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1

Nitrogen-incorporated ultrananocrystalline diamond and multi-layer-graphene-like hybrid carbon films  

PubMed Central

Nitrogen-incorporated ultrananocrystalline diamond (N-UNCD) and multi-layer-graphene-like hybrid carbon films have been synthesized by microwave plasma enhanced chemical vapor deposition (MPECVD) on oxidized silicon which is pre-seeded with diamond nanoparticles. MPECVD of N-UNCD on nanodiamond seeds produces a base layer, from which carbon structures nucleate and grow perpendicularly to form standing carbon platelets. High-resolution transmission electron microscopy and Raman scattering measurements reveal that these carbon platelets are comprised of ultrananocrystalline diamond embedded in multilayer-graphene-like carbon structures. The hybrid carbon films are of low electrical resistivity. UNCD grains in the N-UNCD base layer and the hybrid carbon platelets serve as high-density diamond nuclei for the deposition of an electrically insulating UNCD film on it. Biocompatible carbon-based heaters made of low-resistivity hybrid carbon heaters encapsulated by insulating UNCD for possible electrosurgical applications have been demonstrated.

Tzeng, Yonhua; Yeh, Shoupu; Fang, Wei Cheng; Chu, Yuehchieh

2014-01-01

2

Nitrogen-incorporated ultrananocrystalline diamond and multi-layer-graphene-like hybrid carbon films  

NASA Astrophysics Data System (ADS)

Nitrogen-incorporated ultrananocrystalline diamond (N-UNCD) and multi-layer-graphene-like hybrid carbon films have been synthesized by microwave plasma enhanced chemical vapor deposition (MPECVD) on oxidized silicon which is pre-seeded with diamond nanoparticles. MPECVD of N-UNCD on nanodiamond seeds produces a base layer, from which carbon structures nucleate and grow perpendicularly to form standing carbon platelets. High-resolution transmission electron microscopy and Raman scattering measurements reveal that these carbon platelets are comprised of ultrananocrystalline diamond embedded in multilayer-graphene-like carbon structures. The hybrid carbon films are of low electrical resistivity. UNCD grains in the N-UNCD base layer and the hybrid carbon platelets serve as high-density diamond nuclei for the deposition of an electrically insulating UNCD film on it. Biocompatible carbon-based heaters made of low-resistivity hybrid carbon heaters encapsulated by insulating UNCD for possible electrosurgical applications have been demonstrated.

Tzeng, Yonhua; Yeh, Shoupu; Fang, Wei Cheng; Chu, Yuehchieh

2014-03-01

3

Systematic studies of the nucleation and growth of ultrananocrystalline diamond films on silicon substrates coated with a tungsten layer  

SciTech Connect

We report on effects of a tungsten layer deposited on silicon surface on the effectiveness for diamond nanoparticles to be seeded for the deposition of ultrananocrystalline diamond (UNCD). Rough tungsten surface and electrostatic forces between nanodiamond seeds and the tungsten surface layer help to improve the adhesion of nanodiamond seeds on the tungsten surface. The seeding density on tungsten coated silicon thus increases. Tungsten carbide is formed by reactions of the tungsten layer with carbon containing plasma species. It provides favorable (001) crystal planes for the nucleation of (111) crystal planes by Microwave Plasma Enhanced Chemical Vapor Deposition (MPECVD) in argon diluted methane plasma and further improves the density of diamond seeds/nuclei. UNCD films grown at different gas pressures on tungsten coated silicon which is pre-seeded by nanodiamond along with heteroepitaxially nucleated diamond nuclei were characterized by Raman scattering, field emission-scanning electron microscopy, and high resolution-transmission electron microscopy.

Chu, Yueh-Chieh; Jiang, Gerald [Institute of Microelectronics, No.1, University Road, Tainan 701, Taiwan (China); Tu, Chia-Hao [Institute of Nanotechnology and Microsystems Engineering, No.1, University Road, Tainan 701, Taiwan (China); Department of Materials Science and Engineering, National Cheng Kung University, No.1, University Road, Tainan 701, Taiwan (China); Chang Chi [Institute of Nanotechnology and Microsystems Engineering, No.1, University Road, Tainan 701, Taiwan (China); Liu, Chuan-pu; Ting, Jyh-Ming [Department of Materials Science and Engineering, National Cheng Kung University, No.1, University Road, Tainan 701, Taiwan (China); Lee, Hsin-Li [Industrial Technology Research Institute - South, Tainan 701, Taiwan (China); Tzeng, Yonhua [Institute of Microelectronics, No.1, University Road, Tainan 701, Taiwan (China); Advanced Optoelectronics Technology Center, No.1, University Road, Tainan 701, Taiwan (China); Auciello, Orlando [Argonne National Laboratory, Materials Science Division, 9700 S. Cass Avenue, Argonne, Illinois 60439 (United States)

2012-06-15

4

Nanopatterning of ultrananocrystalline diamond nanowires.  

PubMed

We report the fabrication of horizontally aligned ultrananocrystalline diamond (UNCD) nanowires (NWs) via two different approaches. First, with the top-down approach by using electron beam lithography (EBL) and reactive ion etching (RIE) with a photo resist layer as an etch mask. Using this approach, we demonstrate fabrication of 50 µm long UNCD NWs with widths as narrow as 40 nm. We further present an alternative approach to grow UNCD NWs at pre-defined positions through a selective seeding process. No RIE was needed either to etch the NWs or to remove the mask. In this case, we achieved UNCD NWs with lengths of 50 µm and smallest width of 90 nm respectively. Characterization of these nanowires by using scanning electron microscopy (SEM) and atomic force microscopy (AFM) shows that the UNCD NWs are well defined and fully released, with no indication of residual stress. Characterization using visible and ultraviolet (UV) Raman spectroscopy indicates that in both fabrication approaches, UNCD NWs maintain their intrinsic diamond structure. PMID:22261094

Wang, Xinpeng; Ocola, Leonidas E; Divan, Ralu S; Sumant, Anirudha V

2012-02-24

5

Nanopatterning of ultrananocrystalline diamond thin films via block copolymer lithography.  

SciTech Connect

Nanopatterning of diamond surfaces is critical for the development of diamond-based microelectromechanical system/nanoelectromechanical system (MEMS/NEMS), such as resonators or switches. Micro-/nanopatterning of diamond materials is typically done using photolithography or electron beam lithography combined with reactive ion etching (RIE). In this work, we demonstrate a simple process, block copolymer (BCP) lithography, for nanopatterning of ultrananocrystalline diamond (UNCD) films to produce nanostructures suitable for the fabrication of NEMS based on UNCD. In BCP lithography, nanoscale self-assembled polymeric domains serve as an etch mask for pattern transfer. The authors used thin films of a cylinder-forming organic-inorganic BCP, poly(styrene-block-ferrocenyldimethylsilane), PS-b-PFS, as an etch mask on the surface of UNCD films. Orientational control of the etch masking cylindrical PFS blocks is achieved by manipulating the polymer film thickness in concert with the annealing treatment. We have observed that the surface roughness of UNCD layers plays an important role in transferring the pattern. Oxygen RIE was used to etch the exposed areas of the UNCD film underneath the BCP. Arrays of both UNCD posts and wirelike structures have been created using the same starting polymeric materials as the etch mask.

Ramanathan, M.; Darling, S. B.; Sumant, A. V.; Auciello, O.

2010-07-01

6

Carbon Nanocomposite Based on Carbon Nanotubes and Ultrananocrystalline Diamond  

Microsoft Academic Search

Carbon-based nanostructured materials exhibit many interesting properties that are dictated by the many different bonding configurations available to carbon. Two typical examples are carbon nanotubes (CNTs) and ultrananocrystalline diamond (UNCD), with the former being sp2 bonded carbon and latter being sp3 bonded carbon. Recent advances in micro and nanofabrication techniques have made possible the development of microscale and perhaps even

Xingcheng Xiao; Jian Wang; Orlando Auciello; John A. Carlisle

2004-01-01

7

Microplasma illumination enhancement of vertically aligned conducting ultrananocrystalline diamond nanorods  

PubMed Central

Vertically aligned conducting ultrananocrystalline diamond (UNCD) nanorods are fabricated using the reactive ion etching method incorporated with nanodiamond particles as mask. High electrical conductivity of 275??·cm?1 is obtained for UNCD nanorods. The microplasma cavities using UNCD nanorods as cathode show enhanced plasma illumination characteristics of low threshold field of 0.21?V/?m with plasma current density of 7.06?mA/cm2 at an applied field of 0.35?V/?m. Such superior electrical properties of UNCD nanorods with high aspect ratio potentially make a significant impact on the diamond-based microplasma display technology.

2012-01-01

8

Microplasma illumination enhancement of vertically aligned conducting ultrananocrystalline diamond nanorods.  

PubMed

Vertically aligned conducting ultrananocrystalline diamond (UNCD) nanorods are fabricated using the reactive ion etching method incorporated with nanodiamond particles as mask. High electrical conductivity of 275??·cm-1 is obtained for UNCD nanorods. The microplasma cavities using UNCD nanorods as cathode show enhanced plasma illumination characteristics of low threshold field of 0.21?V/?m with plasma current density of 7.06?mA/cm2 at an applied field of 0.35?V/?m. Such superior electrical properties of UNCD nanorods with high aspect ratio potentially make a significant impact on the diamond-based microplasma display technology. PMID:23009733

Sankaran, Kamatchi Jothiramalingam; Kunuku, Srinivasu; Lou, Shiu-Cheng; Kurian, Joji; Chen, Huang-Chin; Lee, Chi-Young; Tai, Nyan-Hwa; Leou, Keh-Chyang; Chen, Chulung; Lin, I-Nan

2012-01-01

9

Charging characteritiscs of ultrananocrystalline diamond in RF MEMS capacitive switches.  

SciTech Connect

Modifications to a standard capacitive MEMS switch process have been made to allow the incorporation of ultra-nano-crystalline diamond as the switch dielectric. The impact on electromechanical performance is minimal. However, these devices exhibit uniquely different charging characteristics, with charging and discharging time constants 5-6 orders of magnitude quicker than conventional materials. This operation opens the possibility of devices which have no adverse effects of dielectric charging and can be operated near-continuously in the actuated state without significant degradation in reliability.

Sumant, A. V.; Goldsmith, C.; Auciello, O.; Carlisle, J.; Zheng, H.; Hwang, J. C. M.; Palego, C.; Wang, W.; Carpick, R.; Adiga, V.; Datta, A.; Gudeman, C.; O'Brien, S.; Sampath, S.

2010-05-01

10

Characterization of ultrananocrystalline diamond microsensors for in vivo dopamine detection  

PubMed Central

We show the technical feasibility of coating and micro patterning boron-doped ultrananocrystalline diamond (UNCD®) on metal microwires and of applying them as microsensors for the detection of dopamine in vivo using fast-scan cyclic voltammetry. UNCD electrode surface consistently generated electrochemical signals with high signal-to-noise ratio of >800 using potassium ferrocyanide-ferricyanide redox couple. Parylene patterned UNCD microelectrodes were effectively applied to detect dopamine reliably in vitro using flow injection analysis with a detection limit of 27?nM and in the striatum of the anesthetized rat during electrical stimulation of dopamine neurons.

Arumugam, Prabhu U.; Zeng, Hongjun; Siddiqui, Shabnam; Covey, Dan P.; Carlisle, John A.; Garris, Paul A.

2013-01-01

11

Uncovering the Physical Basis Connecting Environment and Tribological Performance of Ultrananocrystalline Diamond.  

National Technical Information Service (NTIS)

In the first year of this project, the researchers studied the nano- scale mechanical and tribological properties of ultrananocrystalline diamond (UNCD), which is a thin-film material known to have extremely high strength and excellent tribological proper...

Y. Jeng

2012-01-01

12

Carbon Nanocomposite Based on Carbon Nanotubes and Ultrananocrystalline Diamond  

NASA Astrophysics Data System (ADS)

Carbon-based nanostructured materials exhibit many interesting properties that are dictated by the many different bonding configurations available to carbon. Two typical examples are carbon nanotubes (CNTs) and ultrananocrystalline diamond (UNCD), with the former being sp2 bonded carbon and latter being sp3 bonded carbon. Recent advances in micro and nanofabrication techniques have made possible the development of microscale and perhaps even nanoscale devices that capitalize on the many intrinsic strengths of these carbon-based materials. The focus of our study has been to prepare CNTs/UNCD composites. We demonstrate in this presentation the simultaneous growth of carbon nanotubes and diamond with the Ar/CH4 (99:1) plasma chemistry. The relative fraction of UNCD and CNTs was controlled by adjusting the relative density of diamond seeds and catalyst particles for the nucleation of UNCD and CNTs. Different methods, including Scanning Electron Microscopy (SEM), Raman Spectroscopy, Transmission Electron Microscopy (TEM) and Near Edge X-ray Absorption Fine Structure (NEXAFS) were used to characterize the composite nanostructures. The field emission and electrochemical properties of the composites were investigated. All these studies provide guidance to further explore the application of the CNTs/UNCD composites as field emitters and novel biosensors.

Xiao, Xingcheng; Wang, Jian; Auciello, Orlando; Carlisle, John A.

2004-03-01

13

Cell Growth on Different Types of Ultrananocrystalline Diamond Thin Films  

PubMed Central

Unique functional materials provide a platform as scaffolds for cell/tissue regeneration. Investigation of cell-materials’ chemical and biological interactions will enable the application of more functional materials in the area of bioengineering, which provides a pathway to the novel treatment for patients who suffer from tissue/organ damage and face the limitation of donation sources. Many studies have been made into tissue/organ regeneration. Development of new substrate materials as platforms for cell/tissue regeneration is a key research area. Studies discussed in this paper focus on the investigation of novel ultrananocrystalline diamond (UNCD) films as substrate/scaffold materials for developmental biology. Specially designed quartz dishes have been coated with different types of UNCD films and cells were subsequently seeded on those films. Results showed the cells’ growth on UNCD-coated culture dishes are similar to cell culture dishes with little retardation, indicating that UNCD films have no or little inhibition on cell proliferation and are potentially appealing as substrate/scaffold materials. The mechanisms of cell adhesion on UNCD surfaces are proposed based on the experimental results. The comparisons of cell cultures on diamond-powder-seeded culture dishes and on UNCD-coated dishes with matrix-assisted laser desorption/ionization—time-of-flight mass spectroscopy (MALDI-TOF MS) and X-ray photoelectron spectroscopy (XPS) analyses provided valuable data to support the mechanisms proposed to explain the adhesion and proliferation of cells on the surface of the UNCD platform.

Shi, Bing; Jin, Qiaoling; Chen, Liaohai; Woods, Amina S.; Schultz, Albert J.; Auciello, Orlando

2012-01-01

14

Effects of pretreatment processes on improving the formation of ultrananocrystalline diamond  

SciTech Connect

Effects of pretreatment on the nuclei formation of ultrananocrystalline diamond (UNCD) on Si substrates were studied. Either precoating a thin layer of titanium ({approx}400 nm) or ultrasonication pretreatment using diamond and titanium mixed powder (D and T process) enhances the nucleation process on Si substrates markedly, and the UNCD nuclei formed and fully covered the Si substrate, when deposition was processed using the microwave-plasma-enhanced chemical-vapor deposition process for 10 min. In contrast, during the same period, ultrasonication pretreatment using diamond powders (D process) can only form large UNCD clusters, which were scarcely distributed on Si substrates. The analyses using x-ray diffractometer, secondary ion mass spectroscopy, and electron spectroscopy for chemical analysis reveal that the titanium layer reacted with carbon species in the plasma, forming crystalline TiC phase, which facilitates the subsequent formation of UNCD nuclei. The beneficial effect of Ti layer on enhancing the nucleation of UNCD is presumably owing to high solubility and high diffusivity of carbon species in Ti materials, as compared with those of Si materials.

Chen, Li-Ju; Tai, Nyan-Hwa; Lee, Chi-Young; Lin, I-Nan. [Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu, Taiwan 300 (China); Department of Physics, Tamkang University, Tamsui, Taiwan 251 (China)

2007-03-15

15

Surface Functionalization of Plasma Treated Ultrananocrystalline Diamond/Amorphous Carbon Composite Films  

NASA Astrophysics Data System (ADS)

Diamond possesses a number of outstanding properties which make it a perspective material as platform for preparation of biosensors. The diamond surface needs to be activated before the chemical attachment of crosslinkers with which biomolecules can interact. In the current work we have investigated the modification of ultrananocrystalline diamond/amorphous carbon (UNCD/a-C) films by oxygen and ammonia plasmas. Afterwards the layers were functionalized in a further step to obtain thiol-active maleimide groups on the surface. We studied the possibility for direct binding of maleimide to terminal OH-groups on the UNCD surface and for silanization with 3-aminopropyltriethoxysilane (APTES) to obtain NH2-groups for the following attachment of sulfosuccinimidyl 4-(N-maleimidomethyl)-cyclohexane-1-carboxylate (SSMCC). The thiol-bearing fluorescein-related dye 5-((2-(and-3)-S-(acetylmercapto) succinoyl) amino) fluorescein (SAMSA) was immobilized as an model biomolecule to evaluate the achieved thiol-activity by fluorescence microscopy. The results of the above mentioned surface modification and functionalization steps were investigated by Auger electron spectroscopy (AES) and contact angle measurements.

Koch, Hermann; Popov, Cyril; Kulisch, Wilhelm; Spassov, G.; Reithmaier, Johann Peter

16

Electron paramagnetic resonance study of hydrogen-incorporated ultrananocrystalline diamond thin films  

Microsoft Academic Search

Hydrogen-incorporated ultrananocrystalline diamond (UNCD) thin films have been deposited in microwave plasma enhanced chemical vapor deposition (MPECVD) system with various hydrogen concentrations in the Ar\\/CH4 gas mixture, and characterized by several techniques including electron paramagnetic resonance (EPR), Raman spectroscopy, scanning electron microscope (SEM), and dc conductivity measurements. The EPR spectrum of diamond film was composed of two Lorentzian lines with

Chao Liu; Xingcheng Xiao; Hsien-Hau Wang; Orlando Auciello; John A. Carlisle

2007-01-01

17

Engineering the interface characteristics of ultrananocrystalline diamond films grown on Au-coated Si substrates.  

PubMed

Enhanced electron field emission (EFE) properties have been observed for ultrananocrystalline diamond (UNCD) films grown on Au-coated Si (UNCD/Au-Si) substrates. The EFE properties of UNCD/Au-Si could be turned on at a low field of 8.9 V/?m, attaining EFE current density of 4.5 mA/cm(2) at an applied field of 10.5 V/?m, which is superior to that of UNCD films grown on Si (UNCD/Si) substrates with the same chemical vapor deposition process. Moreover, a significant difference in current-voltage curves from scanning tunneling spectroscopic measurements at the grain and the grain boundary has been observed. From the variation of normalized conductance (dI/dV)/(I/V) versus V, bandgap of UNCD/Au-Si is measured to be 2.8 eV at the grain and nearly metallic at the grain boundary. Current imaging tunneling spectroscopy measurements show that the grain boundaries have higher electron field emission capacity than the grains. The diffusion of Au into the interface layer that results in the induction of graphite and converts the metal-to-Si interface from Schottky to Ohmic contact is believed to be the authentic factors, resulting in marvelous EFE properties of UNCD/Au-Si. PMID:22823911

Sankaran, Kamatchi Jothiramalingam; Panda, Kalpataru; Sundaravel, Balakrishnan; Chen, Huang-Chin; Lin, I-Nan; Lee, Chi-Young; Tai, Nyan-Hwa

2012-08-01

18

Ultrananocrystalline and nanocrystalline diamond thin films for NEMS/MEMS applications.  

SciTech Connect

There has been a tireless quest by the designers of micro- and nanoelectro mechanical systems (MEMS/NEMS) to find a suitable material alternative to conventional silicon. This is needed to develop robust, reliable, and long-endurance MEMS/NEMS with capabilities for working under demanding conditions, including harsh environments, high stresses, or with contacting and sliding surfaces. Diamond is one of the most promising candidates for this because of its superior physical, chemical, and tribomechanical properties. Ultrananocrystalline diamond (UNCD) and nanocrystalline diamond (NCD) thin films, the two most studied forms of diamond films in the last decade, have distinct growth processes and nanostructures but complementary properties. This article reviews the fundamental and applied science performed to understand key aspects of UNCD and NCD films, including the nucleation and growth, tribomechanical properties, electronic properties, and applied studies on integration with piezoelectric materials and CMOS technology. Several emerging diamond-based MEMS/NEMS applications, including high-frequency resonators, radio frequency MEMS and photonic switches, and the first commercial diamond MEMS product - monolithic diamond atomic force microscopy probes - are discussed.

Sumant, A. V.; Auciello, O.; Carpick, R. W.; Srinivasan, S.; Butler, J. E. (Center for Nanoscale Materials); ( MSD); ( PSC-USR)

2010-04-01

19

On the enhancement of field emission performance of ultrananocrystalline diamond coated nanoemitters  

SciTech Connect

Ultrananocrystalline diamond (UNCD) nanoemitters were synthesized by a microwave plasma enhanced chemical vapor deposition process using silicon nanowires (SiNWs) as the template. Preseeding markedly enhances the nucleation of diamond on the SiNW templates, resulting in UNCD grains of smaller size and uniform distribution, which leads to significantly improved electron field emission (EFE) properties. The EFE for UNCD nanoemitters can be turned on at (E{sub 0}){sub UNCD-NE}=4.4 V/{mu}m, achieving large EFE current density, (J{sub e}){sub UNCD-NE}=13.9 mA/cm{sup 2} at an applied field of 12 V/{mu}m, which is comparable with that of carbon nanotubes, but with much better processing reliability.

Tzeng, Y.-F.; Lee, Y.-C.; Lee, C.-Y.; Lin, I.-N.; Chiu, H.-T. [Department of Materials Science and Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 30043, Taiwan (China); Center of Nanotechnology, Materials Science, and Microsystem, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 30043, Taiwan (China); Department of Physics, Tamkang University, 151 Ying-Chuan Rd., Tamsui 251, Taiwan (China); Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30050, Taiwan (China)

2007-08-06

20

Low-loss lateral-extensional piezoelectric filters on ultrananocrystalline diamond.  

PubMed

In this work, lateral-extensional thin-film piezoelectric- on-diamond (TPoD) filters with very low insertion loss (IL) values (<4 dB) are reported. Two different lateral-extensional modes of a resonant structure are coupled together to realize a two-pole filter. The filters of this work exhibit low IL values, with fractional bandwidth between 0.08% and 0.2%, and have a very small footprint. This paper reports on the lowest IL in the literature for lateral-extensional thin-film piezoelectric filters with 50 ? terminations in the GSM frequency band (~900 MHz). The narrow-band filters of this work are fabricated on three ultrananocrystalline diamond substrates to achieve higher frequencies without excessive reduction in the feature size. The paper also thoroughly studies the parameters that affect the performance of such filters and then discussions are evaluated by the statistical data collected from the fabricated wafers. PMID:24658729

Fatemi, Hediyeh; Abdolvand, Reza

2013-09-01

21

Flexible electron field emitters fabricated using conducting ultrananocrystalline diamond pyramidal microtips on polynorbornene films  

NASA Astrophysics Data System (ADS)

High performance flexible field emitters made of aligned pyramidal shaped conducting ultrananocrystalline diamond (C-UNCD) microtips on polynorbornene substrates is demonstrated. Flexible C-UNCD pyramidal microtips show a low turn-on field of 1.80 V/?m with a field enhancement factor of 4580 and a high emission current density of 5.8 mA/cm2 (at an applied field of 4.20 V/?m) with life-time stability of 210 min. Such an enhancement in the field emission is due to the presence of sp2-graphitic sheath with a nanowire-like diamond core. This high performance flexible C-UNCD field emitter is potentially useful for the fabrication of diverse, flexible electronic devices.

Sankaran, K. J.; Tai, N. H.; Lin, I. N.

2014-01-01

22

Low-temperature electrical transport in B-doped ultrananocrystalline diamond film  

NASA Astrophysics Data System (ADS)

B-doped ultrananocrystalline diamond (UNCD) films are grown using hot-filament chemical vapor deposition method, and their electrical transport properties varying with temperature are investigated. When the B-doped concentration of UNCD film is low, a step-like increase feature of the resistance is observed with decreasing temperature, reflecting at least three temperature-modified electronic state densities at the Fermi level according to three-dimensional Mott's variable range hopping transport mechanism, which is very different from that of reported B-doped nanodiamond. With increasing B-doped concentration, a superconductive transformation occurs in the UNCD film and the highest transformation temperature of 5.3 K is observed, which is higher than that reported for superconducting nanodiamond films. In addition, the superconducting coherence length is about 0.63 nm, which breaks a reported theoretical and experimental prediction about ultra-nanoscale diamond's superconductivity.

Li, Lin; Zhao, Jing; Hu, Zhaosheng; Quan, Baogang; Li, Junjie; Gu, Changzhi

2014-05-01

23

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

EPA Science Inventory

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

24

Improvement in plasma illumination properties of ultrananocrystalline diamond films by grain boundary engineering  

NASA Astrophysics Data System (ADS)

Microstructural evolution of ultrananocrystalline diamond (UNCD) films as a function of substrate temperature (TS) and/or by introducing H2 in Ar/CH4 plasma is investigated. Variation of the sp2 and sp3 carbon content is analyzed using UV-Raman and near-edge X-ray absorption fine structure spectra. Morphological and microstructural studies confirm that films deposited using Ar/CH4 plasma at low TS consist of a random distribution of spherically shaped ultra-nano diamond grains with distinct sp2-bonded grain boundaries, which are attributed to the adherence of CH radicals to the nano-sized diamond clusters. By increasing TS, adhering efficiency of CH radicals to the diamond lattice drops and trans-polyacetylene (t-PA) encapsulating the nano-sized diamond grains break, whereas the addition of 1.5% H2 in Ar/CH4 plasma at low TS induces atomic hydrogen that preferentially etches out the t-PA attached to ultra-nano diamond grains. Both cases make the sp3-diamond phase less passivated. This leads to C2 radicals attaching to the diamond lattice promoting elongated clustered grains along with a complicated defect structure. Such a grain growth model is highly correlated to explain the technologically important functional property, namely, plasma illumination (PI) of UNCD films. Superior PI properties, viz. low threshold field of 0.21 V/?m with a high PI current density of 4.10 mA/cm2 (at an applied field of 0.25 V/?m) and high ?-coefficient (0.2604) are observed for the UNCD films possessing ultra-nano grains with a large fraction of grain boundary phases. The grain boundary component consists of a large amount of sp2-carbon phases that possibly form interconnected paths for facilitating the transport of electrons and the electron field emission process that markedly enhance PI properties.

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

2013-08-01

25

Effects of Boron Doping on the Properties of Ultrananocrystalline Diamond Films  

NASA Astrophysics Data System (ADS)

Boron-doped ultrananocrystalline diamond (UNCD) films were fabricated on silicon substrates by microwave plasma chemical vapor deposition. UNCD films containing different concentrations of boron were prepared by using trimethylboron (B(CH3)3, TMB) as boron doping source and varying the amount of boron in the gas mixture from 0 ppm to 1000 ppm. The effects of boron doping on morphology, lattice parameter, phase composition, crystal size, and residual stress of UNCD films were investigated. No obvious change of the morphology was observed on doping with boron, and all the films had the UNCD crystal grains. Boron doping enhanced (111) growth. The preferred growth direction of the UNCD films was . Residual tensile stress was present in all the films, and increased with increasing the amount of boron in the gas mixture.

Yuan, Wen-Xiang; WU, Q. X.; Luo, Z. K.; Wu, H. S.

2014-04-01

26

Ultrananocrystalline diamond tip integrated onto a heated atomic force microscope cantilever.  

