265, pp.148-158.

Robust superhydrophobic diamond microspheres for no-loss transport of corrosive liquid microdroplets.

PubMed

Wang, Qiang; Bai, Jie; Dai, Bing; Yang, Zhenhuai; Guo, Shuai; Yang, Lei; He, Yurong; Han, Jiecai; Zhu, Jiaqi

2017-02-16

Superhydrophobic surfaces usually lose their characteristics when exposed to a corrosive environment. To solve this issue, we synthesized superhydrophobic diamond microspheres by microwave-plasma-assisted chemical vapor deposition. Commercial epoxy glue was used to bond the microspheres to various substrates. The thus-synthesized composite films exhibited robust superhydrophobicity and an ultrahigh adhesive force.

Effect of added dispersants on diamond particles in Ni-diamond composites fabricated with electrodeposition

NASA Astrophysics Data System (ADS)

Choi, Yongje; Kim, Donghyun; Son, Kyungsik; Lee, Sanghyuk; Chung, Wonsub

2015-11-01

The electrodeposition of Ni-diamond composites was investigated to improve the dispersion and adhesion of the diamond particles, and thus, increase the performance of cutting tools. The additives, so called firstclass brighteners, benzoic sulfimide, benzene sulfonamide, and benzene sulfonic acid were used as dispersants to enhance the dispersivity of diamond particles. The dispersivity was analyzed with Image-Pro software, which was used to asses optical microscopy images, and the number of individual diamond particles and area fraction were calculated. In addition, electrochemical tests were performed, including zeta potential and galvanostatic measurements, and the adhesion strengths was tested by evaluating the wear resistance using ball-on-disk tester. The dispersion and adhesion of the diamond particles were improved when benzoic sulfimide was added to the composite plating bath at a concentration of 0.06 g/L. The number of individual diamond particles was 56 EA/mm2, and the weight loss of alumina ball and specimen was 2.88 mg and 0.80 mg, respectively.

Radiation damage in the diamond based beam condition monitors of the CMS experiment at the Large Hadron Collider (LHC) at CERN

NASA Astrophysics Data System (ADS)

Guthoff, Moritz; Afanaciev, Konstantin; Dabrowski, Anne; de Boer, Wim; Lange, Wolfgang; Lohmann, Wolfgang; Stickland, David

2013-12-01

The Beam Condition Monitor (BCM) of the CMS detector at the LHC is a protection device similar to the LHC Beam Loss Monitor system. While the electronics used is the same, poly-crystalline Chemical Vapor Deposition (pCVD) diamonds are used instead of ionization chambers as the BCM sensor material. The main purpose of the system is the protection of the silicon Pixel and Strip tracking detectors by inducing a beam dump, if the beam losses are too high in the CMS detector. By comparing the detector current with the instantaneous luminosity, the BCM detector efficiency can be monitored. The number of radiation-induced defects in the diamond, reduces the charge collection distance, and hence lowers the signal. The number of these induced defects can be simulated using the FLUKA Monte Carlo simulation. The cross-section for creating defects increases with decreasing energies of the impinging particles. This explains, why diamond sensors mounted close to heavy calorimeters experience more radiation damage, because of the high number of low energy neutrons in these regions. The signal decrease was stronger than expected from the number of simulated defects. Here polarization from trapped charge carriers in the defects is a likely candidate for explaining the difference, as suggested by Transient Current Technique (TCT) measurements. A single-crystalline (sCVD) diamond sensor shows a faster relative signal decrease than a pCVD sensor mounted at the same location. This is expected, since the relative increase in the number of defects is larger in sCVD than in pCVD sensors.

Near-field acoustical holography of military jet aircraft noise

NASA Astrophysics Data System (ADS)

Wall, Alan T.; Gee, Kent L.; Neilsen, Tracianne; Krueger, David W.; Sommerfeldt, Scott D.; James, Michael M.

2010-10-01

Noise radiated from high-performance military jet aircraft poses a hearing-loss risk to personnel. Accurate characterization of jet noise can assist in noise prediction and noise reduction techniques. In this work, sound pressure measurements were made in the near field of an F-22 Raptor. With more than 6000 measurement points, this is the most extensive near-field measurement of a high-performance jet to date. A technique called near-field acoustical holography has been used to propagate the complex pressure from a two- dimensional plane to a three-dimensional region in the jet vicinity. Results will be shown and what they reveal about jet noise characteristics will be discussed.

Nanocrystalline diamond micro-anvil grown on single crystal diamond as a generator of ultra-high pressures

DOE PAGES

Samudrala, Gopi K.; Moore, Samuel L.; Velisavljevic, Nenad; ...

2016-09-29

By combining mask-less lithography and chemical vapor deposition (CVD) techniques, a novel two-stage diamond anvil has been fabricated. A nanocrystalline diamond (NCD) micro-anvil 30 μm in diameter was grown at the center of a [100]-oriented, diamond anvil by utilizing microwave plasma CVD method. The NCD micro-anvil has a diamond grain size of 115 nm and micro-focused Raman and X-ray Photoelectron spectroscopy analysis indicate sp3-bonded diamond content of 72%. Lastly, these CVD grown NCD micro-anvils were tested in an opposed anvil configuration and the transition metals osmium and tungsten were compressed to high pressures of 264 GPa in a diamond anvilmore » cell.« less

APPLICATION OF JET REMPI AND LIBS TO AIR TOXIC MONITORING

EPA Science Inventory

The paper discusses three advanced, laser-based monitoring techniques that the EPA is assisting in developing for real time measurement of toxic aerosol compounds. One of the three techniques is jet resonance enhanced multiphoton ionization (Jet REMPI) coupled with a time-of-flig...

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)

Process for utilizing low-cost graphite substrates for polycrystalline solar cells

NASA Technical Reports Server (NTRS)

Chu, T. L. (Inventor)

1978-01-01

Low cost polycrystalline silicon solar cells supported on substrates were prepared by depositing successive layers of polycrystalline silicon containing appropriate dopants over supporting substrates of a member selected from the group consisting of metallurgical grade polycrystalline silicon, graphite and steel coated with a diffusion barrier of silica, borosilicate, phosphosilicate, or mixtures thereof such that p-n junction devices were formed which effectively convert solar energy to electrical energy. To improve the conversion efficiency of the polycrystalline silicon solar cells, the crystallite size in the silicon was substantially increased by melting and solidifying a base layer of polycrystalline silicon before depositing the layers which form the p-n junction.

In situ observation of quasimelting of diamond and reversible graphite-diamond phase transformations.

PubMed

Huang, J Y

2007-08-01

Because of technique difficulties in achieving the extreme high-pressure and high-temperature (HPHT) simultaneously, direct observation of the structures of carbon at extreme HPHT conditions has not been possible. Banhart and Ajayan discovered remarkably that carbon onions can act as nanoscopic pressure cells to generate high pressures. By heating carbon onions to approximately 700 degrees C and under electron beam irradiation, the graphite-to-diamond transformation was observed in situ by transmission electron microscopy (TEM). However, the highest achievable temperature in a TEM heating holder is less than 1000 degrees C. Here we report that, by using carbon nanotubes as heaters and carbon onions as high-pressure cells, temperatures higher than 2000 degrees C and pressures higher than 40 GPa were achieved simultaneously in carbon onions. At such HPHT conditions and facilitated by electron beam irradiation, the diamond formed in the carbon onion cores frequently changed its shape, size, orientation, and internal structure and moved like a fluid, implying that it was in a quasimelting state. The fluctuation between the solid phase of diamond and the fluid/amorphous phase of diamond-like carbon, and the changes of the shape, size, and orientation of the solid diamond, were attributed to the dynamic crystallization of diamond crystal from the quasimolten state and the dynamic graphite-diamond phase transformations. Our discovery offers unprecedented opportunities to studying the nanostructures of carbon at extreme conditions in situ and at an atomic scale.

Fabrication of diamond shells

DOEpatents

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

2016-11-01

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

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.

Superconductivity in CVD diamond films.

PubMed

Takano, Yoshihiko

2009-06-24

A beautiful jewel of diamond is insulator. However, boron doping can induce semiconductive, metallic and superconducting properties in diamond. When the boron concentration is tuned over 3 × 10(20) cm(-3), diamonds enter the metallic region and show superconductivity at low temperatures. The metal-insulator transition and superconductivity are analyzed using ARPES, XAS, NMR, IXS, transport and magnetic measurements and so on. This review elucidates the physical properties and mechanism of diamond superconductor as a special superconductivity that occurs in semiconductors.

Diamond Pixel Detectors

NASA Astrophysics Data System (ADS)

Adam, W.; Berdermann, E.; Bergonzo, P.; Bertuccio, G.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; D'Angelo, P.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Doroshenko, J.; Dulinski, W.; van Eijk, B.; Fallou, A.; Fizzotti, F.; Foster, J.; Foulon, F.; Friedl, M.; Gan, K. K.; Gheeraert, E.; Gobbi, B.; Grim, G. P.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Kass, R.; Koeth, T.; Krammer, M.; Lander, R.; Logiudice, A.; Lu, R.; mac Lynne, L.; Manfredotti, C.; Meier, D.; Mishina, M.; Moroni, L.; Oh, A.; Pan, L. S.; Pernicka, M.; Perera, L.; Pirollo, S.; Plano, R.; Procario, M.; Riester, J. L.; Roe, S.; Rott, C.; Rousseau, L.; Rudge, A.; Russ, J.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R. J.; Tesarek, R.; Trischuk, W.; Tromson, D.; Vittone, E.; Wedenig, R.; Weilhammer, P.; White, C.; Zeuner, W.; Zoeller, M.

2001-06-01

Diamond based pixel detectors are a promising radiation-hard technology for use at the LHC. We present first results on a CMS diamond pixel sensor. With a threshold setting of 2000 electrons, an average pixel efficiency of 78% was obtained for normally incident minimum ionizing particles.

Ultraprecision finishing of micro-aspherical surface by ultrasonic assisted polishing; Technical Digest

NASA Astrophysics Data System (ADS)

Suzuki, Hirofumi; Kawamori, Ryota; Yamamoto, Yuji; Miyabara, Mitsuru; Okino, Tadashi; Hijikata, Yoshio; Moriwaki, Toshimichi

2005-05-01

Micro aspherical glass lenses are required for electronic devices, optical devices and advanced optical fiber transmission equipments. The glass lenses are manufactured by glass molding method by using micro ceramics dies such as tungsten carbide or silicon carbide (1). Therefore molding dies are most important and they were ground by ultra-precision grinding method with diamond wheel. Recently, the wavelength of used laser is becoming shorter and then the accuracies of the micro molding die are required to be much more precise (2). In this paper, ultrasonic assisted polishing methods/systems were developed in order to finish micro aspherical dies that were ground with micro diamond wheel. In the polishing experiments, the molding die of tungsten carbide was polished with diamond abrasives to test the basic polishing characteristics and the aspheric die was polished with proposed ultrasonic assisted polishing method.

Magnetic Fields Sculpt Narrow Jets From Dying Star

NASA Astrophysics Data System (ADS)

2006-03-01

Molecules spewed outward from a dying star are confined into narrow jets by a tightly-wound magnetic field, according to astronomers who used the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope to study an old star about 8,500 light-years from Earth. Magnetic Field Around Jet Artist's Conception Shows Tightly-Wound Magnetic Field Confining Jet CREDIT: NRAO/AUI/NSF (Click on image for larger version) The star, called W43A, in the constellation Aquila, is in the process of forming a planetary nebula, a shell of brightly-glowing gas lit by the hot ember into which the star will collapse. In 2002, astronomers discovered that the aging star was ejecting twin jets of water molecules. That discovery was a breakthrough in understanding how many planetary nebulae are formed into elongated shapes. "The next question was, what is keeping this outpouring of material confined into narrow jets? Theoreticians suspected magnetic fields, and we now have found the first direct evidence that a magnetic field is confining such a jet," said Wouter Vlemmings, a Marie Curie Fellow working at the Jodrell Bank Observatory of the University of Manchester in England. "Magnetic fields previously have been detected in jets emitted by quasars and protostars, but the evidence was not conclusive that the magnetic fields were actually confining the jets. These new VLBA observations now make that direct connection for the very first time," Vlemmings added. By using the VLBA to study the alignment, or polarization, of radio waves emitted by water molecules in the jets, the scientists were able to determine the strength and orientation of the magnetic field surrounding the jets. "Our observations support recent theoretical models in which magnetically-confined jets produce the sometimes-complex shapes we see in planetary nebulae," said Philip Diamond, also of Jodrell Bank Observatory. During their "normal" lives, stars similar to our Sun are powered by the nuclear fusion

Metal films on the surfaces and within diamond crystals from Arkhangelskaya and Yakutian diamond provinces

NASA Astrophysics Data System (ADS)

Makeev, A. B.; Kriulina, G. Yu.

2012-12-01

Representative samples of diamonds from five kimberlite pipes (Lomonosovskaya, Archangel'sk, Snegurochka, XXIII Congress of the Communist Party of the Soviet Union (CPSU), and Internationalnaya) of the Arkhangelskaya and Yakutian diamond provinces in Russia have been studied. Thirty-three varieties of metal films have been identified as syngenetic associated minerals. The films consist of 15 chemical elements that occur in the form of native metals and their natural alloys. Remnants of metal films were detected within diamond crystals. The metal films coating diamonds are a worldwide phenomenon. To date, these films have been described from Europe, Asia, South America, and Africa. Native metals, their alloys, and intermetallides are actual companion minerals of diamond.

Quantum Computing in Diamond

DTIC Science & Technology

2007-05-28

104 N2 103 N2 (a) (b) (c) Fig. 1: Confocal microscope images of NV centers created in bulk diamond through ion implantation of (a) gallium ions...nitrogen defects in diamond by chemical vapour deposition, J. R. Rabeau, S. Prawer, Y.L. Chin, F. Jelezko, T. Gaebel, and J. Wrachtrup, Applied...Physics Letters, 86, 31926, (2005) 2. Diamond Chemical Vapour Deposition on Opitcal Fibres for Fluorescence Waveguiding, J.R. Rabeau, S.T

Interrogation of Cellular Innate Immunity by Diamond-Nanoneedle-Assisted Intracellular Molecular Fishing.

PubMed

Wang, Zixun; Yang, Yang; Xu, Zhen; Wang, Ying; Zhang, Wenjun; Shi, Peng

2015-10-14

Understanding intracellular signaling cascades and network is one of the core topics in modern biology. Novel tools based on nanotechnologies have enabled probing and analyzing intracellular signaling with unprecedented sensitivity and specificity. In this study, we developed a minimally invasive method for in situ probing specific signaling components of cellular innate immunity in living cells. The technique was based on diamond-nanoneedle arrays functionalized with aptamer-based molecular sensors, which were inserted into cytoplasmic domain using a centrifugation controlled process to capture molecular targets. Simultaneously, these diamond-nanoneedles also facilitated the delivery of double-strand DNAs (dsDNA90) into cells to activate the pathway involving the stimulator of interferon genes (STING). We showed that the nanoneedle-based biosensors can be successfully utilized to isolate transcriptional factor, NF-κB, from intracellular regions without damaging the cells, upon STING activation. By using a reversible protocol and repeated probing in living cells, we were able to examine the singling dynamics of NF-κB, which was quickly translocated from cytoplasm to nucleus region within ∼40 min of intracellular introduction of dsDNA90 for both A549 and neuron cells. These results demonstrated a novel and versatile tool for targeted in situ dissection of intracellular signaling, providing the potential to resolve new sights into various cellular processes.