PubMed

We report a wear-resistant ultrananocrystalline (UNCD) diamond tip integrated onto a heated atomic force microscope (AFM) cantilever and UNCD tips integrated into arrays of heated AFM cantilevers. The UNCD tips are batch-fabricated and have apex radii of approximately 10 nm and heights up to 7 ?m. The solid-state heater can reach temperatures above 600 °C and is also a resistive temperature sensor. The tips were shown to be wear resistant throughout 1.2 m of scanning on a single-crystal silicon grating at a force of 200 nN and a speed of 10 ?m s(-1). Under the same conditions, a silicon tip was completely blunted. We demonstrate the use of these heated cantilevers for thermal imaging in both contact mode and intermittent contact mode, with a vertical imaging resolution of 1.9 nm. The potential application to nanolithography was also demonstrated, as the tip wrote hundreds of polyethylene nanostructures. PMID:23149947

Kim, Hoe Joon; Moldovan, Nicolaie; Felts, Jonathan R; Somnath, Suhas; Dai, Zhenting; Jacobs, Tevis D B; Carpick, Robert W; Carlisle, John A; King, William P

2012-12-14

27

Ultrananocrystalline diamond film as an optimal cell interface for biomedical applications.  

SciTech Connect

Surfaces of materials that promote cell adhesion, proliferation, and growth are critical for new generation of implantable biomedical devices. These films should be able to coat complex geometrical shapes very conformally, with smooth surfaces to produce hermetic bioinert protective coatings, or to provide surfaces for cell grafting through appropriate functionalization. Upon performing a survey of desirable properties such as chemical inertness, low friction coefficient, high wear resistance, and a high Young's modulus, diamond films emerge as very attractive candidates for coatings for biomedical devices. A promising novel material is ultrananocrystalline diamond (UNCD{reg_sign}) in thin film form, since UNCD possesses the desirable properties of diamond and can be deposited as a very smooth, conformal coating using chemical vapor deposition. In this paper, we compared cell adhesion, proliferation, and growth on UNCD films, silicon, and platinum films substrates using different cell lines. Our results showed that UNCD films exhibited superior characteristics including cell number, total cell area, and cell spreading. The results could be attributed to the nanostructured nature or a combination of nanostructure/surface chemistry of UNCD, which provides a high surface energy, hence promoting adhesion between the receptors on the cell surface and the UNCD films.

Bajaj, P.; Akin, D.; Gupta, A.; Sherman, D.; Shi, B.; Auciello, O.; Bashir, R.; Purdue Univ.; Massachusetts General Hospital

2007-12-01

28

Ultrananocrystalline diamond film as an optimal cell interface for biomedical applications.  

PubMed

Surfaces of materials that promote cell adhesion, proliferation, and growth are critical for new generation of implantable biomedical devices. These films should be able to coat complex geometrical shapes very conformally, with smooth surfaces to produce hermetic bioinert protective coatings, or to provide surfaces for cell grafting through appropriate functionalization. Upon performing a survey of desirable properties such as chemical inertness, low friction coefficient, high wear resistance, and a high Young's modulus, diamond films emerge as very attractive candidates for coatings for biomedical devices. A promising novel material is ultrananocrystalline diamond (UNCD) in thin film form, since UNCD possesses the desirable properties of diamond and can be deposited as a very smooth, conformal coating using chemical vapor deposition. In this paper, we compared cell adhesion, proliferation, and growth on UNCD films, silicon, and platinum films substrates using different cell lines. Our results showed that UNCD films exhibited superior characteristics including cell number, total cell area, and cell spreading. The results could be attributed to the nanostructured nature or a combination of nanostructure/surface chemistry of UNCD, which provides a high surface energy, hence promoting adhesion between the receptors on the cell surface and the UNCD films. PMID:17530409

Bajaj, Piyush; Akin, Demir; Gupta, Amit; Sherman, Debby; Shi, Bing; Auciello, Orlando; Bashir, Rashid

2007-12-01

29

Development of ultrananocrystalline diamond (UNCD) coatings for multipurpose mechanical pump seals.  

SciTech Connect

The reliability and performance of silicon carbide (SiC) shaft seals on multipurpose mechanical pumps are improved by applying a protective coating of ultrananocrystalline diamond (UNCD). UNCD exhibits extreme hardness (97 GPa), low friction (0.1 in air) and outstanding chemical resistance. Consequently, the application of UNCD coatings to multipurpose mechanical pump seals can reduce frictional energy losses and eliminate the downtime and hazardous emissions from seal failure and leakage. In this study, UNCD films were prepared by microwave plasma chemical vapor deposition utilizing an argon/methane gas mixture. Prior to coating, the SiC seals were subjected to mechanical polishing using different grades of micron-sized diamond powder to produce different starting surfaces with well-controlled surface roughnesses. Following this roughening process, the seals were seeded by mechanical abrasion with diamond nanopowder, and subsequently coated with UNCD. The coated seals were subjected to dynamic wear testing performed at 3600 RPM and 100 psi for up to 10 days during which the seals were periodically removed and inspected. The UNCD-coated seals were examined using Raman microanalysis, scanning electron microscopy, optical profilometry, and adhesion testing before and after the wear testing. These analyses revealed that delamination of the UNCD films was prevented when the initial SiC seal surface had an initial roughness >0.1 {micro}m. In addition, the UNCD surfaces showed no measurable wear as compared to approximately 0.2 {micro}m of wear for the untreated SiC surfaces.

Kovalchenko, A. M.; Elam, J. W.; Erdemir, A.; Carlisle, J. A.; Auciello, O.; Libera, J. A.; Pellin, M. J.; Gruen, D. M.; Hryn, J. N. (Materials Science Division); (Georgia Inst. of Tech.)

2011-01-01

30

Electrically conductive ultrananocrystalline diamond-coated natural graphite-copper anode for new long life lithium-ion battery.  

PubMed

Science and technology are presented for novel nitrogen-incorporated ultrananocrystalline diamond (N-UNCD) encapsulated NG/copper anode and UNCD coatings that may enable next generation Li-ion batteries (LIBs) with potential 10x longer lifetime and superior performance than current LIBs. N-UNCD films (?5-10 nm grain size) exhibit electrical conductivity and extreme resistance to chemical corrosion, providing superior performance with respect to current uncoated anodes. PMID:24665020

Cheng, Yin-Wei; Lin, Chi-Kai; Chu, Yueh-Chieh; Abouimrane, Ali; Chen, Zonghai; Ren, Yang; Liu, Chuan-Pu; Tzeng, Yonhua; Auciello, Orlando

2014-06-01

31

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

32

Cell adhesion and growth on ultrananocrystalline diamond and diamond-like carbon films after different surface modifications  

NASA Astrophysics Data System (ADS)

Diamond and diamond-like carbon (DLC) films possess a set of excellent physical and chemical properties which together with a high biocompatibility make them attractive candidates for a number of medical and biotechnological applications. In the current work thin ultrananocrystalline diamond (UNCD) and DLC films were comparatively investigated with respect to cell attachment and proliferation after different surface modifications. The UNCD films were prepared by microwave plasma enhanced chemical vapor deposition, the DLC films by pulsed laser deposition (PLD). The films were comprehensively characterized with respect to their basic properties, e.g. crystallinity, morphology, chemical bonding nature, etc. Afterwards the UNCD and DLC films were modified applying O2 or NH3/N2 plasmas and UV/O3 treatments to alter their surface termination. The surface composition of as-grown and modified samples was studied by X-ray photoelectron spectroscopy (XPS). Furthermore the films were characterized by contact angle measurements with water, formamide, 1-decanol and diiodomethane; from the results obtained the surface energy with its dispersive and polar components was calculated. The adhesion and proliferation of MG63 osteosarcoma cells on the different UNCD and DLC samples were assessed by measurement of the cell attachment efficiency and MTT assays. The determined cell densities were compared and correlated with the surface properties of as-deposited and modified UNCD and DLC films.

Miksovsky, J.; Voss, A.; Kozarova, R.; Kocourek, T.; Pisarik, P.; Ceccone, G.; Kulisch, W.; Jelinek, M.; Apostolova, M. D.; Reithmaier, J. P.; Popov, C.

2014-04-01

33

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

34

Ultrananocrystalline Diamond Cantilever Wide Dynamic Range Acceleration/Vibration /Pressure Sensor  

DOEpatents

An ultrananocrystalline diamond (UNCD) element formed in a cantilever configuration is used in a highly sensitive, ultra-small sensor for measuring acceleration, shock, vibration and static pressure over a wide dynamic range. The cantilever UNCD element may be used in combination with a single anode, with measurements made either optically or by capacitance. In another embodiment, the cantilever UNCD element is disposed between two anodes, with DC voltages applied to the two anodes. With a small AC modulated voltage applied to the UNCD cantilever element and because of the symmetry of the applied voltage and the anode-cathode gap distance in the Fowler-Nordheim equation, any change in the anode voltage ratio V1/V2 required to maintain a specified current ratio precisely matches any displacement of the UNCD cantilever element from equilibrium. By measuring changes in the anode voltage ratio required to maintain a specified current ratio, the deflection of the UNCD cantilever can be precisely determined. By appropriately modulating the voltages applied between the UNCD cantilever and the two anodes, or limit electrodes, precise independent measurements of pressure, uniaxial acceleration, vibration and shock can be made. This invention also contemplates a method for fabricating the cantilever UNCD structure for the sensor.

Krauss, Alan R. (Naperville, IL); Gruen, Dieter M. (Downers Grove, IL); Pellin, Michael J. (Naperville, IL); Auciello, Orlando (Bolingbrook, IL)

2003-09-02

35

Ultrananocrystalline diamond cantilever wide dynamic range acceleration/vibration/pressure sensor  

DOEpatents

An ultrananocrystalline diamond (UNCD) element formed in a cantilever configuration is used in a highly sensitive, ultra-small sensor for measuring acceleration, shock, vibration and static pressure over a wide dynamic range. The cantilever UNCD element may be used in combination with a single anode, with measurements made either optically or by capacitance. In another embodiment, the cantilever UNCD element is disposed between two anodes, with DC voltages applied to the two anodes. With a small AC modulated voltage applied to the UNCD cantilever element and because of the symmetry of the applied voltage and the anode-cathode gap distance in the Fowler-Nordheim equation, any change in the anode voltage ratio V1/N2 required to maintain a specified current ratio precisely matches any displacement of the UNCD cantilever element from equilibrium. By measuring changes in the anode voltage ratio required to maintain a specified current ratio, the deflection of the UNCD cantilever can be precisely determined. By appropriately modulating the voltages applied between the UNCD cantilever and the two anodes, or limit electrodes, precise independent measurements of pressure, uniaxial acceleration, vibration and shock can be made. This invention also contemplates a method for fabricating the cantilever UNCD structure for the sensor.

Krauss, Alan R. (Naperville, IL); Gruen, Dieter M. (Downers Grove, IL); Pellin, Michael J. (Naperville, IL); Auciello, Orlando (Bolingbrook, IL)

2002-07-23

36

Enhanced electron field emission properties of conducting ultrananocrystalline diamond films after cu and au ion implantation.  

PubMed

The effects of Cu and Au ion implantation on the structural and electron field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films were investigated. High electrical conductivity of 186 (?•cm)(-1) and enhanced EFE properties with low turn-on field of 4.5 V/?m and high EFE current density of 6.70 mA/cm(2) have been detected for Au-ion implanted UNCD (Au-UNCD) films that are superior to those of Cu-ion implanted UNCD (Cu-UNCD) ones. Transmission electron microscopic investigations revealed that Au-ion implantation induced a larger proportion of nanographitic phases at the grain boundaries for the Au-UNCD films in addition to the formation of uniformly distributed spherically shaped Au nanoparticles. In contrast, for Cu-UNCD films, plate-like Cu nanoparticles arranged in the row-like pattern were formed, and only a smaller proportion of nanographite phases along the grain boundaries was induced. From current imaging tunneling spectroscopy and local current-voltage curves of scanning tunneling spectroscopic measurements, it is observed that the electrons are dominantly emitted from the grain boundaries. Consequently, the presence of nanosized Au particles and the induction of abundant nanographitic phases in the grain boundaries of Au-UNCD films are believed to be the authentic factors, ensuing in high electrical conductivity and outstanding EFE properties of the films. PMID:24624900

Sankaran, Kamatchi Jothiramalingam; Chen, Huang-Chin; Panda, Kalpataru; Sundaravel, Balakrishnan; Lee, Chi-Young; Tai, Nyan-Hwa; Lin, I-Nan

2014-04-01

37

Synthesis and field emission properties of ultra-nanocrystalline diamond fibers and helices.  

PubMed

We propose a novel template method for large scale synthesis of Ultra-Nanocrystalline Diamond (UNCD) fibres and helices with lengths of thousands of microns and diameters ranging from 0.5 to 5 microm: (i) Large quantities of submicrometer- or nanometer-diameter silica (a-SiO2) nanostructures, with lengths in the order of 2 to 4 mm, were synthesized by Vapor-Liquid-Solid (VLS) method; (ii) UNCD coating of as-synthesized a-SiO2 micro- or nanonanostructures by Microwave Plasma Chemical Vapour Deposition (MPCVD) technique in hydrogen-deficient condition. Electron Field Emission (EFE) of as-synthesized UNCD structures was observed with a threshold field of 3.4 V/microm. These micro- or nanostructures may find potential applications in high power electronics, vertical field-effect transistors in vacuum electronics, heat sinks in microelectronics and structural materials in Micro- and Nano-Electro-Mechanical Systems (MEMS/NEMS). The successful preparation of various types of UNCD structures suggests that this templating process can be used for a wide range of materials. PMID:20355444

Singh, M K; Titus, E; Willinger, M G; Grácio, J

2010-04-01

38

Electroplate and Lift Lithography for Patterned Micro/Nanowires Using Ultrananocrystalline Diamond (UNCD) as a Reusable Template  

PubMed Central

A fast, simple, scalable technique is described for the controlled, solution-based, electrochemical synthesis of patterned metallic and semiconducting nanowires from reusable, nonsacrificial, ultrananocrystalline diamond (UNCD) templates. This enables the repeated fabrication of arrays of complex patterns of nanowires, potentially made of any electrochemically depositable material. Unlike all other methods of patterning nanowires, this benchtop technique quickly mass-produces patterned nanowires whose diameters are not predefined by the template, without requiring intervening vacuum or clean room processing. This technique opens a pathway for studying nanoscale phenomena with minimal equipment, allowing the process-scale development of a new generation of nanowire-based devices.

2011-01-01

39

Fast growth of ultrananocrystalline diamond films by bias-enhanced nucleation and growth process in CH4/Ar plasma  

NASA Astrophysics Data System (ADS)

This letter describes the fast growth of ultrananocrystalline diamond (UNCD) films by bias-enhanced nucleation and growth process in CH4/Ar plasma. The UNCD grains were formed at the beginning of the film's growth without the necessity of forming the amorphous carbon interlayer, reaching a thickness of ˜380 nm in 10 min. Transmission electron microscopic investigations revealed that the application of bias voltage induced the formation of graphitic phase both in the interior and at the interface regions of UNCD films that formed interconnected paths, facilitating the transport of electrons and resulting in enhanced electron field emission properties.

Saravanan, A.; Huang, B. R.; Sankaran, K. J.; Dong, C. L.; Tai, N. H.; Lin, I. N.

2014-05-01

40

Electroplate and lift lithography for patterned micro/nanowires using ultrananocrystalline diamond (uncd) as a reusable template  

SciTech Connect

A fast, simple, scalable technique is described for the controlled, solution-based, electrochemical synthesis of patterned metallic and semiconducting nanowires from reusable, nonsacrificial, ultrananocrystalline diamond (UNCD) templates. This enables the repeated fabrication of arrays of complex patterns of nanowires, potentially made of any electrochemically depositable material. Unlike all other methods of patterning nanowires, this benchtop technique quickly mass-produces patterned nanowires whose diameters are not predefined by the template, without requiring intervening vacuum or clean room processing. This technique opens a pathway for studying nanoscale phenomena with minimal equipment, allowing the process-scale development of a new generation of nanowire-based devices.

Seley, D. B.; Dissing, D. A.; Divan, R.; Miller, C. S.; Auciello, O.; Terrell, E. A.; Shogren, T. S.; Fahrner, D.; Hamilton, J. P.; Zach, M. P.; Sumant, V. (Center for Nanoscale Materials); ( MSD); ( PSC-USR)

2011-01-01

41

Surface chemistry and bonding configuration of ultrananocrystalline diamond surfaces and their effects on nanotribological properties  

NASA Astrophysics Data System (ADS)

We present a comprehensive study of surface composition and nanotribology for ultrananocrystalline diamond (UNCD) surfaces, including the influence of film nucleation on these properties. We describe a methodology to characterize the underside of the films as revealed by sacrificial etching of the underlying substrate. This enables the study of the morphology and composition resulting from the nucleation and initial growth of the films, as well as the characterization of nanotribological properties which are relevant for applications including micro-/nanoelectromechanical systems. We study the surface chemistry, bonding configuration, and nanotribological properties of both the topside and the underside of the film with synchrotron-based x-ray absorption near-edge structure spectroscopy to identify the bonding state of the carbon atoms, x-ray photoelectron spectroscopy to determine the surface chemical composition, Auger electron spectroscopy to further verify the composition and bonding configuration, and quantitative atomic force microscopy to study the nanoscale topography and nanotribological properties. The films were grown on SiO2 after mechanically polishing the surface with detonation synthesized nanodiamond powder, followed by ultrasonication in a methanol solution containing additional nanodiamond powder. The sp2 fraction, morphology, and chemistry of the as-etched underside are distinct from the topside, exhibiting a higher sp2 fraction, some oxidized carbon, and a smoother morphology. The nanoscale single-asperity work of adhesion between a diamond nanotip and the as-etched UNCD underside is far lower than for a silicon-silicon interface ( 59.2±2 vs 826±186mJ/m2 , respectively). Exposure to atomic hydrogen dramatically reduces nanoscale adhesion to 10.2±0.4mJ/m2 , at the level of van der Waals’ interactions and consistent with recent ab initio calculations. Friction is substantially reduced as well, demonstrating a direct link between the surface chemistry and nanoscale friction. The proposed mechanism, supported by the detailed surface spectroscopic analysis, is the elimination of reactive (e.g., C*? ), polar (e.g., C?O ), and ? -bonded (C?C) surface groups, which are replaced by fully saturated, hydrogen-terminated surface bonds to produce an inert surface that interacts minimally with the contacting counterface.

Sumant, A. V.; Grierson, D. S.; Gerbi, J. E.; Carlisle, J. A.; Auciello, O.; Carpick, R. W.

2007-12-01

42

Surface chemistry and bonding configuration of ultrananocrystalline diamond surfaces and their effects on nanotribological properties  

SciTech Connect

We present a comprehensive study of surface composition and nanotribology for ultrananocrystalline diamond (UNCD) surfaces, including the influence of film nucleation on these properties. We describe a methodology to characterize the underside of the films as revealed by sacrificial etching of the underlying substrate. This enables the study of the morphology and composition resulting from the nucleation and initial growth of the films, as well as the characterization of nanotribological properties which are relevant for applications including micro-/nanoelectromechanical systems. We study the surface chemistry, bonding configuration, and nanotribological properties of both the topside and the underside of the film with synchrotron-based x-ray absorption near-edge structure spectroscopy to identify the bonding state of the carbon atoms, x-ray photoelectron spectroscopy to determine the surface chemical composition, Auger electron spectroscopy to further verify the composition and bonding configuration, and quantitative atomic force microscopy to study the nanoscale topography and nanotribological properties. The films were grown on SiO{sub 2} after mechanically polishing the surface with detonation synthesized nanodiamond powder, followed by ultrasonication in a methanol solution containing additional nanodiamond powder. The sp{sup 2} fraction, morphology, and chemistry of the as-etched underside are distinct from the topside, exhibiting a higher sp{sup 2} fraction, some oxidized carbon, and a smoother morphology. The nanoscale single-asperity work of adhesion between a diamond nanotip and the as-etched UNCD underside is far lower than for a silicon-silicon interface (59.2{+-}2 vs 826{+-}186 mJ/m{sup 2}, respectively). Exposure to atomic hydrogen dramatically reduces nanoscale adhesion to 10.2{+-}0.4 mJ/m{sup 2}, at the level of van der Waals' interactions and consistent with recent ab initio calculations. Friction is substantially reduced as well, demonstrating a direct link between the surface chemistry and nanoscale friction. The proposed mechanism, supported by the detailed surface spectroscopic analysis, is the elimination of reactive (e.g., C*-), polar (e.g., C=O), and {pi}-bonded (C=C) surface groups, which are replaced by fully saturated, hydrogen-terminated surface bonds to produce an inert surface that interacts minimally with the contacting counterface.

Sumant, A. V.; Grierson, D. S.; Carpick, R. W. [Department of Engineering Physics, University of Wisconsin-Madison, Wisconsin 53706 (United States); Gerbi, J. E. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Carlisle, J. A.; Auciello, O. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2007-12-15

43

Surface chemistry and bonding configuration of ultrananocrystalline diamond surfaces and their effects on nanotribological properties.  

SciTech Connect

We present a comprehensive study of surface composition and nanotribology for ultrananocrystalline diamond (UNCD) surfaces, including the influence of film nucleation on these properties. We describe a methodology to characterize the underside of the films as revealed by sacrificial etching of the underlying substrate. This enables the study of the morphology and composition resulting from the nucleation and initial growth of the films, as well as the characterization of nanotribological properties which are relevant for applications including micro-/nanoelectromechanical systems. We study the surface chemistry, bonding configuration, and nanotribological properties of both the topside and the underside of the film with synchrotron-based x-ray absorption near-edge structure spectroscopy to identify the bonding state of the carbon atoms, x-ray photoelectron spectroscopy to determine the surface chemical composition, Auger electron spectroscopy to further verify the composition and bonding configuration, and quantitative atomic force microscopy to study the nanoscale topography and nanotribological properties. The films were grown on SiO{sub 2} after mechanically polishing the surface with detonation synthesized nanodiamond powder, followed by ultrasonication in a methanol solution containing additional nanodiamond powder. The sp{sup 2} fraction, morphology, and chemistry of the as-etched underside are distinct from the topside, exhibiting a higher sp{sup 2} fraction, some oxidized carbon, and a smoother morphology. The nanoscale single-asperity work of adhesion between a diamond nanotip and the as-etched UNCD underside is far lower than for a silicon-silicon interface (59.2 {+-} 2 vs 826 {+-} 186 mJ/m{sup 2}, respectively). Exposure to atomic hydrogen dramatically reduces nanoscale adhesion to 10.2 {+-} 0.4 mJ/m{sup 2}, at the level of van der Waals interactions and consistent with recent ab initio calculations. Friction is substantially reduced as well, demonstrating a direct link between the surface chemistry and nanoscale friction. The proposed mechanism, supported by the detailed surface spectroscopic analysis, is the elimination of reactive (e.g., C*-), polar (e.g., C-O), and {pi}-bonded (C-C) surface groups, which are replaced by fully saturated, hydrogen-terminated surface bonds to produce an inert surface that interacts minimally with the contacting counterface.

Sumant, A. V.; Grierson, D. S.; Gerbi, J. E.; Carlisle, J. A.; Auciello, O.; Carpick, R. W.; Univ. of Wisconsin at Madison

2007-12-01

44

Synthesis and characterization of smooth ultrananocrystalline diamond films via low pressure bias-enhanced nucleation and growth.  

SciTech Connect

This letter describes the fundamental process underlying the synthesis of ultrananocrystalline diamond (UNCD) films, using a new low-pressure, heat-assisted bias-enhanced nucleation (BEN)/bias enhanced growth (BEG) technique, involving H{sub 2}/CH{sub 4} gas chemistry. This growth process yields UNCD films similar to those produced by the Ar-rich/CH{sub 4} chemistries, with pure diamond nanograins (3-5 nm), but smoother surfaces ({approx}6 nm rms) and higher growth rate ({approx}1 {micro}m/h). Synchrotron-based x-Ray absorption spectroscopy, atomic force microscopy, and transmission electron microscopy studies on the BEN-BEG UNCD films provided information critical to understanding the nucleation and growth mechanisms, and growth condition-nanostructure-property relationships.

Chen, Y. C.; Zhong, X. Y.; Koniceek, A. R.; Grierson, D. S.; Tai, N. H.; Lin, I. N.; Kabius, B.; Hiller, J. M.; Sumant, A. V.; Carpick, R. W.; Auciello, O.; National Tsing-Hua Univ.; Univ. of Wisconsin at Madison; Tamkang Univ.; Univ. Pennsylvania

2008-03-31

45

Elasticity, strength, and toughness of single crystal silicon carbide, ultrananocrystalline diamond, and hydrogen-free tetrahedral amorphous carbon  

NASA Astrophysics Data System (ADS)

In this work, the authors report the mechanical properties of three emerging materials in thin film form: single crystal silicon carbide (3C-SiC), ultrananocrystalline diamond, and hydrogen-free tetrahedral amorphous carbon. The materials are being employed in micro- and nanoelectromechanical systems. Several reports addressed some of the mechanical properties of these materials but they are based in different experimental approaches. Here, they use a single testing method, the membrane deflection experiment, to compare these materials' Young's moduli, characteristic strengths, fracture toughnesses, and theoretical strengths. Furthermore, they analyze the applicability of Weibull theory [Proc. Royal Swedish Inst. Eng. Res. 153, 1 (1939); ASME J. Appl. Mech. 18, 293 (1951)] in the prediction of these materials' failure and document the volume- or surface-initiated failure modes by fractographic analysis. The findings are of particular relevance to the selection of micro- and nanoelectromechanical systems materials for various applications of interest.

Espinosa, H. D.; Peng, B.; Moldovan, N.; Friedmann, T. A.; Xiao, X.; Mancini, D. C.; Auciello, O.; Carlisle, J.; Zorman, C. A.; Merhegany, M.

2006-08-01

46

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

NASA Astrophysics Data System (ADS)

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

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

2010-01-01

47

Oxygen Ion Implantation Enhanced Silicon-Vacancy Photoluminescence and n-Type Conductivity of Ultrananocrystalline Diamond Films  

NASA Astrophysics Data System (ADS)

We report the enhanced silicon-vacancy (Si-V) photoluminescence (PL) intensity and n-type conductivity of ultrananocrystalline diamond (UNCD) films by oxygen ion (O+) implantation. With O+ dose increasing from 1014 to 1015 cm-2, the PL intensity and n-type conductivity significantly increase by 6 and 45 times, respectively, after 1000°C annealing. The secondary ion mass spectroscopy mapping measurements show that the content of oxygen is larger in the zone, which has larger content of silicon, indicating that oxygen tends to adhere to silicon. It is suggested that oxygen related Si-V defects are formed, which will enhance the PL intensity and n-type conductivity of UNCD films.

Hu, Xiao-Jun; Li, Nian

2013-08-01

48

Synthesis of highly transparent ultrananocrystalline diamond films from a low-pressure, low-temperature focused microwave plasma jet  

PubMed Central

This paper describes a new low-temperature process underlying the synthesis of highly transparent ultrananocrystalline diamond [UNCD] films by low-pressure and unheated microwave plasma jet-enhanced chemical vapor deposition with Ar-1%CH4-10%H2 gas chemistry. The unique low-pressure/low-temperature [LPLT] plasma jet-enhanced growth even with added H2 and unheated substrates yields UNCD films similar to those prepared by plasma-enhanced growth without addition of H2 and heating procedure. This is due to the focused plasma jet which effectively compensated for the sluggish kinetics associated with LPLT growth. The effects of pressure on UNCD film synthesis from the microwave plasma jet were systematically investigated. The results indicated that the substrate temperature, grain size, surface roughness, and sp3 carbon content in the films decreased with decreasing pressure. The reason is due to the great reduction of H? emission to lower the etching of sp2 carbon phase, resulting from the increase of mean free path with decreasing pressure. We have demonstrated that the transition from nanocrystalline (80 nm) to ultrananocrystalline (3 to 5 nm) diamond films grown via microwave Ar-1%CH4-10%H2 plasma jets could be controlled by changing the pressure from 100 to 30 Torr. The 250-nm-thick UNCD film was synthesized on glass substrates (glass transition temperature [Tg] 557°C) using the unique LPLT (30 Torr/460°C) microwave plasma jet, which produced UNCD films with a high sp3 carbon content (95.65%) and offered high optical transmittance (approximately 86% at 700 nm).