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

NASA Astrophysics Data System (ADS)

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

2016-11-01

Diamonds in alluvial deposits in Southeast Asia are not accompanied by indicator minerals suggesting primary kimberlite or lamproite sources. The Meratus Mountains in Southeast Borneo (Province Kalimantan Selatan, Indonesia) provide the largest known deposit of these so-called "headless" diamond deposits. Proposals for the origin of Kalimantan diamonds include the adjacent Meratus ophiolite complex, ultra-high pressure (UHP) metamorphic terranes, obducted subcontinental lithospheric mantle and undiscovered kimberlite-type sources. Here we report results from detailed sediment provenance analysis of diamond-bearing Quaternary river channel material and from representative outcrops of the oldest known formations within the Alino Group, including the diamond-bearing Campanian-Maastrichtian Manunggul Formation. Optical examination of surfaces of diamonds collected from artisanal miners in the Meratus area (247 stones) and in West Borneo (Sanggau Area, Province Kalimantan Barat; 85 stones) points toward a classical kimberlite-type source for the majority of these diamonds. Some of the diamonds host mineral inclusions suitable for deep single-crystal X-ray diffraction investigation. We determined the depth of formation of two olivines, one coesite and one peridotitic garnet inclusion. Pressure of formation estimates for the peridotitic garnet at independently derived temperatures of 930-1250 °C are between 4.8 and 6.0 GPa. Sediment provenance analysis includes petrography coupled to analyses of detrital garnet and glaucophane. The compositions of these key minerals do not indicate kimberlite-derived material. By analyzing almost 1400 zircons for trace element concentrations with laser ablation ICP-MS (LA-ICP-MS) we tested the mineral's potential as an alternative kimberlite indicator. The screening ultimately resulted in a small subset of ten zircons with a kimberlitic affinity. Subsequent U-Pb dating resulting in Cretaceous ages plus a detailed chemical reflection make

Process Research of Polycrystalline Silicon Material (PROPSM)

NASA Technical Reports Server (NTRS)

Culik, J. S.

1984-01-01

A passivation process (hydrogenation) that will improve the power generation of solar cells fabricated from presently produced, large grain, cast polycrystalline silicon (Semix), a potentially low cost material are developed. The first objective is to verify the operation of a DC plasma hydrogenation system and to investigate the effect of hydrogen on the electrical performance of a variety of polycrystalline silicon solar cells. The second objective is to parameterize and optimize a hydrogenation process for cast polycrystalline silicon, and will include a process sensitivity analysis. The sample preparation for the first phase is outlined. The hydrogenation system is described, and some early results that were obtained using the hydrogenation system without a plasma are summarized. Light beam induced current (LBIC) measurements of minicell samples, and their correlation to dark current voltage characteristics, are discussed.

Method for microwave plasma assisted supersonic gas jet deposition of thin films

DOEpatents

Schmitt, J.J. III; Halpern, B.L.

1994-10-18

A thin film is formed on a substrate positioned in a vacuum chamber by use of a gas jet apparatus affixed to a vacuum chamber port and having an outer nozzle with an interior cavity into which carrier gas is fed, an inner nozzle located within the outer nozzle interior cavity into which reactant gas is introduced, a tip of the inner nozzle being recessed from the vacuum chamber port within the outer nozzle interior cavity, and a microwave discharge device configured about the apparatus for generating a discharge in the carrier gas and reactant gas only in a portion of the outer nozzle interior cavity extending from approximately the inner nozzle tip towards the vacuum chamber. A supersonic free jet of carrier gas transports vapor species generated in the microwave discharge to the surface of the substrate to form a thin film on the substrate. The substrate can be translated from the supersonic jet to a second supersonic jet in less time than needed to complete film formation so that the film is chemically composed of chemical reaction products of vapor species in the jets. 5 figs.

Method for microwave plasma assisted supersonic gas jet deposition of thin films

DOEpatents

Schmitt, III, Jerome J.; Halpern, Bret L.

1994-01-01

A thin film is formed on a substrate positioned in a vacuum chamber by use of a gas jet apparatus affixed to a vacuum chamber port and having an outer nozzle with an interior cavity into which carrier gas is fed, an inner nozzle located within the outer nozzle interior cavity into which reactant gas is introduced, a tip of the inner nozzle being recessed from the vacuum chamber port within the outer nozzle interior cavity, and a microwave discharge device configured about the apparatus for generating a discharge in the carrier gas and reactant gas only in a portion of the outer nozzle interior cavity extending from approximately the inner nozzle tip towards the vacuum chamber. A supersonic free jet of carrier gas transports vapor species generated in the microwave discharge to the surface of the substrate to form a thin film on the substrate. The substrate can be translated from the supersonic jet to a second supersonic jet in less time than needed to complete film formation so that the film is chemically composed of chemical reaction products of vapor species in the jets.

Atomistic modeling of mechanical properties of polycrystalline graphene.

PubMed

Mortazavi, Bohayra; Cuniberti, Gianaurelio

2014-05-30

We performed molecular dynamics (MD) simulations to investigate the mechanical properties of polycrystalline graphene. By constructing molecular models of ultra-fine-grained graphene structures, we studied the effect of different grain sizes of 1-10 nm on the mechanical response of graphene. We found that the elastic modulus and tensile strength of polycrystalline graphene decrease with decreasing grain size. The calculated mechanical proprieties for pristine and polycrystalline graphene sheets are found to be in agreement with experimental results in the literature. Our MD results suggest that the ultra-fine-grained graphene structures can show ultrahigh tensile strength and elastic modulus values that are very close to those of pristine graphene sheets.

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.

Ultrananocrystalline diamond contacts for electronic devices

DOEpatents

Sumant, Anirudha V.; Smedley, John; Muller, Erik

2016-11-01

A method of forming electrical contacts on a diamond substrate comprises producing a plasma ball using a microwave plasma source in the presence of a mixture of gases. The mixture of gases include a source of a p-type or an n-type dopant. The plasma ball is disposed at a first distance from the diamond substrate. The diamond substrate is maintained at a first temperature. The plasma ball is maintained at the first distance from the diamond substrate for a first time, and a UNCD film, which is doped with at least one of a p-type dopant and an n-type dopant, is disposed on the diamond substrate. The doped UNCD film is patterned to define UNCD electrical contacts on the diamond substrate.

Ultrananocrystalline diamond contacts for electronic devices

DOEpatents

Sumant, Anirudha V.; Smedley, John; Muller, Erik

2017-12-12

A method of forming electrical contacts on a diamond substrate comprises producing a plasma ball using a microwave plasma source in the presence of a mixture of gases. The mixture of gases include a source of a p-type or an n-type dopant. The plasma ball is disposed at a first distance from the diamond substrate. The diamond substrate is maintained at a first temperature. The plasma ball is maintained at the first distance from the diamond substrate for a first time, and a UNCD film, which is doped with at least one of a p-type dopant and an n-type dopant, is disposed on the diamond substrate. The doped UNCD film is patterned to define UNCD electrical contacts on the diamond substrate.

Microplasma device architectures with various diamond nanostructures

NASA Astrophysics Data System (ADS)

Kunuku, Srinivasu; Jothiramalingam Sankaran, Kamatchi; Leou, Keh-Chyang; Lin, I.-Nan

2017-02-01

Diamond nanostructures (DNSs) were fabricated from three different morphological diamonds, microcrystalline diamond (MCD), nanocrystalline diamond (NCD), and ultrananocrystalline diamond (UNCD) films, using a reactive ion etching method. The plasma illumination (PI) behavior of microplasma devices using the DNSs and the diamond films as cathode were investigated. The Paschen curve approach revealed that the secondary electron emission coefficient (γ value) of diamond materials is similar irrespective of the microstructure (MCD, NCD, and UNCD) and geometry of the materials (DNSs and diamond films). The diamond materials show markedly larger γ-coefficient than conventional metallic cathode materials such as Mo that resulted in markedly better PI behavior for the corresponding microplasma devices. Moreover, the PI behavior, i.e. the voltage dependence of plasma current density (J pl-V), plasma density (n e-V), and the robustness of the devices, varied markedly with the microstructure and geometry of the cathode materials that was closely correlated to the electron field emission (EFE) properties of the cathode materials. The UNCD nanopillars, possessing good EFE properties, resulted in superior PI behavior, whereas the MCD diamond films with insufficient EFE properties led to inferior PI behavior. Consequently, enhancement of plasma characteristics is the collective effects of EFE behavior and secondary electron emission characteristics of diamond-based cathode materials.

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

Properties of Diamond and Diamond-Like Clusters in Nanometric Dimensions

NASA Technical Reports Server (NTRS)

Halicioglu, Timur; Langhoff, Stephen R. (Technical Monitor)

1996-01-01

Variations in materials properties of small clusters of nanometric dimensions were investigated. Investigations were carried out for diamond and diamond-like particles in spherical shapes. Calculations were performed for clusters containing over 1000 carbon atoms. Results indicate that as the cluster size diminishes, (i) the average cohesive energy becomes weaker, (ii) the excess surface energy increases, and (iii) the value for stiffness decreases.

Characterization of a low pressure supersonic plasma jet

NASA Astrophysics Data System (ADS)

Caldirola, S.; Barni, R.; Riccardi, C.

2014-11-01

Plasma assisted supersonic jet deposition (PA-SJD) is a technique which combines a inductively coupled plasma (ICP) with a supersonic jet for the fabrication of thin films having a desired morphology. A reactive argon-oxygen plasma is employed to dissociate an organic precursor (titanium tetra-isopropoxide for TiO2 thin films) in a first vacuum chamber which is connected through a nozzle to a lower pressure chamber. The pressure difference produces a supersonic jet, seeded with nanoparticles. Along the jet the nucleation and aggregation of nanoparticles can be controlled to obtain nanostructured depositions. We report here the results of an analysis performed with a quadrupole mass spectrometer (QMS) which was used to sample neutrals and ions from the jet at different positions along the centerline of the supersonic expansion.

Single crystal diamond membranes for nanoelectronics.

PubMed

Bray, Kerem; Kato, Hiromitsu; Previdi, Rodolfo; Sandstrom, Russell; Ganesan, Kumaravelu; Ogura, Masahiko; Makino, Toshiharu; Yamasaki, Satoshi; Magyar, Andrew P; Toth, Milos; Aharonovich, Igor

2018-02-22

Single crystal, nanoscale diamond membranes are highly sought after for a variety of applications including nanophotonics, nanoelectronics and quantum information science. However, so far, the availability of conductive diamond membranes has remained an unreachable goal. In this work we present a complete nanofabrication methodology for engineering high aspect ratio, electrically active single crystal diamond membranes. The membranes have large lateral directions, exceeding ∼500 × 500 μm 2 and are only several hundreds of nanometers thick. We further realize vertical single crystal p-n junctions made from the diamond membranes that exhibit onset voltages of ∼10 V and a current of several mA. Moreover, we deterministically introduce optically active color centers into the membranes, and demonstrate for the first time a single crystal nanoscale diamond LED. The robust and scalable approach to engineer the electrically active single crystal diamond membranes offers new pathways for advanced nanophotonic, nanoelectronic and optomechanical devices employing diamond.

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.

Mono or polycrystalline alumina-modified hybrid ceramics.

PubMed

Kaizer, Marina R; Gonçalves, Ana Paula R; Soares, Priscilla B F; Zhang, Yu; Cesar, Paulo F; Cava, Sergio S; Moraes, Rafael R

2016-03-01

This study evaluated the effect of addition of alumina particles (polycrystalline or monocrystalline), with or without silica coating, on the optical and mechanical properties of a porcelain. Groups tested were: control (C), polycrystalline alumina (PA), polycrystalline alumina-silica (PAS), monocrystalline alumina (MA), monocrystalline alumina-silica (MAS). Polycrystalline alumina powder was synthesized using a polymeric precursor method; a commercially available monocrystalline alumina powder (sapphire) was acquired. Silica coating was obtained by immersing alumina powders in a tetraethylorthosilicate solution, followed by heat-treatment. Electrostatic stable suspension method was used to ensure homogenous dispersion of the alumina particles within the porcelain powder. The ceramic specimens were obtained by heat-pressing. Microstructure, translucency parameter, contrast ratio, opalescence index, porosity, biaxial flexural strength, roughness, and elastic constants were characterized. A better interaction between glass matrix and silica coated crystalline particles is suggested in some analyses, yet further investigation is needed to confirm it. The materials did not present significant differences in biaxial flexural strength, due to the presence of higher porosity in the groups with alumina addition. Elastic modulus was higher for MA and MAS groups. Also, these were the groups with optical qualities and roughness closer to control. The PA and PAS groups were considerably more opaque as well as rougher. Porcelains with addition of monocrystalline particles presented superior esthetic qualities compared to those with polycrystalline particles. In order to eliminate the porosity in the ceramic materials investigated herein, processing parameters need to be optimized as well as different glass frites should be tested. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Amorphous-diamond electron emitter

DOEpatents

Falabella, Steven

2001-01-01

An electron emitter comprising a textured silicon wafer overcoated with a thin (200 .ANG.) layer of nitrogen-doped, amorphous-diamond (a:D-N), which lowers the field below 20 volts/micrometer have been demonstrated using this emitter compared to uncoated or diamond coated emitters wherein the emission is at fields of nearly 60 volts/micrometer. The silicon/nitrogen-doped, amorphous-diamond (Si/a:D-N) emitter may be produced by overcoating a textured silicon wafer with amorphous-diamond (a:D) in a nitrogen atmosphere using a filtered cathodic-arc system. The enhanced performance of the Si/a:D-N emitter lowers the voltages required to the point where field-emission displays are practical. Thus, this emitter can be used, for example, in flat-panel emission displays (FEDs), and cold-cathode vacuum electronics.

46 CFR 45.33 - Diamond.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Diamond. 45.33 Section 45.33 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Load Line Marks § 45.33 Diamond. (a) Each vessel must be marked with the diamond mark described in figure 2 of § 45.35 amidships below...

46 CFR 45.33 - Diamond.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Diamond. 45.33 Section 45.33 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Load Line Marks § 45.33 Diamond. (a) Each vessel must be marked with the diamond mark described in figure 2 of § 45.35 amidships below...

46 CFR 45.33 - Diamond.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Diamond. 45.33 Section 45.33 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Load Line Marks § 45.33 Diamond. (a) Each vessel must be marked with the diamond mark described in figure 2 of § 45.35 amidships below...

46 CFR 45.33 - Diamond.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Diamond. 45.33 Section 45.33 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Load Line Marks § 45.33 Diamond. (a) Each vessel must be marked with the diamond mark described in figure 2 of § 45.35 amidships below...

46 CFR 45.33 - Diamond.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Diamond. 45.33 Section 45.33 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Load Line Marks § 45.33 Diamond. (a) Each vessel must be marked with the diamond mark described in figure 2 of § 45.35 amidships below...

Surface properties of atomically flat poly-crystalline SrTiO3

PubMed Central

Woo, Sungmin; Jeong, Hoidong; Lee, Sang A.; Seo, Hosung; Lacotte, Morgane; David, Adrian; Kim, Hyun You; Prellier, Wilfrid; Kim, Yunseok; Choi, Woo Seok

2015-01-01

Comparison between single- and the poly-crystalline structures provides essential information on the role of long-range translational symmetry and grain boundaries. In particular, by comparing single- and poly-crystalline transition metal oxides (TMOs), one can study intriguing physical phenomena such as electronic and ionic conduction at the grain boundaries, phonon propagation, and various domain properties. In order to make an accurate comparison, however, both single- and poly-crystalline samples should have the same quality, e.g., stoichiometry, crystallinity, thickness, etc. Here, by studying the surface properties of atomically flat poly-crystalline SrTiO3 (STO), we propose an approach to simultaneously fabricate both single- and poly-crystalline epitaxial TMO thin films on STO substrates. In order to grow TMOs epitaxially with atomic precision, an atomically flat, single-terminated surface of the substrate is a prerequisite. We first examined (100), (110), and (111) oriented single-crystalline STO surfaces, which required different annealing conditions to achieve atomically flat surfaces, depending on the surface energy. A poly-crystalline STO surface was then prepared at the optimum condition for which all the domains with different crystallographic orientations could be successfully flattened. Based on our atomically flat poly-crystalline STO substrates, we envision expansion of the studies regarding the TMO domains and grain boundaries. PMID:25744275

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.