2012-01-01

49

Ultrananocrystalline diamond films with optimized dielectric properties for advanced RF MEMS capacitive switches  

SciTech Connect

An efficient deposition process is provided for fabricating reliable RF MEMS capacitive switches with multilayer ultrananocrystalline (UNCD) films for more rapid recovery, charging and discharging that is effective for more than a billion cycles of operation. Significantly, the deposition process is compatible for integration with CMOS electronics and thereby can provide monolithically integrated RF MEMS capacitive switches for use with CMOS electronic devices, such as for insertion into phase array antennas for radars and other RF communication systems.

Sumant, Anirudha V.; Auciello, Orlando H.; Mancini, Derrick C.

2013-01-15

50

Fundamentals and application of materials integration for low-power piezoelectrically actuated ultra-nanocrystalline diamond MEMS/NEMS.  

SciTech Connect

Most current micro/nanoelectromechanical systems (MEMS/NEMS) are based on silicon. However, silicon exhibits relatively poor mechanical/tribological properties, compromising applications to several projected MEMS/NEMS devices, particularly those that require materials with high Young's modulus for MEMS resonators or low surface adhesion forces for MEMS/NEMS working in conditions with extensive surface contact. Diamond films with superior mechanical/tribological properties provide an excellent alternative platform material. Ultrananocrystalline diamond (UNCD{cflx W}) in film form with 2-5 nm grains exhibits excellent properties for high-performance MEMS/NEMS devices. Concurrently, piezoelectric Pb(Zr{sub x}Ti{sub 1-x})O{sub 3} (PZT) films provide high sensitivity/low electrical noise for sensing/high-force actuation at relatively low voltages. Therefore, integration of PZT and UNCD films provides a high-performance platform for advanced MEMS/NEMS devices. This paper describes the bases of such integration and demonstration of low voltage piezoactuated hybrid PZT/UNCD cantilevers.

Auciello, O.; Srinivasan, S.; Hiller, J.; Kabius, B. (Center for Nanoscale Materials); ( MSD)

2009-01-01

51

Enhancement in electron field emission in ultrananocrystalline and microcrystalline diamond films upon 100 MeV silver ion irradiation  

SciTech Connect

Enhanced electron field emission (EFE) behavior was observed in ultrananocrystalline diamond (UNCD) and microcrystalline diamond (MCD) films upon irradiation with 100 MeV Ag{sup 9+}-ions in a fluence of 5x10{sup 11} ions/cm{sup 2}. Transmission electron microscopy indicated that while the overall crystallinity of these films remained essentially unaffected, the local microstructure of the materials was tremendously altered due to heavy ion irradiation, which implied that the melting and recrystallization process have occurred along the trajectory of the heavy ions. Such a process induced the formation of interconnected nanocluster networks, facilitating the electron conduction and enhancing the EFE properties for the materials. The enhancement in the EFE is more prominent for MCD films than that for UNCD films, reaching a low turn-on field of E{sub 0}=3.2 V/mum and large EFE current density of J{sub e}=3.04 mA/cm{sup 2} for 5x10{sup 11} ions/cm{sup 2} heavy ion irradiated samples.

Chen, H.-C.; Palnitkar, Umesh; Pong, W.-F.; Lin, I-N. [Department of Physics, Tamkang University, Tamsui, Taiwan 251 (China); Singh, Abhinav Pratap; Kumar, Ravi [Inter-University Accelerator Center, Aruna Asaf Ali Marg, New Delhi 110007 (India)

2009-04-15

52

Enhancing electrical conductivity and electron field emission properties of ultrananocrystalline diamond films by copper ion implantation and annealing  

NASA Astrophysics Data System (ADS)

Copper ion implantation and subsequent annealing at 600 °C achieved high electrical conductivity of 95.0 (?cm)-1 for ultrananocrystalline diamond (UNCD) films with carrier concentration of 2.8 × 1018 cm-2 and mobility of 6.8 × 102 cm2/V s. Transmission electron microscopy examinations reveal that the implanted Cu ions first formed Cu nanoclusters in UNCD films, which induced the formation of nanographitic grain boundary phases during annealing process. From current imaging tunneling spectroscopy and local current-voltage curves of scanning tunneling spectroscopic measurements, it is observed that the electrons are dominantly emitted from the grain boundaries. Consequently, the nanographitic phases presence in the grain boundaries formed conduction channels for efficient electron transport, ensuing in excellent electron field emission (EFE) properties for copper ion implanted/annealed UNCD films with low turn-on field of 4.80 V/?m and high EFE current density of 3.60 mA/cm2 at an applied field of 8.0 V/?m.

Sankaran, K. J.; Panda, K.; Sundaravel, B.; Tai, N. H.; Lin, I. N.

2014-02-01

53

Construction of a ultrananocrystalline diamond-based cold cathode arrays for a flat-panel x-ray source  

NASA Astrophysics Data System (ADS)

A novel cold cathode field emission array (FEA) X-ray source based on ultra-nanocrystalline diamond (UNCD) field emitters is being constructed as an alternative for detection of obscured objects and material. Depending on the geometry of the given situation the flat-panel X-ray source could be used in tomography, radiography, or tomosynthesis. Furthermore, the unit could be used as a portable X-ray scanner or an integral part of an existing detection system. UNCD field emitters show great field emission output and can be deposited over large areas as the case with carbon nanotube "forest" (CNT) cathodes. Furthermore, UNCDs have better mechanical and thermal properties as compared to CNT tips which further extend the lifetime of UNCD based FEA. This work includes the first generation of the UNCD based FEA prototype which is being manufactured at the Center for Nanoscale Materials within Argonne National Laboratory with standard microfabrication techniques. The prototype is a 3x3 pixel FEA, with a pixel pitch of 500 ?m, where each pixel is individually controllable.

Grant, E. J.; Posada, C. M.; Divan, R.; Sumant, A. V.; Rosenmann, D.; Stan, L.; Avachat, A.; Castano, C. H.; Lee, H. K.

2013-06-01

54

Improvement of field emission performance on nitrogen ion implanted ultrananocrystalline diamond films through visualization of structure modificaitons.  

SciTech Connect

The relationship between the electron field emission properties and structure of ultra-nanocrystalline diamond (UNCD) films implanted by nitrogen ions or carbon ions was investigated. The electron field emission properties of nitrogen-implanted UNCD films and carbon-implanted UNCD films were pronouncedly improved with respect to those of as-grown UNCD films, that is, the turn-on field decreased from 23.2 V/{micro}m to 12.5 V/{micro}m and the electron field emission current density increased from 10E-5 mA/cm{sup 2} to 1 x 10E-2 mA/cm{sup 2}. The formation of a graphitic phase in the nitrogen-implanted UNCD films was demonstrated by Raman microscopy and cross-sectional high-resolution transmission electron microscopy. The possible mechanism is presumed to be that the nitrogen ion irradiation induces the structure modification (converting sp{sup 3}-bonded carbons into sp{sup 2}-bonded ones) in UNCD films.

Chen, Y.-C.; Zhong, X-Y.; Kabius, B.; Hiller, J. M.; Tai, N.-H.; Lin, I.-N. (Materials Science Division); (National Tsing-Hua Univ.); (Tamkang Univ.)

2011-02-01

55

Near-Edge X-ray Absorption Fine Structure Imaging of Spherical and Flat Counterfaces of Ultrananocrystalline Diamond Tribological Contacts: A Correlation of Surface Chemistry and Friction  

SciTech Connect

A recently installed synchrotron radiation near-edge X-ray absorption fine structure (NEXAFS) full field imaging electron spectrometer was used to spatially resolve the chemical changes of both counterfaces from an ultra-nanocrystalline diamond (UNCD) tribological contact. A silicon flat and Si{sub 3}N{sub 4} sphere were both coated with UNCD, and employed to form two wear tracks on the flat in a linear reciprocating tribometer. The first wear track was produced using a new, unconditioned sphere whose surface was thus conditioned during this first experiment. This led to faster run-in and lower friction when producing a second wear track using the conditioned sphere. The large depth of field of the magnetically guided NEXAFS imaging detector enabled rapid, large area spectromicroscopic imaging of both the spherical and flat surfaces. Laterally resolved NEXAFS data from the tribological contact area revealed that both substrates had an as-grown surface layer that contained a higher fraction of sp{sup 2}-bonded carbon and oxygen which was mechanically removed. Unlike the flat, the film on the sphere showed evidence of having graphitic character, both before and after sliding. These results show that the graphitic character of the sphere is not solely responsible for low friction and short run-in. Rather, conditioning the sphere, likely by removing asperities and passivating dangling bonds, leads to lower friction with less chemical modification of the substrate in subsequent tests. The new NEXAFS imaging spectroscopy detector enabled a more complete understanding of the tribological phenomena by imaging, for the first time, the surface chemistry of the spherical counterface which had been in continual contact during wear track formation.

A Konicek; C Jaye; M Hamilton; W Sawyer; D Fischer; R Carpick

2011-12-31

56

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

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

57

Patterning of nanocrystalline diamond films for diamond microstructures useful in MEMS and other devices  

DOEpatents

MEMS structure and a method of fabricating them from ultrananocrystalline diamond films having average grain sizes of less than about 10 nm and feature resolution of less than about one micron . The MEMS structures are made by contacting carbon dimer species with an oxide substrate forming a carbide layer on the surface onto which ultrananocrystalline diamond having average grain sizes of less than about 10 nm is deposited. Thereafter, microfabrication process are used to form a structure of predetermined shape having a feature resolution of less than about one micron.

Gruen, Dieter M. (Downers Grove, IL); Busmann, Hans-Gerd (Bremen, DE); Meyer, Eva-Maria (Bremen, DE); Auciello, Orlando (Bolingbrook, IL); Krauss, Alan R. (late of Naperville, IL); Krauss, Julie R. (Naperville, IL)

2004-11-02

58

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

EPA Science Inventory

This Small Business Innovative Research (SBIR) project will develop and ready for commercialization a scalable, low-cost process for purification of water containing Contaminants of Emerging Concern (CECs) using anodic oxidation with boron-doped ultrananocrystalline diam...

59

Science and technology of piezoelectric/diamond heterostructures for monolithically integrated high performance MEMS/NEMS/CMOS devices.  

SciTech Connect

This paper describes the fundamental and applied science performed to integrate piezoelectric PbZr{sub x}Ti{sub 1-x}O{sub 3} and AlN films with a novel mechanically robust ultrananocrystalline diamond layer to enable a new generation of low voltage/high-performance piezoactuated hybrid piezoelectric/diamond MEMS/NEMS devices.

Auciello, O.; Sumant, A. V.; Hiller, J.; Kabius, B.; Ma, Z.; Srinivasan, S. (Center for Nanoscale Materials); ( MSD); (Univ. of Wisconsin at Madison); (INTEL)

2008-12-01

60

Ultrananocrystalline diamond film deposition by direct-current plasma assisted chemical vapor deposition using hydrogen-rich precursor gas in the absence of the positive column  

NASA Astrophysics Data System (ADS)

We have investigated the ultrananocrystalline diamond (UNCD) deposition by direct-current plasma assisted chemical vapor deposition on 4 in. Si wafer using CH4-H2 as well as CH4-Ar gas chemistry containing additive nitrogen. CH4/N2/H2 (5%/0.5%/94.5%) and CH4/N2/H2/Ar (0.5%/5%/6%/88.5%) gas mixtures were compared as the precursor gas. Molybdenum and tungsten were compared as cathode material. Discharge voltage and current were 480 V/45 A and 320 V/60 A, for respective gas chemistry. Chamber pressure and substrate temperature were 110-150 Torr and 750-850 °C, respectively. The film was characterized by near edge x-ray absorption fine structure spectroscopy, x-ray diffraction, high-resolution transmission electron microscope, electron energy loss spectroscopy, and high-resolution scanning electron microscope. We have demonstrated that (1) elimination of the positive column, by adopting very small interelectrode distance, gave some important and beneficial effects; (2) the plasma stability and impurity incorporation was sensitive to the cathode material and the precursor gas; (3) using the conventional CH4/H2 precursor gas and tungsten cathode, the mirror-smooth 4 in. UNCD film of excellent phase-purity and grain size below 10 nm could be deposited even in the absence of the positive column. The high electric field in the unusually narrow interelectrode space and the consequent high electron kinetic energy, in conjunction with the unusually high electron current thereof, directed to the substrate, i.e., the anode, was proposed to be the source of the grain refinement to achieve UNCD at such high chamber pressure around 110-150 Torr, in the absence of the usual ion bombardment assistance.

Lee, Hak-Joo; Jeon, Hyeongtag; Lee, Wook-Seong

2011-01-01

61

Effect of CH4 concentration on the growth behavior, structure, and transparent properties of ultrananocrystalline diamond films synthesized by focused microwave Ar/CH4/H2 plasma jets  

NASA Astrophysics Data System (ADS)

The effects of CH4 concentration (0.5-5%) on the growth mechanisms, nanostructures, and optically transparent properties of ultrananocrystalline diamond (UNCD) films grown from focused microwave Ar/CH4/H2 (argon-rich) plasma jets were systematically studied. The research results indicated that the grain size and surface roughness of the diamond films increased with increasing CH4 concentration in the plasma jet, however, the nondiamond contents in films would not be correspondingly decreased resulting from the dispersed diamond nanocrystallites in the films synthesized at higher CH4 concentration. The reason is due to that the relative emission intensity ratios of the C2/H? and the CH/C2 in the plasma jets were increased and decreased with increasing CH4 concentration, respectively, to lower the etching of nondiamond phase and the renucleation of diamond during synthesis. The studies of transmission electron microscopy demonstrated that, while the CH4 introduction of 1% into the plasma jet produced the UNCD films with a spherical geometry (4-8 nm) and the CH4 introduction of 5% into the plasma jet led to the elongated (˜90 nm in length and ˜35 nm in width) grains in the nanocrystalline diamond (NCD) films with a dendrite-like geometry. The transmittance of diamond films was decreased gradually by films transition from UNCD to NCD, resulting from the enhanced surface roughness and nondiamond contents in films to concurrently increase the light scattering and absorption during photon transmission.

Liao, Wen-Hsiang; Lin, Chii-Ruey; Wei, Da-Hua

2013-04-01

62

Optical defect centers and surface morphology of isotopically enriched diamond layers in designer diamond anvils  

Microsoft Academic Search

We have studied optical defect centers and surface morphology of isotopically enriched layers grown on diamond anvils by microwave plasma chemical vapor deposition for applications as designer diamond anvils in high-pressure diamond anvil cell devices. Various mixtures of methane isotopes were used to grow homoepitaxial diamond with 13C molar fractions of 0.01, 0.41, 0.83, and 0.99 as determined from Raman

Randolph S. Peterson; Paul A. Baker; Shane A. Catledge; Yogesh K. Vohra; Samuel T. Weir

2005-01-01

63

High current density diamond based electron emitters for vacuum thermionic energy conversion  

Microsoft Academic Search

Vacuum thermionic energy conversion utilizes thermionic emission to release electrons from an emitter into vacuum and collection at a counter-electrode. In our approach for an efficient thermionic emitter a multi-layer diamond thin film structure was synthesized by plasma-assisted CVD on a metallic substrate with controlled surface roughness including a nanodiamond pretreatment step. Introduction of nitrogen during ultra-nanocrystalline diamond (UNCD) film

Franz Koeck; Robert Nemanich

2010-01-01

64

Progress toward atomic layer epitaxy of diamond: Diamond films grown one layer at a time  

NASA Astrophysics Data System (ADS)

Diamond would be the ultimate coating for many applications; it is the hardest material known, it is chemically inert in most environments, it has a thermal conductivity five times that of copper, and it is optically transparent from ultraviolet through the mid- and far-infrared. However, conventional CVD methods for diamond have important limitations: many substrates of interest cannot withstand the 500-1000 C temperatures commonly employed, and the typically low nucleation density generates films with large crystal grains and rough morphologies. We are developing a novel low-pressure method for atomic layer epitaxy of diamond which should enable high-quality film growth at modest temperatures with very high nucleation densities. The method uses alternating fluxes of halocarbon radicals and atomic hydrogen, generated by reaction with atomic fluorine. Under suitable conditions, carbonatom additions to the growing film and subsequent rehydrogenation of the surface should each be self-limiting reactions resulting in deposition of one atomic layer of diamond per cycle. To date we have obtained evidence for diamond growth at rates up to 0.1 microns/hr from continuous flows of hydrogen and CHCL3, CH4, or C2H2 at reactor pressures between 10(exp -4) and 10(exp -2) Torr.

Gat, Roy; Hukka, Terttu I.; Rawles, Robin E.; Develyn, Mark P.

1993-05-01

65

Effect of pretreatment bias on the nucleation and growth mechanisms of ultrananocrystalline diamond films via bias-enhanced nucleation and growth: An approach to interfacial chemistry analysis via chemical bonding mapping  

SciTech Connect

The effect of pretreatment bias on the nucleation and growth mechanisms of the ultrananocrystalline diamond (UNCD) films on the Si substrate via bias-enhanced nucleation and bias-enhanced growth (BEN-BEG) was investigated using cross-sectional high-resolution transmission electron microscopy, chemical bonding mapping, and Raman spectroscopy. The mirror-polished substrate surface showed the formation of a triangular profile produced by a dominant physical sputtering mechanism induced by ion bombardment of ions from the hydrogen plasma accelerated toward the substrate due to biasing and a potential hydrogen-induced chemical reaction component before synthesizing the UNCD films. The BEN-BEG UNCD films grown on the Si substrate with biased and unbiased pretreatments in the hydrogen plasma were compared. In the case of the bias-pretreated substrate, the SiC phases were formed at the peaks of the Si surface triangular profile due to the active unsaturated Si bond and the enhanced local electrical field. The UNCD grains grew preferentially at the peaks of the triangular substrate surface profile and rapidly covered the amorphous carbon (a-C) and oriented graphite phases formed in the valley of the surface profile. In the case of the substrate with unbiased pretreatment, the SiC phases were formed via the reactions between the hydrocarbon species and the active Si atoms released from the substrate with assistance of the hydrogen plasma. The UNCD grains nucleated on the nucleating sites consisting of the SiC, a-C, and graphite phases. Growth mechanisms for the BEN-BEG UNCD films on both Si substrates were proposed to elucidate the different nucleation processes. Applying bias on the Si substrate pretreated in the hydrogen plasma optimized the nucleation sites for growth of UNCD grains, resulting in the low content of the nondiamond phases in UNCD films.

Zhong, X. Y.; Hiller, J. M. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Chen, Y. C.; Tai, N. H. [Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu 300, Taiwan (China); Lin, I. N. [Department of Physics, Tamkamg University, Tamsui 251, Taiwan (China); Auciello, O. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2009-02-01

66

Theoretical study on SAW characteristics of layered structures including a diamond layer  

Microsoft Academic Search

Diamond has the highest surface acoustic wave (SAW) velocity among all materials and thus can provide much advantage for fabrication of high frequency SAW devices when it is combined with a piezoelectric thin film. Basic SAW properties of layered structures consisting of a piezoelectric material layer, a diamond layer and a substrate were examined by theoretical calculation. Rayleigh mode SAW's

Hideaki Nakahata; Akihiro Hachigo; Kenjiro Higaki; Satoshi Fujii; Shin-ichi Shikata; Naoji Fujimori

1995-01-01

67

Effects of initial crystal size of diamond powder on surface residual stress and morphology in polycrystalline diamond (PCD) layer  

NASA Astrophysics Data System (ADS)

Polycrystalline diamond compacts (PDC) were synthesized using diamond powder of average crystal size 3-20 ?m by the Ni70Mn25Co5 alloy infiltration technique at high temperature and high pressure (HPHT). The surface residual stress of polycrystalline diamond (PCD) layer was measured using micro-Raman spectroscopy with hydrostatic stress model and X-ray diffraction (XRD). Measurements of the stress levels of PCDs show that the residual compressive stresses range from 0.12 to 0.22 GPa, which increase with the crystal size of diamond. Scanning electron microscopy (SEM) was used to observe the morphology of initial diamond grains and PCD cross-section. The results indicate that PCD has a dense and interlaced microstructure with diamond-diamond (D-D) direct bonding. And the smaller the crystal size of diamond, the better the growth of diamond direct bonding and the smaller the binder metal between diamond boundaries will be.

Jia, HongSheng; Jia, XiaoPeng; Xu, Yue; Wan, LianRu; Jie, KaiKai; Ma, HongAn

2011-01-01

68

FEM modelling of surface acoustic wave in diamond layered structure  

Microsoft Academic Search

This paper describes a general finite element method (FEM) for the AC steady state analysis of two-dimensional piezoelectric devices. The method is applied to a diamond based surface acoustic wave (SAW) layered structure. We determined the penetration depth of the elastic waves corresponding to ZnO layer of 1 mum thick and spatial periodicity of 4 mum. The structure admittance response

L. Le Brizoual; F. Sarry; F. Moreira; O. Elmazria

2006-01-01

69

Thermal conduction in nonhomogeneous CVD diamond layers in electronic microstructures  

Microsoft Academic Search

Chemical-vapor-deposited diamond layers of thickness between 0.1 and 5 μm have the potential to improve conduction cooling in electronic microstructures. However, thermal conduction in these layers is strongly impeded by phonon scattering on defects, whose concentrations can be highly nonhomogeneous, and on layer boundaries. By assuming that defects are concentrated near grain boundaries, this work relates the internal phonon scattering

K. E. Goodson

1996-01-01

70

Optical defect centers and surface morphology of isotopically enriched diamond layers in designer diamond anvils  

NASA Astrophysics Data System (ADS)

We have studied optical defect centers and surface morphology of isotopically enriched layers grown on diamond anvils by microwave plasma chemical vapor deposition for applications as designer diamond anvils in high-pressure diamond anvil cell devices. Various mixtures of methane isotopes were used to grow homoepitaxial diamond with 13C molar fractions of 0.01, 0.41, 0.83, and 0.99 as determined from Raman spectroscopy. Defect centers were studied at temperatures between 80 and 320 K using micro-photoluminescence (PL) spectroscopy with an argon ion and krypton laser excitation source. The defect spectra were dominated by zero phonon lines (ZPL) from nitrogen-related defect centers at nominal energies of 1.945 eV (640 nm defect) and 2.156 eV (575 nm defect), especially for the non-(100) surfaces. Polished (100) surfaces fluoresced weakly. ZPL's at 1.77 and 1.68 eV are observed, but not for all isotopically mixed samples. The 1.77 eV ZPL appears to be associated from the original diamonds, while the 1.68 eV ZPL is known to originate with silicon-based defects. Atomic force microscopy of as-grown isotopically enriched layers show rough growth steps in areas with surface roughness of hundred nanometers and smooth areas with surface roughness of few nanometers. Our studies indicate that (100) polished surfaces of isotopically enriched designer diamonds with low concentration of nitrogen defect centers can be fabricated for a variety of applications in high pressure research.

Peterson, Randolph S.; Baker, Paul A.; Catledge, Shane A.; Vohra, Yogesh K.; Weir, Samuel T.

2005-04-01

71

Effects of initial crystal size of diamond powder on surface residual stress and morphology in polycrystalline diamond (PCD) layer  

Microsoft Academic Search

Polycrystalline diamond compacts (PDC) were synthesized using diamond powder of average crystal size 3–20 ?m by the Ni70Mn25Co5 alloy infiltration technique at high temperature and high pressure (HPHT). The surface residual stress of polycrystalline\\u000a diamond (PCD) layer was measured using micro-Raman spectroscopy with hydrostatic stress model and X-ray diffraction (XRD).\\u000a Measurements of the stress levels of PCDs show that the

Hongsheng Jia; Xiaopeng Jia; Yue Xu; Lianru Wan; Kaikai Jie; Hongan Ma

2011-01-01

72

Chemical vapour deposition of diamond on stainless steel: the effect of Ni-diamond composite coated buffer layer  

Microsoft Academic Search

Diamond films were grown on nickel and nickel-diamond composite coated stainless steel substrates using microwave plasma chemical vapour deposition (MPCVD). X-ray diffraction (XRD), scanning electron microscopy and Raman spectroscopy studies give clear evidence for the growth of diamond on buffer layered substrates. XRD results further suggest that after CVD treatment the interface nickel (a = 3.522 Å) shows an increase

A. K. Sikder; T. Sharda; D. S. Misra; D. Chandrasekaram; P. Selvam

1998-01-01

73

Layer-by-Layer assembly and redox properties of undoped HPHT diamond particles  

Microsoft Academic Search

The surface properties of undoped diamond particles are investigated by a combination of zeta potential measurements in solution and electrochemical studies in thin layer assemblies. High-Pressure High-Temperature (HPHT) 500nm diamond particles exhibit positive and negative zeta potentials depending on pH. The estimated point of zero zeta potential (pzzp) was 6.6, while mobility measurements provided an average charge per particle of

Wiphada Hongthani; David J. Fermín

2010-01-01

74

Diamond Deposition on WC/Co Alloy with a Molybdenum Intermediate Layer  

NASA Astrophysics Data System (ADS)

It is known that in the condition of chemical vapor deposition (CVD) diamond process, molybdenum is capable of forming carbide known as the "glue" which promotes growth of the CVD diamond, and aids its adhesion by (partial) relief of stresses at the interface. Furthermore, the WC grains are reaction bonded to the Mo2C phase. Therefore, molybdenum is a good candidate material for the intermediate layer between WC-Co substrates and diamond coatings. A molybdenum intermediate layer of 1-3 ?m thickness was magnetron sputter-deposited on WC/Co alloy prior to the deposition of diamond coatings. Diamond films were deposited by hot filament chemical vapor deposition (HFCVD). The chemical quality, morphology, and crystal structure of the molybdenum intermediate layer and the diamond coatings were characterized by means of SEM, EDX, XRD and Raman spectroscopy. It was found that the continuous Mo intermediate layer emerged in spherical shapes and had grain sizes of 0.5-1.5 ?m after 30 min sputter deposition. The diamond grain growth rate was slightly slower as compared with that of uncoated Mo layer on the WC-Co substrate. The morphologies of the diamond films on the WC-Co substrate varied with the amount of Mo and Co on the substrate. The Mo intermediate layer was effective to act as a buffer layer for both Co diffusion and diamond growth.

Liu, Sha; Yu, Zhi-Ming; Yi, Dan-Qing

75

Dielectric properties of hydrogen-incorporated chemical vapor deposited diamond thin films  

Microsoft Academic Search

Diamond thin films with a broad range of microstructures from a ultrananocrystalline diamond (UNCD) form developed at Argonne National Laboratory to a microcrystalline diamond (MCD) form have been grown with different hydrogen percentages in the Ar\\/CH4 gas mixture used in the microwave plasma enhanced chemical vapor deposition (CVD) process. The dielectric properties of the CVD diamond thin films have been

Chao Liu; Xingcheng Xiao; Jian Wang; Bing Shi; Vivekananda P. Adiga; Robert W. Carpick; John A. Carlisle; Orlando Auciello

2007-01-01

76

Method of forming fluorine-bearing diamond layer on substrates, including tool substrates  

Microsoft Academic Search

A method of forming a fluorine-bearing diamond layer on non-diamond substrates, especially on tool substrates comprising a metal matrix and hard particles, such as tungsten carbide particles, in the metal matrix. The substrate and a fluorine-bearing plasma or other gas are then contacted under temperature and pressure conditions effective to nucleate fluorine-bearing diamond on the substrate. A tool insert substrate

R. P. H. Chang; Kevin J. Grannen

2002-01-01

77

Note: Laser ablation technique for electrically contacting a buried implant layer in single crystal diamond  

NASA Astrophysics Data System (ADS)

The creation of thin, buried, and electrically conducting layers within an otherwise insulating diamond by annealed ion implantation damage is well known. Establishing facile electrical contact to the shallow buried layer has been an unmet challenge. We demonstrate a new method, based on laser micro-machining (laser ablation), to make reliable electrical contact to a buried implant layer in diamond. Comparison is made to focused ion beam milling.

Ray, M. P.; Baldwin, J. W.; Feygelson, T. I.; Butler, J. E.; Pate, B. B.

2011-05-01

78

Method of forming fluorine-bearing diamond layer on substrates, including tool substrates  

DOEpatents

A method of forming a fluorine-bearing diamond layer on non-diamond substrates, especially on tool substrates comprising a metal matrix and hard particles, such as tungsten carbide particles, in the metal matrix. The substrate and a fluorine-bearing plasma or other gas are then contacted under temperature and pressure conditions effective to nucleate fluorine-bearing diamond on the substrate. A tool insert substrate is treated prior to the diamond nucleation and growth operation by etching both the metal matrix and the hard particles using suitable etchants.

Chang, R. P. H. (Glenview, IL); Grannen, Kevin J. (Evanston, IL)

2002-01-01

79

Lamb Wave Characteristics of Composite Plates Including a Diamond Layer with Distinct Electrode Arrangements  

NASA Astrophysics Data System (ADS)

Diamond films have been utilized to develop surface acoustic wave filters and micromechanical resonators because of the highest acoustic wave velocity and largest product of frequency and quality factor (f\\cdot Q) of diamond among all materials. A theoretical analysis of Lamb wave characteristics in multilayer piezoelectric plates including a diamond layer is presented in this paper. Formulae for effective permittivity are derived using the transfer matrix method and are further employed to calculate Lamb wave phase velocity dispersions. The electromechanical coupling coefficients (ECCs) are also calculated exactly by Green's function method. Detailed calculations are carried out for ZnO/diamond and AlN/diamond composite plates with four distinct electrode arrangements. Results show that the ZnO/diamond structure yields a phase velocity of 6420 m/s and a large ECC of 7.41%, which makes it suitable for high-frequency wideband filter applications. Moreover, in the AlN/diamond structure, the S0 mode exhibits a large phase velocity of up to 10.3 km/s and a moderate ECC of 1.97%. Such favorable characteristics are expected to contribute to the development of AlN/diamond Lamb wave oscillators operating at approximately 5--10 GHz without the need for a sub-micrometer-resolution lithographic process. Therefore, both ZnO/diamond and AlN/diamond Lamb wave devices are highly promising candidates for RF devices in modern communication systems with advantages over conventional surface acoustic wave devices.

Chen, Yung-Yu

2013-07-01

80

Graphene-on-diamond devices with increased current-carrying capacity: carbon sp2-on-sp3 technology.  

PubMed

Graphene demonstrated potential for practical applications owing to its excellent electronic and thermal properties. Typical graphene field-effect transistors and interconnects built on conventional SiO(2)/Si substrates reveal the breakdown current density on the order of 1 ?A/nm(2) (i.e., 10(8) A/cm(2)), which is ~100× larger than the fundamental limit for the metals but still smaller than the maximum achieved in carbon nanotubes. We show that by replacing SiO(2) with synthetic diamond, one can substantially increase the current-carrying capacity of graphene to as high as ~18 ?A/nm(2) even at ambient conditions. Our results indicate that graphene's current-induced breakdown is thermally activated. We also found that the current carrying capacity of graphene can be improved not only on the single-crystal diamond substrates but also on an inexpensive ultrananocrystalline diamond, which can be produced in a process compatible with a conventional Si technology. The latter was attributed to the decreased thermal resistance of the ultrananocrystalline diamond layer at elevated temperatures. The obtained results are important for graphene's applications in high-frequency transistors, interconnects, and transparent electrodes and can lead to the new planar sp(2)-on-sp(3) carbon-on-carbon technology. PMID:22329428

Yu, Jie; Liu, Guanxiong; Sumant, Anirudha V; Goyal, Vivek; Balandin, Alexander A

2012-03-14

81

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

82

Evidence for layered growth of (100) textured diamond films  

SciTech Connect

The growth of diamond films synthesized by the hot filament chemical vapor deposition method has been studied by scanning tunneling microscopy (STM). The smooth (100) faces of micron-sized diamond crystallites were found to exhibit pyramidal shaped architecture at the nano level. The STM data for chemical vapor deposited diamond is analyzed in the light of recently developed dynamical scaling approach. The value of the scaling exponent {alpha}{congruent}0.85 signifies a growth primarily driven by the transport of reacting species on the surface rather than molecular diffusion in gas phase. {copyright} {ital 1997 American Institute of Physics.}

Godbole, V.P.; Sumant, A.V.; Kshirsagar, R.B.; Dharmadhikari, C.V. [Department of Physics, Center for Advanced Studies in Materials Sciences and Solid State Physics, University of Pune, Pune 411 007 (India)] [Department of Physics, Center for Advanced Studies in Materials Sciences and Solid State Physics, University of Pune, Pune 411 007 (India)

1997-11-01

83

Growth and electrical characterisation of {delta}-doped boron layers on (111) diamond surfaces  

SciTech Connect

A plasma enhanced chemical vapor deposition protocol for the growth of {delta}-doping of boron in diamond is presented, using the (111) diamond plane as a substrate for diamond growth. AC Hall effect measurements have been performed on oxygen terminated {delta}-layers and desirable sheet carrier densities ({approx}10{sup 13} cm{sup -2}) for field-effect transistor application are reported with mobilities in excess of what would expected for equivalent but thicker heavily boron-doped diamond films. Temperature-dependent impedance spectroscopy and secondary ion mass spectroscopy measurements show that the grown layers have metallic-like electrical properties with high cut-off frequencies and low thermal impedance activation energies with estimated boron concentrations of approximately 10{sup 20} cm{sup -3}.

Edgington, Robert; Jackman, Richard B. [London Centre for Nanotechnology, and Department of Electronic and Electrical Engineering, University College London, 17-19 Gordon Street, London, WC1H 0AH (United Kingdom); Sato, Syunsuke; Ishiyama, Yuichiro; Kawarada, Hiroshi [Department of Electronic and Photonic Systems, Waseda University, Okubo 3-4-1, Shinjuku, Tokyo 169-8555 (Japan); Morris, Richard [Advanced SIMS Projects, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

2012-02-01

84

Design and fabrication of piezoresistive strain gauges based on nanocrystalline diamond layers  

Microsoft Academic Search

The paper reports on design, fabrication and characterization of piezoresistive sensors based on boron doped nanocrystalline diamond (NCD) layers. The shape and position of the piezoresistive element was optimized using finite element 3D modeling. Mechanical and piezoresistive simulations were performed. The piezoresistive sensing boron doped diamond thin films were realized on SiO2\\/Si3N4\\/Si substrates by microwave plasma enhanced chemical vapor deposition

Pavel Kulha; Oleg Babchenko; Alexander Kromka; Miroslav Husak; Ken Haenen

85

Towards improving the quality of semiconducting diamond layers doped with large atoms  

Microsoft Academic Search

Previous studies on phosphorus- and aluminium-dopant activation in ion-implanted diamonds indicated that vacancies can either act to compensate the dopants or, when annealed at a temperature where they diffuse (600°C), they can interact to passivate these same dopant atoms. In order to improve the quality of diamond layers doped with large atoms, ways must be found to counteract such passivation.

Johan F. Prins

1999-01-01

86

Enhancement of the nucleation of smooth and dense nanocrystalline diamond films by using molybdenum seed layers  

NASA Astrophysics Data System (ADS)

A method for the nucleation enhancement of nanocrystalline diamond (NCD) films on silicon substrates at low temperature is discussed. A sputter deposition of a Mo seed layer with thickness 50 nm on Si substrates was applied followed by an ultrasonic seeding step with nanosized detonation diamond powders. Hot-filament chemical vapor deposition (HF-CVD) was used to nucleate and grow NCD films on substrates heated up at 550 °C. The nucleation of diamond and the early stages of NCD film formation were investigated at different methane percentages in methane/hydrogen gas mixtures by atomic force microscopy, micro-Raman spectroscopy, scanning electron microscopy, and grazing incidence x-ray analyses in order to gain specific insight in the nucleation process of NCD films. The nucleation kinetics of diamond on the Mo-coated Si substrates was found to be up to ten times higher than on blank Si substrates. The enhancement of the nucleation of diamond on thin Mo interlayers results from two effects, namely, (a) the nanometer rough Mo surface shows an improved embedding of ultrasonically introduced nanosized diamond seeds that act as starting points for the diamond nucleation during HF-CVD and (b) the rapid carbonization of the Mo surface causes the formation of Mo2C onto which diamond easily nucleates. The diamond nucleation density progressively increases at increasing methane percentages and is about 5×1010 cm-2 at 4.0% methane. The improved nucleation kinetics of diamond on Mo interlayers facilitates the rapid formation of NCD films possessing a very low surface roughness down to ~6 nm, and allows a submicron thickness control.

Buijnsters, J. G.; Vázquez, L.; van Dreumel, G. W. G.; Ter Meulen, J. J.; van Enckevort, W. J. P.; Celis, J. P.

2010-11-01

87

Temperature-dependent orientation of diamond films on titanium and structural evolution of interfacial layers  

SciTech Connect

X-ray diffraction analytical techniques have been used to investigate the influence of the deposition temperature (650{endash}850{degree}C) on the composition and microstructure of the transition layers formed at the interface between titanium substrates and diamond thin films. The diamond coatings were produced by hot-filament chemical vapor deposition using a 1{percent} methane/hydrogen mixture. X-ray diffraction analysis, performed both through {theta}{endash}2{theta} scans and at grazing incidence, allowed investigation of the crystallographic properties and of the structural evolution of the various phases (TiC, TiH{sub 2}, {alpha}-Ti) generated inside the intermediate reaction layers. The temperature-dependent orientation of diamond crystallites is discussed with reference to the complex structure of these interfacial layers. {copyright} {ital 1996 American Institute of Physics.}

Cappuccio, G. [Istituto di Strutturistica Chimica, CNR, Monterotondo Staz.] [Istituto di Strutturistica Chimica, CNR, Monterotondo Staz.; [Laboratorio Dafne Luce, INFN-LNF, P.O.B. 13, 00044 Frascati (Italy); Sessa, V.; Terranova, M.L. [Dipartimento di Scienze e Tecnologie Chimiche, Universita di Tor Vergata] [Dipartimento di Scienze e Tecnologie Chimiche, Universita di Tor Vergata; [Consorzio Interuniversitario di Chimica dei Materiali, Via della Ricerca Scientifica, 00133 Roma (Italy)

1996-12-01

88

Epitaxial synthesis of diamond layers on a monocrystalline diamond substrate in a torch microwave plasmatron  

SciTech Connect

The epitaxial growth of a diamond single-crystal film in a torch microwave discharge excited by a magnetron of a domestic microwave oven with the power of {<=}1 kW in an argon-hydrogen-methane mixture with a high concentration of methane (up to 25% with respect to hydrogen) at atmospheric pressure on a sub-strate of a synthetic diamond single crystal (HPHP) with the orientation (100) and 4 Multiplication-Sign 4 mm in size is obtained. A discharge with the torch diameter of {approx}2 mm and the concentration of the microwave power absorbed in the torch volume of >10{sup 3} W/cm{sup 3} is shown to be effective for epitaxial enlargement of a single crystal of synthetic diamond. The structure of the deposited film with the thickness up to 10 {mu}m with high-quality morphology is investigated with an optical microscope as well as using the methods of the Raman scattering and scanning electron microscopy.

Sergeichev, K. F., E-mail: kserg@fpl.gpi.ru; Lukina, N. A. [Prokhorov Institute of General Physics (Russian Federation)

2011-12-15

89

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

PubMed

The ability to measure weak signals such as pressure, force, electric field and temperature with nanoscale devices and high spatial resolution offers a wide range of applications in fundamental and applied sciences. Here we present a proposal for a hybrid device composed of thin film layers of diamond with colour centres and piezoactive elements for the transduction and measurement of physical signals. The magnetic response of a piezomagnetic layer to an external stress or a stress induced by a signal is shown to affect significantly the spin properties of nitrogen-vacancy centres in diamond. Under ambient conditions, realistic environmental noise and material imperfections, we show that this hybrid device can achieve significant improvements in sensitivity over the pure diamond-based approach in combination with nanometre-scale spatial resolution. Furthermore, the proposed hybrid architecture offers novel possibilities for engineering strong coherent couplings between nanomechanical oscillator and solid state spin qubits. PMID:24909637

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

2014-01-01

90

Chemical vapor deposition of diamond onto iron based substrates. The use of barrier layers.  

National Technical Information Service (NTIS)

When Fe is exposed to the plasma environment suitable for the chemical vapor deposition (CVD) of diamond, the surface is rapidly covered with a thick layer graphitic soot and C swiftly diffuses into the Fe substrate. Once the soot reaches a critical thick...

P. S. Weiser S. Prawer

1995-01-01

91

Liquid Crystal Alignment Capabilities on a New Diamond-Like Carbon Thin Film Layer  

NASA Astrophysics Data System (ADS)

Contained in this report are studies on liquid crystal (LC) alignment capabilities and the generation of pre-tilt angles with ion beam (IB) exposure on a diamond like carbon (DLC) thin film layer. A high pre-tilt angle of 3.5° via IB exposure on the DLC thin film layer can be obtained. Superior LC alignment via the IB alignment method on the DLC thin film layer was observed up to an annealing temperature of 200°C. A high LC pre-tilt angle and good thermal stability during LC alignment via the IB alignment method on the DLC thin film layer can be achieved.

Hwang, Jeoung-Yeon; Jo, Yong-Min; Seo, Dae-Shik; Rho, Soon Joon; Lee, Dae Kyu; Baik, Hong Koo

2002-06-01

92

Analysis of diamond surface channel field-effect transistors with AlN passivation layers  

NASA Astrophysics Data System (ADS)

Diamond surface channel field effect transistors were passivated with thin AlN layers grown by metal-organic chemical vapor deposition in order to improve the chemical stability of the surface-near p-type channel. Electrical characterization showed that the surface-near conductivity in the diamond is preserved during AlN overgrowth if the process temperature does not exceed 800 °C. However, the sheet carrier density is decreased by a factor of about 5 compared to the unpassivated hydrogen-terminated surface. A combination of TEM and XPS analysis showed that this effect is not induced by a partial modification of the surface termination or by a polarization of the AlN passivation. The preserved, but reduced surface-near conductivity in the diamond can however be explained by a hydrogen double bond between the diamond and the AlN film. Field-effect transistor structures fabricated on the passivated diamond substrates showed stable operation up drain-source voltages to -70 V and might therefore be promising candidates for future high-voltage applications.

Pietzka, C.; Scharpf, J.; Fikry, M.; Heinz, D.; Forghani, K.; Meisch, T.; Diemant, Th.; Behm, R. J.; Bernhard, J.; Biskupek, J.; Kaiser, U.; Scholz, F.; Kohn, E.

2013-09-01

93

Synthesis of diamond in a hydrogen plasma jet: Simulations of XRD patterns of diamond polytypes and boundary layer on a substrate  

NASA Astrophysics Data System (ADS)

Two kinds of diamond film were obtained by synthesizing diamond film on Mo substrates in a hydrogen plasma jet. One (type A) was random oriented cubic diamond film with clear habit planes. The other (type B) was film with no habit plane. It was inferred that the majority of type B film consisted of oriented hexagonal diamond polytypes. In order to confirm this fact, XRD (x ray diffraction) patterns of the polytypes was simulated. From the results of the simulated XRD patterns and the analysis of SAD (selected area diffraction) patterns, it can be concluded that type B film consists mainly of a mixture of many kinds of higher hexagonal diamond polytypes, and that these polytypes show a strong bracket 110 bracket orientation in the growth direction; that is, a direction vertical to the substrate surface. The flow and temperature field just above the substrate were simulated to find growth conditions for hexagonal diamond polytypes. It was found that the polytypes could be synthesized when the temperature gradient of boundary layer is greater than the gradient at which cubic diamond is synthesized.

Kikukawa, Nobuyuki; Makino, Mitsuo; Maruyama, Katsuhisa; Shiraishi, Minoru

1993-05-01

94

Enhanced thermal performances of silicon-on-diamond wafers incorporating ultrathin nanocrystalline diamond and silicon layers: Raman and micro-Raman analysis  

NASA Astrophysics Data System (ADS)

Silicon-on-diamond (SOD) wafers potentially present thermal advantages over standard silicon-on-insulator (SOI) counterparts based on SiO2 as the buried insulating layer. This work reports the fabrication of high quality SOD wafers by the bond and etch back SOI process. One key parameter in the CVD diamond growth process is the substrate temperature. We focused here on two processes based on either high or low processing temperature to produce nanocrystalline diamond (NCD) on silicon. Both type of NCD films have been analyzed via Raman spectroscopy. Results have been correlated with scanning electron microscopy observations. In a second part, SOD wafers are fabricated and the crystalline quality of the active silicon layer is assessed via Raman measurements and high resolution transmission electron microscopy imaging. It is shown that the growth of diamond did not induce any structural defect or strain in the thin top silicon layer. Eventually, we demonstrate the efficiency of diamond integration thanks to micro-Raman spectroscopy, where the probing laser simultaneously generates Raman signal and controlled local heating. Our SOD wafers evidence a thermal resistance reduction of about 70% compared to conventional SOI materials, with heat source spatial extension in the micron range.

Mazellier, Jean-Paul; Mermoux, Michel; Andrieu, Francois; Widiez, Julie; Dechamp, Jérôme; Saada, Samuel; Lions, Mathieu; Hasegawa, Masataka; Tsugawa, Kazuo; Bergonzo, Philippe; Faynot, Olivier

2011-10-01

95

Low-friction diamond-like carbon (DLC)-layers for humid environment  

Microsoft Academic Search

Even though amorphous diamond-like carbon (DLC) coated tools with their low friction and high wear resistance are well established in a wide field of industrial applications, their employment into humid environments is limited. In humid environments hydrogenated DLC-layers show high friction coefficients and low wear resistance.This work is focused on the development of DLC-coating systems with high wear resistance and

Wolfgang Tillmann; Evelina Vogli; Fabian Hoffmann

2007-01-01

96

Various Liquid Crystal Alignments on Fluorinated Diamond-Like Carbon Layer by Ion Beam Treatment  

NASA Astrophysics Data System (ADS)

Fluorinated diamond-like carbon (FDLC) thin films with various wetting properties were introduced as liquid crystal (LC) alignment layers. We applied the ion beam (IB) treatment as an LC alignment method. Although the carbon-rich FDLC favored parallel LC orientation, the fluorine-rich FDLC favored vertical or tilted vertical orientation. Microscopic mechanisms of different orientations are discussed and insight into the role of fluorine and carbon binding is discussed.

Ahn, Han Jin; Kim, Kyung Chan; Kim, Jong Bok; Hwang, Byoung Har

2007-06-01

97

Formation of diamond-clusters within a surface layer of carbon steels\\/cast iron induced by excimer laser irradiation  

Microsoft Academic Search

A thin layer of diamond-cluster\\/iron composite was formed near the surface of carbon steels\\/cast iron after a repeated irradiation by a short-pulsed ArF excimer laser. The presence of diamond is characterized by SEM and Raman spectroscopy. The formation mechanism is discussed in terms of sp3-carbon aggregation in the locally melted carbon-containing iron. The catalytic effect of iron on the formation

Rong-Fu Xiao; Zhi-Feng Li

1998-01-01

98

Graphitized Layer Buried in a Diamond: SAW Generation under Picosecond Optical Excitation  

NASA Astrophysics Data System (ADS)

The excitation of SAW was detected on diamond with built-in ion-implanted graphitized layer under its illumination with femtosecond laser pulses. The spectral width of a SAW pulses were in the range of 1.5÷2 GHz. It was found out that the anisotropy of the SAW propagation was practically absent. The increase in the implantation dose from 4·1015 cm?2 to 12·1015 cm?2 was shown to give rise to a dispersion of SAW propagation.

Klokov, A.; Tsvetkov, V.; Sharkov, A.; Aminev, D.; Khmelnitskiy, R.

2014-06-01

99

Enhanced electron field emission properties of diamond-like carbon films using a titanium intermediate layer  

Microsoft Academic Search

Substantially improved uniformity and enhanced electron field emission properties of hydrogen-free diamond-like carbon (DLC) films were obtained using a titanium intermediate layer after the annealing process. Large emission current densities of 2.08 mA cm-2 at 14.3 V µm-1 and 7.20 mA cm-2 at 25.7 V µm-1 were achieved for DLC\\/Ti\\/Si film annealed at 430 °C for 0.5 h. Its field

D. S. Mao; J. Zhao; W. Li; X. Wang; X. H. Liu; Y. K. Zhu; Z. Fan; J. Y. Zhou; Q. Li; J. F. Xu

1999-01-01

100

Diamond-like carbon layer formation on graphite by excimer laser irradiation  

NASA Astrophysics Data System (ADS)

Irradiation of highly oriented pyrolytic graphite (HOPG) with ArF excimer laser (?=193 nm) pulses of 2 J/cm2 fluence results in the formation of a thin hydrogen-free diamond-like carbon (DLC) film on the surface. The density of the laser-formed DLC layer is approximately 2.8 g/cm3, as calculated from area-selective Raman spectroscopy and atomic force microscopic (AFM) measurements. The proportion of the sp3 hybrid states of carbon is estimated to be approximately 50%. Annealing in air at 650 °C for 30 min recovers the graphite structure.

Mechler, Á.; Heszler, P.; Kántor, Z.; Szörényi, T.; Bor, Z.

101

High current density diamond based electron emitters for vacuum thermionic energy conversion  

NASA Astrophysics Data System (ADS)

Vacuum thermionic energy conversion utilizes thermionic emission to release electrons from an emitter into vacuum and collection at a counter-electrode. In our approach for an efficient thermionic emitter a multi-layer diamond thin film structure was synthesized by plasma-assisted CVD on a metallic substrate with controlled surface roughness including a nanodiamond pretreatment step. Introduction of nitrogen during ultra-nanocrystalline diamond (UNCD) film growth resulted in a low resistivity interstitial layer significantly enhancing emission current density which can be related to the Richardson constant. The top layer of polycrystalline nitrogen doped diamond was exposed to a hydrogen plasma inducing negative electron affinity characteristic presenting a low effective emitter work function < 1.3 eV. Thermionic emission from this material commences at temperatures as low as 260^oC and observes the law of Richardson -- Dushman. From a data fit a significant Richardsons constant > 2 A/cm^2 K^2 was extracted and at a temperature of 500^oC a thermionic emission current > 5 mA was measured. This may well be the highest current density reported from a thermionic emitter operating at the moderate temperature of 500^oC.

Koeck, Franz; Nemanich, Robert

2010-03-01

102

N-type droping of nanocrystalline diamond films with nitrogen and electrodes made therefrom  

DOEpatents

An electrically conducting n-type ultrananocrystalline diamond (UNCD) having no less than 10.sup.19 atoms/cm.sup.3 of nitrogen is disclosed. A method of making the n-doped UNCD. A method for predictably controlling the conductivity is also disclosed.

Gruen, Dieter M. (Downers Grove, IL); Krauss, Alan R. (late of Naperville, IL); Auciello, Orlando H. (Bolingbrook, IL); Carlisle, John A. (Plainfield, IL)

2004-09-21

103

Improvement in low-voltage performance of surface-electrode soft-X-ray detectors composed of undoped homoepitaxial CVD/HPHT Ib diamond layers  

NASA Astrophysics Data System (ADS)

We have successfully fabricated diamond soft-X-ray (SXR) detectors with interdigitated surface electrodes that significantly improve the low-voltage performance using high-quality chemical-vapour-deposited (CVD) diamond films homoepitaxially grown on high-pressure/high-temperature-synthesised (HPHT) diamond Ib substrates. In the present study, the collection efficiencies of photon-excited carriers were evaluated using monochromatised SXRs at applied voltages ?12 V for two types of diamond detectors with different stacking structures of the CVD layers. We found that the diamond detectors with an electrically floating B-doped layer sandwiched between two undoped CVD layers yield significantly larger carrier collection efficiencies compared to those without an inserted B-doped layer, even under the no-applied-voltage condition; moreover, the carrier collection efficiencies only slightly increase with increases in applied voltages below 12 V. This result indicates that the inserted B-doped layer can work independently (without electrical connection to any external circuit) as a potential barrier against carrier diffusions to a HPHT diamond substrate with much poorer quality than CVD diamond film of a photon absorption layer. The detector performances are discussed relative to the potential distribution formed in the active undoped diamond layer and the crystalline quality, which is based on the cathodoluminescence intensity of exciton emissions at room temperature.

Kanasugi, M.; Iwakaji, Y.; Yamamoto, T.; Maida, O.; Takeda, Y.; Saitoh, Y.; Ito, T.

2010-09-01

104

Hydrogen-free diamond-like carbon deposited by a layer-by-layer technique using PECVD  

SciTech Connect

The authors developed a hydrogen-free diamond like carbon (DLC) film by a novel deposition technique of a layer-by-layer technique using plasma enhanced chemical vapor deposition (PECVD) in which a repeated deposition of a thin DLC layer and subsequently CF{sub 4} plasma treatment on its surface have been carried out. The electrical, optical and structural properties of the DLC films deposited depend on the CF{sub 4} plasma exposure time. The hydrogen content is less than 1 at % when the CF{sub 4} plasma exposure time is 140s. Its emission current is much higher and stability is much improved compared with conventional DLC.N-type, hydrogen-free DLC could be obtained by N ion doping or by N{sub 2} gas-phase doping in the CH{sub 4} plasma. The optimum [N{sub 2}]/[CH{sub 4}] flow rate ratio was found to be 9% for the efficient electron emission, at which the onset-field was 7.2 V/{micro}m. The nitrogen gas-phase doped hydrogen-free DLC coating on Mo tip field emitter arrays (FEAs) increased the electron emission current from 160{micro}A to 1.52 mA and improved the stability in electron emission current.

Jang, J.; Chung, S.J.

2000-01-30

105

Tantalum as a buffer layer in diamond-like carbon coated artificial hip joints.  

PubMed

The acid resistance of tantalum coated and uncoated human hip joint prostheses was studied with commercial CrCoMo acetabular cups. The samples were exposed to 10% HCl solution and the quantities of dissolved Cr, Co, and Mo were measured with proton-induced X-ray emission (PIXE). The absolute quantities were obtained with the use of Cr and Se solution standards. Tantalum coatings (thicknesses 4-6 microm) were prepared in vacuum with magnetron sputtering. Tantalum coating decreased the corrosion rate by a factor of 10(6). As a spinoff from recent wear tests on artificial hip joints it was shown that tantalum has excellent mechanical properties as an intermediate layer of diamond-like carbon (DLC) coatings. When tantalum was tested together with DLC on three metal-on-metal hip joint pairs in a hip simulator, no observable defects occurred during 15 million walking cycles with a periodic 50-300-kg load (Paul curve). PMID:12808604

Kiuru, Mirjami; Alakoski, Esa; Tiainen, Veli-Matti; Lappalainen, Reijo; Anttila, Asko

2003-07-15

106

Lowering of work function induced by deposition of ultra-thin rubidium fluoride layer on polycrystalline diamond surface  

NASA Astrophysics Data System (ADS)

Ultra-thin rubidium fluoride (RbF) was thermally evaporated onto polycrystalline diamond surface. The role of RbF as a strong dipole layer to lower the surface work function was investigated using ultraviolet photoemission spectroscopy, Kelvin probe and Auger electron spectroscopy. It was found that deposition of sub-monolayer of RbF could greatly reduce the work function of the diamond surface. Also, the ultra-thin RbF overlayer is very sensitive to electron irradiation. The electron irradiation can seriously weaken the effect of RbF as a surface dipole.