Polycrystalline Superconducting Thin Films: Texture Control and Critical Current Density

NASA Astrophysics Data System (ADS)

Yang, Feng

1995-01-01

The growth processes of polycrystalline rm YBa_2CU_3O_{7-X} (YBCO) and yttria-stabilized-zirconia (YSZ) thin films have been developed. The effectiveness of YSZ buffer layers on suppression of the reaction between YBCO thin films and metallic substrates was carefully studied. Grown on the chemically inert surfaces of YSZ buffer layers, YBCO thin films possessed good quality of c-axis alignment with the c axis parallel to the substrate normal, but without any preferred in-plane orientations. This leads to the existence of a large percentage of the high-angle grain boundaries in the YBCO films. The critical current densities (rm J_{c}'s) found in these films were much lower than those in single crystal YBCO thin films, which was the consequence of the weak -link effect of the high-angle grain boundaries in these films. It became clear that the in-plane alignment is vital for achieving high rm J_{c }s in polycrystalline YBCO thin films. To induce the in-plane alignment, ion beam-assisted deposition (IBAD) technique was integrated into the conventional pulsed laser deposition process for the growth of the YSZ buffer layers. It was demonstrated that using IBAD the in-plane orientations of the YSZ grains could be controlled within a certain range of a common direction. This ion -bombardment induced in-plane texturing was explained using the anisotropic sputtering yield theory. Our observations and analyses have provided valuable information on the optimization of the IBAD process, and shed light on the texturing mechanism in YSZ. With the in-plane aligned YSZ buffer layers, YBCO thin films grown on metallic substrates showed improved rm J_{c}s. It was found that the in-plane alignment of YSZ and that of YBCO were closely related. A direct correlation was revealed between the rm J_{c} value and the degree of the in-plane alignment for the YBCO thin films. To explain this correlation, a numerical model was applied to multi-grain superconducting paths with different

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.

High efficiency diamond solar cells

DOEpatents

Gruen, Dieter M [Downers Grove, IL

2008-05-06

A photovoltaic device and method of making same. A layer of p-doped microcrystalline diamond is deposited on a layer of n-doped ultrananocrystalline diamond such as by providing a substrate in a chamber, providing a first atmosphere containing about 1% by volume CH.sub.4 and about 99% by volume H.sub.2 with dopant quantities of a boron compound, subjecting the atmosphere to microwave energy to deposit a p-doped microcrystalline diamond layer on the substrate, providing a second atmosphere of about 1% by volume CH.sub.4 and about 89% by volume Ar and about 10% by volume N.sub.2, subjecting the second atmosphere to microwave energy to deposit a n-doped ultrananocrystalline diamond layer on the p-doped microcrystalline diamond layer. Electrodes and leads are added to conduct electrical energy when the layers are irradiated.

Bactericidal activity of biomimetic diamond nanocone surfaces.

PubMed

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

2016-03-17

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

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.

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.

Effect of electronic structure of the diamond surface on the strength of the diamond-metal interface

NASA Technical Reports Server (NTRS)

Pepper, S. V.

1981-01-01

A diamond surface undergoes a transformation in its electronic structure by a vacuum anneal at approximately 900 C. The polished surface has no electronic states in the band gap, whereas the annealed surface has both occupied and unoccupied states in the and gap and exhibits some electrical conductivity. The effect of this transformation on the strength of the diamond metal interface was investigated by measuring the static friction force of an atomically clean meta sphere on a diamond flat in ultrahigh vacuum. It was found that low friction (weak bonding) is associated with the diamond surface devoid of gap states whereas high friction (strong bonding) is associated with the diamond surface with gap states. Exposure of the annealed surface to excited hydrogen also leads to weak bonding. The interfacial bond is discussed in terms of interaction of the metal conduction band electrons with the band gap states on the diamond surface. Effects of surface electrical conductivity on the interfacial bond are also be considered.

Diamonds: Exploration, mines and marketing

NASA Astrophysics Data System (ADS)

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

2009-11-01

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

A unifying picture of gas-phase formation and growth of PAH (Polycyclic Aromatic Hydrocarbons), soot, diamond and graphite

NASA Technical Reports Server (NTRS)

Frenklach, Michael

1990-01-01

A variety of seemingly different carbon formation processes -- polycyclic aromatic hydrocarbons and diamond in the interstellar medium, soot in hydrocarbon flames, graphite and diamond in plasma-assisted-chemical vapor deposition reactors -- may all have closely related underlying chemical reaction mechanisms. Two distinct mechanisms for gas-phase carbon growth are discussed. At high temperatures it proceeds via the formation of carbon clusters. At lower temperatures it follows a polymerization-type kinetic sequence of chemical reactions of acetylene addition to a radical, and reactivation of the resultant species through H-abstraction by a hydrogen atom.

Mechanisms limiting the performance of large grain polycrystalline silicon solar cells

NASA Technical Reports Server (NTRS)

Culik, J. S.; Alexander, P.; Dumas, K. A.; Wohlgemuth, J. W.

1984-01-01

The open-circuit voltage and short-circuit current of large-grain (1 to 10 mm grain diameter) polycrystalline silicon solar cells is determined by the minority-carrier diffusion length within the bulk of the grains. This was demonstrated by irradiating polycrystalline and single-crystal (Czochralski) silicon solar cells with 1 MeV electrons to reduce their bulk lifetime. The variation of short-circuit current with minority-carrier diffusion length for the polycrystalline solar cells is identical to that of the single-crystal solar cells. The open-circuit voltage versus short-circuit current characteristic of the polycrystalline solar cells for reduced diffusion lengths is also identical to that of the single-crystal solar cells. The open-circuit voltage of the polycrystalline solar cells is a strong function of quasi-neutral (bulk) recombination, and is reduced only slightly, if at all, by grain-boundary recombination.

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.

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.

Transparent nanocrystalline diamond coatings and devices

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

Sumant, Anirudha V.; Khan, Adam

2017-08-22

A method for coating a substrate comprises producing a plasma ball using a microwave plasma source in the presence of a mixture of gases. The plasma ball has a diameter. The plasma ball is disposed at a first distance from the substrate and the substrate is maintained at a first temperature. The plasma ball is maintained at the first distance from the substrate, and a diamond coating is deposited on the substrate. The diamond coating has a thickness. Furthermore, the diamond coating has an optical transparency of greater than about 80%. The diamond coating can include nanocrystalline diamond. The microwavemore » plasma source can have a frequency of about 915 MHz.« less

Characterization of silicon carbide and diamond detectors for neutron applications

NASA Astrophysics Data System (ADS)

Hodgson, M.; Lohstroh, A.; Sellin, P.; Thomas, D.

2017-10-01

The presence of carbon atoms in silicon carbide and diamond makes these materials ideal candidates for direct fast neutron detectors. Furthermore the low atomic number, strong covalent bonds, high displacement energies, wide bandgap and low intrinsic carrier concentrations make these semiconductor detectors potentially suitable for applications where rugged, high-temperature, low-gamma-sensitivity detectors are required, such as active interrogation, electronic personal neutron dosimetry and harsh environment detectors. A thorough direct performance comparison of the detection capabilities of semi-insulating silicon carbide (SiC-SI), single crystal diamond (D-SC), polycrystalline diamond (D-PC) and a self-biased epitaxial silicon carbide (SiC-EP) detector has been conducted and benchmarked against a commercial silicon PIN (Si-PIN) diode, in a wide range of alpha (Am-241), beta (Sr/Y-90), ionizing photon (65 keV to 1332 keV) and neutron radiation fields (including 1.2 MeV to 16.5 MeV mono-energetic neutrons, as well as neutrons from AmBe and Cf-252 sources). All detectors were shown to be able to directly detect and distinguish both the different radiation types and energies by using a simple energy threshold discrimination method. The SiC devices demonstrated the best neutron energy discrimination ratio (E\\max (n=5 MeV)/E\\max (n=1 MeV)  ≈5), whereas a superior neutron/photon cross-sensitivity ratio was observed in the D-PC detector (E\\max (AmBe)/E\\max (Co-60)  ≈16). Further work also demonstrated that the cross-sensitivity ratios can be improved through use of a simple proton-recoil conversion layer. Stability issues were also observed in the D-SC, D-PC and SiC-SI detectors while under irradiation, namely a change of energy peak position and/or count rate with time (often referred to as the polarization effect). This phenomenon within the detectors was non-debilitating over the time period tested (> 5 h) and, as such, stable operation was

Polycrystalline semiconductor processing

DOEpatents

Glaeser, Andreas M.; Haggerty, John S.; Danforth, Stephen C.

1983-01-01

A process for forming large-grain polycrystalline films from amorphous films for use as photovoltaic devices. The process operates on the amorphous film and uses the driving force inherent to the transition from the amorphous state to the crystalline state as the force which drives the grain growth process. The resultant polycrystalline film is characterized by a grain size that is greater than the thickness of the film. A thin amorphous film is deposited on a substrate. The formation of a plurality of crystalline embryos is induced in the amorphous film at predetermined spaced apart locations and nucleation is inhibited elsewhere in the film. The crystalline embryos are caused to grow in the amorphous film, without further nucleation occurring in the film, until the growth of the embryos is halted by imgingement on adjacently growing embryos. The process is applicable to both batch and continuous processing techniques. In either type of process, the thin amorphous film is sequentially doped with p and n type dopants. Doping is effected either before or after the formation and growth of the crystalline embryos in the amorphous film, or during a continuously proceeding crystallization step.

Polycrystalline semiconductor processing

DOEpatents

Glaeser, A.M.; Haggerty, J.S.; Danforth, S.C.

1983-04-05

A process is described for forming large-grain polycrystalline films from amorphous films for use as photovoltaic devices. The process operates on the amorphous film and uses the driving force inherent to the transition from the amorphous state to the crystalline state as the force which drives the grain growth process. The resultant polycrystalline film is characterized by a grain size that is greater than the thickness of the film. A thin amorphous film is deposited on a substrate. The formation of a plurality of crystalline embryos is induced in the amorphous film at predetermined spaced apart locations and nucleation is inhibited elsewhere in the film. The crystalline embryos are caused to grow in the amorphous film, without further nucleation occurring in the film, until the growth of the embryos is halted by impingement on adjacently growing embryos. The process is applicable to both batch and continuous processing techniques. In either type of process, the thin amorphous film is sequentially doped with p and n type dopants. Doping is effected either before or after the formation and growth of the crystalline embryos in the amorphous film, or during a continuously proceeding crystallization step. 10 figs.

Shock induced spall fracture in polycrystalline copper

NASA Astrophysics Data System (ADS)

Mukherjee, D.; Rav, Amit; Sur, Amit; Joshi, K. D.; Gupta, Satish C.

2014-04-01

The plate impact experiments have been conducted on commercially available 99.99% pure polycrystalline samples of copper using single stage gas gun facility. The free surface velocity history of the sample plate measured using VISAR instrument is utilized to determine the dynamic yield strength and spall strength of copper. The dynamic yield strength and spall strength of polycrystalline copper sample has been determined to be 0.14 GPa and 1.32 GPa, respectively with corresponding strain rates of the order of 104/s.

Ultimate Atomic Bling: Nanotechnology of Diamonds

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

Dahl, Jeremy

2010-05-25

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

78 FR 11143 - Diamond Sawblades and Parts Thereof From the People's Republic of China: Final Results of...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-15

... Air Freight Brokerage and Handling Cores Diamond Powder Electricity Financial Ratios Gasoline Paraffin... Analysis,'' dated January 8, 2013. See also Memorandum to Paul Piquado, Assistant Secretary for Import... is dispositive. Analysis of Comments Received All issues raised in the case briefs by parties to this...

Theoretical Study of Diamond-Like Carbons and Nucleation of Diamond

NASA Astrophysics Data System (ADS)

Lee, Choon-Heung

Different forms of amorphous carbon and hydrocarbons with varying elastic and optical properties, hardness, density and hydrogen content exist depending on the preparation technique. The structure can vary from graphitic to diamond -like, i.e., from mainly threefold coordinated to mainly four-fold coordinated. In order to study the properties of such materials, microscopic models must be developed. These studies include the modelling of crosslinked defective graphite, diamond nucleation along the graphite edges, and diamond-like carbons. Tamor's proposed structure for diamondlike carbon consists of crosslinked graphitic regions. We studied a concrete realization of this model in which the cross -links are produced by shortening the interplanar bond lengths. The model study was accomplished with a pure rhombohedral graphite cell. For this study we used a semi-empirical potential based on Tersoff's environment-dependent potential which contains angular terms. It is enhanced by a long-range potential which describes the interplanar interactions. We found a configuration corresponding to a local minimum. More general features such as the randomness of the distribution of cross-links are needed for a realistic model. A model study of diamond/graphite interfaces was motivated by recent observations by Li and Angus. They observed a significant enhancement of diamond nucleation on the graphite edge planes with the preferential orientation relationship: {0001} _{g} | {111 }_{d}, < 1120 >_{g} | < 101>_{d}. Two possible interface structures were studied using the Tersoff potential. We found that the models have comparable low interface energies even if they contain some dangling bonds. Moreover, lower interface energies were found when the dangling bonds of the non-bonded diamond layer were satisfied with hydrogen. We have proposed a growth mechanism based on this study. Finally, we constructed realistic models of dense amorphous carbon. The WWW (introduced earlier for a

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

NASA Astrophysics Data System (ADS)

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

2014-05-01

In recent years, several studies have focused on the growth conditions of the diamonds through the analysis of the mineral inclusions trapped in them (Howell, 2012 and references therein). Nevertheless, to obtain rigorous information about chemical and physical conditions of diamond formation, it is crucial to determine if the crystallization of the inclusions occurred before (protogenetic nature), during (syngenetic nature) or after (epigenetic nature) the growth of diamond (Wiggers de Vries et al., 2011). X-ray topography (XRDT) can be a helpful tool to verify the genetic nature of inclusions in diamond. This technique characterizes the extended defects and reconstructs the growth history of the samples (Agrosì et al., 2013 and references therein) and, consequently contributes to elucidation of the relationship between the inclusions and the host-diamond. With this aim a diamond from the Udachnaya kimberlite, Siberia, was investigated. The diamond crystal was the one previously studied by Nestola et al. (2011) who performed in-situ crystal structure refinement of the inclusions to obtain data about the formation pressure. The inclusions were iso-oriented olivines that did not show evident cracks and subsequently could not be considered epigenetic. Optical observations revealed an anomalous birefringence in the adjacent diamond and the inclusions had typical "diamond-imposed cubo-octahedral" shape for the largest olivine. The diffraction contrast study shows that the diamond exhibits significant deformation fields related to plastic post growth deformation. The crystallographic direction of strains was established applying the extinction criterion. Section topographs were taken to minimize the overlapping of the strain field associate with the different defects and revealed that no dislocations nucleated from the olivine inclusions. Generally, when a solid inclusion has been incorporated in the growing crystal, the associated volume distortion can be minimized by

Study of supersonic plasma technology jets

NASA Astrophysics Data System (ADS)

Selezneva, Svetlana; Gravelle, Denis; Boulos, Maher; van de Sanden, Richard; Schram, Dc

2001-10-01

Recently some new techniques using remote thermal plasma for thin film deposition and plasma chemistry processes were developed. These techniques include PECVD of diamonds, diamond-like and polymer films; a-C:H and a-Si:H films. The latter are of especial interest because of their applications for solar cell production industry. In remote plasma deposition, thermal plasma is formed by means of one of traditional plasma sources. The chamber pressure is reduced with the help of continuous pumping. In that way the flow is accelerated up to the supersonic speed. The plasma expansion is controlled using a specific torch nozzle design. To optimize the deposition process detailed knowledge about the gas dynamic structure of the jet and chemical kinetics mechanisms is required. In the paper, we show how the flow pattern and the character of the deviations from local thermodynamic equilibrium differs in plasmas generated by different plasma sources, such as induction plasma torch, traditional direct current arc and cascaded arc. We study the effects of the chamber pressure, nozzle design and carrier gas on the resulting plasma properties. The analysis is performed by means of numerical modeling using commercially available FLUENT program with incorporated user-defined subroutines for two-temperature model. The results of continuum mechanics approach are compared with that of the kinetic Monte Carlo method and with the experimental data.

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.