Wong, K. W.; Wang, Y. M.; Lee, S. T.; Kwok, R. W. M.

1999-02-01

107

Diamond layers grown by chemical vapor deposition on NbN systems and NbN/SiO2-based devices.  

PubMed

Deposits of individual diamond grains and continuous polycrystalline diamond layers have been generated by means of a HFCVD technique onto different types of untreated or seeded NbN surfaces. To test the feasibility of using diamond layers as protective coatings for aerospace applications, we carried out diamond deposition onto the lithographically defined NbN microelectrodes of a NbN/SiO2 multifinger device. The morphological and structural features of the diamond deposits and of the substrates were characterized by FE-SEM, XRD and Raman spectroscopy. The preferential growth of diamond on the superconductive NbN enables the selective coating of the NbN microstripes sputtered on the insulating SiO2. Moreover the diamond coating procedure is able to preserve the structural integrity of the substrate material and to retain the shaped architecture of the device. For the polycrystalline diamond layers grown on NbN a residual stress of -9.8 GPa, largely due to thermal stress, has been estimated by Raman analysis. The diamond coatings of the NbN-based architectures result to be mechanically stable. PMID:22097552

Orlanducci, S; Guglielmotti, V; Cianchetta, I; Lucci, M; Toschi, F; Tamburri, E; Terranova, M L

2011-09-01

108

Prevention of nanoscale wear in atomic force microscopy through the use of monolithic ultrananocrystaline diamond probes.  

SciTech Connect

Nanoscale wear is a key limitation of conventional atomic force microscopy (AFM) probes that results in decreased resolution, accuracy, and reproducibility in probe-based imaging, writing, measurement, and nanomanufacturing applications. Diamond is potentially an ideal probe material due to its unrivaled hardness and stiffness, its low friction and wear, and its chemical inertness. However, the manufacture of monolithic diamond probes with consistently shaped small-radius tips has not been previously achieved. The first wafer-level fabrication of monolithic ultrananocrystalline diamond (UNCD) probes with <5-nm grain sizes and smooth tips with radii of 30-40 nm is reported, which are obtained through a combination of microfabrication and hot-filament chemical vapor deposition. Their nanoscale wear resistance under contact-mode scanning conditions is compared with that of conventional silicon nitride (SiN{sub x}) probes of similar geometry at two different relative humidity levels ({approx}15 and {approx}70%). While SiN{sub x} probes exhibit significant wear that further increases with humidity, UNCD probes show little measurable wear. The only significant degradation of the UNCD probes observed in one case is associated with removal of the initial seed layer of the UNCD film. The results show the potential of a new material for AFM probes and demonstrate a systematic approach to studying wear at the nanoscale.

Liu, J.; Grierson, D. S.; Notbohm, J.; Li, S.; O'Connor, S. D.; Turner, K. T.; Sumant, A. V.; Neelakantan, N.; Moldovan, N.; Carlisle, J. A.; Jaroenapibal, P.; Carpick, R. W. (Center for Nanoscale Materials); ( PSC-USR); (Univ. of Wisconsin at Madison); (Advanced Diamond Tech.); (Univ. of Pennsylvania)

2010-01-01

109

Synthesis of diamond in a hydrogen plasma jet: Simulations of XRD patterns of diamond polytypes and boundary layer on a substrate  

Microsoft Academic Search

Two kinds of diamond film were obtained by synthesizing diamond film on Mo substrates in a hydrogen plasma jet. One (type A) was random oriented cubic diamond film with clear habit planes. The other (type B) was film with no habit plane. It was inferred that the majority of type B film consisted of oriented hexagonal diamond polytypes. In order

Nobuyuki Kikukawa; Mitsuo Makino; Katsuhisa Maruyama; Minoru Shiraishi

1993-01-01

110

Diamond-Like-Carbon LC-Alignment Layers for Application in LCOS Microdisplays  

SciTech Connect

To improve the lifetime and yield of LCOS microdisplays, non-contact LC alignment techniques using inorganic materials are under investigation. This report focuses on oblique ion-beam treatment of diamond-like carbon (DLC) layers, and in particular on the influence of the ion dose on the LC alignment on DLC, keeping the ion-beam angle (40 degrees) and ion-beam energy (170 eV) the same. LC alignment on ion-milled DLC layers is uniform if the ion dose is between 3.8 x 10{sup -4} C/cm{sup 2} and 5.5x10{sup -3} C/cm{sup 2}. Above and below this ion dose range, non-uniform alignment is observed. NEXAFS experiments show that this is caused by lack of molecular anisotropy on the surface of the ion-milled DLC layers. By varying the ion dose between 3.8 x 10{sup -4} C/cm{sup 2} and 5.5 x 10{sup -3} C/cm{sup 2}, LC molecules have an average pre-tilt between 3 and 5 degrees, which is within the desired range for application in LCOS microdisplays. The lifetime of the LCOS microdisplays with ion-milled DLC for projection-TV application is, however, shorter than the lifetime of microdisplays with PI layers. Ion milling probably creates a reactive surface that is unstable under the high light fluxes used in projection TVs. A solution for this problem could be chemical passivation of the ion-milled alignment layers. Initial experiments with passivation of ion-milled PI resulted in an increase in lifetime, but the lifetime after passivation was still lower than the lifetime of rubbed PI layers (factor 0.7). Nevertheless, ion-milling of DLC or PI can be a good alternative LC alignment technique in other LCD applications. LC-alignment layers based on inorganic layers such as obliquely deposited SiO{sub 2} films would be a better option for application in LCOS microdisplays due to their higher light stability.

Bol,A.; Dvorak, J.; Arena, D.

2005-01-01

111

Interaction between sputtered beta-Ta films and diamond-like carbon with Ru intermediate layer.  

PubMed

Interaction between beta-tantalum film and Diamond-like Carbon (DLC) film was studied with and without ruthenium intermediate barrier layer. Phase identification using X-ray Diffraction showed that the phase transformation of tantalum film from beta to alpha crystalline structure was delayed by 100 degrees C and the formation of tantalum carbide was also hindered when ruthenium interlayer is present. X-ray reflectivity measurements indicate that the surface and interfacial area of C/Ta film was maintained to achieve desired magnetic and tribological performance even after N2 annealing at 400 degrees C. In C/Ru/Ta film there is minimum intermixing between tantalum and DLC. In C/Ta film, severe reaction between tantalum and carbon took place. Raman spectroscopy analysis revealed the as-deposited carbon film possessed amorphous structure regardless of the existence of Ru interlayer. Graphitization of carbon film was observed in both structures, upon annealing, however the films with Ru layer was thermodynamically more stable thus desirable in magnetic recording. PMID:21128472

Wang, Jianhui; Zhang, Sam; Li, Yibin; Zhao, Jinmin; Zhu, Lei; Yao, Fang

2010-07-01

112

Enhanced electron field emission properties of diamond-like carbon films using a titanium intermediate layer  

NASA Astrophysics Data System (ADS)

Substantially improved uniformity and enhanced electron field emission properties of hydrogen-free diamond-like carbon (DLC) films were obtained using a titanium intermediate layer after the annealing process. Large emission current densities of 2.08 mA cm-2 at 14.3 V µm-1 and 7.20 mA cm-2 at 25.7 V µm-1 were achieved for DLC/Ti/Si film annealed at 430 °C for 0.5 h. Its field emission was much more uniform than that of as-prepared DLC/Ti/Si and DLC/Si films. Secondary ion mass spectroscopy (SIMS) showed that C has been amply diffused into the Ti layer. An x-ray photoelectron spectroscopy (XPS) spectrum of the annealed DLC/Ti/Si film after 10 min of argon ion sputtering showed the formation of TiC at the interface between the DLC and Ti/Si substrate. This interaction and interdiffusion of C and Ti could significantly lower the Schottky barrier height between the DLC and Ti/Si substrate. The result was that electrons induced from the Ti/Si substrate can be easily penetrated into DLC films, which enhances the field emission properties.

Mao, D. S.; Zhao, J.; Li, W.; Wang, X.; Liu, X. H.; Zhu, Y. K.; Fan, Z.; Zhou, J. Y.; Li, Q.; Xu, J. F.

1999-07-01

113

The effects of defects on the electrical properties of amorphous carbon layer formed by ion implantation into CVD diamond films  

SciTech Connect

Correlation between defects and electrical properties in an amorphous carbon layer, formed by ion implantation into diamond film, have been studied by EST method. The ion implantation produced dense defect structures (carbon dangling bonds) in the surface layer and led the implanted layer to a low resistance, as the high-density defect introduced variable range hopping conduction. The variable range hopping conduction was observed even after annealing at 1,000 C, because the high-density defect existed in the surface region.

Show, Yoshiyuki; Sekine, Daisuke; Ito, Hirokazu; Izumi, Tomio; Iwase, Mitsuo

2000-01-30

114

Excimer laser irradiation induced formation of diamond-like carbon layer on graphite  

NASA Astrophysics Data System (ADS)

Highly oriented pyrolytic graphite (HOPG) was irradiated by an ArF excimer ( ?=193 nm) laser above the ablation threshold, at approx. 0.45 and 2 J/cm 2. The surface morphology and the quality of the remaining material was investigated by atomic force microscopy (AFM) and area-selective Raman spectroscopy. At the lower fluence a material removal rate of several monolayers per laser pulse was detected, without changing the quality of the remaining material. Irradiation at the higher fluence resulted in ablation rates of the order of 10 nm/pulse and the formation of an approx. 300 nm thick diamond-like carbon (DLC) film with approx. 50% concentration of the sp3 hybrid-states of carbon. In the surroundings of the ablated hole a narrow ring of mechanically soft, nanocrystalline and turbostratic carbon was observed. Upon annealing the irradiated surfaces in air at 650°C for 30 min, the graphite structure of the laser-modified layer was perfectly recovered with the disappearance of the surrounding ring.

Mechler, Ádám; Heszler, Péter; Kántor, Zoltán; Szörényi, Tamás; Bor, Zsolt

1999-01-01

115

FAST TRACK COMMUNICATION: High pressure superconductivity in iron-based layered compounds studied using designer diamonds  

Microsoft Academic Search

High pressure superconductivity in iron-based superconductor FeSe0.5Te0.5 has been studied up to 15 GPa and 10 K using an eight probe designer diamond anvil in a diamond anvil cell device. Four probe electrical resistance measurements show the onset of superconductivity (Tc) at 14 K at ambient pressure with Tc increasing with increasing pressure to 19 K at a pressure of

Georgiy Tsoi; Andrew K. Stemshorn; Yogesh K. Vohra; Phillip M. Wu; F. C. Hsu; Y. L. Huang; M. K. Wu; K. W. Yeh; Samuel T. Weir

2009-01-01

116

High pressure superconductivity in iron-based layered compounds studied using designer diamonds  

Microsoft Academic Search

High pressure superconductivity in iron-based superconductor FeSe0.5Te0.5 has been studied up to 15 GPa and 10 K using an eight probe designer diamond anvil in a diamond anvil cell device. Four probe electrical resistance measurements show the onset of superconductivity (Tc) at 14 K at ambient pressure with Tc increasing with increasing pressure to 19 K at a pressure of

Georgiy Tsoi; Andrew K. Stemshorn; Yogesh K. Vohra; Phillip M. Wu; F. C. Hsu; Y. L. Huang; M. K. Wu; K. W. Yeh; Samuel T. Weir

2009-01-01

117

Thermally stable diamond brazing  

DOEpatents

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.

Radtke, Robert P. (Kingwood, TX) [Kingwood, TX

2009-02-10

118

Analyzing the design of vibration reduction with the rubber-layered laminates in the precision turning with a diamond cutting tool  

Microsoft Academic Search

Using a diamond cutting tool in the precision turning process, the vibration of tool-tip has an undesirable effect on the\\u000a machined surface’s quality. The objective of this paper is to analyze the design of turning tool-bar combined with the rubber-layered\\u000a laminates for minimizing the vibration amplitude of tool-tip in the precision turning with the diamond tool. The selected\\u000a rubber materials

Chih-Cherng Chen; Ko-Ta Chiang

119

Combination of e-beam lithography and of high velocity AIN/diamond-layered structure for SAW filters in X band.  

PubMed

In this work, we report on the fabrication results of surface acoustic wave (SAW) devices operating at frequencies up to 8 GHz. In previous work, we have shown that high acoustic velocities (9 to 12 km/s) are obtained from the layered AIN/diamond structure. The interdigital transducers (IDTs) made of aluminium with resolutions up to 250 nm were successfully patterned on AIN/diamond-layered structures with an adapted technological process. The uniformity and periodicity of IDTs were confirmed by field emission scanning electron microscopy and atomic force microscopy analyses. A highly oriented (002) piezoelectric aluminum nitride thin film was deposited on the nucleation side of the CVD diamond by magnetron sputtering technique. The X-ray diffraction effectuated on the AIN/diamond-layered structure exhibits high intensity peaks related to the (002) AIN and (111) diamond orientations. According to the calculated dispersion curves of velocity and the electromechanical coupling coefficient (K2), the AIN layer thickness was chosen in order to combine high velocity and high K2. Experimental data extracted from the fabricated SAW devices match with theoretical values quite well. PMID:17718340

Kirsch, Philippe; Assouar, Mohamed B; Elmazria, Omar; Hakiki, M El; Mortet, Vincent; Alnot, Patrick

2007-07-01

120

Surface Evaluation of Fluorinated Diamond-Like Carbon Thin Film as an Antisticking Layer of Nanoimprint Mold  

NASA Astrophysics Data System (ADS)

The surface property of fluorinated diamond-like carbon (F-DLC) thin film, which is expected to be a new antisticking layer of nanoimprint mold, was evaluated with reference to the commercial diamond-like carbon (DLC) thin film formed by radio-frequency (RF) plasma chemical vapor deposition (CVD) and the fluorinated self-assembled monolayer (SAM). From the measurement of X-ray photoelectron spectrum (XPS), the surface of the F-DLC thin film was found to be overspread with hydrophobic CFx components. In addition, the durability of the F-DLC thin film was evaluated by the contact angle measurement of a water drop against repeating times of the thermal imprint process. After over 100 times of imprinting, the contact angles of the F-DLC thin film were almost kept constant with the initial value and a fine replicated pattern was obtained. From these results, the F-DLC thin film was found to be suitable as a novel antisticking layer of the thermal nanoimprint mold.

Yamada, Noriko; Nakamatsu, Ken-ichiro; Kanda, Kazuhiro; Haruyama, Yuichi; Matsui, Shinji

2007-09-01

121

High pressure superconductivity in iron-based layered compounds studied using designer diamonds.  

PubMed

High pressure superconductivity in iron-based superconductor FeSe(0.5)Te(0.5) has been studied up to 15 GPa and 10 K using an eight probe designer diamond anvil in a diamond anvil cell device. Four probe electrical resistance measurements show the onset of superconductivity (T(c)) at 14 K at ambient pressure with T(c) increasing with increasing pressure to 19 K at a pressure of 3.6 GPa. At higher pressures beyond 3.6 GPa, T(c) decreases and extrapolation suggests non-superconducting behavior above 10 GPa. The loss of superconductivity coincides with the pressure induced disordering of the Fe(SeTe)(4) tetrahedra reported at 11 GPa in x-ray diffraction studies at ambient temperature. PMID:21825575

Tsoi, Georgiy; Stemshorn, Andrew K; Vohra, Yogesh K; Wu, Phillip M; Hsu, F C; Huang, Y L; Wu, M K; Yeh, K W; Weir, Samuel T

2009-06-10

122

FAST TRACK COMMUNICATION: High pressure superconductivity in iron-based layered compounds studied using designer diamonds  

NASA Astrophysics Data System (ADS)

High pressure superconductivity in iron-based superconductor FeSe0.5Te0.5 has been studied up to 15 GPa and 10 K using an eight probe designer diamond anvil in a diamond anvil cell device. Four probe electrical resistance measurements show the onset of superconductivity (Tc) at 14 K at ambient pressure with Tc increasing with increasing pressure to 19 K at a pressure of 3.6 GPa. At higher pressures beyond 3.6 GPa, Tc decreases and extrapolation suggests non-superconducting behavior above 10 GPa. The loss of superconductivity coincides with the pressure induced disordering of the Fe(SeTe)4 tetrahedra reported at 11 GPa in x-ray diffraction studies at ambient temperature.

Tsoi, Georgiy; Stemshorn, Andrew K.; Vohra, Yogesh K.; Wu, Phillip M.; Hsu, F. C.; Huang, Y. L.; Wu, M. K.; Yeh, K. W.; Weir, Samuel T.

2009-06-01

123

Liquid Crystal Aligning Capabilities and EO Characteristics of the TN-LCD with Ion-Beam Exposure on a New Diamond-like Carbon Thin Film Layer  

Microsoft Academic Search

Liquid crystal (LC) alignment capabilities with ion beam (IB) exposure on a diamond like carbon (DLC) layer were studied. A high pretilt angle of 3.5° with IB exposure on the DLC layer can be obtained. Superior LC alignment with the IB alignment method on the DLC layer was observed until an annealing temperature of 200°C. Also, excellent voltage-transmittance (V-T) curve

Yong-Min Jo; Jeoung-Yeon Hwang; Dae-Shik Seo; Soon-Jun Rho; Hong-Koo Baik

2004-01-01

124

Homoepitaxial single crystal diamond grown on natural diamond seeds (type IIa) with boron-implanted layer demonstrating the highest mobility of 1150 cm 2\\/V s at 300 K for ion-implanted diamond  

Microsoft Academic Search

The homoepitaxial single crystal diamond growth by microwave plasma assisted CVD at high microwave power density 200W\\/cm3 in a 2.45GHz MPACVD reactor using natural diamond seeds (type IIa) was investigated. The semiconductor CVD diamond of p-type was obtained by doping technique of ion implantation. Boron ions were implanted at the acceleration energy of 80keV with two cases of dose: 5·1014

A. K. Ratnikova; M. P. Dukhnovsky; Yu. Yu. Fedorov; V. E. Zemlyakov; A. B. Muchnikov; A. L. Vikharev; A. M. Gorbachev; D. B. Radishev; A. A. Altukhov; A. V. Mitenkin

2011-01-01

125

Shallow donors with high n-type electrical conductivity in homoepitaxial deuterated boron-doped diamond layers  

Microsoft Academic Search

Diamond is a unique semiconductor for the fabrication of electronic and opto-electronic devices because of its exceptional physical and chemical properties. However, a serious obstacle to the realization of diamond-based devices is the lack of n-type diamond with satisfactory electrical properties. Here we show that high-conductivity n-type diamond can be achieved by deuteration of particularly selected homo-epitaxially grown (100) boron-doped

Zéphirin Teukam; Jacques Chevallier; Cécile Saguy; Rafi Kalish; Dominique Ballutaud; Michel Barbé; François Jomard; Annie Tromson-Carli; Catherine Cytermann; James E. Butler; Mathieu Bernard; Céline Baron; Alain Deneuville

2003-01-01

126

Deposition of Diamond-Like Carbon Film Using RF Plasma Enhanced CVD foran AntiReflection Layer on Polarizers in TFT LCD Display  

Microsoft Academic Search

This paper describes the deposition of diamond-like carbon (DLC) film using RF plasma enhanced CVD for an anti-reflection layer on polarizers in TFT LCD display. The materials of polarizers in TFT LCD display are polymers, which are easily scratched. They need anti- reflection coating for using the LCD outside under sunlight. The DLC film has following properties : mechanically hard,

Y. K. Lee; K. C. Park; K. W. Lee; J. W. Lee; H. B. Lee; K. B. Kim

1996-01-01

127

Effect of surface defects by RF oxygen plasma on the electrical properties of thin boron-doped diamond layers in electrolyte  

Microsoft Academic Search

The effect of surface defects induced by RF oxygen plasma treatment on the electrical properties of thin boron-doped epitaxial diamond layers was investigated by electrochemical analysis in the modes of electrochemical electrode and ion sensitive field-effect transistor (ISFET). The doping profile employed allowed almost full depletion in the electrolyte used within the potential window of water electrolysis. The high near

J. Scharpf; A. Denisenko; C. Pietzka; E. Kohn

2011-01-01

128

High-reliability passivation of hydrogen-terminated diamond surface by atomic layer deposition of Al2O3  

NASA Astrophysics Data System (ADS)

Although the two-dimensional hole gas (2DHG) of a hydrogen-terminated diamond surface provides a unique p-type conducting layer for high-performance transistors, the conductivity is highly sensitive to its environment. Therefore, the surface must be passivated to preserve the 2DHG, especially at high temperature. We passivated the surface at high temperature (450 °C) without the loss of C-H surface bonds by atomic layer deposition (ALD) and investigated the thermal reliability of the Al2O3 film. As a result, C-H bonds were preserved, and the hole accumulation effect appeared after the Al2O3 deposition by ALD with H2O as an oxidant. The sheet resistivity and hole density were almost constant between room temperature and 500 °C by the passivation with thick Al2O3 film thicker than 38 nm deposited by ALD at 450 °C. After the annealing at 550 °C in air The sheet resistivity and hole density were preserved. These results indicate the possibility of high-temperature application of the C-H surface diamond device in air. In the case of lower deposition temperatures, the sheet resistivity increased after air annealing, suggesting an insufficient protection capability of these films. Given the result of sheet resistivity after annealing, the increase in the sheet resistivity of these samples was not greatly significant. However, bubble like patterns were observed in the Al2O3 films formed from 200 to 400 °C by air annealing at 550 °C for 1 h. On the other hand, the patterns were no longer observed at 450 °C deposition. Thus, this 450 °C deposition is the sole solution to enabling power device application, which requires high reliability at high temperatures.

Daicho, Akira; Saito, Tatsuya; Kurihara, Shinichiro; Hiraiwa, Atsushi; Kawarada, Hiroshi

2014-06-01

129

Friction and durability characteristics of ultrathin perfluoropolyether lubricant film composed of bonded and mobile molecular layers on diamond-like carbon surfaces  

Microsoft Academic Search

Molecularly thin perfluoropolyether (PFPE) lubricant film composed of bonded and mobile molecular layers was dip-coated on diamond-like carbon (DLC) surfaces, and experiments using a ball-on-disk tribotester were carried out for the friction and durability characteristics of the thin lubricant film. The average thicknesses of the bonded and mobile layers were varied independently up to 1.5 and 4nm, respectively, by changing

Takahisa Kato; Masahiro Kawaguchi; Mayeed M Sajjad; Junho Choi

2004-01-01

130

Industrial diamond  

USGS Publications Warehouse

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.

Olson, D. W.

2001-01-01

131

Studies on distribution of element contents in transient layer at interface between boron-doped diamond film electrode and tantalum substrate  

NASA Astrophysics Data System (ADS)

The boron-doped diamond film (BDD) grown on tantalum (Ta) substrate as an electrode (BDD/Ta) was prepared by hot filament chemical vapor deposition method. The experimental results demonstrated that our BDD/Ta had high current efficiency, strong ability to degrade wastewater, good corrosion stability and long lifetime. These excellent characteristics of BDD/Ta have been explained in terms of Rutherford backscattering (RBS) experiments. RBS investigation revealed that the continuous transient layer at the interface between boron-doped diamond film and Ta-substrate was formed and the microstructure of the continuous transient layer given by the continuous distribution of all element contents at the interface was obtained. The thicknesses of boron-doped diamond film and the continuous transient layer were about equal to 8000 × 10 15 atoms/cm 2 and 5800 × 10 15 atoms/cm 2, respectively. The formation of the continuous transient layer at the interface can eliminate the mismatch of thermal expansion coefficients (TEC) at the interface and only lead to the slow change of TEC because of the continuous distribution of element contents of the film and substrate in the transient layer at the interface. Thus, there is no residual stress to concentrate on the interface and the stress-corrosion delamination of the film disappears. Therefore, the corrosion stability and lifetime of BDD/Ta increase and last well, that have been verified by X-ray diffraction (XRD) experiments.

Liang, Jiachang; Gao, Chengyao; Zhang, Liping; Jiang, Lihui; Yang, Zhengquan; Wang, Zhiping; Ji, Chaohui; Le, Xiaoyun; Rong, Cuihua; Zhang, Jian

2011-05-01

132

Graphitized layer buried in a diamond: photothermal properties and hypersound generation under picosecond optical excitation  

NASA Astrophysics Data System (ADS)

We assume that a coherent phonon generation was found out in structures with a single graphitized layer under picosecond laser excitation by means of the Pump/Probe method. The thermal component of the response was calculated that allowed us to define the photothermal coefficient of the graphitized layer as well as its thermal conductivity from the experimental results. The thermal-conductivity coefficient of the graphitized layer appears to grow with the thickness decrease. This makes it possible to assume that the microstructure of the graphitized layer produced during annealing depends on its thickness.

Klokov, A.; Kochiev, M.; Sharkov, A.; Tsvetkov, V.; Khmelnitskiy, R.

2011-01-01

133

Microstructural evolution of diamond growth during HFCVD  

NASA Technical Reports Server (NTRS)

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.

Singh, J.

1994-01-01

134

Surface damages in diamond by Ar/O{sub 2} plasma and their effect on the electrical and electrochemical characteristics of boron-doped layers  

SciTech Connect

Epitaxial single crystal and boron-doped diamond layers were exposed to reactive ion etching in Ar/O{sub 2} plasma (rf power of 25 W and self-bias of 100 V); and the electrical, structural, and electrochemical characteristics of the exposed surface were investigated. Angle-resolved x-ray photoemission spectroscopy (XPS) measurements revealed a nonuniform layer of amorphous carbon at the exposed surface with an average thickness of approximately 4 nm, as confirmed also by atomic force microscopy profiling of selectively etched areas. On highly boron-doped diamond, the plasma-induced damages resulted also in a nonconductive surface layer. This damaged and insulating surface layer remained resistant to graphite-etching chemicals and to rf oxygen plasma but it was removed completely in microwave hydrogen plasma at 700 deg. C. The surface characteristics after the H-plasma process followed by wet chemical oxidation were restored back to the initial state, as confirmed by XPS. Such ''recovery'' treatment had been applied to an all-diamond submicrometer electrode array initially patterned by an Ar/O{sub 2} plasma etching. The electrochemical characteristics of this electrode array were improved by more than two orders of magnitude, approaching theoretical limit for the given geometrical configuration.

Denisenko, A.; Pietzka, C.; Scharpf, J.; Kohn, E. [Institute of Electron Devices and Circuits, University of Ulm, 89069 Ulm (Germany); Romanyuk, A. [Institute of Physics, University of Basel, 4056 Basel (Switzerland)

2010-10-15

135

Industrial diamond  

USGS Publications Warehouse

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.

Olson, D. W.

2003-01-01

136

Diamond Smoothing Tools  

NASA Technical Reports Server (NTRS)

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.

Voronov, Oleg

2007-01-01

137

Dielectric properties of hydrogen-incorporated chemical vapor deposited diamond thin films  

NASA Astrophysics Data System (ADS)

Diamond thin films with a broad range of microstructures from a ultrananocrystalline diamond (UNCD) form developed at Argonne National Laboratory to a microcrystalline diamond (MCD) form have been grown with different hydrogen percentages in the Ar/CH4 gas mixture used in the microwave plasma enhanced chemical vapor deposition (CVD) process. The dielectric properties of the CVD diamond thin films have been studied using impedance and dc measurements on metal-diamond-metal test structures. Close correlations have been observed between the hydrogen content in the bulk of the diamond films, measured by elastic recoil detection (ERD), and their electrical conductivity and capacitance-frequency (C-f) behaviors. Addition of hydrogen gas in the Ar/CH4 gas mixture used to grow the diamond films appears to have two main effects depending on the film microstructure, namely, (a) in the UNCD films, hydrogen incorporates into the atomically abrupt grain boundaries satisfying sp2 carbon dangling bonds, resulting in increased resistivity, and (b) in MCD, atomic hydrogen produced in the plasma etches preferentially the graphitic phase codepositing with the diamond phase, resulting in the statistical survival and growth of large diamond grains and dominance of the diamond phase, and thus having significant impact on the dielectric properties of these films.

Liu, Chao; Xiao, Xingcheng; Wang, Jian; Shi, Bing; Adiga, Vivekananda P.; Carpick, Robert W.; Carlisle, John A.; Auciello, Orlando

2007-10-01

138

Dielectric properties of hydrogen-incorporated chemical vapor deposited diamond thin films.  

SciTech Connect

Diamond thin films with a broad range of microstructures from a ultrananocrystalline diamond (UNCD) form developed at Argonne National Laboratory to a microcrystalline diamond (MCD) form have been grown with different hydrogen percentages in the Ar/CH{sub 4} gas mixture used in the microwave plasma enhanced chemical vapor deposition (CVD) process. The dielectric properties of the CVD diamond thin films have been studied using impedance and dc measurements on metal-diamond-metal test structures. Close correlations have been observed between the hydrogen content in the bulk of the diamond films, measured by elastic recoil detection (ERD), and their electrical conductivity and capacitance-frequency (C-f) behaviors. Addition of hydrogen gas in the Ar/CH{sub 4} gas mixture used to grow the diamond films appears to have two main effects depending on the film microstructure, namely, (a) in the UNCD films, hydrogen incorporates into the atomically abrupt grain boundaries satisfying sp{sup 2} carbon dangling bonds, resulting in increased resistivity, and (b) in MCD, atomic hydrogen produced in the plasma etches preferentially the graphitic phase codepositing with the diamond phase, resulting in the statistical survival and growth of large diamond grains and dominance of the diamond phase, and thus having significant impact on the dielectric properties of these films.

Liu, C.; Xiao, X.; Wang, J.; Shi, B.; Auciello, O.; Carlisle, J. A.; Carpick, R.; Adiga, V.; Univ. of Wisconsin at Madison; Univ. of Pennsylvania

2007-01-01

139

Boron concentration profiling by high angle annular dark field-scanning transmission electron microscopy in homoepitaxial ?-doped diamond layers  

NASA Astrophysics Data System (ADS)

To develop further diamond related devices, the concentration and spatial location of dopants should be controlled down to the nanometer scale. Scanning transmission electron microscopy using the high angle annular dark field mode is shown to be sensitive to boron doping in diamond epilayers. An analytical procedure is described, whereby local boron concentrations above 1020 cm-3 were quantitatively derived down to nanometer resolution from the signal dependence on thickness and boron content. Experimental boron local doping profiles measured on diamond p-/p++/p- multilayers are compared to macroscopic profiles obtained by secondary ion mass spectrometry, avoiding reported artefacts.

Araújo, D.; Alegre, M. P.; Piñero, J. C.; Fiori, A.; Bustarret, E.; Jomard, F.

2013-07-01

140

Boron concentration profiling by high angle annular dark field-scanning transmission electron microscopy in homoepitaxial ?-doped diamond layers  

SciTech Connect

To develop further diamond related devices, the concentration and spatial location of dopants should be controlled down to the nanometer scale. Scanning transmission electron microscopy using the high angle annular dark field mode is shown to be sensitive to boron doping in diamond epilayers. An analytical procedure is described, whereby local boron concentrations above 10{sup 20} cm{sup ?3} were quantitatively derived down to nanometer resolution from the signal dependence on thickness and boron content. Experimental boron local doping profiles measured on diamond p{sup ?}/p{sup ++}/p{sup ?} multilayers are compared to macroscopic profiles obtained by secondary ion mass spectrometry, avoiding reported artefacts.

Araújo, D.; Alegre, M. P.; Piñero, J. C. [Dpto Ciencia de los Materiales, Facultad de Ciencias, Universidad de Cádiz, 11510 Puerto Real (Cádiz) (Spain)] [Dpto Ciencia de los Materiales, Facultad de Ciencias, Universidad de Cádiz, 11510 Puerto Real (Cádiz) (Spain); Fiori, A.; Bustarret, E. [Institut Néel, CNRS-Université Joseph Fourier, 25 av. des Martyrs, 38042 Grenoble (France)] [Institut Néel, CNRS-Université Joseph Fourier, 25 av. des Martyrs, 38042 Grenoble (France); Jomard, F. [Groupe d'Etude de la Matière Condensée (GEMaC), UMR 8635 du CNRS, UVSQ, 45 av. des Etats-Unis, 78035 Versailles Cedex (France)] [Groupe d'Etude de la Matière Condensée (GEMaC), UMR 8635 du CNRS, UVSQ, 45 av. des Etats-Unis, 78035 Versailles Cedex (France)

2013-07-22

141

Ohmic contact properties of p-type surface conductive layer on H-terminated diamond films prepared by DC arc jet CVD  

NASA Astrophysics Data System (ADS)

With the advantages of high deposition rate and large deposition area, polycrystalline diamond films prepared by direct current (DC) arc jet chemical vapor deposition (CVD) are considered to be one of the most promising materials for high-frequency and high-power electronic devices. In this paper, high-quality self-standing polycrystalline diamond films with the diameter of 100 mm were prepared by DC arc jet CVD, and then, the p-type surface conductive layer with the sheet carrier density of 1011-1013 cm-2 on the H-terminated diamond film was obtained by micro-wave hydrogen plasma treatment for 40 min. Ti/Au and Au films were deposited on the H-terminated diamond surface as the ohmic contact electrode, respectively, afterwards, they were treated by rapid vacuum annealing at different temperatures. The properties of these two types of ohmic contacts were investigated by measuring the specific contact resistance using the transmission line method (TLM). Due to the formation of Ti-related carbide at high temperature, the specific contact resistance of Ti/Au contact gradually decreases to 9.95 × 10-5 ?·cm2 as the temperature increases to 820°C. However, when the annealing temperature reaches 850°C, the ohmic contact for Ti/Au is degraded significantly due to the strong diffusion and reaction between Ti and Au. As for the as-deposited Au contact, it shows an ohmic contact. After annealing treatment at 550°C, low specific contact resistance was detected for Au contact, which is derived from the enhancement of interdiffusion between Au and diamond films.

Liu, Jin-long; Li, Cheng-ming; Zhu, Rui-hua; Chen, Liang-xian; Wang, Jing-jing; Feng, Zhi-hong

2013-08-01

142

Diamond films for electronic packaging  

SciTech Connect

Diamond has the potential for greatly enhancing the thermal performance of electronic packaging by virtue of its extreme thermal conductivity. This is usually envisaged in electronic packaging as relatively thick plates to serve as a heat spreader. Diamond may also be used in electronic packaging as thin (dielectric) layers to a copper heat sink. This and other thin film applications require that there be adequate adhesion between diamond and the metal substrate; an issue greatly complicated by the large thermal expansion differences between diamond and metals. Recent efforts to deposit diamond on metals will be discussed with an emphasis on achieving an adherent coating. {copyright} {ital 1996 American Institute of Physics.}

Drory, M.D. [Crystallume, 3506 Bassett Street, Santa Clara, California 95054 (United States)

1996-03-01

143

Diamond-based capacitive micromachined ultrasonic transducers in immersion.  

PubMed

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

Cetin, Ahmet M; Bayram, Baris

2013-02-01

144

Nanocrystalline Diamond Films for Biosensor Applications  

NASA Astrophysics Data System (ADS)

Diamond is a material with quite a number of excellent properties, like extreme hardness, high elastic modulus, high wear resistance, optical transparency in a broad spectral range, resistivity controllable by the level of dopants, etc. which make it a promising candidate for different sensor applications, e.g. for X-ray detection. Due to its outstanding electrochemical properties, superior chemical inertness and biocompatibility, artificially grown diamond has been recognised as an extremely attractive material for both (bio-)chemical sensing and as an interface to biological systems. This holds for all forms of diamond: monocrystalline (natural or artificial) and poly- (PCD), nano- (NCD) and ultrananocrystalline (UNCD) films. This paper is devoted to possible biosensor application of NCD and UNCD films. The first part will briefly introduce UNCD films (composed of diamond nanocrystallites of 3-5 nm diameter embedded in an amorphous carbon matrix with a grain boundary thickness of 1.0-1.5 nm), their deposition by microwave plasma chemical vapour deposition, their growth mechanisms and the characterization of their bulk properties, comparing them with other types of diamond films. The second part deals with surface modifications of UNCD films, which is the first step towards preparation of a biosensor, including different plasma and chemical processes, the thorough characterization of the resulting surfaces by a variety of techniques (AFM, XPS, ToF-SIMS, contact angle measurements, etc.) and the possibility to pattern the surface properties. The third part will describe possible pathways for the immobilization of biomolecules (proteins, DNA) on UNCD surfaces and the techniques for the characterization of this step, including force measurements, AFM and spectroscopic analyses. In the final part, different examples of biosensors based on UNCD as well as on NCD will be demonstrated in order to reveal the potential of diamond (films) in this field.

Popov, Cyril; Kulisch, Wilhelm

145

On Interlayer Stability and High-Cycle Simulator Performance of Diamond-Like Carbon Layers for Articulating Joint Replacements  

PubMed Central

Diamond like carbon (DLC) coatings have been proven to be an excellent choice for wear reduction in many technical applications. However, for successful adaption to the orthopaedic field, layer performance, stability and adhesion in physiologically relevant setups are crucial and not consistently investigated. In vitro wear testing as well as adequate corrosion tests of interfaces and interlayers are of great importance to verify the long term stability of DLC coated load bearing implants in the human body. DLC coatings were deposited on articulating lumbar spinal disks made of CoCr28Mo6 biomedical implant alloy using a plasma-activated chemical vapor deposition (PACVD) process. As an adhesion promoting interlayer, tantalum films were deposited by magnetron sputtering. Wear tests of coated and uncoated implants were performed in physiological solution up to a maximum of 101 million articulation cycles with an amplitude of ±2° and ?3/+6° in successive intervals at a preload of 1200 N. The implants were characterized by gravimetry, inductively coupled plasma optical emission spectrometry (ICP-OES) and cross section scanning electron microscopy (SEM) analysis. It is shown that DLC coated surfaces with uncontaminated tantalum interlayers perform very well and no corrosive or mechanical failure could be observed. This also holds true in tests featuring overload and third-body wear by cortical bone chips present in the bearing pairs. Regarding the interlayer tolerance towards interlayer contamination (oxygen), limits for initiation of potential failure modes were established. It was found that mechanical failure is the most critical aspect and this mode is hypothetically linked to the ?-? tantalum phase switch induced by increasing oxygen levels as observed by X-ray diffraction (XRD). It is concluded that DLC coatings are a feasible candidate for near zero wear articulations on implants, potentially even surpassing the performance of ceramic vs. ceramic.

Thorwarth, Kerstin; Thorwarth, Gotz; Figi, Renato; Weisse, Bernhard; Stiefel, Michael; Hauert, Roland

2014-01-01

146

On interlayer stability and high-cycle simulator performance of diamond-like carbon layers for articulating joint replacements.  

PubMed

Diamond like carbon (DLC) coatings have been proven to be an excellent choice for wear reduction in many technical applications. However, for successful adaption to the orthopaedic field, layer performance, stability and adhesion in physiologically relevant setups are crucial and not consistently investigated. In vitro wear testing as well as adequate corrosion tests of interfaces and interlayers are of great importance to verify the long term stability of DLC coated load bearing implants in the human body. DLC coatings were deposited on articulating lumbar spinal disks made of CoCr28Mo6 biomedical implant alloy using a plasma-activated chemical vapor deposition (PACVD) process. As an adhesion promoting interlayer, tantalum films were deposited by magnetron sputtering. Wear tests of coated and uncoated implants were performed in physiological solution up to a maximum of 101 million articulation cycles with an amplitude of ±2° and -3/+6° in successive intervals at a preload of 1200 N. The implants were characterized by gravimetry, inductively coupled plasma optical emission spectrometry (ICP-OES) and cross section scanning electron microscopy (SEM) analysis. It is shown that DLC coated surfaces with uncontaminated tantalum interlayers perform very well and no corrosive or mechanical failure could be observed. This also holds true in tests featuring overload and third-body wear by cortical bone chips present in the bearing pairs. Regarding the interlayer tolerance towards interlayer contamination (oxygen), limits for initiation of potential failure modes were established. It was found that mechanical failure is the most critical aspect and this mode is hypothetically linked to the ?-? tantalum phase switch induced by increasing oxygen levels as observed by X-ray diffraction (XRD). It is concluded that DLC coatings are a feasible candidate for near zero wear articulations on implants, potentially even surpassing the performance of ceramic vs. ceramic. PMID:24921709

Thorwarth, Kerstin; Thorwarth, Götz; Figi, Renato; Weisse, Bernhard; Stiefel, Michael; Hauert, Roland

2014-01-01

147

Diamond crown bit  

SciTech Connect

This patent describes a diamond crown bit, comprising: a body; a matrix secured on one of the end faces of the body; mud discharge ports subdividing the matrix into sections separated from one another; each sector consisting of: a weld-on layer on the one end face of the body where the sectors are held to the body; a diamond-impregnated layer shaped as a parelleleipiped and held to the weld-on layer to have its front and rear faces inclined; and an insert shaped as a triangular prism having side face rigidly held to the weld-on layer and its face face rigidly held to the inclined rear face of the diamond-impregnated layer.

Aubakirov, M.T.; Limanov, E.L.; Syzdykov, A.K.; Abdrazakov, R.S.; Tleuov, M.G.; Khazhuer, V.S.; Buzdov, R.D.; Khashirov, V.K.

1987-07-21

148

Characterization of single-crystal diamond grown from the vapor phase on substrates of natural diamond  

SciTech Connect

The results of studies of single-crystal diamond layers with orientation (100) grown on substrates of IIa-type natural diamond by chemical-vapor deposition and of semiconductor diamond obtained subsequently by doping by implantation of boron ions are reported. Optimal conditions of postimplantation annealing of diamond that provide the hole mobility of 1150 cm{sup 2} V{sup -1} s{sup -1} (the highest mobility obtained so far for semiconductor diamond after ion implantation) are given.

Altukhov, A. A. [ITC UralAlmazInvest (Russian Federation); Vikharev, A. L.; Gorbachev, A. M. [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation); Dukhnovsky, M. P.; Zemlyakov, V. E. [FSUE Istok (Russian Federation); Ziablyuk, K. N.; Mitenkin, A. V. [ITC UralAlmazInvest (Russian Federation); Muchnikov, A. B., E-mail: mabl@appl.sci-nnov.ru; Radishev, D. B. [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation); Ratnikova, A. K.; Fedorov, Yu. Yu. [FSUE Istok (Russian Federation)

2011-03-15

149

Pressure sensor using p-type polycrystalline diamond piezoresistors  

Microsoft Academic Search

Prototype pressure sensor was fabricated using piezoresistive effect of boron-doped diamond. Undoped and boron-doped polycrystalline diamonds were deposited on Si substrate using hot filament chemical vapor deposition (CVD) method. The boron-doped diamond was deposited on an isolation layer of the undoped diamond film. Selective diamond deposition was carried out by metal mask, and 30-?m width patterning of the diamond was

Akira Yamamoto; Norio Nawachi; Takahiro Tsutsumoto; Akira Terayama

2005-01-01

150

Suiso Purazuma Jetto Ni Yoru Daiyamondo Gosei: Ropposho Daiyamondo Poritaipu No Xrd Patan Oyobi Kibanjo Kyokaiso No Shimyureshon (Synthesis of Diamond in a Hydrogen Plasma Jet: Simulations of Xrd Patterns of Diamond Polytypes and Boundary Layer on a Substrate).  

National Technical Information Service (NTIS)

Two kinds of diamond film were obtained by synthesizing diamond film on Mo substrates in a hydrogen plasma jet. One (type A) was random oriented cubic diamond film with clear habit planes. The other (type B) was film with no habit plane. It was inferred t...

N. Kikukawa M. Makino K. Maruyama M. Shiraishi

1993-01-01

151

Industrial diamond  

USGS Publications Warehouse

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.

Olson, D. W.

2012-01-01

152

Industrial diamond  

USGS Publications Warehouse

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.

Olson, D. W.

2006-01-01

153

Industrial diamond  

USGS Publications Warehouse

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.

Olson, D. W.

2011-01-01

154

Industrial diamond  

USGS Publications Warehouse

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.

Olson, D. W.

2013-01-01

155

Industrial diamond  

USGS Publications Warehouse

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.

Olson, D. W.

2000-01-01

156

Nucleation and growth of chemical vapor deposited diamond films  

Microsoft Academic Search

This research involves a study of the nucleation and growth processes during diamond chemical vapor deposition (CVD) via numerical modeling and simulations. Numerical models have been developed: (1) to examine the chemistry of the intermediate layer that forms at the interface between diamond and non-diamond substrate, (2) to understand the nucleation, size and structure of diamond phase carbon clusters on

Pushpa Mahalingam

1997-01-01

157

Laser ablation time-of-flight mass spectrometry (LA-TOF-MS) of “nitrogen doped diamond-like carbon (DLN) nano-layers  

NASA Astrophysics Data System (ADS)

Nitrogen-doped diamond-like carbon (DLC) layers (a-C:H:N, N-DLC or DLN) were prepared by the plasma-enhanced chemical vapor deposition (PECVD) technique, using a RF capacitive discharge (13.56 MHz), at low pressures (20 Pa), produced from a mixture of methane, nitrogen and hexamethyldisiloxane (HMDSO), deposited on single-crystalline silicon wafers placed on steel samples. The films, of differing deposition times, were subjected to laser ablation time-of-flight (LA-TOF) mass spectrometric measurements, using different commercial instrumentation to characterize their structures. The analysis of mass spectra was made and the following positively singly charged species were detected and identified: Cn+ (n=4 30), Sin+ (n=2, 3), SinH+ (n=2, 3), SiOK+, Si3H4+, Si2N+, Si2NH2+, and Si3C+. The later three species could reflect the presence of nitrogen silica and carbon silica chemical bonds in the structure of the DLN layer. The stoichiometry of all species was confirmed by isotopic pattern simulation. In the negative detection mode, the Cn- (n=2 12) clusters were observed. The findings are discussed in the light of the current research concerning analysis of the DLN thin layers and it is concluded that namely Si2N+, Si2NH2+ and Si3C+ species are reflecting the chemical structure of the DLN layer. LA-TOF-MS was found useful supplementary method for the characterization of DLN nano-layers.

Buršíková, Vilma; ?ehulka, Pavel; Chmelík, Josef; Alberti, Milan; Špalt, Zbyn?k; Jan?a, Jan; Havel, Josef

2007-05-01

158

Diamond-like carbon (DLC) thin film bioelectrodes: effect of thermal post-treatments and the use of Ti adhesion layer.  

PubMed

The effect of thermal post-treatments and the use of Ti adhesion layer on the performance of thin film diamond like carbon bioelectrodes (DLC) have been investigated in this work. The following results were obtained: (i) The microstructure of the DLC layer after the deposition was amorphous and thermal annealing had no marked effect on the structure, (ii) formation of oxygen containing SiOx and Ti[O,C] layers were detected at the Si/Ti and Ti/DLC interfaces with the help of transmission electron microscope (TEM), (iii) thermal post-treatments increased the polar fraction of the surface energy, (iv) cyclic voltammetry (CV) measurements showed that the DLC films had wide water windows and were stable in contact with dilute sulphuric acid and phosphate buffered saline (PBS) solutions, (v) use of Ti interlayer between Pt(Ir) microwire and DLC layer was crucial for the electrodes to survive the electrochemical measurements without the loss of adhesion of the DLC layer, (vi) DLC electrodes with small exposed Pt areas were an order of magnitude more sensitive towards dopamine than Pt electrodes and (vii) thermal post-treatments did not markedly change the electrochemical behavior of the electrodes despite the significant increase in the polar nature of the surfaces. It can be concluded that thin DLC bioelectrodes are stable under physiological conditions and can detect dopamine in micro molar range, but their sensitivity must be further improved. PMID:24268281

Laurila, Tomi; Rautiainen, Antti; Sintonen, Sakari; Jiang, Hua; Kaivosoja, Emilia; Koskinen, Jari

2014-01-01

159

Extreme synthesis and chemical doping of diamond aerogel  

NASA Astrophysics Data System (ADS)

Amorphous carbon aerogels have attracted much interest in recent years due to their low density, large intrinsic surface areas (>1000 m^2/g), large pore volume, low dielectric constant, and high strength. We use high-pressure (˜20 GPa) laser-heating (>600 C) within a diamond anvil cell (DAC) to convert the amorphous network of a low-density (40mg/cc) carbon aerogel into an ultrananocrystalline diamond aerogel. Photoluminescence spectroscopy and confocal time-correlated single-photon counting indicate the recovered material contains both negatively-charged and neutral nitrogen-vacancy (NV) complexes. Synchrotron scanning transmission x-ray microscopy (STXM) is used to compare the carbon electronic density-of-states of the amorphous starting material with the recovered diamond aerogel with ˜100 meV energy resolution. Finally, we use nanoscale secondary ion mass spectrometry to investigate doping of the resorcinol-formaldehyde starting material with the aim of chemically tuning heteroatomic point defects within this diamond material system.

Pauzauskie, Peter J.; Crowhurst, Jonathan C.; Worsley, Marcus A.; Laurence, Ted A.; Wang, Yinmin; Kilcoyne, A. L. D.; Weber, Peter K.; Willey, Trevor M.; Visbeck, Kenneth S.; Evans, William J.; Satcher, Joe H., Jr.

2010-03-01

160

Electron field emission from diamond-like carbon films and a patterned array by using a Ti interfacial layer  

Microsoft Academic Search

Electron field emission from diamond-like carbon (DLC) films deposited on Si, Ti\\/Si, and Au\\/Si substrates by a filtered arc deposition technique was studied. As compared to DLC\\/Si and DLC\\/Au\\/Si, electron field emission from DLC\\/Ti\\/Si was enhanced, showing an increased emission current density and emission site density (?1.2×103\\/cm2). An emission site density up to 2.2?2.2×103\\/cm2 was obtained after the DLC\\/Ti\\/Si had

D. S. Mao; X. H. Liu; X. Wang; W. Zhu

2002-01-01

161

Electron field emission from diamond-like carbon films and a patterned array by using a Ti interfacial layer  

Microsoft Academic Search

Electron field emission from diamond-like carbon (DLC) films deposited on Si, Ti\\/Si, and Au\\/Si substrates by a filtered arc deposition technique was studied. As compared to DLC\\/Si and DLC\\/Au\\/Si, electron field emission from DLC\\/Ti\\/Si was enhanced, showing an increased emission current density and emission site density (~1.2×103\\/cm2). An emission site density up to 2.2~2.2×103\\/cm2 was obtained after the DLC\\/Ti\\/Si had

D. S. Mao; X. H. Liu; X. Wang; W. Zhu

2002-01-01

162

Electrical stimulation of retinal ganglion cells with diamond and the development of an all diamond retinal prosthesis.  

PubMed

Electronic retinal implants for the blind are already a market reality. A world wide effort is underway to find the technology that offers the best combination of performance and safety for potential patients. Our approach is to construct an epi-retinally targeted device entirely encapsulated in diamond to maximise longevity and biocompatibility. The stimulating array of our device comprises a monolith of electrically insulating diamond with thousands of hermetic, microscale nitrogen doped ultra-nanocrystalline diamond (N-UNCD) feedthroughs. Here we seek to establish whether the conducting diamond feedthroughs of the array can be used as stimulating electrodes without further modification with a more traditional neural stimulation material. Efficacious stimulation of retinal ganglion cells was established using single N-UNCD microelectrodes in contact with perfused, explanted, rat retina. Evoked rat retinal ganglion cell action potentials were recorded by patch clamp recording from single ganglion cells, adjacent to the N-UNCD stimulating electrode. Separately, excellent electrochemical stability of N-UNCD was established by prolonged pulsing in phosphate buffered saline at increasing charge density up to the measured charge injection limit for the material. PMID:22613134

Hadjinicolaou, Alex E; Leung, Ronald T; Garrett, David J; Ganesan, Kumaravelu; Fox, Kate; Nayagam, David A X; Shivdasani, Mohit N; Meffin, Hamish; Ibbotson, Michael R; Prawer, Steven; O'Brien, Brendan J

2012-08-01

163

Electron field emission from diamond-like carbon films and a patterned array by using a Ti interfacial layer  

NASA Astrophysics Data System (ADS)

Electron field emission from diamond-like carbon (DLC) films deposited on Si, Ti/Si, and Au/Si substrates by a filtered arc deposition technique was studied. As compared to DLC/Si and DLC/Au/Si, electron field emission from DLC/Ti/Si was enhanced, showing an increased emission current density and emission site density (~1.2×103/cm2). An emission site density up to 2.2~2.2×103/cm2 was obtained after the DLC/Ti/Si had been annealed at 430 °C for 0.5 h. A patterned DLC/Ti/Si array fabricated by the oxygen reactive ion beam etching technique showed further field emission enhancement. An emission site density up to 3.2~3.5×103/cm2 and a threshold field as low as 2.1 V/?m were achieved. It was shown that the low potential barrier at the interface and high local geometric electric field enhancement around the edges produced by reactive ion beam etching were possible causes of the enhancing effects. It could also be explained by Geis' metal-diamond-vacuum triple junction emission mechanism.

Mao, D. S.; Liu, X. H.; Wang, X.; Zhu, W.

2002-03-01

164

Diamond photonics  

Microsoft Academic Search

Diamond, a material marvelled for its strength, beauty and perfection, was first used to polish stone axes in Neolithic times. This most ancient of materials is now being touted by many as the ideal platform for quantum-age technologies. In this Review, we describe how the properties of diamond match the requirements of the 'second quantum revolution'. We also discuss recent

Igor Aharonovich; Andrew D. Greentree; Steven Prawer

2011-01-01

165

Diamond optics IV; Proceedings of the Meeting, San Diego, CA, July 22, 23, 1991  

NASA Astrophysics Data System (ADS)

The proceedings on diamond optics include topics on diamond film growth, growth mechanisms, optical properties, diamondlike carbon and bulk diamond, growth mechanisms and diamond composites, and deposition processes and characterizations. Papers are presented on pressure effects in the microwave plasma growth of polycrystalline diamond, diagnostics of a DC plasma torch, effects of interfacial modifications on diamond film adhesion, polishing of filament-assisted CVD diamond films, diamond growth on the (110) surface, and critical-point phonons of diamond. Other papers include those on optical properties of amorphous hydrogenated carbon layers, fundamental studies of chemical-vapor-deposition diamond growth processes, optical properties of ZnS/diamond composites, a study of impurities in CVD diamond using cathodoluminescence, smooth diamond films by reactive ion-beam polishing, and morphological phenomena of CVD diamond.

Feldman, Albert; Holly, Sandor

1991-12-01

166

Diamond Electronic Devices  

SciTech Connect

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

Isberg, J. [Division for Electricity, Uppsala University, Box 534, S-751 21 Uppsala (Sweden)

2010-11-01

167

Diamond Coatings  

NASA Technical Reports Server (NTRS)

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.

1990-01-01

168

Industrial diamond  

USGS Publications Warehouse

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.

Olson, D. W.

2007-01-01

169

Industrial diamond  

USGS Publications Warehouse

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.

Olson, D. W.

2004-01-01

170

Thermally induced alkylation of diamond.  