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

NASA Astrophysics Data System (ADS)

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

2017-04-01

Traditional models for diamond formation within the lithospheric mantle invoke either carbonate reduction or methane oxidation. Both these mechanisms require some oxygen exchange with the surrounding wall-rock at the site of diamond precipitation. However, peridotite does not have sufficient buffering capacity to allow for diamond formation via these traditional models and instead peridotitic diamonds may form through isochemical cooling of H2O-rich CHO fluids [1]. Marange mixed-habit diamonds from eastern Zimbabwe provide the first natural confirmation of this new diamond growth model [2]. Although Marange diamonds do not contain any silicate or sulphide inclusions, they contain Ni-N-vacancy complexes detected through photoluminescence (PL) spectroscopy that suggest the source fluids equilibrated in the Ni-rich depleted peridotitic lithosphere. Cuboid sectors also contain abundant micro-inclusions of CH4, the first direct observation of reduced CH4-rich fluids that are thought to percolate through the lithospheric mantle [2]. In fluid inclusion-free diamonds, core-to-rim trends in δ13C and N content are used to infer the speciation of the diamond-forming fluid. Core to rim trends of increasing δ13C with decreasing N content are interpreted as diamond growth from oxidized CO2- or carbonate-bearing fluids. Diamond growth from reduced species should show the opposite trends - decreasing δ13C from core to rim with decreasing N content. Within the CH4-bearing growth sectors of Marange diamonds, however, such a 'reduced' trend is not observed. Rather, δ13C increases from core to rim within a homogeneously grown zone [2]. These contradictory observations can be explained through either mixing between CH4- and CO2-rich end-members of hydrous fluids [2] or through closed system precipitation from an already mixed CH4-CO2 H2O-maximum fluid with XCO2 (CO2/[CO2+CH4]) between 0.3 and 0.7 [3]. These results demonstrate that Marange diamonds precipitated from cooling CH4-CO2

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.

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.

Diamond nanowires: fabrication, structure, properties, and applications.

PubMed

Yu, Yuan; Wu, Liangzhuan; Zhi, Jinfang

2014-12-22

C(sp(3) )C-bonded diamond nanowires are wide band gap semiconductors that exhibit a combination of superior properties such as negative electron affinity, chemical inertness, high Young's modulus, the highest hardness, and room-temperature thermal conductivity. The creation of 1D diamond nanowires with their giant surface-to-volume ratio enhancements makes it possible to control and enhance the fundamental properties of diamond. Although theoretical comparisons with carbon nanotubes have shown that diamond nanowires are energetically and mechanically viable structures, reproducibly synthesizing the crystalline diamond nanowires has remained challenging. We present a comprehensive, up-to-date review of diamond nanowires, including a discussion of their synthesis along with their structures, properties, and applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diamond Technology Initiative

DTIC Science & Technology

1994-05-01

thermal stresses of 10 million Watts per meter, 1,000 times better than Zerodur *. This property is also important for many thermal management...products UTD has coated to date include: • Optical windows, lenses, and mirrors . Zinc sulfide infrared windows coated with a 2.5 micron-thick...implants 16, 49 microwave plasma-enhanced CVD 2 mirrors , diamond-coated 49 models of diamond growth 10, 25, 33, 34, 39 moderators 10

Polycrystalline silicon study: Low-cost silicon refining technology prospects and semiconductor-grade polycrystalline silicon availability through 1988

NASA Technical Reports Server (NTRS)

Costogue, E. N.; Ferber, R.; Lutwack, R.; Lorenz, J. H.; Pellin, R.

1984-01-01

Photovoltaic arrays that convert solar energy into electrical energy can become a cost effective bulk energy generation alternative, provided that an adequate supply of low cost materials is available. One of the key requirements for economic photovoltaic cells is reasonably priced silicon. At present, the photovoltaic industry is dependent upon polycrystalline silicon refined by the Siemens process primarily for integrated circuits, power devices, and discrete semiconductor devices. This dependency is expected to continue until the DOE sponsored low cost silicon refining technology developments have matured to the point where they are in commercial use. The photovoltaic industry can then develop its own source of supply. Silicon material availability and market pricing projections through 1988 are updated based on data collected early in 1984. The silicon refining industry plans to meet the increasing demands of the semiconductor device and photovoltaic product industries are overviewed. In addition, the DOE sponsored technology research for producing low cost polycrystalline silicon, probabilistic cost analysis for the two most promising production processes for achieving the DOE cost goals, and the impacts of the DOE photovoltaics program silicon refining research upon the commercial polycrystalline silicon refining industry are addressed.

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.

Ohmic contacts to semiconducting diamond

NASA Astrophysics Data System (ADS)

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

1990-10-01

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

Ultratough single crystal boron-doped diamond

DOEpatents

Hemley, Russell J [Carnegie Inst. for Science, Washington, DC ; Mao, Ho-Kwang [Carnegie Inst. for Science, Washington, DC ; Yan, Chih-Shiue [Carnegie Inst. for Science, Washington, DC ; Liang, Qi [Carnegie Inst. for Science, Washington, DC

2015-05-05

The invention relates to a single crystal boron doped CVD diamond that has a toughness of at least about 22 MPa m.sup.1/2. The invention further relates to a method of manufacturing single crystal boron doped CVD diamond. The growth rate of the diamond can be from about 20-100 .mu.m/h.

Recent results on CVD diamond radiation sensors

NASA Astrophysics Data System (ADS)

Weilhammer, P.; Adam, W.; Bauer, C.; Berdermann, E.; Bogani, F.; Borchi, E.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; v. d. Eijk, R.; van Eijk, B.; Fallou, A.; Fish, D.; Fried, M.; Gan, K. K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Kass, R.; Knopfle, K. T.; Krammer, M.; Manfredi, P. F.; Meier, D.; LeNormand; Pan, L. S.; Pernegger, H.; Pernicka, M.; Plano, R.; Re, V.; Riester, J. L.; Roe, S.; Roff; Rudge, A.; Schieber, M.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Stone, R.; Tapper, R. J.; Tesarek, R.; Thomson, G. B.; Trawick, M.; Trischuk, W.; Turchetta, R.; RD 42 Collaboration

1998-02-01

CVD diamond radiation sensors are being developed for possible use in trackers in the LHC experiments. The diamond promises to be radiation hard well beyond particle fluences that can be tolerated by Si sensors. Recent results from the RD 42 collaboration on charge collection distance and on radiation hardness of CVD diamond samples will be reported. Measurements with diamond tracking devices, both strip detectors and pixel detectors, will be discussed. Results from beam tests using a diamond strip detector which was read out with fast, 25 ns shaping time, radiation-hard pipeline electronics will be presented.

Method for machining steel with diamond tools

DOEpatents

Casstevens, J.M.

1984-01-01

The present invention is directed to a method for machine optical quality finishes and contour accuracies of workpieces of carbon-containing metals such as steel with diamond tooling. The wear rate of the diamond tooling is significantly reduced by saturating the atmosphere at the interface of the workpiece and the diamond tool with a gaseous hydrocarbon during the machining operation. The presence of the gaseous hydrocarbon effectively eliminates the deterioration of the diamond tool by inhibiting or preventing the conversion of the diamond carbon to graphite carbon at the point of contact between the cutting tool and the workpiece.

Method for machining steel with diamond tools

DOEpatents

Casstevens, John M.

1986-01-01

The present invention is directed to a method for machining optical quality inishes and contour accuracies of workpieces of carbon-containing metals such as steel with diamond tooling. The wear rate of the diamond tooling is significantly reduced by saturating the atmosphere at the interface of the workpiece and the diamond tool with a gaseous hydrocarbon during the machining operation. The presence of the gaseous hydrocarbon effectively eliminates the deterioration of the diamond tool by inhibiting or preventing the conversion of the diamond carbon to graphite carbon at the point of contact between the cutting tool and the workpiece.

Diamond nanostructures for drug delivery, bioimaging, and biosensing.

PubMed

Chen, Xianfeng; Zhang, Wenjun

2017-02-06

Diamond features an attractive combination of outstanding mechanical, optical, thermal and electrical properties; tunable surface characteristics; and unprecedented biocompatibility. Additionally, diamond can possess unique nitrogen-vacancy emission centers that are highly photostable and extremely sensitive to magnetic fields, temperatures, ion concentrations, and spin densities. With these inherent merits, diamond in various nanoscale configurations has demonstrated a variety of distinctive applications in a broad range of fields. In particular, research on diamond nanoparticles (0-dimensional structures) and arrays of diamond nanoneedles/nanowires (1-dimensional structures) has witnessed important and exciting progress in recent years. Here, we systematically review the superior properties of diamond nanomaterials and the nitrogen-vacancy centers they contain as well as their uses in biomedical applications, including biosensing, bioimaging and drug delivery. Moreover, systematic studies of the biocompatibility and toxicity of diamond nanostructures, which constitute an important issue for the biomedical applications of diamond that has not yet been thoroughly addressed in previous reviews, are also discussed. Finally, we present our insights into the key issues concerning these diamond nanomaterials and their future development for applications.

Drilling of optical glass with electroplated diamond tools

NASA Astrophysics Data System (ADS)

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

2010-10-01

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

Fluid inclusions in Ebelyakh diamonds: Evidence of CO2 liberation in eclogite and the effect of H2O on diamond habit

NASA Astrophysics Data System (ADS)

Smith, Evan M.; Kopylova, Maya G.; Frezzotti, Maria Luce; Afanasiev, Valentin P.

2015-02-01

Fluid inclusions were studied in six octahedrally-grown, eclogitic diamonds from the Ebelyakh River mine, northern Russia, using microthermometry and Raman spectroscopy. The fluids are CO2-N2 mixtures with 40 ± 4 mol% N2, which are trapped along fractures that healed in the diamond stability field. The CO2-rich composition of the fluids provides the first empirical evidence that CO2 can be liberated as a free phase in eclogite in the diamond stability field of the lithospheric mantle, as has been previously predicted from theory. This finding means that the interpretation of carbon isotopes in eclogitic diamonds should not overlook isotopic fractionation due to CO2 liberation from carbonatitic diamond-forming media as it percolates through eclogites. Preferential nucleation of CO2 bubbles in eclogite compared to peridotite may lead to a rock type-specific fracturing mechanism and sampling bias that would help explain the overabundance of eclogite xenoliths in kimberlites. Fluid inclusions in octahedrally-grown, non-fibrous diamonds from both the studied Ebelyakh diamonds and those from other cratons do not show detectable amounts of water. In comparison, fibrous diamond fluid inclusions typically contain 10-25 wt.% water. The absence of "dry" fluids in fibrous diamonds and the presence of these in octahedrally-grown diamonds may indicate different compositions of fluids equilibrated with these two types of diamonds. If there is variability in the water content in diamond-forming fluids, it should affect diamond growth morphology. Water could be responsible for causing fibrous diamond growth, by inhibiting the advancement of growth steps within octahedral faces.

Wedge Shock and Nozzle Exhaust Plume Interaction in a Supersonic Jet Flow

NASA Technical Reports Server (NTRS)

Castner, Raymond; Zaman, Khairul; Fagan, Amy; Heath, Christopher

2014-01-01

Fundamental research for sonic boom reduction is needed to quantify the interaction of shock waves generated from the aircraft wing or tail surfaces with the nozzle exhaust plume. Aft body shock waves that interact with the exhaust plume contribute to the near-field pressure signature of a vehicle. The plume and shock interaction was studied using computational fluid dynamics and compared with experimental data from a coaxial convergent-divergent nozzle flow in an open jet facility. A simple diamond-shaped wedge was used to generate the shock in the outer flow to study its impact on the inner jet flow. Results show that the compression from the wedge deflects the nozzle plume and shocks form on the opposite plume boundary. The sonic boom pressure signature of the nozzle exhaust plume was modified by the presence of the wedge. Both the experimental results and computational predictions show changes in plume deflection.

High-pressure studies with x-rays using diamond anvil cells

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

Shen, Guoyin; Mao, Ho Kwang

2016-11-22

Pressure profoundly alters all states of matter. The symbiotic development of ultrahigh-pressure diamond anvil cells, to compress samples to sustainable multi-megabar pressures; and synchrotron x-ray techniques, to probe materials' properties in situ, has enabled the exploration of rich high-pressure (HP) science. In this article, we first introduce the essential concept of diamond anvil cell technology, together with recent developments and its integration with other extreme environments. We then provide an overview of the latest developments in HP synchrotron techniques, their applications, and current problems, followed by a discussion of HP scientific studies using x-rays in the key multidisciplinary fields. Thesemore » HP studies include: HP x-ray emission spectroscopy, which provides information on the filled electronic states of HP samples; HP x-ray Raman spectroscopy, which probes the HP chemical bonding changes of light elements; HP electronic inelastic x-ray scattering spectroscopy, which accesses high energy electronic phenomena, including electronic band structure, Fermi surface, excitons, plasmons, and their dispersions; HP resonant inelastic x-ray scattering spectroscopy, which probes shallow core excitations, multiplet structures, and spin-resolved electronic structure; HP nuclear resonant x-ray spectroscopy, which provides phonon densities of state and time-resolved Mössbauer information; HP x-ray imaging, which provides information on hierarchical structures, dynamic processes, and internal strains; HP x-ray diffraction, which determines the fundamental structures and densities of single-crystal, polycrystalline, nanocrystalline, and non-crystalline materials; and HP radial x-ray diffraction, which yields deviatoric, elastic and rheological information. Integrating these tools with hydrostatic or uniaxial pressure media, laser and resistive heating, and cryogenic cooling, has enabled investigations of the structural, vibrational, electronic, and

High-pressure studies with x-rays using diamond anvil cells

NASA Astrophysics Data System (ADS)

Shen, Guoyin; Mao, Ho Kwang

2017-01-01

Pressure profoundly alters all states of matter. The symbiotic development of ultrahigh-pressure diamond anvil cells, to compress samples to sustainable multi-megabar pressures; and synchrotron x-ray techniques, to probe materials’ properties in situ, has enabled the exploration of rich high-pressure (HP) science. In this article, we first introduce the essential concept of diamond anvil cell technology, together with recent developments and its integration with other extreme environments. We then provide an overview of the latest developments in HP synchrotron techniques, their applications, and current problems, followed by a discussion of HP scientific studies using x-rays in the key multidisciplinary fields. These HP studies include: HP x-ray emission spectroscopy, which provides information on the filled electronic states of HP samples; HP x-ray Raman spectroscopy, which probes the HP chemical bonding changes of light elements; HP electronic inelastic x-ray scattering spectroscopy, which accesses high energy electronic phenomena, including electronic band structure, Fermi surface, excitons, plasmons, and their dispersions; HP resonant inelastic x-ray scattering spectroscopy, which probes shallow core excitations, multiplet structures, and spin-resolved electronic structure; HP nuclear resonant x-ray spectroscopy, which provides phonon densities of state and time-resolved Mössbauer information; HP x-ray imaging, which provides information on hierarchical structures, dynamic processes, and internal strains; HP x-ray diffraction, which determines the fundamental structures and densities of single-crystal, polycrystalline, nanocrystalline, and non-crystalline materials; and HP radial x-ray diffraction, which yields deviatoric, elastic and rheological information. Integrating these tools with hydrostatic or uniaxial pressure media, laser and resistive heating, and cryogenic cooling, has enabled investigations of the structural, vibrational, electronic, and

The impact of diamond nanocrystallinity on osteoblast functions.

PubMed

Yang, Lei; Sheldon, Brian W; Webster, Thomas J

2009-07-01

Nanocrystalline diamond has been proposed as an anti-abrasive film on orthopedic implants. In this study, osteoblast (bone forming cells) functions including adhesion (up to 4h), proliferation (up to 5 days) and differentiation (up to 21 days) on different diamond film topographies were systematically investigated. In order to exclude interferences from changes in surface chemistry and wettability (energy), diamond films with nanometer and micron scale topographies were fabricated through microwave plasma enhanced chemical-vapor-deposition and hydrogen plasma treatment. Scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy and water contact angle measurements verified the similar surface chemistry and wettability but varied topographies for all of the diamond films prepared on silicon in this study. Cytocompatibility assays demonstrated enhanced osteoblast functions (including adhesion, proliferation, intracellular protein synthesis, alkaline phosphatase activity and extracellular calcium deposition) on nanocrystalline diamond compared to submicron diamond grain size films for all time periods tested up to 21 days. An SEM study of osteoblast attachment helped to explain the topographical impact diamond had on osteoblast functions by showing altered filopodia extensions on the different diamond topographies. In summary, these results provided insights into understanding the role diamond nanotopography had on osteoblast interactions and more importantly, the application of diamond films to improve orthopedic implant lifetimes.

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.

Electrical applications of CVD diamond films

NASA Astrophysics Data System (ADS)

Fujimori, Naoji

Electronics applications of CVD diamond films are reported. The properties of epitaxial diamond films are affected by the orientation of the substrate and the deposition conditions. Boron-doped epitaxial films are found to have the same characteristics as natural IIb diamonds. An LED and an FET were successfully fabricated using boron-doped epitaxial films and Schottky junctions. However, these devices did not exhibit satisfactory properties. Other applications of CVD diamond films include speaker diaphragms (as both a thin-film coating and a free-standing film), and as an ideal packaging material (due to its high thermal conductivity and low dielectric constant).

Diamond Thin-Film Thermionic Generator

NASA Astrophysics Data System (ADS)

Clewell, J. M.; Ordonez, C. A.; Perez, J. M.

1997-03-01

Since the eighteen-hundreds scientists have sought to develop the highest thermal efficiency in heat engines such as thermionic generators. Modern research in the emerging diamond film industry has indicated the work functions of diamond thin-films can be much less than one electron volt, compelling fresh investigation into their capacity as thermionic generators and inviting new methodology for determining that efficiency. Our objective is to predict the efficiency of a low-work-function, degenerate semiconductor (diamond film) thermionic generator operated as a heat engine between two constant-temperature thermal reservoirs. Our presentation will focus on a theoretical model which predicts the efficiency of the system by employing a Monte Carlo computational technique from which we report results for the thermal efficiency and the thermionic current densities of diamond thin-films.

Effect of Turbulence Modeling on an Excited Jet

NASA Technical Reports Server (NTRS)

Brown, Clifford A.; Hixon, Ray

2010-01-01

The flow dynamics in a high-speed jet are dominated by unsteady turbulent flow structures in the plume. Jet excitation seeks to control these flow structures through the natural instabilities present in the initial shear layer of the jet. Understanding and optimizing the excitation input, for jet noise reduction or plume mixing enhancement, requires many trials that may be done experimentally or computationally at a significant cost savings. Numerical simulations, which model various parts of the unsteady dynamics to reduce the computational expense of the simulation, must adequately capture the unsteady flow dynamics in the excited jet for the results are to be used. Four CFD methods are considered for use in an excited jet problem, including two turbulence models with an Unsteady Reynolds Averaged Navier-Stokes (URANS) solver, one Large Eddy Simulation (LES) solver, and one URANS/LES hybrid method. Each method is used to simulate a simplified excited jet and the results are evaluated based on the flow data, computation time, and numerical stability. The knowledge gained about the effect of turbulence modeling and CFD methods from these basic simulations will guide and assist future three-dimensional (3-D) simulations that will be used to understand and optimize a realistic excited jet for a particular application.

On the failure load and mechanism of polycrystalline graphene by nanoindentation

PubMed Central

Sha, Z. D.; Wan, Q.; Pei, Q. X.; Quek, S. S.; Liu, Z. S.; Zhang, Y. W.; Shenoy, V. B.

2014-01-01

Nanoindentation has been recently used to measure the mechanical properties of polycrystalline graphene. However, the measured failure loads are found to be scattered widely and vary from lab to lab. We perform molecular dynamics simulations of nanoindentation on polycrystalline graphene at different sites including grain center, grain boundary (GB), GB triple junction, and holes. Depending on the relative position between the indenter tip and defects, significant scattering in failure load is observed. This scattering is found to arise from a combination of the non-uniform stress state, varied and weakened strengths of different defects, and the relative location between the indenter tip and the defects in polycrystalline graphene. Consequently, the failure behavior of polycrystalline graphene by nanoindentation is critically dependent on the indentation site, and is thus distinct from uniaxial tensile loading. Our work highlights the importance of the interaction between the indentation tip and defects, and the need to explicitly consider the defect characteristics at and near the indentation site in polycrystalline graphene during nanoindentation. PMID:25500732

Ion Beam Processing of Diamond

DTIC Science & Technology

1990-05-07

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

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.m^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.

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

NASA Astrophysics Data System (ADS)

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

2011-12-01

Mysterious Raman bands at 1430-1480 cm-1 suggesting carbon (or carbon-bearing) species have been discovered in UHP metamorphic microdiamonds entirely enclosed in dolomite marble from Kokchetav Massif (Igarashi et al., 2011). Such Raman bands first discovered at some domains in a T-type (see Ishida et al., 2003) diamond in dolomite marble in 2005, but we have not reported this because of the possibility of misidentification by contamination. Later, similar bands were also found in the rim and the core of S-type and R-type. The relative intensities of these Raman bands to diamond (at 1332 cm-1) were 10-40 % in average (max. 90-110 %) and FWHMs are broad (25-45 cm-1). The possibility of the appearance of these Raman bands was low. As we used ordinary polished thin sections (thickness: 25 μm) and the organic materials used in thin section making have Raman bands at ca. 1450 cm-1, we carefully examined observed Raman spectra and the positions of the source materials of these bands to exclude the possibility of contaminations. Examined microdiamond grains are entirely enclosed in the host garnet, and no crack was observed in the host. We conducted 2D Raman mappings at different depths with 2 μm intervals. The result showed that the domains having these Raman bands were located within diamond grains and limited area (1-3 μm). These bands were never detected from outside diamond grains (e.g., host garnet). Thus, the unknown Raman bands at 1430-1480 cm-1 were attributed to some materials inside microdiamonds entirely included in the host garnet. The possibility of contamination was denied. Recently, we found similar Raman bands in the microdiamonds in garnet in Grt-Bt gneiss. Examined microdiamonds are entirely enclosed in garnet grain and no extra phase observed near laser spots in these microdiamond grains under an optical microscope. The Raman bands at 1430-1480 cm-1 were found from 4 microdiamond grains. The peak positions and FWHMs of these bands were as follows: (a

Dichotomy of Solar Coronal Jets: Standard Jets and Blowout Jets

NASA Technical Reports Server (NTRS)

Moore, R. L.; Cirtain, J. W.; Sterling, A. C.; Falconer, D. A.

2010-01-01

By examining many X-ray jets in Hinode/XRT coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H alpha macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major CMEs. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jets that were also caught in He II 304 Angstrom snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T 10(exp 4) - 10(exp 5) K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets.

Atmospheric Pressure Plasma Jet as a Dry Alternative to Inkjet Printing in Flexible Electronics

NASA Technical Reports Server (NTRS)

Gandhiraman, Ram Prasad; Lopez, Arlene; Koehne, Jessica; Meyyappan, M.

2016-01-01

We have developed an atmospheric pressure plasma jet printing system that works at room temperature to 50 deg C unlike conventional aerosol assisted techniques which require a high temperature sintering step to obtain desired thin films. Multiple jets can be configured to increase throughput or to deposit multiple materials, and the jet(s) can be moved across large areas using a x-y stage. The plasma jet has been used to deposit carbon nanotubes, graphene, silver nanowires, copper nanoparticles and other materials on substrates such as paper, cotton, plastic and thin metal foils.

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.

Macroscopic damping model for structural dynamics with random polycrystalline configurations

NASA Astrophysics Data System (ADS)

Yang, Yantao; Cui, Junzhi; Yu, Yifan; Xiang, Meizhen

2018-06-01

In this paper the macroscopic damping model for dynamical behavior of the structures with random polycrystalline configurations at micro-nano scales is established. First, the global motion equation of a crystal is decomposed into a set of motion equations with independent single degree of freedom (SDOF) along normal discrete modes, and then damping behavior is introduced into each SDOF motion. Through the interpolation of discrete modes, the continuous representation of damping effects for the crystal is obtained. Second, from energy conservation law the expression of the damping coefficient is derived, and the approximate formula of damping coefficient is given. Next, the continuous damping coefficient for polycrystalline cluster is expressed, the continuous dynamical equation with damping term is obtained, and then the concrete damping coefficients for a polycrystalline Cu sample are shown. Finally, by using statistical two-scale homogenization method, the macroscopic homogenized dynamical equation containing damping term for the structures with random polycrystalline configurations at micro-nano scales is set up.

Vertically aligned nanowires from boron-doped diamond.

PubMed

Yang, Nianjun; Uetsuka, Hiroshi; Osawa, Eiji; Nebel, Christoph E

2008-11-01

Vertically aligned diamond nanowires with controlled geometrical properties like length and distance between wires were fabricated by use of nanodiamond particles as a hard mask and by use of reactive ion etching. The surface structure, electronic properties, and electrochemical functionalization of diamond nanowires were characterized by atomic force microscopy (AFM) and scanning tunneling microscopy (STM) as well as electrochemical techniques. AFM and STM experiments show that diamond nanowire etched for 10 s have wire-typed structures with 3-10 nm in length and with typically 11 nm spacing in between. The electrode active area of diamond nanowires is enhanced by a factor of 2. The functionalization of nanowire tips with nitrophenyl molecules is characterized by STM on clean and on nitrophenyl molecule-modified diamond nanowires. Tip-modified diamond nanowires are promising with respect to biosensor applications where controlled biomolecule bonding is required to improve chemical stability and sensing significantly.

Mineral resource of the month: diamond

USGS Publications Warehouse

Olson, Donald W.

2009-01-01

The article presents information on diamond, which is regarded as the world's most popular gemstone. It states that there is strength in the covalent bonding between its carbon atoms, resulting to the strength of its physical properties. The presence of colors in diamonds may be attributed to the impurities that settle in the crystal lattice. Diamonds have been used as decorative items since the ancient era.

Effect of nitrogen on the growth of boron doped single crystal diamond

DOE PAGES

Karna, Sunil; Vohra, Yogesh

2013-11-18

Boron-doped single crystal diamond films were grown homoepitaxially on synthetic (100) Type Ib diamond substrates using microwave plasma assisted chemical vapor deposition. A modification in surface morphology of the film with increasing boron concentration in the plasma has been observed using atomic force microscopy. Use of nitrogen during boron doping has been found to improve the surface morphology and the growth rate of films but it lowers the electrical conductivity of the film. The Raman spectra indicated a zone center optical phonon mode along with a few additional bands at the lower wavenumber regions. The change in the peak profilemore » of the zone center optical phonon mode and its downshift were observed with the increasing boron content in the film. Furthermore, sharpening and upshift of Raman line was observed in the film that was grown in presence of nitrogen along with diborane in process gas.« less

Highly Doped Polycrystalline Silicon Microelectrodes Reduce Noise in Neuronal Recordings In Vivo

PubMed Central

Saha, Rajarshi; Jackson, Nathan; Patel, Chetan; Muthuswamy, Jit

2013-01-01

The aims of this study are to 1) experimentally validate for the first time the nonlinear current-potential characteristics of bulk doped polycrystalline silicon in the small amplitude voltage regimes (0–200 μV) and 2) test if noise amplitudes (0–15 μV) from single neuronal electrical recordings get selectively attenuated in doped polycrystalline silicon microelectrodes due to the above property. In highly doped polycrystalline silicon, bulk resistances of several hundred kilo-ohms were experimentally measured for voltages typical of noise amplitudes and 9–10 kΩ for voltages typical of neural signal amplitudes (>150–200 μV). Acute multiunit measurements and noise measurements were made in n = 6 and n = 8 anesthetized adult rats, respectively, using polycrystalline silicon and tungsten microelectrodes. There was no significant difference in the peak-to-peak amplitudes of action potentials recorded from either microelectrode (p > 0.10). However, noise power in the recordings from tungsten microelectrodes (26.36 ± 10.13 pW) was significantly higher (p < 0.001) than the corresponding value in polycrystalline silicon microelectrodes (7.49 ± 2.66 pW). We conclude that polycrystalline silicon microelectrodes result in selective attenuation of noise power in electrical recordings compared to tungsten microelectrodes. This reduction in noise compared to tungsten microelectrodes is likely due to the exponentially higher bulk resistances offered by highly doped bulk polycrystalline silicon in the range of voltages corresponding to noise in multiunit measurements. PMID:20667815

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

HUBBLE VIEWS OF THREE STELLAR JETS

NASA Technical Reports Server (NTRS)

2002-01-01

These NASA Hubble Space Telescope views of gaseous jets from three newly forming stars show a new level of detail in the star formation process, and are helping to solve decade-old questions about the secrets of star birth. Jets are a common 'exhaust product' of the dynamics of star formation. They are blasted away from a disk of gas and dust falling onto an embryonic star. [upper left] - This view of a protostellar object called HH-30 reveals an edge-on disk of dust encircling a newly forming star. Light from the forming star illuminates the top and bottom surfaces of the disk, making them visible, while the star itself is hidden behind the densest parts of the disk. The reddish jet emanates from the inner region of the disk, and possibly directly from the star itself. Hubble's detailed view shows, for the first time, that the jet expands for several billion miles from the star, but then stays confined to a narrow beam. The protostar is 450 light-years away in the constellation Taurus. Credit: C. Burrows (STScI and ESA), the WFPC 2 Investigation Definition Team, and NASA [upper right] - This view of a different and more distant jet in object HH-34 shows a remarkable beaded structure. Once thought to be a hydrodynamic effect (similar to shock diamonds in a jet aircraft exhaust), this structure is actually produced by a machine-gun-like blast of 'bullets' of dense gas ejected from the star at speeds of one-half million miles per hour. This structure suggests the star goes through episodic 'fits' of construction where chunks of material fall onto the star from a surrounding disk. The protostar is 1,500 light- years away and in the vicinity of the Orion Nebula, a nearby star birth region. Credit: J. Hester (Arizona State University), the WFPC 2 Investigation Definition Team, and NASA [bottom] - This view of a three trillion mile-long jet called HH-47 reveals a very complicated jet pattern that indicates the star (hidden inside a dust cloud near the left edge of the

Structural control of In2Se3 polycrystalline thin films by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Okamoto, T.; Nakada, Y.; Aoki, T.; Takaba, Y.; Yamada, A.; Konagai, M.

2006-09-01

Structural control of In2Se3 polycrystalline thin films was attempted by molecular beam epitaxy (MBE) technique. In2Se3 polycrystalline films were obtained on glass substrates at substrate temperatures above 400 °C. VI/III ratio greatly affected crystal structure of In2Se3 polycrystalline films. Mixtures of -In2Se3 and γ-In2Se3 were obtained at VI/III ratios greater than 20, and layered InSe polycrystalline films were formed at VI/III ratios below 1. γ-In2Se3 polycrystalline thin films without α-phase were successfully deposited with VI/III ratios in a range of 2 to 4. Photocurrent spectra of the γ-In2Se3 polycrystalline films showed an abrupt increase at approximately 1.9 eV, which almost corresponds with the reported bandgap of γ-In2Se3. Dark conductivity and photoconductivity measured under solar simulator light (AM 1.5, 100 mW/cm2) were approximately 10-9 and 10-5 S/cm in the γ-In2Se3 polycrystalline thin films, respectively.

Process Research On Polycrystalline Silicon Material (PROPSM). [flat plate solar array project

NASA Technical Reports Server (NTRS)

Culik, J. S.

1983-01-01

The performance-limiting mechanisms in large-grain (greater than 1 to 2 mm in diameter) polycrystalline silicon solar cells were investigated by fabricating a matrix of 4 sq cm solar cells of various thickness from 10 cm x 10 cm polycrystalline silicon wafers of several bulk resistivities. Analysis of the illuminated I-V characteristics of these cells suggests that bulk recombination is the dominant factor limiting the short-circuit current. The average open-circuit voltage of the polycrystalline solar cells is 30 to 70 mV lower than that of co-processed single-crystal cells; the fill-factor is comparable. Both open-circuit voltage and fill-factor of the polycrystalline cells have substantial scatter that is not related to either thickness or resistivity. This implies that these characteristics are sensitive to an additional mechanism that is probably spatial in nature. A damage-gettering heat-treatment improved the minority-carrier diffusion length in low lifetime polycrystalline silicon, however, extended high temperature heat-treatment degraded the lifetime.