PubMed

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. PMID:21090790

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

2010-12-21

171

Diamond coatings exposure to fusion-relevant plasma conditions  

NASA Astrophysics Data System (ADS)

Several types of diamond layers have been deposited on molybdenum tiles by chemical vapour deposition techniques, and exposed under erosion-dominated conditions in the SOL of TEXTOR in order to assess them as a suitable candidate for plasma-facing material. Post-exposure characterisation of physical properties and surface modification induced by the plasma was performed by SEM imaging, investigation of diamond surface by micro-Raman spectroscopy and deuterium retention measurements by NRA. The analyses evidenced that lightly boron-doped micro-crystalline diamond is performing better than undoped and heavily doped samples, and nano-crystalline diamond and diamond-like carbon, as it showed lower surface modification, lower presence of arcing traces at the surface and lower deuterium retention. High concentration of boron in the layers led to higher retention of deuterium, whereas undoped (insulating) diamond showed increased arcing activity. Nano-crystalline diamond and diamond-like carbon layers generally showed poorer mechanical properties.

Porro, S.; Temmerman, G. De; Lisgo, S.; Rudakov, D. L.; Litnovsky, A.; Petersson, P.; John, P.; Wilson, J. I. B.

2011-08-01

172

Diamond fiber field emitters  

SciTech Connect

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.

Blanchet-Fincher, Graciela B. (Wilmington, DE); Coates, Don M. (Santa Fe, NM); Devlin, David J. (Los Alamos, NM); Eaton, David F. (Wilmington, DE); Silzars, Aris K. (Landenburg, PA); Valone, Steven M. (Santa Fe, NM)

1996-01-01

173

Micro abrasive pencils with CVD diamond coating  

Microsoft Academic Search

Abrasive pencils (burs) for grinding can be made by coating cemented carbide bodies with a rough chemical vapour deposition (CVD) diamond layer. These tools have advantages compared to conventional abrasive pencils made by electroplating or sintering of diamond grains. Different CVD diamond abrasive pencils were manufactured with tip diameters ranging from 0.06 to 2.0 mm. A hot-filament CVD reactor was

Jan Gäbler; Lothar Schäfer; Bernd Menze; Hans-Werner Hoffmeister

2003-01-01

174

Advanced Diamond Anvil Techniques (Customized Diamond Anvils)  

SciTech Connect

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

Weir, S

2009-02-11

175

Growth of Thin Hetero-Epitaxial Layers of Graphite and Diamond on SIC for Carbon Based Electronics.  

National Technical Information Service (NTIS)

During the course of this work atmospheric and UHV techniques were developed for the production of few layer graphene on the Si and C face of SiC. In was found that control of the rate of Si loss (as determined by the surface temperature gradient) was nec...

M. G. Spencer

2010-01-01

176

Diamond nanorods from nanocrystalline diamond films  

NASA Astrophysics Data System (ADS)

Diamond nanorods (DNRs) have been prepared by hydrogen plasma post-treatment of nanocrystalline diamond films in radio-frequency (RF) plasma-assisted hot-filament chemical vapor deposition. Single-crystal diamond nanorods with diameters of 3-5 nm and with lengths up to 200 nm grow under hydrogen plasma irradiation of nanocrystalline diamond thin film on the Si substrate at high temperatures. The DNRs growth occurs from graphite clusters. The graphite clusters arises from the etching of diamond carbon atoms and from the non-diamond phase present in the parent film. The graphite clusters recrystallized to form nanocrystalline diamonds which further grow for diamond nanorods. The negative applied bias and surface stresses are suggested to support one-dimensional growth. The growth direction of diamond nanorods is perpendicular to the (1 1 1) crystallographic planes of diamond. The studies address the structure and growth mechanism of diamond nanorods.

Rakha, Sobia Allah; Guojun, Yu; Xingtai, Zhou; Ahmed, Ishaq; Zhu, Dezhang; Gong, Jinlong

177

'Diamond' in 3-D  

NASA Technical Reports Server (NTRS)

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.

2004-01-01

178

Nanostructured Diamond  

NASA Astrophysics Data System (ADS)

In the recent years, diamonds with diameter distributions peaked around 3 nanometers have been evidenced in an intriguing variety of environments : on meteorites, comets and in detonation residues, but also in diamond films produced under specific (low) hydrogen partial pressures in CVD experiments and even in petroleum (diamondoids). If diamond particles get more stable than their graphitic counterparts in the nanometer range, the competition between those two structures and the effect of size reduction make the properties of nanoscale diamond unique. We address the properties of nanoscale diamond using first-principles molecular dynamics simulation. Structural models are obtained for sizes up to 3 nanometers and their optical properties, computed using Time-Dependent Density Functional Theory, are compared to X-ray absorption and emission spectra. We conclude that, contrary to silicon and germanium, there is no more a quantum confinement effect on the optical gap above sizes of 2-3 nanometers [1]. Also for these sizes, specific surface reconstructions that have signatures in the aborption spectra occur : the particle's diamond core gets surrounded by fullerene-like caps. We studied surface reconstructions as a function of hydrogen chemical potential. These model simulations indicate that for sizes of about 2 nanometers, surface hydrogen tends to be released, favoring fullerene-like surface reconstructions. This provides an explanation for the similar size distributions of nanodiamonds produced under extremely different temperature/pressure conditions [2]. We also show that below some hydrogen potential value threshold, the CVD process of diamond film would lead to an agglomeration of nanodiamonds (called UltraNanocrystallineDiamond) rather than the growth of bulk diamond, as observed experimentally. Finally we discuss the possibility of N-doping nanodiamonds and show that the nitrogen incorporation is very much dependent on the particle size and affected by the surface reconstructions. This work has been done in collaboration with Dr. Giulia Galli under the auspices of the U.S. DOE at the University of California/LLNL under contract No W-7405-Eng-48 and was supported by the FNRS. [1] Physical Review Letters 90 (2003) 037401-1 [2] Nature Materials 2 (2003) 792

Raty, Jean-Yves

2004-03-01

179

Optimised plasma enhanced chemical vapour deposition (PECVD) process for double layer diamond-like carbon (DLC) deposition on germanium substrates  

Microsoft Academic Search

Double layer DLC-films were deposited on germanium substrates by the PECVD-method, using ethyne as reactant gas during RF plasma excitation in a parallel plate reactor. The electric field distribution in the plasma chamber was simulated by FEM. The basic concept was the utilization of coatings with graded interfaces and without other materials.The bias voltage, working pressure and substrate temperature were

Jan Heeg; Markus Rosenberg; Christian Schwarz; Torsten Barfels; Marion Wienecke

2008-01-01

180

CVD diamond growth on germanium for IR window applications  

Microsoft Academic Search

We show that the production of adherent polycrystalline diamond films upon Ge substrates by chemical vapour deposition is problematical for three reasons: (a) the melting point of Ge is close to the optimum diamond deposition temperature which leads to partial melting of the Ge surface, retarding diamond nucleation, (b) there is no Ge carbide layer formed at the interface to

C. A. Rego; P MAY; E WILLIAMSON; M ASHFOLD; Q CHIA; K ROSSER; N EVERITT

1994-01-01

181

Superconducting nanowire single photon detector on diamond  

NASA Astrophysics Data System (ADS)

Superconducting nanowire single photon detectors are fabricated directly on diamond substrates and their optical and electrical properties are characterized. Dark count performance and photon count rates are measured at varying temperatures for 1310 nm and 632 nm photons. A multi-step diamond surface polishing procedure is reported, involving iterative reactive ion etching and mechanical polishing to create a suitable diamond surface for the deposition and patterning of thin film superconducting layers. Using this approach, diamond substrates with less than 300 pm Root Mean Square surface roughness are obtained.

Atikian, Haig A.; Eftekharian, Amin; Jafari Salim, A.; Burek, Michael J.; Choy, Jennifer T.; Hamed Majedi, A.; Lon?ar, Marko

2014-03-01

182

Pulse-doped diamond p-channel metal semiconductor field-effect transistor  

Microsoft Academic Search

A p-type diamond metal semiconductor field-effect transistor (MESFET) structure, utilizing a boron pulse-doped layer as the conducting channel, has been successfully fabricated. The pulse-doped structure consists of an undoped diamond buffer layer, a highly doped thin diamond active layer, and an undoped diamond cap layer grown by the microwave plasma assisted chemical vapor deposition method. It is shown that this

Hiromu Shiomi; Yoshiki Nishibayashi; Naohiro Toda; Shin-ichi Shikata

1995-01-01

183

Enhanced diamond nucleation on monodispersed nanocrystalline diamond  

NASA Astrophysics Data System (ADS)

A method for improving the nucleation density of nanocrystalline diamond growth is demonstrated. Detonation nanodiamond powder was bead-milled and processed to stable aqueous colloid of core particles. This colloid was applied to various substrates to yield a very high density of individual spaced diamond nanoparticles. These diamond islands act as nucleation sites for chemical vapour deposition of nanocrystalline diamond.

Williams, Oliver A.; Douhéret, Olivier; Daenen, Michael; Haenen, Ken; ?sawa, Eiji; Takahashi, Makoto

2007-09-01

184

Large-area low-temperature ultrananocrystaline diamond (UNCD) films and integration with CMOS devices for monolithically integrated diamond MEMD/NEMS-CMOS systems.  

SciTech Connect

Because of exceptional mechanical, chemical, and tribological properties, diamond has a great potential to be used as a material for the development of high-performance MEMS and NEMS such as resonators and switches compatible with harsh environments, which involve mechanical motion and intermittent contact. Integration of such MEMS/NEMS devices with complementary metal oxide semiconductor (CMOS) microelectronics will provide a unique platform for CMOS-driven commercial MEMS/NEMS. The main hurdle to achieve diamond-CMOS integration is the relatively high substrate temperatures (600-800 C) required for depositing conventional diamond thin films, which are well above the CMOS operating thermal budget (400 C). Additionally, a materials integration strategy has to be developed to enable diamond-CMOS integration. Ultrananocrystalline diamond (UNCD), a novel material developed in thin film form at Argonne, is currently the only microwave plasma chemical vapor deposition (MPCVD) grown diamond film that can be grown at 400 C, and still retain exceptional mechanical, chemical, and tribological properties comparable to that of single crystal diamond. We have developed a process based on MPCVD to synthesize UNCD films on up to 200 mm in diameter CMOS wafers, which will open new avenues for the fabrication of monolithically integrated CMOS-driven MEMS/NEMS based on UNCD. UNCD films were grown successfully on individual Si-based CMOS chips and on 200 mm CMOS wafers at 400 C in a MPCVD system, using Ar-rich/CH4 gas mixture. The CMOS devices on the wafers were characterized before and after UNCD deposition. All devices were performing to specifications with very small degradation after UNCD deposition and processing. A threshold voltage degradation in the range of 0.08-0.44V and transconductance degradation in the range of 1.5-9% were observed.

Sumant, A.V.; Auciello, O.; Yuan, H.-C; Ma, Z.; Carpick, R. W.; Mancini, D. C.; Univ. of Wisconsin; Univ. of Pennsylvania

2009-05-01

185

Laser activation of diamond surface for electroless metal plating  

Microsoft Academic Search

Selective area electroless nickel and copper deposition onto the surface of diamond single crystals and polycrystalline diamond films has been realized. Three methods of laser-assisted activation of diamond surface were applied: (i) prenucleation of diamond surface with a thin layer of palladium catalyst via laser-induced decomposition of a palladium acetyl-acetonate [Pd(acac)2] solid film; (ii) deposition of palladium by means of

S. M. Pimenov; G. A. Shafeev; V. A. Laptev; E. N. Loubnin

1994-01-01

186

Epitaxial growth of europium monoxide on diamond  

SciTech Connect

We report the epitaxial integration of phase-pure EuO on both single-crystal diamond and on epitaxial diamond films grown on silicon utilizing reactive molecular-beam epitaxy. The epitaxial orientation relationship is (001) EuO ? (001) diamond and [110] EuO ?[100] diamond. The EuO layer is nominally unstrained and ferromagnetic with a transition temperature of 68 ± 2 K and a saturation magnetization of 5.5 ± 0.1 Bohr magnetons per europium ion on the single-crystal diamond, and a transition temperature of 67 ± 2 K and a saturation magnetization of 2.1 ± 0.1 Bohr magnetons per europium ion on the epitaxial diamond film.

Melville, A.; Heeg, T. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States)] [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Mairoser, T.; Schmehl, A. [Zentrum für elektronische Korrelationen und Magnetismus, Universität Augsburg, Universitätsstraße 1, 86159 Augsburg (Germany)] [Zentrum für elektronische Korrelationen und Magnetismus, Universität Augsburg, Universitätsstraße 1, 86159 Augsburg (Germany); Fischer, M.; Gsell, S.; Schreck, M. [Institut für Physik, Universität Augsburg, D-86135 Augsburg (Germany)] [Institut für Physik, Universität Augsburg, D-86135 Augsburg (Germany); Awschalom, D. D. [Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637 (United States)] [Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637 (United States); Holländer, B.; Schubert, J. [Peter Grünberg Institute, PGI9-IT, JARA-FIT, Research Centre Jülich, D-52425 Jülich (Germany)] [Peter Grünberg Institute, PGI9-IT, JARA-FIT, Research Centre Jülich, D-52425 Jülich (Germany); Schlom, D. G. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States) [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States)

2013-11-25

187

Double bias HF CVD multilayer diamond films on WC–Co cutting tools  

Microsoft Academic Search

Diamond layers are nowadays of increasing importance for mechanical applications. In our laboratory we grow diamond and DLC layers on WC–Co cutting tools using HF CVD method improved by double biasing. Optimization of growth parameters facilitates to control grain size of polycrystalline diamond layers from microcrystalline to nanocrystalline. Five steps of this process are described and demonstrated. SEM, AFM, Raman

M. Vojsa; M. Veselý; R. Redhammer; J. Janík; M. Kadlecÿõ ´ kova; T. Danisÿa; M. Marton; M. Michalka; P. Šutta

2005-01-01

188

CONDENSED MATTER: STRUCTURE, THERMAL AND MECHANICAL PROPERTIES: Deposition mechanism of nano-structured single-layered C36 film on a diamond (100) crystal plane  

Microsoft Academic Search

The Brenner-LJ potential is adopted to describe the interaction between C36 clusters and diamond surface, and the deposition mechanism of multi-C36 clusters on the diamond surface is also studied by using the method of molecular dynamics simulation. The simulation results show that the competition effects of two interactions, i.e. the interaction between cluster and cluster and the interaction between cluster

Ming-Jun Chen; Ying-Chun Liang; Yi-Jie Yuan; Dan Li

2008-01-01

189

Heteroepitaxial Diamond Growth.  

National Technical Information Service (NTIS)

Progress continued in 1992 in the two major thrust areas of the diamond program; diamond consolidation, and heteroepitaxial nucleation. We have been developing a consolidation technology as one approach to large area diamond single crystals. During this p...

R. A. Rudder R. J. Markunas J. B. Posthill R. E. Thomas G. C. Hudson

1993-01-01

190

Adherent diamond film deposited on Cu substrate by carbon transport from nanodiamond buried under Pt interlayer  

NASA Astrophysics Data System (ADS)

Diamond film deposited on Cu suffered from poor adhesion mainly due to the large mismatch of thermal expansion coefficients and the lack of affinity between carbon and Cu. Enhancing diamond nucleation by carbon transport from buried nanodiamond through a Pt ultrathin interlayer, adherent diamond film was then deposited on Cu substrate without distinctly metallic interlayer. This novel nucleation mechanism increased diamond nucleation density to 1011 cm-2, and developed diamond film with a composite structure of nano-crystalline diamond (NCD) layer and micro-crystalline diamond layer. Diamond film was characterized by the scanning electron microscope (SEM) and Raman spectroscope, respectively. The composition of diamond film/Cu substrate interface was examined by electron probe microanalysis (EPMA). The adhesion of diamond film was evaluated by indentation test. Those results show that a Pt ultrathin interlayer provides stronger chemically bonded interfaces and improve film adhesion.

Liu, Xuezhang; Wei, Qiuping; Yu, Zhiming; Yang, Taiming; Zhai, Hao

2013-01-01

191

Diamond Tours  

NASA Technical Reports Server (NTRS)

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

2007-01-01

192

Study of diamond film growth and properties  

NASA Technical Reports Server (NTRS)

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.

Albin, Sacharial

1990-01-01

193

The mechanical properties of various chemical vapor deposition diamond structures compared to the ideal single crystal  

NASA Astrophysics Data System (ADS)

The structural and electronic properties of the diamond lattice, leading to its outstanding mechanical properties, are discussed. These include the highest elastic moduli and fracture strength of any known material. Its extreme hardness is strongly connected with the extreme shear modulus, which even exceeds the large bulk modulus, revealing that diamond is more resistant to shear deformation than to volume changes. These unique features protect the ideal diamond lattice also against mechanical failure and fracture. Besides fast heat conduction, the fast vibrational movement of carbon atoms results in an extreme speed of sound and propagation of crack tips with comparable velocity. The ideal mechanical properties are compared with those of real diamond films, plates, and crystals, such as ultrananocrystalline (UNC), nanocrystalline, microcrystalline, and homo- and heteroepitaxial single-crystal chemical vapor deposition (CVD) diamond, produced by metastable synthesis using CVD. Ultrasonic methods have played and continue to play a dominant role in the determination of the linear elastic properties, such as elastic moduli of crystals or the Young's modulus of thin films with substantially varying impurity levels and morphologies. A surprising result of these extensive measurements is that even UNC diamond may approach the extreme Young's modulus of single-crystal diamond under optimized deposition conditions. The physical reasons for why the stiffness often deviates by no more than a factor of two from the ideal value are discussed, keeping in mind the large variety of diamond materials grown by various deposition conditions. Diamond is also known for its extreme hardness and fracture strength, despite its brittle nature. However, even for the best natural and synthetic diamond crystals, the measured critical fracture stress is one to two orders of magnitude smaller than the ideal value obtained by ab initio calculations for the ideal cubic lattice. Currently, fracture is studied mainly by indentation or mechanical breaking of freestanding films, e.g., by bending or bursting. It is very difficult to study the fracture mechanism, discriminating between tensile, shear, and tearing stress components (mode I-III fracture) with these partly semiquantitative methods. A novel ultrasonic laser-based technique using short nonlinear surface acoustic wave pulses, developing shock fronts during propagation, has recently been employed to study mode-resolved fractures of single-crystal silicon. This method allows the generation of finite cracks and the evaluation of the fracture strength for well-defined crystallographic configurations. Laser ultrasonics reaches the critical stress at which real diamond fails and therefore can be employed as a new tool for mechanistic studies of the fracture behavior of CVD diamond in the future.

Hess, Peter

2012-03-01

194

Below-Band-Gap Laser Ablation Of Diamond For TEM  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

195

Production of diamond single crystals for synchrotron x-ray beamlines  

NASA Astrophysics Data System (ADS)

The physical properties of diamond represent in very many cases an extreme. Consequently it is predicted that diamond may be an excellent material to use in many applications. One of these is in intense X-ray fluxes such as produced by modern synchrotron sources. In this paper the implications in deploying diamond for such purposes are addressed. This includes a consideration of the nature of natural diamond, and in particular its characteristic defects. Progress in attempts to emulate Nature in diamond genesis makes available to us man-made diamond produced at high temperature and high pressure: such material is considered as an alternative to the natural form for diamond targets. In recent times man-made diamond has been produced by chemical vapor deposition: the characteristics of this type of diamond are identified. In regard to the preparation of the actual target, three areas are considered, the 'thick' diamond target, the 'thin' diamond target, and the 'composite' diamond target. Traditional methods are described for the preparation of thick diamonds, while new approach based on amorphizing layer of diamond in the prepared stone at a predetermined depth, which can be etched away releasing the superficial layer of undamaged diamond. Some applications of diamond targets are presented.

Sellschop, Jacques P.

1998-12-01

196

Method for the formation of ohmic contacts on diamond crystals  

Microsoft Academic Search

Connection of the diamond with the current supply was carried out at this temperature in an argon atmosphere or in a 5.10 to the-5th power mm vacuum. The molten titanium etches the diamond surface, and a carbide layer is formed on the interface boundary. The thickness of the layer is determined by the temperature, duration of presence and quantities of

V. F. Ivanov

1982-01-01

197

Plasma spraying method for forming diamond and diamond-like coatings  

DOEpatents

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.

Holcombe, Cressie E. (Farragut, TN); Seals, Roland D. (Oak Ridge, TN); Price, R. Eugene (Knoxville, TN)

1997-01-01

198

Metal diamond semiconductor interface and photodiode application  

NASA Astrophysics Data System (ADS)

Carrier transport mechanism at p-diamond/metal interfaces are studied by analyzing dependencies of specific contact resistance ( ?c) on measurement temperature and acceptor concentration ( NA). A variety of metals, such as Ti, Mo, Cr (carbide-forming metals), Pd, and Co (carbon-soluble metals), are deposited on boron-doped polycrystalline diamond layers, and the ?c values are measured by a transmission line method. Thermal annealing which produces metallurgical reactions between diamond and metal reduces Schottky barrier heights of the contact metals to a constant value. It is found that use of a metal compound which does not react with diamond at elevated temperatures is the key to develop the thermally stable Schottky contact material for p-diamond. Along this guideline, we test the suitability of tungsten carbide (WC) and hafnium nitride (HfN) as thermally stable Schottky contacts to develop a thermally stable, deep-ultraviolet (DUV) photodiode using a boron-doped homoepitaxial p-diamond epilayer. Thermal annealing at 500 °C improves the rectifying current-voltage characteristics of the photodiode, resulting in the excellent thermal stability. The discrimination ratio between DUV and visible light is measured to be as large as 10 6 at a reverse bias voltage as small as 2 V, and it remains almost constant after annealing at 500 °C for 5 h. Metal carbide and nitride contacts for diamond are thus useful for developing a thermally stable diamond DUV photodetector.

Koide, Yasuo

2008-07-01

199

Diamond coated total hip replacements.  

PubMed

Diamond has many superior, desired characteristics of implant materials such as low friction, high wear and corrosion resistance, and well bonding surface to bone. The potential of diamond for total hip replacement implants was studied in the form of amorphous diamond coatings on conventional metal implant materials. Amorphous diamond coatings (sp3 bonding fraction 80%, thickness 0.2 to 10 microns) were deposited on stainless steel AISI316L, Ti6A14V, and CoCrMo alloys using filtered pulsed plasma are discharge method. Superior attachment of coatings to the implant materials was achieved by using high energy plasma beams to deposit amorphous diamond and proper intermediate layers. Previously it was shown that these coatings are biocompatible causing no local tissue reactions. Tribologic studies using a pin on disk apparatus with coated or uncoated implant materials in 1 wt.% NaCl distilled water were performed. A simplified hip joint simulator was used for preliminary testing of metal on polyethylene and metal on metal artificial hip joints modified with amorphous diamond coating. The average coefficients of friction were typically in the range of 0.03 to 0.11 for amorphous diamond coated materials. In the case of metal on metal hip implants, the average friction during initial running in period was improved (coefficient of friction = 0.07) compared with the same metal on metal pair (coefficient of friction = 0.22) and sliding was significantly smoother. In pin on disk wear tests, the average wear factors obtained were 140.10(-6), 5.0.10(-6), and < 0.1.10(-6) mm3/Nm for the pairs of AISI316L, CoCrMo, and the same materials with amorphous diamond coating. The corrosion rates of these implant materials in 10 wt.% HCl solution were decreased by a factor of 10,000 to 15,000 and any damage of the coatings was not observed in 6 months. The results of the tests show that in all the combinations studied, amorphous diamond coating improved definitely the wear and corrosion resistance compared with the uncoated materials. PMID:9678039

Lappalainen, R; Anttila, A; Heinonen, H

1998-07-01

200

Effects of high energy Au-ion irradiation on the microstructure of diamond films  

NASA Astrophysics Data System (ADS)

The effects of 2.245 GeV Au-ion irradiation and subsequent annealing processes on the evolution of microstructure of diamond films with microcrystalline (MCD) or ultra-nanocrystalline (UNCD) granular structure were investigated, using near edge x-ray absorption fine structure and electron energy loss spectroscopy in transmission electron microscopy. For MCD films, the Au-ion irradiation disintegrated some of the diamond grains, resulting in the formation of nano-sized carbon clusters embedded in a matrix of amorphous carbon (a-C). The annealing process recrystallized the diamond grains and converted the a-C into nano-sized graphite particulates and, at the same time, induced the formation of nano-sized i-carbon clusters, the bcc structured carbon with a0 = 0.432 nm. In contrast, for UNCD films, the Au-ion irradiation transformed the grain boundary phase into nano-sized graphite, but insignificantly altered the crystallinity of the grains of the UNCD films. The annealing process recrystallized the materials. In some of the regions, the residual a-C phases were transformed into nano-sized graphites, whereas in other regions i-carbon nanoclusters were formed. The difference in irradiation-induced microstructural transformation behavior between the MCD and the UNCD films is ascribed to the different granular structures of the two types of films.

Chen, Shih-Show; Chen, Huang-Chin; Wang, Wei-Cheng; Lee, Chi-Young; Lin, I.-Nan; Guo, Jinghua; Chang, Ching-Lin

2013-03-01

201

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

PubMed

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. PMID:24738731

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

2014-06-24

202

Method of Joining Diamond Structures.  

National Technical Information Service (NTIS)

This invention relates to diamond materials and more particular to methods of bonding diamond pieces together. Diamond is the ideal material for a large number of applications. Diamond is highly transparent to infrared radiation (IR) and radar, has the hi...

L. T. Kabacoff J. Barkyoumb

1991-01-01

203

Physical and Tribological Characteristics of Ion-Implanted Diamond Films  

NASA Technical Reports Server (NTRS)

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.

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

204

Molecular Structure of diamond  

NSDL National Science Digital Library

Diamonds were first mined over 4,000 years ago in India. During this period, however, diamonds were of no use as jewelry. Louis de Berqueur, was the first who discovered how to cut facets of a diamond, changing the world of fine jewelry. The diamond is not only found in India but also in South Africa, Brazil, Russia, Austria, and Arkansas. A diamond can be used for several things. The most obvious includes a gemstone for jewelry purposes. It is also used for various industrial functions, such as cutting, grinding, and polishing. These characteristics make the diamond "a girl's best friend."

2002-08-23

205

A polycrystalline diamond thin-film-based hydrogen sensor  

Microsoft Academic Search

A new microelectronic gas sensor utilizing polycrystalline diamond film in conjunction with a catalytic metal has been developed for hydrogen detection. The sensor is fabricated in a layered Pd\\/i-diamond\\/p-diamond metal-insulator-semiconductor (MIS) Schottky-diode configuration on a tungsten substrate. The performance of the sensor for H2 detection has been examined in the temperature range 27-300°C. The analysis of the steady-state reaction kinetics

W. P. Kang; Y. Gurbuz; J. L. Davidson; D. V. Kerns

1995-01-01

206

Ion implantation of diamond: Damage, doping, and lift-off  

SciTech Connect

In order to make good quality economical diamond electronic devices, it is essential to grow films and to dope these films to obtain n- and p- type conductivity. This review talk discuss first doping by ion implantation plus annealing of the implantation damage, and second flow to make large area single crystal diamonds. C implantation damage below an estimated Frenkel defect concentration of 7% could be recovered almost completely by annealing at 950C. For a defect concentration between 7 and 10%, a stable damage form of diamond (``green diamond``) was formed by annealing. At still higher damage levels, the diamond graphitized. To introduce p-type doping, we have co-implanted B and C into natural diamond at 77K, followed by annealing up to 1100C. The resulting semiconducting material has electrical properties similar to those of natural B-doped diamond. To create n-type diamond, we have implanted Na{sup +}, P+ and As{sup +} ions and have observed semiconducting behavior. This has been compared with carbon or noble element implantation, in an attempt to isolate the effect of radiation damage. Recently, in order to obtain large area signal crystals, we have developed a novel technique for removing thin layers of diamond from bulk or homoepitaxial films. This method consists of ion implantation, followed by selective etching. High energy (4--5 MeV) implantation of carbon or oxygen ions creates a well-defined layer of damaged diamond buried at a controlled depth. This layer is graphitized and selectivity etched either by heating at 550C in an oxygen ambient or by electrolysis. This process successfully lifts off the diamond plate above the graphite layer. The lift-off method, combined with well-established homoepitaxial growth processes, has potential for fabrication of large area single-crystal diamond sheets.