Method and apparatus for making diamond-like carbon films

DOEpatents

Pern, Fu-Jann [Golden, CO; Touryan, Kenell J [Indian Hills, CO; Panosyan, Zhozef Retevos [Yerevan, AM; Gippius, Aleksey Alekseyevich [Moscow, RU

2008-12-02

Ion-assisted plasma enhanced deposition of diamond-like carbon (DLC) films on the surface of photovoltaic solar cells is accomplished with a method and apparatus for controlling ion energy. The quality of DLC layers is fine-tuned by a properly biased system of special electrodes and by exact control of the feed gas mixture compositions. Uniform (with degree of non-uniformity of optical parameters less than 5%) large area (more than 110 cm.sup.2) DLC films with optical parameters varied within the given range and with stability against harmful effects of the environment are achieved.

DICHOTOMY OF SOLAR CORONAL JETS: STANDARD JETS AND BLOWOUT JETS

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

Moore, Ronald L.; Cirtain, Jonathan W.; Sterling, Alphonse C.

2010-09-01

By examining many X-ray jets in Hinode/X-Ray Telescope coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H{alpha} macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major coronal mass ejections. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jetsmore » that were also caught in He II 304 A snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T {approx} 10{sup 4} - 10{sup 5} K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets.« less

Diamond-silicon carbide composite and method

DOEpatents

Zhao, Yusheng [Los Alamos, NM

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.

Microhabitat use of the diamond darter

USGS Publications Warehouse

Welsh, Stuart A.; Smith, Dustin M.; Taylor, Nate D.

2013-01-01

The only known extant population of the diamond darter (Crystallaria cincotta) exists in the lower 37 km of Elk River, WV, USA. Our understanding of diamond darter habitat use was previously limited, because few individuals have been observed during sampling with conventional gears. We quantified microhabitat use of diamond darters based on measurements of water depth, water velocity and per cent substrate composition. Using spotlights at night-time, we sampled 16 sites within the lower 133 km of Elk River and observed a total of 82 diamond darters at 10 of 11 sampling sites within the lower 37 km. Glides, located immediately upstream of riffles, were the primary habitats sampled for diamond darters, which included relatively shallow depths (<1 m), moderate-to-low water velocities (often < 0.5 m·s−1) and a smooth water surface. Microhabitat use (mean ± SE) of diamond darters was estimated for depth (0.47 ± 0.02 m), average velocity (0.27 ± 0.01 m·s−1) and bottom velocity (0.15 ± 0.01 m·s−1). Substrate used (mean ± SE) by diamond darters was predominantly sand intermixed with lesser amounts of gravel and cobble: % sand (52.1 ± 1.6), % small gravel (12.2 ± 0.78), % large gravel (14.2 ± 0.83), % cobble (19.8 ± 0.96) and % boulder (1.6 ± 0.36). Based on our microhabitat use data, conservation and management efforts for this species should consider preserving glide habitats within Elk River. Spotlighting, a successful sampling method for diamond darters, should be considered for study designs of population estimation and long-term monitoring.

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

NASA Astrophysics Data System (ADS)

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

2017-04-01

Diamond inclusions are potentially fundamental to understanding the formation conditions of diamond and the volatile cycles in the deep mantle. In order to fully understand the implications of the compositional information recorded by inclusions it is vital to know whether the inclusions are proto-, syn-, or epigenetic and the extent to which they have equilibrated with diamond forming fluids. In previous studies, the widespread assumption was made that the majority of diamond inclusions are syngenetic, based upon observation of cubo-octahedral morphology imposed on the inclusions. Recent work has reported the crystallographic relationship between inclusions and the host diamond to be highly complex and the lack of crystallographic relationships between inclusions and diamonds has led some to question the significance of imposed cubo-octahedral morphology. This study presents an integrated EBSD and CL study of 9 diamonds containing 20 pyropes, 2 diopsides, 1 forsterite and 1 rutile from the Jwaneng and Letlhakane kimberlite clusters, Botswana. A new method was developed to analyze the crystallographic orientation of the host diamond and the inclusions with EBSD. Diamonds plates were sequentially polished to expose inclusions at different levels in the diamond. CL imaging at different depths was performed in order to produce a 3D view of diamond growth zones around the inclusions. Standard diamond polishing techniques proved too aggressive for silicate inclusions as they were damaged to such a degree that EBSD measurements on the inclusions were impossible. The inclusions were milled with a Ga+ focused ion beam (FIB) at a 12° angle to clean the surface for EBSD measurements. Of the 24 inclusions, 9 have an imposed cubo-octahedral morphology. Of these inclusions, 6 have faces orientated parallel to diamond growth zones and/or appear to have nucleated on a diamond growth surface, implying syngenesis. In contrast, other diamonds record resorption events such that

Orientation relationship between diamond and magnesiochromite inclusions

NASA Astrophysics Data System (ADS)

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

2017-04-01

The correct determination of the relative crystallographic orientations of single crystals has many applications. When single crystals undergo phase transitions, especially at high pressures, the relative orientations of the two phases yields insights into transition mechanisms (Dobson et al 2013). On the other hand, determination of the crystallographic orientations of minerals included in diamonds can provide insights into the mechanisms of their entrapment and the timing of their formation relative to the host diamond (e.g. Nestola et al. 2014, Milani et al. 2016). The reported occurrence of non-trivial orientations for some minerals in diamonds, suggesting an epitaxial relationship, has long been considered to reflect contemporaneous growth of the diamond and the inclusion (e.g. syngenesis). Correct interpretation of such orientations requires (i) a statistically significant crystallographic data set for single and multiple inclusions in a large number of diamonds, and (ii) a robust data-processing method, capable of removing ambiguities derived from the high symmetry of the diamond and the inclusion. We have developed a software to perform such processing (OrientXplot, Angel et al. 2015), starting from crystallographic orientation matrixes obtained by X-ray diffractometry or EBSD data. Previous studies of inclusions in lithospheric diamonds, by single-crystal X-ray diffraction and EBSD, indicate a wide variety in the orientations of different inclusion phases with respect to their diamond host (Futergendler & Frank-Kamenetsky 1961; Frank-Kamenetsky 1964; Wiggers de Vries et al. 2011; Nestola et al. 2014, Milani et al. 2016). For example, olivine inclusions in lithospheric diamonds from Udachnaya do not show any preferred orientations with respect to their diamond hosts, but multiple inclusions in a single diamond often show very similar orientations within few degrees. In the present work on magnesiochromite inclusions in diamonds from Udachnaya, there is a

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

NASA Astrophysics Data System (ADS)

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

2003-12-01

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

Rapid Growth of Nanocrystalline Diamond on Single Crystal Diamond for Studies on Materials under Extreme Conditions

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

Moore, Samuel L.; Samudrala, Gopi K.; Catledge, Shane A.

Early stage nucleation morphologies of spatially localized nanocrystalline diamond (NCD) micro-anvils grown on (100)-oriented single crystal diamond (SCD) anvil surfaces were analyzed and investigated for applications in high pressure studies on materials. NCD was grown on SCD using Microwave Plasma Chemical Vapor Deposition (MPCVD) for brief time intervals ranging from 1-15 minutes. Early stage film morphologies were characterized using scanning electron microscopy (SEM) and Raman spectroscopy and were compared to films grown for several hours. Rapid nucleation and growth of NCD on SCD is demonstrated without any pre-growth seeding of the substrate surface. As grown NCD diamond micro-anvils on SCDmore » were used to generate static pressure of 0.5 Terapascal (TPa) on a tungsten sample as measured by synchrotron x-ray diffraction in a diamond anvil cell. Atomic force microscopy (AFM) analysis after decompression from ultrahigh pressures showed that the detachment of the NCD stage occurred in the bulk of the SCD and not at the interface, suggesting significant adhesive bond strength between nanocrystalline and single crystal diamond.« less

Rapid Growth of Nanocrystalline Diamond on Single Crystal Diamond for Studies on Materials under Extreme Conditions

DOE PAGES

Moore, Samuel L.; Samudrala, Gopi K.; Catledge, Shane A.; ...

2018-01-23

Early stage nucleation morphologies of spatially localized nanocrystalline diamond (NCD) micro-anvils grown on (100)-oriented single crystal diamond (SCD) anvil surfaces were analyzed and investigated for applications in high pressure studies on materials. NCD was grown on SCD using Microwave Plasma Chemical Vapor Deposition (MPCVD) for brief time intervals ranging from 1-15 minutes. Early stage film morphologies were characterized using scanning electron microscopy (SEM) and Raman spectroscopy and were compared to films grown for several hours. Rapid nucleation and growth of NCD on SCD is demonstrated without any pre-growth seeding of the substrate surface. As grown NCD diamond micro-anvils on SCDmore » were used to generate static pressure of 0.5 Terapascal (TPa) on a tungsten sample as measured by synchrotron x-ray diffraction in a diamond anvil cell. Atomic force microscopy (AFM) analysis after decompression from ultrahigh pressures showed that the detachment of the NCD stage occurred in the bulk of the SCD and not at the interface, suggesting significant adhesive bond strength between nanocrystalline and single crystal diamond.« less

Effect of grain size on optical transmittance of birefringent polycrystalline ceramics

NASA Astrophysics Data System (ADS)

Wen, Tzu-Chien

Polycrystalline ceramics are increasingly used for fabricating windows and domes for the mid infra-red regime (3-5 mum) due to their superior durability as compared to glass and the lower cost of their fabrication and finishing relative to single crystals without significant compromise in optical properties. Due to the noncubic structure, MgF2 and Al2O3 are birefringent ceramics. Birefringence causes scatter of light at the grain boundaries and diminishes in-line transmittance and optical performance. This dissertation presents experimental results and analyses of the grain-size and wavelength dependence of the in-line transmittance of polycrystalline MgF2 and Al2O3. Chapter 2 presents experimental results and analyses of light transmission in polycrystalline MgF2 as a function of the mean grain size at different wavelengths. The scattering coefficient of polycrystalline MgF 2 increased linearly with the mean grain size and inversely with the square of the wavelength of light. These trends are consistent with theoretical models based on both a limiting form of the Raleigh-Gans-Debye theory of particle scattering and light retardation theories that take refractive-index variations along the light path. Chapter 3 investigates the applicability of particle light scattering theories to light attenuation in birefringent polycrystalline ceramics by measuring light transmittance in a model two-phase system. The system consisted of microspheres of silica dispersed in a solution of glycerol in water. It was found that RGD theory showed the systematic deviation for higher particle volume fraction (φ > 0.2) and larger particle size (d p > 1 mum). This result suggested that light scattering models based on single particle scattering are unlikely to provide viable physical explanation for the effect of grain size on light transmittance in birefringent polycrystalline ceramics due to the high volume fraction in dense polycrystalline ceramics. Chapter 4 analyses light

21 CFR 872.4535 - Dental diamond instrument.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Dental diamond instrument. 872.4535 Section 872...) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4535 Dental diamond instrument. (a) Identification. A dental diamond instrument is an abrasive device intended to smooth tooth surfaces during the...

21 CFR 872.4535 - Dental diamond instrument.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Dental diamond instrument. 872.4535 Section 872...) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4535 Dental diamond instrument. (a) Identification. A dental diamond instrument is an abrasive device intended to smooth tooth surfaces during the...

21 CFR 872.4535 - Dental diamond instrument.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental diamond instrument. 872.4535 Section 872...) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4535 Dental diamond instrument. (a) Identification. A dental diamond instrument is an abrasive device intended to smooth tooth surfaces during the...

21 CFR 872.4535 - Dental diamond instrument.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Dental diamond instrument. 872.4535 Section 872...) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4535 Dental diamond instrument. (a) Identification. A dental diamond instrument is an abrasive device intended to smooth tooth surfaces during the...

21 CFR 872.4535 - Dental diamond instrument.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Dental diamond instrument. 872.4535 Section 872...) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4535 Dental diamond instrument. (a) Identification. A dental diamond instrument is an abrasive device intended to smooth tooth surfaces during the...

The role of scattering and absorption on the optical properties of birefringent polycrystalline ceramics: Modeling and experiments on ruby (Cr:Al2O3)

NASA Astrophysics Data System (ADS)

Penilla, E. H.; Hardin, C. L.; Kodera, Y.; Basun, S. A.; Evans, D. R.; Garay, J. E.

2016-01-01

Light scattering due to birefringence has prevented the use of polycrystalline ceramics with anisotropic optical properties in applications such as laser gain media. However, continued development of processing technology has allowed for very low porosity and fine grains, significantly improving transparency and is paving the way for polycrystalline ceramics to be used in demanding optical applications. We present a method for producing highly transparent Cr3+ doped Al2O3 (ruby) using current activated pressure assisted densification. The one-step doping/densification process produces fine grained ceramics with well integrated (doped) Cr, resulting in good absorption and emission. In order to explain the light transmission properties, we extend the analytical model based on the Rayleigh-Gans-Debye approximation that has been previously used for undoped alumina to include absorption. The model presented captures reflection, scattering, and absorption phenomena in the ceramics. Comparison with measured transmission confirms that the model adequately describes the properties of polycrystalline ruby. In addition the measured emission spectra and emission lifetime are found to be similar to single crystals, confirming the high optical quality of the ceramics.

Atmospheric Pressure Plasma Jet-Assisted Synthesis of Zeolite-Based Low-k Thin Films.

PubMed

Huang, Kai-Yu; Chi, Heng-Yu; Kao, Peng-Kai; Huang, Fei-Hung; Jian, Qi-Ming; Cheng, I-Chun; Lee, Wen-Ya; Hsu, Cheng-Che; Kang, Dun-Yen

2018-01-10

Zeolites are ideal low-dielectric constant (low-k) materials. This paper reports on a novel plasma-assisted approach to the synthesis of low-k thin films comprising pure-silica zeolite MFI. The proposed method involves treating the aged solution using an atmospheric pressure plasma jet (APPJ). The high reactivity of the resulting nitrogen plasma helps to produce zeolite crystals with high crystallinity and uniform crystal size distribution. The APPJ treatment also remarkably reduces the time for hydrothermal reaction. The zeolite MFI suspensions synthesized with the APPJ treatment are used for the wet deposition to form thin films. The deposited zeolite thin films possessed dense morphology and high crystallinity, which overcome the trade-off between crystallinity and film quality. Zeolite thin films synthesized using the proposed APPJ treatment achieve low leakage current (on the order of 10 -8 A/cm 2 ) and high Young's modulus (12 GPa), outperforming the control sample synthesized without plasma treatment. The dielectric constant of our zeolite thin films was as low as 1.41. The overall performance of the low-k thin films synthesized with the APPJ treatment far exceed existing low-k films comprising pure-silica MFI.

Roughness transitions of diamond(100) induced by hydrogen-plasma treatment

NASA Astrophysics Data System (ADS)

Koslowski, B.; Strobel, S.; Wenig, M. J.; Ziemann, P.

To investigate the influence of hydrogen-plasma treatment on diamond(100) surfaces, heavily boron (B)-doped HPHT diamond crystals were mechanically and chemo-mechanically polished, and exposed to a microwave-assisted hydrogen plasma on a time scale of several minutes. The resulting surface morphology was analyzed on macroscopic scales by stylus profilometry (PFM) and on microscopic scales by STM and AFM. The polished samples have a roughness of typically 100 pmrms (PFM), with no obvious anisotropic structures at the surface. After exposure of the B-doped diamond(100) to the H-plasma, the roughness increases dramatically, and pronounced anisotropic structures appear, these being closely aligned with the crystallographic axis' and planes. An exposure for 3 minutes to the plasma leads to an increase of the roughness to 2-4 nmrms (STM), and a `brick-wall' pattern appears, formed by weak cusps running along <110>. Very frequently, the cusps are replaced by `negative' pyramids that are bordered by {11X} facets. After an exposure of an additional 5 minutes, the surface roughness of the B-doped samples increases further to 20-40 nmrms (STM), and frequently exhibits a regular pattern with structures at a characteristic length scale of about 100 nm. Those structures are aligned approximately with <110> and they are faceted with faces of approximately {XX1}. These results will be discussed in terms of strain relaxation, similar to the surface roughening observed on SiGe/Si and anisotropic etching.

Heteroepitaxial Diamond Growth

DTIC Science & Technology

1993-01-12

Si(1 11) = CH2F + H-Si(l 11) 12 20 3 These results and similar results for gas phase reactions involving CHxF4_x species with SilH3 suggest a modified...absent in the signal from diamond.7,8 Glassy carbon also exhibits spectral characteristics similar to those of graphite. 7 The diamond substrate laser...PECVD on Si(100) using an acetic acid/water/methanol mixture at 0.5 Torr and 350 C, similar to results described elsewhere 3. For comparison, a

Diamond based adsorbents and their application in chromatography.

PubMed

Peristyy, Anton A; Fedyanina, Olga N; Paull, Brett; Nesterenko, Pavel N

2014-08-29

The idea of using diamond and diamond containing materials in separation sciences has attracted a strong interest in the past decade. The combination of a unique range of properties, such as chemical inertness, mechanical, thermal and hydrolytic stability, excellent thermal conductivity with minimal thermal expansion and intriguing adsorption properties makes diamond a promising material for use in various modes of chromatography. This review summarises the recent research on the preparation of diamond and diamond based stationary phases, their properties and chromatographic performance. Special attention is devoted to the dominant retention mechanisms evident for particular diamond containing phases, and their subsequent applicability to various modes of chromatography, including chromatography carried out under conditions of high temperature and pressure. Copyright © 2014 Elsevier B.V. All rights reserved.

Jet in jet in M87

NASA Astrophysics Data System (ADS)

Sob'yanin, Denis Nikolaevich

2017-11-01

New high-resolution Very Long Baseline Interferometer observations of the prominent jet in the M87 radio galaxy show a persistent triple-ridge structure of the transverse 15-GHz profile with a previously unobserved ultra-narrow central ridge. This radio structure can reflect the intrinsic structure of the jet, so that the jet as a whole consists of two embedded coaxial jets. A relativistic magnetohydrodynamic model is considered in which an inner jet is placed inside a hollow outer jet and the electromagnetic fields, pressures and other physical quantities are found. The entire jet is connected to the central engine that plays the role of a unipolar inductor generating voltage between the jets and providing opposite electric currents, and the charge neutrality and current closure together with the electromagnetic fields between the jets can contribute to the jet stabilization. The constant voltage is responsible for the similar widening laws observed for the inner and outer jets. This jet-in-jet structure can indicate simultaneous operation of two different jet-launching mechanisms, one relating to the central supermassive black hole and the other to the surrounding accretion disc. An inferred magnetic field of 80 G at the base is sufficient to provide the observed jet luminosity.

9 CFR 311.6 - Diamond-skin disease.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Diamond-skin disease. 311.6 Section... CERTIFICATION DISPOSAL OF DISEASED OR OTHERWISE ADULTERATED CARCASSES AND PARTS § 311.6 Diamond-skin disease. Carcasses of hogs affected with diamond-skin disease when localized and not associated with systemic change...

9 CFR 311.6 - Diamond-skin disease.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 false Diamond-skin disease. 311.6 Section... CERTIFICATION DISPOSAL OF DISEASED OR OTHERWISE ADULTERATED CARCASSES AND PARTS § 311.6 Diamond-skin disease. Carcasses of hogs affected with diamond-skin disease when localized and not associated with systemic change...

9 CFR 311.6 - Diamond-skin disease.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 9 Animals and Animal Products 2 2013-01-01 2013-01-01 false Diamond-skin disease. 311.6 Section... CERTIFICATION DISPOSAL OF DISEASED OR OTHERWISE ADULTERATED CARCASSES AND PARTS § 311.6 Diamond-skin disease. Carcasses of hogs affected with diamond-skin disease when localized and not associated with systemic change...

9 CFR 311.6 - Diamond-skin disease.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 9 Animals and Animal Products 2 2014-01-01 2014-01-01 false Diamond-skin disease. 311.6 Section... CERTIFICATION DISPOSAL OF DISEASED OR OTHERWISE ADULTERATED CARCASSES AND PARTS § 311.6 Diamond-skin disease. Carcasses of hogs affected with diamond-skin disease when localized and not associated with systemic change...

9 CFR 311.6 - Diamond-skin disease.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Diamond-skin disease. 311.6 Section... CERTIFICATION DISPOSAL OF DISEASED OR OTHERWISE ADULTERATED CARCASSES AND PARTS § 311.6 Diamond-skin disease. Carcasses of hogs affected with diamond-skin disease when localized and not associated with systemic change...

27 CFR 9.166 - Diamond Mountain District.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Diamond Mountain District... Diamond Mountain District. (a) Name. The name of the viticultural area described in this section is “Diamond Mountain District.” (b) Approved map. The appropriate maps for determining the boundary of the...

27 CFR 9.166 - Diamond Mountain District.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Diamond Mountain District... Diamond Mountain District. (a) Name. The name of the viticultural area described in this section is “Diamond Mountain District.” (b) Approved map. The appropriate maps for determining the boundary of the...

27 CFR 9.166 - Diamond Mountain District.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Diamond Mountain District... Diamond Mountain District. (a) Name. The name of the viticultural area described in this section is “Diamond Mountain District.” (b) Approved map. The appropriate maps for determining the boundary of the...

Organophosphonate biofunctionalization of diamond electrodes.

PubMed

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

2014-08-27

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

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.

Status and Applications of Diamond and Diamond-Like Materials: An Emerging Technology

DTIC Science & Technology

1990-04-30

solar -blind detectors. * Modulated structures incorporating layers of BN and diamond, for example, to develop materials that are harder and/or tougher...hundredfold increase in power capability over silicon transistors. e Solar -blind detectors, which take advantage of the large energy gap (greater than...Some success has already been achieved, for example, in applying diamond-like coatings to ZnS and ZnSe windows using a Ge-C intermediate layer . " Anti

Isotopic Characterization of Diamond Growth in Fluids

NASA Astrophysics Data System (ADS)

Bureau, Hélène; Remusat, Laurent; Esteve, Imène; Pinti, Daniele; Cartigny, Pierre

2017-04-01

Trapping inclusions in diamonds has been used as a diagnostic to constrain diamond growth media (e.g. Navon et al., 1994; Weiss et al., 2015) in the Earth's upper mantle. Experimental works now generate inclusion-bearing diamonds from seeds in mixtures of carbonates, graphite, and silicates in the presence of excess of pure water or saline fluids (H2O-NaCl) and investigate in more details the conditions of natural diamond growth (Bureau et al., 2012; 2016). Experiments were carried at conditions compatible with the Earth's geotherm between 6-7 GPa (1300-1675°C) in multi-anvil presses at the Bayerisches Geoinstitut, Bayreuth from a few hours two a few days. Results show that within the timescale of the experiments diamond growth occurs on seeds if water and alkali-bearing carbonates are present. We show that water promotes fast diamond growth, which is favorable to the formation of inclusions. Thin sections of a few diamond seeds containing exposed inclusions were prepared using a Focus Ion Beam (about 2 to 5 µm thickness). These sections were deposited on silicon wafers and gold coated for micron-scale determination of the delta 13C isotopic compositions using the NanoSIMS 50 installed at the Muséum National d'Histoire Naturelle, Paris. Carbon isotope measurement with NanoSIMS were calibrated against a natural Ia and a synthetic IIa diamond used for diamond anvil cells, whose compositions were determined by gas-source mass spectrometry at IPGP at 3.6±0.1‰ and -20.9±0.1‰, respectively (Pinti et al., 2016). All the starting materials used for the experiments were also characterized for their delta 13C by the same technique at GEOTOP, Montréal. The isotopic composition of the new diamond grown areas were measured close to the inclusions. They exhibit a different isotopic signature than that of the starting seeds (starting diamond composition: -29.6 to -30.4±1.4‰). The new diamond signatures are falling into the range of signatures of the starting

Microwave-assisted efficient conjugation of nanodiamond and paclitaxel.

PubMed

Hsieh, Yi-Han; Liu, Kuang-Kai; Sulake, Rohidas S; Chao, Jui-I; Chen, Chinpiao

2015-01-01

Nanodiamond has recently received considerable attention due to the various possible applications in medical field such as drug delivery and bio-labeling. For this purpose suitable and effective surface functionalization of the diamond material are required. A versatile and reproducible surface modification method of nanoscale diamond is essential for functionalization. We introduce the input of microwave energy to assist the functionalization of nanodiamond surface. The feasibility of such a process is illustrated by comparing the biological assay of ND-paclitaxel synthesized by conventional and microwave irradiating. Using a microwave we manage to have approximately doubled grafted molecules per nanoparticle of nanodiamond. Copyright © 2015 Elsevier Ltd. All rights reserved.

Behavior of Explosives Under Pressure in a Diamond Anvil Cell

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

Foltz, M F

2006-06-20

Diamond anvil cell (DAC) studies can yield information about the pressure dependence of materials and reactions under conditions comparable to shock loading. The pressure gradient across the face of the diamonds is often deliberately minimized to create uniform pressure over much of the sample and a simplified data set. To reach very high pressures (30-40 GPa), however, it may be necessary to use ''softer'', high nitrogen content diamonds that are more susceptible to bending under pressure. The resulting enhanced pressure gradient then provides a view of high-pressure behavior under anisotropic conditions similar to those found at the burn front inmore » a bulk sample. We discuss visual observations of pressure-induced changes relative to variations in burn rate of several explosives (Triaminotrinitrobenzene, Nitromethane, CL-20) in the DAC. The burn rate behavior of both Nitromethane (NM) and Triaminotrinitrobenzene (TATB) were previously reported for pressures up to {approx}40 GPa. Nitromethane showed a near monotonic increase in burn rate to a maximum at {approx}30 GPa after which the burn rate decreased, all without color change. At higher pressures, the TATB samples had shiny (metallic) polycrystalline zones or inclusions where the pressure was highest in the sample. Around the shiny zones was a gradation of color (red to yellow) that appeared to follow the pressure gradient. The color changes are believed related to disturbances in the resonance structure of this explosive as the intermolecular separations decrease with pressure. The color and type of residue found in unvented gaskets after the burn was complete also varied with pressure. The four polymorphs of CL-20 ({alpha}, {beta}, {gamma}, {var_epsilon}-Hexanitrohexaazaisowurtzitane, HNIW) did not change color up to the highest pressure applied ({approx}30 GPa), and each polymorph demonstrated a distinctly different burn rate signature. One polymorph {beta} was so sensitive to laser ignition over a

14 MeV calibration of JET neutron detectors—phase 1: calibration and characterization of the neutron source

NASA Astrophysics Data System (ADS)

Batistoni, P.; Popovichev, S.; Cufar, A.; Ghani, Z.; Giacomelli, L.; Jednorog, S.; Klix, A.; Lilley, S.; Laszynska, E.; Loreti, S.; Packer, L.; Peacock, A.; Pillon, M.; Price, R.; Rebai, M.; Rigamonti, D.; Roberts, N.; Tardocchi, M.; Thomas, D.; Contributors, JET

2018-02-01

In view of the planned DT operations at JET, a calibration of the JET neutron monitors at 14 MeV neutron energy is needed using a 14 MeV neutron generator deployed inside the vacuum vessel by the JET remote handling system. The target accuracy of this calibration is  ±10% as also required by ITER, where a precise neutron yield measurement is important, e.g. for tritium accountancy. To achieve this accuracy, the 14 MeV neutron generator selected as the calibration source has been fully characterised and calibrated prior to the in-vessel calibration of the JET monitors. This paper describes the measurements performed using different types of neutron detectors, spectrometers, calibrated long counters and activation foils which allowed us to obtain the neutron emission rate and the anisotropy of the neutron generator, i.e. the neutron flux and energy spectrum dependence on emission angle, and to derive the absolute emission rate in 4π sr. The use of high resolution diamond spectrometers made it possible to resolve the complex features of the neutron energy spectra resulting from the mixed D/T beam ions reacting with the D/T nuclei present in the neutron generator target. As the neutron generator is not a stable neutron source, several monitoring detectors were attached to it by means of an ad hoc mechanical structure to continuously monitor the neutron emission rate during the in-vessel calibration. These monitoring detectors, two diamond diodes and activation foils, have been calibrated in terms of neutrons/counts within  ±5% total uncertainty. A neutron source routine has been developed, able to produce the neutron spectra resulting from all possible reactions occurring with the D/T ions in the beam impinging on the Ti D/T target. The neutron energy spectra calculated by combining the source routine with a MCNP model of the neutron generator have been validated by the measurements. These numerical tools will be key in analysing the results from the in

Single-Crystal Diamond Nanobeam Waveguide Optomechanics

NASA Astrophysics Data System (ADS)

Khanaliloo, Behzad; Jayakumar, Harishankar; Hryciw, Aaron C.; Lake, David P.; Kaviani, Hamidreza; Barclay, Paul E.

2015-10-01

Single-crystal diamond optomechanical devices have the potential to enable fundamental studies and technologies coupling mechanical vibrations to both light and electronic quantum systems. Here, we demonstrate a single-crystal diamond optomechanical system and show that it allows excitation of diamond mechanical resonances into self-oscillations with amplitude >200 nm . The resulting internal stress field is predicted to allow driving of electron spin transitions of diamond nitrogen-vacancy centers. The mechanical resonances have a quality factor >7 ×105 and can be tuned via nonlinear frequency renormalization, while the optomechanical interface has a 150 nm bandwidth and 9.5 fm /√{Hz } sensitivity. In combination, these features make this system a promising platform for interfacing light, nanomechanics, and electron spins.

Investigation of the shape transferability of nanoscale multi-tip diamond tools in the diamond turning of nanostructures

NASA Astrophysics Data System (ADS)

Luo, Xichun; Tong, Zhen; Liang, Yingchun

2014-12-01

In this article, the shape transferability of using nanoscale multi-tip diamond tools in the diamond turning for scale-up manufacturing of nanostructures has been demonstrated. Atomistic multi-tip diamond tool models were built with different tool geometries in terms of the difference in the tip cross-sectional shape, tip angle, and the feature of tool tip configuration, to determine their effect on the applied forces and the machined nano-groove geometries. The quality of machined nanostructures was characterized by the thickness of the deformed layers and the dimensional accuracy achieved. Simulation results show that diamond turning using nanoscale multi-tip tools offers tremendous shape transferability in machining nanostructures. Both periodic and non-periodic nano-grooves with different cross-sectional shapes can be successfully fabricated using the multi-tip tools. A hypothesis of minimum designed ratio of tool tip distance to tip base width (L/Wf) of the nanoscale multi-tip diamond tool for the high precision machining of nanostructures was proposed based on the analytical study of the quality of the nanostructures fabricated using different types of the multi-tip tools. Nanometric cutting trials using nanoscale multi-tip diamond tools (different in L/Wf) fabricated by focused ion beam (FIB) were then conducted to verify the hypothesis. The investigations done in this work imply the potential of using the nanoscale multi-tip diamond tool for the deterministic fabrication of period and non-periodic nanostructures, which opens up the feasibility of using the process as a versatile manufacturing technique in nanotechnology.

Quantum Molecular Dynamics Simulations of Nanotube Tip Assisted Reactions

NASA Technical Reports Server (NTRS)

Menon, Madhu

1998-01-01

In this report we detail the development and application of an efficient quantum molecular dynamics computational algorithm and its application to the nanotube-tip assisted reactions on silicon and diamond surfaces. The calculations shed interesting insights into the microscopic picture of tip surface interactions.

Coulometric Study of Rates of Oxalic Acid Adsorption at a Polycrystalline Platinum Electrode

DTIC Science & Technology

2012-09-01

Coulometric Study of Rates of Oxalic Acid Adsorption at a Polycrystalline Platinum Electrode by Sol Gilman ARL-TR-6165 September 2012...6165 September 2012 Coulometric Study of Rates of Oxalic Acid Adsorption at a Polycrystalline Platinum Electrode Sol Gilman Sensors and...3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Coulometric Study of Rates of Oxalic Acid Adsorption at a Polycrystalline Platinum Electrode

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

Enhanced magnetic and thermoelectric properties in epitaxial polycrystalline SrRuO3 thin films.

PubMed

Woo, Sungmin; Lee, Sang A; Mun, Hyeona; Choi, Young Gwan; Zhung, Chan June; Shin, Soohyeon; Lacotte, Morgane; David, Adrian; Prellier, Wilfrid; Park, Tuson; Kang, Won Nam; Lee, Jong Seok; Kim, Sung Wng; Choi, Woo Seok

2018-03-01

Transition metal oxide thin films show versatile electric, magnetic, and thermal properties which can be tailored by deliberately introducing macroscopic grain boundaries via polycrystalline solids. In this study, we focus on the modification of magnetic and thermal transport properties by fabricating single- and polycrystalline epitaxial SrRuO 3 thin films using pulsed laser epitaxy. Using the epitaxial stabilization technique with an atomically flat polycrystalline SrTiO 3 substrate, an epitaxial polycrystalline SrRuO 3 thin film with the crystalline quality of each grain comparable to that of its single-crystalline counterpart is realized. In particular, alleviated compressive strain near the grain boundaries due to coalescence is evidenced structurally, which induced the enhancement of ferromagnetic ordering of the polycrystalline epitaxial thin film. The structural variations associated with the grain boundaries further reduce the thermal conductivity without deteriorating the electronic transport, and lead to an enhanced thermoelectric efficiency in the epitaxial polycrystalline thin films, compared with their single-crystalline counterpart.

Determination of the Tribological Fundamentals of Solid Lubricated Ceramics. Volume 1. Summary

DTIC Science & Technology

1990-11-01

the length of the C-axis), leading to increased critical resolved shear stress/surface shear strength of the polycrystalline graphite and...weaker nature of the graphitic regions. Wear rates of pure, polycrystalline diamond range from -4 x 10- 16 m 3/N • m in vacuum to I x 10ൗ m3/N• m...Intercalated Graphite Molds. Triboflats hand-cut, oc-SiC paper- san !ed and fine diamond paper-polished from NiCI2/ HOPG and CdCl2/ HOPG (to remove the outer 0.5

Investigation of laser ablation of CVD diamond film

NASA Astrophysics Data System (ADS)

Chao, Choung-Lii; Chou, W. C.; Ma, Kung-Jen; Chen, Ta-Tung; Liu, Y. M.; Kuo, Y. S.; Chen, Ying-Tung

2005-04-01

Diamond, having many advanced physical and mechanical properties, is one of the most important materials used in the mechanical, telecommunication and optoelectronic industry. However, high hardness value and extreme brittleness have made diamond extremely difficult to be machined by conventional mechanical grinding and polishing. In the present study, the microwave CVD method was employed to produce epitaxial diamond films on silicon single crystal. Laser ablation experiments were then conducted on the obtained diamond films. The underlying material removal mechanisms, microstructure of the machined surface and related machining conditions were also investigated. It was found that during the laser ablation, peaks of the diamond grains were removed mainly by the photo-thermal effects introduced by excimer laser. The diamond structures of the protruded diamond grains were transformed by the laser photonic energy into graphite, amorphous diamond and amorphous carbon which were removed by the subsequent laser shots. As the protruding peaks gradually removed from the surface the removal rate decreased. Surface roughness (Ra) was improved from above 1μm to around 0.1μm in few minutes time in this study. However, a scanning technique would be required if a large area was to be polished by laser and, as a consequence, it could be very time consuming.

Ion-Implanted Diamond Films and Their Tribological Properties

NASA Technical Reports Server (NTRS)

Wu, Richard L. C.; Miyoshi, Kazuhisa; Korenyi-Both, Andras L.; Garscadden, Alan; Barnes, Paul N.

1993-01-01

This paper reports the physical characterization and tribological evaluation of ion-implanted diamond films. Diamond films were produced by microwave plasma, chemical vapor deposition technique. Diamond films with various grain sizes (0.3 and 3 microns) and roughness (9.1 and 92.1 nm r.m.s. respectively) were implanted with C(+) (m/e = 12) at an ion energy of 160 eV and a fluence of 6.72 x 10(exp 17) ions/sq cm. Unidirectional sliding friction experiments were conducted in ultrahigh vacuum (6.6 x 10(exp -7)Pa), dry nitrogen and humid air (40% RH) environments. The effects of C(+) ion bombardment on fine and coarse-grained diamond films are as follows: the surface morphology of the diamond films did not change; the surface roughness increased (16.3 and 135.3 nm r.m.s.); the diamond structures were damaged and formed a thin layer of amorphous non-diamond carbon; the friction coefficients dramatically decreased in the ultrahigh vacuum (0.1 and 0.4); the friction coefficients decreased slightly in the dry nitrogen and humid air environments.

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.

Tailoring nanocrystalline diamond film properties

DOEpatents

Gruen, Dieter M [Downers Grove, IL; McCauley, Thomas G [Somerville, MA; Zhou, Dan [Orlando, FL; Krauss, Alan R [Naperville, IL

2003-07-15

A method for controlling the crystallite size and growth rate of plasma-deposited diamond films. A plasma is established at a pressure in excess of about 55 Torr with controlled concentrations of hydrogen up to about 98% by volume, of unsubstituted hydrocarbons up to about 3% by volume and an inert gas of one or more of the noble gases and nitrogen up to about 98% by volume. The volume ratio of inert gas to hydrogen is preferably maintained at greater than about 4, to deposit a diamond film on a suitable substrate. The diamond film is deposited with a predetermined crystallite size and at a predetermined growth rate.

A new computer-aided simulation model for polycrystalline silicon film resistors

NASA Astrophysics Data System (ADS)

Ching-Yuan Wu; Weng-Dah Ken

1983-07-01

A general transport theory for the I-V characteristics of a polycrystalline film resistor has been derived by including the effects of carrier degeneracy, majority-carrier thermionic-diffusion across the space charge regions produced by carrier trapping in the grain boundaries, and quantum mechanical tunneling through the grain boundaries. Based on the derived transport theory, a new conduction model for the electrical resistivity of polycrystalline film resitors has been developed by incorporating the effects of carrier trapping and dopant segregation in the grain boundaries. Moreover, an empirical formula for the coefficient of the dopant-segregation effects has been proposed, which enables us to predict the dependence of the electrical resistivity of phosphorus-and arsenic-doped polycrystalline silicon films on thermal annealing temperature. Phosphorus-doped polycrystalline silicon resistors have been fabricated by using ion-implantation with doses ranged from 1.6 × 10 11 to 5 × 10 15/cm 2. The dependence of the electrical resistivity on doping concentration and temperature have been measured and shown to be in good agreement with the results of computer simulations. In addition, computer simulations for boron-and arsenic-doped polycrystalline silicon resistors have also been performed and shown to be consistent with the experimental results published by previous authors.

Selected Topics in CVD Diamond Research

NASA Astrophysics Data System (ADS)

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

2006-10-01

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

The creation of a biomimetic interface between boron-doped diamond and immobilized proteins.

PubMed

Hoffmann, René; Kriele, Armin; Obloh, Harald; Tokuda, Norio; Smirnov, Waldemar; Yang, Nianjun; Nebel, Christoph E

2011-10-01

Immobilization of proteins on a solid electrode is to date done by chemical cross-linking or by addition of an adjustable intermediate. In this paper we introduce a concept where a solid with variable surface properties is optimized to mediate binding of the electron-transfer protein Cytochrome c (Cyt c) by mimicking the natural binding environment. It is shown that, as a carbon-based material, boron-doped diamond can be adjusted by simple electrochemical surface treatments to the specific biochemical requirements of Cyt c. The structure and functionality of passively adsorbed Cyt c on variously terminated diamond surfaces were characterized in detail using a combination of electrochemical techniques and atomic force microscopy with single-molecule resolution. Partially oxidized diamond allowed stable immobilization of Cyt c together with high electron transfer activity, driven by a combination of electrostatic and hydrophobic interactions. This surface mimics the natural binding partner, where coarse orientation is governed by electrostatic interaction of the protein's dipole and hydrophobic interactions assist in formation of the electron transfer complex. The optimized surface mediated electron transfer kinetics around 100 times faster than those reported for other solids and even faster kinetics than on self-assembled monolayers of alkanethiols. Copyright © 2011 Elsevier Ltd. All rights reserved.

High Thermal Conductivity NARloy-Z-Diamond Composite Liner for Advanced Rocket Engines

NASA Technical Reports Server (NTRS)

Bhat, Biliyar; Greene, Sandra

2015-01-01

NARloy-Z (Cu-3Ag-0.5Zr) alloy is state-of-the-art combustion chamber liner material used in liquid propulsion engines such as the RS-68 and RS-25. The performance of future liquid propulsion systems can be improved significantly by increasing the heat transfer through the combustion chamber liner. Prior work1 done at NASA Marshall Space Flight Center (MSFC) has shown that the thermal conductivity of NARloy-Z alloy can be improved significantly by embedding high thermal conductivity diamond particles in the alloy matrix to form NARloy-Z-diamond composite (fig. 1). NARloy-Z-diamond composite containing 40vol% diamond showed 69% higher thermal conductivity than NARloy-Z. It is 24% lighter than NARloy-Z and hence the density normalized thermal conductivity is 120% better. These attributes will improve the performance and life of the advanced rocket engines significantly. The research work consists of (a) developing design properties (thermal and mechanical) of NARloy-Z-D composite, (b) fabrication of net shape subscale combustion chamber liner, and (c) hot-fire testing of the liner to test performance. Initially, NARloy-Z-D composite slabs were made using the Field Assisted Sintering Technology (FAST) for the purpose of determining design properties. In the next step, a cylindrical shape was fabricated to demonstrate feasibility (fig. 3). The liner consists of six cylinders which are sintered separately and then stacked and diffusion bonded to make the liner (fig. 4). The liner will be heat treated, finish-machined, and assembled into a combustion chamber and hot-fire tested in the MSFC test facility (TF 115) to determine perform.

'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.

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.

16 CFR 23.13 - Disclosure of treatments to diamonds

Code of Federal Regulations, 2010 CFR

2010-01-01

... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Disclosure of treatments to diamonds 23.13... JEWELRY, PRECIOUS METALS, AND PEWTER INDUSTRIES § 23.13 Disclosure of treatments to diamonds A diamond is a gemstone product. Treatments to diamonds should be disclosed in the manner prescribed in § 23.22...

16 CFR 23.13 - Disclosure of treatments to diamonds.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Disclosure of treatments to diamonds. 23.13... JEWELRY, PRECIOUS METALS, AND PEWTER INDUSTRIES § 23.13 Disclosure of treatments to diamonds. A diamond is a gemstone product. Treatments to diamonds should be disclosed in the manner prescribed in § 23.22...

16 CFR 23.13 - Disclosure of treatments to diamonds

Code of Federal Regulations, 2011 CFR

2011-01-01

... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Disclosure of treatments to diamonds 23.13... JEWELRY, PRECIOUS METALS, AND PEWTER INDUSTRIES § 23.13 Disclosure of treatments to diamonds A diamond is a gemstone product. Treatments to diamonds should be disclosed in the manner prescribed in § 23.22...

16 CFR 23.13 - Disclosure of treatments to diamonds.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 16 Commercial Practices 1 2012-01-01 2012-01-01 false Disclosure of treatments to diamonds. 23.13... JEWELRY, PRECIOUS METALS, AND PEWTER INDUSTRIES § 23.13 Disclosure of treatments to diamonds. A diamond is a gemstone product. Treatments to diamonds should be disclosed in the manner prescribed in § 23.22...

16 CFR 23.13 - Disclosure of treatments to diamonds.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 16 Commercial Practices 1 2013-01-01 2013-01-01 false Disclosure of treatments to diamonds. 23.13... JEWELRY, PRECIOUS METALS, AND PEWTER INDUSTRIES § 23.13 Disclosure of treatments to diamonds. A diamond is a gemstone product. Treatments to diamonds should be disclosed in the manner prescribed in § 23.22...

Polycrystalline silicon availability for photovoltaic and semiconductor industries

NASA Technical Reports Server (NTRS)

Ferber, R. R.; Costogue, E. N.; Pellin, R.

1982-01-01

Markets, applications, and production techniques for Siemens process-produced polycrystalline silicon are surveyed. It is noted that as of 1982 a total of six Si materials suppliers were servicing a worldwide total of over 1000 manufacturers of Si-based devices. Besides solar cells, the Si wafers are employed for thyristors, rectifiers, bipolar power transistors, and discrete components for control systems. An estimated 3890 metric tons of semiconductor-grade polycrystalline Si will be used in 1982, and 6200 metric tons by 1985. Although the amount is expected to nearly triple between 1982-89, research is being carried out on the formation of thin films and ribbons for solar cells, thereby eliminating the waste produced in slicing Czolchralski-grown crystals. The free-world Si production in 1982 is estimated to be 3050 metric tons. Various new technologies for the formation of polycrystalline Si at lower costs and with less waste are considered. New entries into the industrial Si formation field are projected to produce a 2000 metric ton excess by 1988.

Double-charming Higgs boson identification using machine-learning assisted jet shapes

NASA Astrophysics Data System (ADS)

Lenz, Alexander; Spannowsky, Michael; Tetlalmatzi-Xolocotzi, Gilberto

2018-01-01

We study the possibility of identifying a boosted resonance that decays into a charm pair against different sources of background using QCD event shapes, which are promoted to jet shapes. Using a set of jet shapes as input to a boosted decision tree, we find that observables utilizing the simultaneous presence of two charm quarks can access complementary information compared to approaches relying on two independent charm tags. Focusing on Higgs associated production with subsequent H →c c ¯ decay and on a C P -odd scalar A with mA≤10 GeV we obtain the limits B r (H →c c ¯ )≤6.48 % and B r (H →A (→c c ¯ )Z )≤0.01 % at 95% C.L.

Preparation of fluorescent nanodiamond suspensions using bead-assisted ultrasonic disintegration

NASA Astrophysics Data System (ADS)

Głowacki, Maciej J.; Gardas, Mateusz; Ficek, Mateusz; Sawczak, Mirosław; Bogdanowicz, Robert

2017-08-01

Nitrogen-vacancy (N-V) centers are the most widely studied crystallographic defect in the diamond lattice since their presence causes strong and stable fluorescence. The negative charge state of the defect (NV-) is especially desired because of its potential for quantum information processing. In this study, fluorescent suspensions of diamond particles have been produced by microbead-assisted ultrasonic disintegration of commercially obtained diamond powder containing N-V color centers. Zirconium dioxide ZrO2 was chosen as an abrasive and a mixture of deionized water and dimethyl sulfoxide (DMSO) was used as a solvent. Raman spectrum of the starting material has been obtained and the resulting liquids have been measured in terms of photoluminescence. Moreover, thin layer of the diamond particles has been deposited on a silicon substrate and examined using scanning electron microscopy (SEM). During the course of the experiment a new method, which uses sodium chloride NaCl as an abrasive, has been proposed. The results of fluorescence measurements of the suspension prepared using this technique are highly promising.

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

Nondestructive method and apparatus for imaging grains in curved surfaces of polycrystalline articles

DOEpatents

Carpenter, Donald A.

1995-01-01

A nondestructive method, and associated apparatus, are provided for determining the grain flow of the grains in a convex curved, textured polycrystalline surface. The convex, curved surface of a polycrystalline article is aligned in a horizontal x-ray diffractometer and a monochromatic, converging x-ray beam is directed onto the curved surface of the polycrystalline article so that the converging x-ray beam is diffracted by crystallographic planes of the grains in the polycrystalline article. The diffracted x-ray beam is caused to pass through a set of horizontal, parallel slits to limit the height of the beam and thereafter. The linear intensity of the diffracted x-ray is measured, using a linear position sensitive proportional counter, as a function of position in a direction orthogonal to the counter so as to generate two dimensional data. An image of the grains in the curved surface of the polycrystalline article is provided based on the two-dimensional data.

Nondestructive method and apparatus for imaging grains in curved surfaces of polycrystalline articles