Parikh, N.R.; McGucken, E.; Swanson, M.L. [North Carolina Univ., Chapel Hill, NC (United States). Dept. of Physics and Astronomy; Hunn, J.D.; White, C.W.; Zuhr, R.A. [Oak Ridge National Lab., TN (United States)

1993-09-01

207

Diamond Sheet: A new diamond tool material  

NASA Technical Reports Server (NTRS)

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

Mackey, C. R.

1982-01-01

208

Single Crystal Diamond Films.  

National Technical Information Service (NTIS)

Diamond films are important for radiation tolerant devices. However, fabrication of single crystal films has proven to be much more difficult than polycrystalline deposits. A novel deposition process is proposed which can be used to deposit diamond on a s...

S. N. Bunker R. Sahagian

1993-01-01

209

Diamond nonlinear photonics  

NASA Astrophysics Data System (ADS)

Despite progress towards integrated diamond photonics, studies of optical nonlinearities in diamond have been limited to Raman scattering in bulk samples. Diamond nonlinear photonics, however, could enable efficient, in situ frequency conversion of single photons emitted by diamond's colour centres, as well as stable and high-power frequency microcombs operating at new wavelengths. Both of these applications depend crucially on efficient four-wave mixing processes enabled by diamond's third-order nonlinearity. Here, we have realized a diamond nonlinear photonics platform by demonstrating optical parametric oscillation via four-wave mixing using single-crystal ultrahigh-quality-factor (1 × 106) diamond ring resonators operating at telecom wavelengths. Threshold powers as low as 20 mW are measured, and up to 20 new wavelengths are generated from a single-frequency pump laser. We also report the first measurement of the nonlinear refractive index due to the third-order nonlinearity in diamond at telecom wavelengths.

Hausmann, B. J. M.; Bulu, I.; Venkataraman, V.; Deotare, P.; Lon?ar, M.

2014-05-01

210

'Diamond Jenness': After the Grind  

NASA Technical Reports Server (NTRS)

This microscopic imager mosaic taken by NASA's Mars Exploration Rover Opportunity shows the rock dubbed 'Diamond Jenness.' It was taken on sol 177 (July 23, 2004) after the rover first ground into the rock with its rock abrasion tool, or 'Rat.' The rover later ground into the rock a second time. A sliced spherule, or 'blueberry,' is visible in the upper left corner of the hole.

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.

2004-01-01

211

'Diamond Jenness': A Tough Grind  

NASA Technical Reports Server (NTRS)

This microscopic imager mosaic of the target area 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.

2004-01-01

212

'Diamond Jenness': Before the Grind  

NASA Technical Reports Server (NTRS)

This microscopic imager mosaic of the rock called 'Diamond Jenness' was snapped on sol 177 before NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool, or 'Rat.'

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.

2004-01-01

213

Electrically conductive diamond electrodes  

DOEpatents

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.

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

2009-05-19

214

The Nature of Diamonds  

NSDL National Science Digital Library

This Web site looks at how diamonds are created (naturally and synthetically), and how they have been used throughout history. It contains information on composition and structure, the origins and history of diamonds, mining & distribution and an overview of the many uses of diamonds and how they are grown synthetically. A bibliography provides a listing of more than 75 resources for further study.

215

The metallicity of B-doped diamond surface by first-principles study  

Microsoft Academic Search

The first-principles study is performed to boron-doped diamond (100) and (111) surface structures, respectively. The total energy values of the relaxed structures indicate that the more stable structure can be obtained for diamond (100) structure when the carbon atoms in the surface few layers are substituted by boron atoms; while for diamond (111) structure, the boron atoms have a more

C. Lu; Z. L. Wang; L. F. Xu; H. X. Yang; J. J. Li; C. Z. Gu

2010-01-01

216

Polycrystalline Diamond Junction Field Effect Transistors (JFETS)1.  

National Technical Information Service (NTIS)

Diodes were fabricated from in situ doped 'N'-diamond/P-diamond layer structures. The 'N'-dopants investigated were nitrogen and oxygen. The majority of the diodes fabricated to date have has either'leaky' characteristics or displayed high series resistan...

D. Moyer M. Landstrass

1990-01-01

217

Mechanics in alumina ceramics modified by ultradispersed diamonds  

Microsoft Academic Search

Alumina coating modified by ultra-dispersed diamonds (UDD) have been produced by combination of thermal flame spraying and micro arc oxidizing technologies on sprayed aluminum substrate was. Structures of alumina-based ultra dispersed diamond particles composite coatings were investigated in detail by transmission electron microscopy and SEM imaging. The particles were deposited with alumina layer on aluminum substrates under various conditions and

Maksim V. Kireitseu; Sergey G. Yerakhavets; Vladimir L. Basenuk; Victor Jornik

2003-01-01

218

Brazing diamond grits onto a steel substrate using copper alloys as the filler metals  

NASA Astrophysics Data System (ADS)

Surface-set diamond tools were fabricated by an active metal brazing process, using bronze (Cu-8.9Sn) powder and 316L stainless steel powder mixed to various ratios as the braze filler metals. The diamond grits were brazed onto a steel substrate at 1050 °C for 30 min in a dry hydrogen atmosphere. After brazing practice, an intermediate layer rich in chromium formed between the braze filler metal and diamond. A braze filler metal composed of 70 wt % bronze powder and 30 wt % stainless steel powder was found to be optimum in that the diamond grits were strongly impregnated in the filler metal by both mechanical and chemical types of holding. The diamond tools thus fabricated performed better than conventional nickel-plated diamond tools. In service, the braze filler metal wore at almost the same rate as the diamond grits, and no pullout of diamond grits or peeling of the filler metal layer took place.

Chen, S.-M.; Lin, S.-T.

1996-12-01

219

Ultra thin CVD diamond film deposition by electrostatic self-assembly seeding process with nano-diamond particles.  

PubMed

Ultra thin and smooth nano crystalline diamond films were fabricated with electrostatic self-assembly seeding of explosively synthesized nano-diamond particles. Hard aggregates of nano-diamond particles were crushed by high revolution attrition milling at 1000 RPM to regulate the particle size. Through this process, cationic nano-diamond particles were coated with anionic PSS (poly sodium 4-styrene sulfonate) electrolytes. Anionic Si(100) substrate was coated with cationic PDDA (poly diallyldimethyl ammonium chloride) solution. Si(100)/PDDA/PSS/ND (nano-diamond) layer-by-layer structure was formed as a seeding layer by the simple dipping and rinsing of positively charged substrate into anionic PSS/nano-diamond solution. Throughout the seeding process, neither mechanical damage nor chemical attack was observed on the substrate. Every stage of this preparation was carried out at room temperature and pressure. The effect of attrition milling was determined by changing the milling time from 1 hr to 5 hrs. Through the attritional milling and monolayer formation of the nano-diamond, nucleation density was increased up to 3 x 10(11)/cm2. Typical hot filament chemical vapor deposition system was used to coat the diamond film on the ESA (electrostatic self-assembly) seeded Si(100) substrate. Although typical diamond deposition conditions (90 torr/1% CH4 in H2/800 degrees C) were maintained, ultra thin (< 100 nm) and continuous nano crystalline diamond films were deposited. Regardless of metallic or ceramic substrate, ESND (ESA Seeding of nano-diamond) process is applicable if the substrate has any charge. This simple nano technology based process ensures high thickness uniformity of diamond coating without visible edge effect. PMID:19916418

Kim, J H; Lee, S K; Kwon, O M; Lim, D S

2009-07-01

220

The Nature of Diamonds  

NASA Astrophysics Data System (ADS)

The paragon of physical perfection and a sparkling example of Earth's forces at work, the diamond has fascinated all realms of society, from starlets to scientists. The Nature of Diamonds is a comprehensive look at nature's most coveted gem. A handsome, large-format book, The Nature of Diamonds is an authoritative and richly-illustrated tribute to the diamond. Leading geologists, gemologists, physicists, and cultural observers cover every facet of the stone, from its formation in the depths of the Earth, its ascent to the surface, and its economic, regal, social, and technological roles. Cutting-edge research takes the reader to the frontiers of diamond exploration and exploitation, from the Arctic wastes to the laboratories where diamonds are created for massive road shredders that rip up and then re-create superhighways. Here also is an overview of cutting, from the rough stones in Roman rings to the highly-faceted stones we see today, and a glimpse into the business of diamonds. Finally, The Nature of Diamonds chronicles scientific and cultural history and explores the diamond as both a sacred and a social symbol, including a picture history of betrothal rings. Wide-ranging illustrations explain the geology of diamonds, chart the history of mining from its origins in India and Brazil through the diamond rush in South Africa and today's high-tech enterprises, and capture the brilliance and beauty of this extraordinary gem. _

Harlow, George E.

1997-10-01

221

Optical defect centers and surface morphology of diamond single crystals grown by chemical vapor deposition  

Microsoft Academic Search

A study was performed on the optical defect centers and surface morphology of isotopically enriched layers grown on diamond anvils by microwave plasma chemical vapor deposition for applications as designer diamond anvils in high-pressure diamond anvil cell devices. Various mixtures of methane isotopes were used to grow homoepitaxial diamond with 13 C molar fractions of 0.01, 0.41, 0.83, and 0.99

Paul A. Baker

2005-01-01

222

Atomic Layer Etching Specification.  

National Technical Information Service (NTIS)

An apparatus, and method therefor, for removing a single atomic layer from the surface of a crystalline diamond. In a preferred embodiment, the apparatus comprises: a first delivery system for flooding the surface of the diamond with a pulse of nitrogen d...

M. N. Yoder

1987-01-01

223

HPHT preparation and Micro-Raman characterization of polycrystalline diamond compact with low residual stress  

NASA Astrophysics Data System (ADS)

High quality grown polycrystalline diamond compact (PDC) with low residual stress was prepared using the infiltration method with nickel based alloys as the solvent under high temperature and high pressure (HPHT). Scanning electron microscopy (SEM) was used to observe the micro morphology of the diamond layer and the diamond/WC substrate interface. It was found that dense and interlaced microstructure with diamond-diamond (D-D) direct bonding formed in the diamond layer of PDC. Micro-Raman spectroscopy was used to measure the Raman shift of diamonds in the polycrystalline diamond (PCD) layer and the residual stress was calculated based on the Raman shift of diamonds. Experimental results show that the residual stress of PCD layer is compressive stress, and the range of the residual stress is from 0.075 to 0.250 GPa in the whole PCD layer, much lower than that of other reports (up to 1.400 GPa). Moreover, the distribution of the residual stress from the diamond surface layer to the inner cross-section is homogeneous.

Jia, Hongsheng; Ma, Hongan; Guo, Wei; Jia, Xiaopeng

2010-08-01

224

Diamond tool machining of materials which react with diamond  

DOEpatents

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.

Lundin, Ralph L. (Los Alamos, NM); Stewart, Delbert D. (Los Alamos, NM); Evans, Christopher J. (Gaithersburg, MD)

1992-01-01

225

Diamond tool machining of materials which react with diamond  

SciTech Connect

This invention is comprised of an 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.

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

1991-04-01

226

Boron-Doped Nanocrystalline Diamond.  

National Technical Information Service (NTIS)

A conductive boron doped nanocrystalline diamond is described. The boron doped diamond has a conductivity which uses the boron in the crystals as a charge carrier. The diamond is particularly useful for electrochemical electrodes in oxidation-reduction re...

G. M. Swain M. Witek P. Sonthalia Y. Show

2004-01-01

227

Liquid Crystal Alignment Effects and Electro Optical Performances of Twisted Nematic-Liquid Crystal Display Using Ion-Beam Alignment Method on Nitrogen-doped Diamond Like Carbon Thin Film Layer  

Microsoft Academic Search

Nitrogen-doped diamond-like carbon (NDLC) thin films exhibit a high electrical resistivity that is similar to the properties shown by diamond-like carbon (DLC) thin films. The diamond-like transport property in NDLC thin films comes from a material consisting of sp2-bonded carbon versus the sp3-bonded carbon of DLC. In addition, NDLC thin films have a better thermal stability than the DLC thin

Chang-Joon Park; Jeoung-Yeon Hwang; Hyung-Ku Kang; Dae-Shik Seo; Han-Jin Ahn; Jong-Bok Kim; Kyung-Chan Kim; Hong-Koo Baik

2005-01-01

228

Synthesis and Characterization of Multilayered Diamond Coatings for Biomedical Implants.  

PubMed

With incredible hardness and excellent wear-resistance, nanocrystalline diamond (NCD) coatings are gaining interest in the biomedical community as articulating surfaces of structural implant devices. The focus of this study was to deposit multilayered diamond coatings of alternating NCD and microcrystalline diamond (MCD) layers on Ti-6Al-4V alloy surfaces using microwave plasma chemical vapor deposition (MPCVD) and validate the multilayer coating's effect on toughness and adhesion. Multilayer samples were designed with varying NCD to MCD thickness ratios and layer numbers. The surface morphology and structural characteristics of the coatings were studied with X-ray diffraction (XRD), Raman spectroscopy, and atomic force microscopy (AFM). Coating adhesion was assessed by Rockwell indentation and progressive load scratch adhesion tests. Multilayered coatings shown to exhibit the greatest adhesion, comparable to single-layered NCD coatings, were the multilayer samples having the lowest average grain sizes and the highest titanium carbide to diamond ratios. PMID:21603588

Booth, Leigh; Catledge, Shane A; Nolen, Dustin; Thompson, Raymond G; Vohra, Yogesh K

2011-05-01

229

Diamond nanoimprint lithography  

Microsoft Academic Search

Electron beam (EB) lithography using polymethylmethacrylate (PMMA) and oxygen gas reactive ion etching (RIE) were used to fabricate fine patterns in a diamond mould. To prevent charge-up during EB lithography, thin conductive polymer was spin-coated over the PMMA resist, yielding dented line patterns 2 mu m wide and 270 nm deep. The diamond mould was pressed into PMMA on a

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

2002-01-01

230

Diamond nucleation using polyethene  

DOEpatents

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.

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

2013-07-23

231

Forearc diamond from Japan  

NASA Astrophysics Data System (ADS)

Convergent margins are not generally considered to be suitableplaces for the formation of diamond and its transport to Earth'ssurface. Microdiamonds found in xenoliths within a lamprophyredike in southwest Japan show that this assumption is incorrectand, furthermore, that diamond occurs in a wider range of geologicalsettings than previously realized. Petrological constraintsshow that these diamond-bearing minerals rose from depths ofaround 160 km (~5.5. GPa) and cooled from temperatures of ~1500°C. The location of the diamond-bearing rocks in the forearcand close to the subducting plate requires the existence ofmantle up-flow, which brought the diamond to shallow mantlelevels before traveling 100-km-scale horizontal distances. Ifthe dimensions of this flow are large, it can help explain bothforearc magmatism and perhaps the development of subductionzones hot enough to melt sediments.

Mizukami, T.; Wallis, S.; Enami, M.; Kagi, H.

2008-03-01

232

Adhesion improvement of diamond films on steel subtrates using chromium nitride interlayers  

Microsoft Academic Search

Direct deposition of diamond on ferrous materials suffers from adhesion problems due to the build up of a graphitic layer at the interface. A successful solution to this problem was attained through the use of an intermediate layer consisting of 20 ?m thick nitrided chromium film. The initial stage of diamond deposition resulted in the partial carburization of the chromium

O. Glozman; A. Hoffman

1997-01-01

233

Interactions of diamond surfaces with fusion relevant plasmas  

NASA Astrophysics Data System (ADS)

The outstanding thermal properties of diamond and its low reactivity towards hydrogen may make it an attractive plasma-facing material for fusion and calls for a proper evaluation of its behaviour under exposure to fusion-relevant plasma conditions. Micro and nanocrystalline diamond layers, deposited on Mo and Si substrates by hot filament chemical vapour deposition (CVD), have been exposed both in tokamaks and in linear plasma devices to measure the erosion rate of diamond and study the modification of the surface properties induced by particle bombardment. Experiments in Pilot-PSI and PISCES-B have shown that the sputtering yield of diamond (both physical and chemical) was a factor of 2 lower than that of graphite. Exposure to detached plasma conditions in the DIII-D tokamak have evidenced a strong resistance of diamond against erosion under those conditions.

De Temmerman, G.; Doerner, R. P.; John, P.; Lisgo, S.; Litnovsky, A.; Marot, L.; Porro, S.; Petersson, P.; Rubel, M.; Rudakov, D. L.; Van Rooij, G.; Westerhout, J.; Wilson, J. I. B.

2009-12-01

234

Ion Beam Processing of Diamonds  

Microsoft Academic Search

Diamond based semiconductor devices may turn out to be of significant importance due to the unique physical, chemical and electrical properties of diamond. Such devices have not been realized till now because of the absence of reliable processing techniques for doping, etching and making contacts to diamond. The most promising way to dope diamond in a controlled way is by

Gurtej Singh Sandhu

1989-01-01

235

Comparative studies on photonic band structures of diamond and hexagonal diamond using the multiple scattering method  

NASA Astrophysics Data System (ADS)

Photonic band structures are investigated for both diamond and hexagonal diamond crystals composed of dielectric spheres, and absolute photonic band gaps (PBGs) are found in both cases. In agreement with both Karathanos and Moroz's calculations, a large PBG occurs between the eighth and ninth bands in diamond crystal, but a PBG in hexagonal diamond crystal is found to occur between the sixteenth and seventeenth bands because of the doubling of dielectric spheres in the primitive cell. To explore the physical mechanism of how the photonic band gap might be broadened, we have compared the electric field distributions (|E|2) of the 'valence' and 'conduction' band edges. Results show that the field intensity for the 'conduction' band locates in the inner core of the sphere while that of the 'valence' band concentrates in the outer shell. With this motivation, double-layer spheres are designed to enhance the corresponding photonic band gaps; the PBG is increased by 35% for the diamond structure, and 14% for the hexagonal diamond structure.

Chen, Hui; Zhang, Weiyi; Wang, Zhenlin

2004-02-01

236

Diamond and diamond-like carbon films for advanced electronic applications  

SciTech Connect

Aim of this laboratory-directed research and development (LDRD) project was to develop diamond and/or diamond-like carbon (DLC) films for electronic applications. Quality of diamond and DLC films grown by chemical vapor deposition (CVD) is not adequate for electronic applications. Nucleation of diamond grains during growth typically results in coarse films that must be very thick in order to be physically continuous. DLC films grown by CVD are heavily hydrogenated and are stable to temperatures {le} 400{degrees}C. However, diamond and DLC`s exceptional electronic properties make them candidates for integration into a variety of microelectronic structures. This work studied new techniques for the growth of both materials. Template layers have been developed for the growth of CVD diamond films resulting in a significantly higher nucleation density on unscratched or unprepared Si surfaces. Hydrogen-free DLC with temperature stability {le} 800{degrees}C has been developed using energetic growth methods such as high-energy pulsed-laser deposition. Applications with the largest system impact include electron-emitting materials for flat-panel displays, dielectrics for interconnects, diffusion barriers, encapsulants, and nonvolatile memories, and tribological coatings that reduce wear and friction in integrated micro-electro-mechanical devices.

Siegal, M.P.; Friedmann, T.A.; Sullivan, J.P. [and others

1996-03-01

237

Chemical vapor infiltration of porous substrates with diamond by using a new designed hot-filament plant  

Microsoft Academic Search

We designed a new hot-filament plant which features some new operating states for chemical vapor infiltration with diamond.\\u000a Complete infiltration of porous substrates with diamond by using standard hot filament plants is not possible. Chemical vapor\\u000a infiltration with diamond is limited by the overgrowing diamond layer at the surface primarily caused by high recombination\\u000a rates of atomic hydrogen on surfaces.

A. Glaser; S. M. Rosiwal

2007-01-01

238

The diamonds of South Australia  

NASA Astrophysics Data System (ADS)

Diamonds in South Australia occur in kimberlites at Eurelia (Orroroo), and in placer deposits, which include the Springfield Basin and the historic Echunga goldfield. To identify the kimberlitic and mantle sources of the placer diamonds, and to determine any possible connections between the placer diamonds and the diamonds from the Eurelia kimberlites, we examined the physical and compositional characteristics, and the mineral inclusion content of 122 diamonds from the Springfield Basin and 43 diamonds from kimberlites at Eurelia. Additional morphological data for three Echunga diamonds are also given. Most of the diamonds from the Springfield Basin are similar to the diamonds from Eurelia with respect to their crystal shapes, surface textures, and colors. The diamond populations from both areas are characterized by a high abundance of low-nitrogen (< 100 ppm) diamonds with variable nitrogen aggregation states. The stable carbon isotope compositions of the Springfield Basin diamonds are similar to the Eurelia diamonds with ?13C values in the range - 20.0 to - 2.5‰, and a mode at - 6.5‰. Ferropericlase inclusions in two diamonds from the Springfield Basin are consistent with ferropericlase-bearing mineral inclusion assemblages found in the Eurelia diamonds and indicate that part of the diamond population from both areas is of sublithospheric origin. One diamond from the Springfield Basin contained an inclusion of lherzolitic garnet. The overall similarities between the Springfield Basin and Eurelia diamonds indicates that the bulk of the Springfield Basin diamonds are derived from kimberlitic sources that are similar (or identical) to those at Eurelia. However, three diamonds from the Springfield Basin are markedly distinct. These have well-developed crystal shapes, large sizes, yellow body colorations, and brown irradiation spots. The brown irradiation spots and abrasion textures provide evidence that these diamonds are much older than the other diamonds in the Springfield Basin, and that they are derived from distal kimberlitic sources. The diamonds are most likely derived from Permian glacigene sediments and may ultimately be sourced from kimberlites on the East Antarctic craton. Abrasion textures and brown irradiation spots are also present on diamonds from Echunga. This provides a link to the three "old" Springfield Basin diamonds and other alluvial diamonds in Eastern Australia, and suggests that Permian glaciations caused a widespread distribution of diamonds over large parts of southern Australia, which at that time was part of the supercontinent Gondwana.

Tappert, Ralf; Foden, John; Stachel, Thomas; Muehlenbachs, Karlis; Tappert, Michelle; Wills, Kevin

2009-11-01

239

Diamonds in detonation soot  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

240

Isotopically Enriched C-13 Diamond Anvil as a Stress Sensor in High Pressure Experiments  

NASA Astrophysics Data System (ADS)

The conventional high pressure diamond anvils were modified by growing an isotopically pure C-13 diamond layer by microwave plasma chemical vapor deposition using methane/hydrogen/oxygen chemistry. The isotopically pure C-13 nature of the culet of the diamond anvil was confirmed by the Raman spectroscopy measurements. This isotopically engineered diamond anvil was used against a natural abundance diamond anvil for high pressure experiments in a diamond anvil cell. Spatial resolved Raman spectroscopy was used to measure the stress induced shift in the C-13 layer as well as the undelying C-12 layer to ultra high pressures. The observed shift and splitiing of the diamond first order Raman spectrum was correlated with the stress distribution in the diamond anvil cell. The experimental results will be compared with the finite element modeling results using NIKE-2D software in order to create a mathematical relationship between sets of the following parameters: vertical (z axis) distance; horizontal (r axis) distance; max shear stress, and pressure. The isotopically enriched diamond anvils offer unique opportunities to measure stress distribution in the diamond anvil cell devices.

Vohra, Yogesh; Qiu, Wei; Kondratyev, Andreiy; Velisavljevic, Nenad; Baker, Paul

2004-03-01

241

Realising epitaxial growth of GaN on (001) diamond  

NASA Astrophysics Data System (ADS)

By an extensive investigation of the principal growth parameters on the deposition process, we realized the epitaxial growth of crystalline wurtzite GaN thin films on single crystal (001) diamond substrates by metal organic chemical vapor deposition. From the influence of pressure, V/III ratio, and temperature, it was deduced that the growth process is determined by the mass-transport of gallium precursor material toward the substrate. The highest temperature yielded an improved epitaxial relationship between grown layer and substrate. X ray diffraction (XRD) pole figure analysis established the presence of two domains of epitaxial layers, namely (0001) <1010> GaN? (001)[110] diamond and (0001) <1010> GaN? (001) [110] diamond, which are 90? rotated with respect to each other. The presence of these domains is explained by the occurrence of areas of (2×1) and (1×2) surface reconstruction of the diamond substrate. When applying highly misoriented diamond substrates toward the [110] diamond direction, one of the growth domains is suppressed and highly epitaxial GaN on (001) diamond is realized.

van Dreumel, G. W. G.; Tinnemans, P. T.; van den Heuvel, A. A. J.; Bohnen, T.; Buijnsters, J. G.; Ter Meulen, J. J.; van Enckevort, W. J. P.; Hageman, P. R.; Vlieg, E.

2011-07-01

242

Diamond at 800 GPa  

SciTech Connect

A new compression technique, which enables the study of solids into the TPa regime, is described and used to ramp (or quasi-isentropically) compress diamond to a peak pressure of 1400 GPa. Diamond stress versus density data are reported to 800 GPa and suggest that the diamond phase is stable and has significant material strength up to at least this stress level. Data presented here are the highest ramp compression pressures by more than a factor of 5 and the highest-pressure solid equation-of-state data ever reported.

Bradley, D. K.; Eggert, J. H.; Smith, R. F.; Prisbrey, S. T.; Hicks, D. G.; Braun, D. G.; Biener, J.; Hamza, A. V.; Rudd, R. E.; Collins, G. W. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)

2009-02-20

243

Mechanical stresses and amorphization of ion-implanted diamond  

NASA Astrophysics Data System (ADS)

Scanning white light interferometry and Raman spectroscopy were used to investigate the mechanical stresses and structural changes in ion-implanted natural diamonds with different impurity content. The uniform distribution of radiation defects in implanted area was obtained by the regime of multiple-energy implantation of keV He+ ions. A modification of Bosia's et al. (Nucl. Instrum. Meth. B 268 (2010) 2991) method for determining the internal stresses and the density variation in an ion-implanted diamond layer was proposed that suggests measuring, in addition to the surface swelling of a diamond plate, the radius of curvature of the plate. It is shown that, under multiple-energy implantation of He+, mechanical stresses in the implanted layer may be as high as 12 GPa. It is shown that radiation damage reaches saturation for the implantation fluence characteristic of amorphization of diamond but is appreciably lower than the graphitization threshold.

Khmelnitsky, R. A.; Dravin, V. A.; Tal, A. A.; Latushko, M. I.; Khomich, A. A.; Khomich, A. V.; Trushin, A. S.; Alekseev, A. A.; Terentiev, S. A.

2013-06-01

244

Diamond diode-based chemical gas sensors  

NASA Astrophysics Data System (ADS)

The successful utilization of microelectronic-based gas sensors (MOS Capacitor, MOSFET, MS, and MIS diodes) in many practical applications such as automotive, aeronautical, commercial, and environmental has not been achieved due to the limited operating temperature range of Si and GaAs semiconductors (less than 200sp°C). Present development in the diamond technology provides an opportunity to address this problem. Along with its well known physical and optical properties, the superior semiconductor properties of diamond over Si, GaAs, and SiC (higher breakdown voltage, energy band gap, carrier mobility, and thermal conductivity) are useful for gas sensor applications. We have developed a novel family of diamond-based chemical gas sensors for the detection of hydrogen, oxygen and carbon monoxide at a higher operating temperature range than currently possible with Si- and GaAs-based microelectronic gas sensors. The new devices were fabricated in the form of a Pd/i-diamond/psp+-diamond MIS structure for the detection hydrogen and a Pt/SnOsb{x}/i-diamond/psp+-diamond CAIS structure for the detection of oxygen and carbon monoxide. Sensor performances have been investigated over a wide temperature range (22sp° C{-}400sp° C). The gas sensitivity of the devices have been found to be large, fast, selective, repeatable, and reproducible. Detection mechanisms of the sensors have been developed. The hydrogen detection mechanism of the diamond-based MIS device is due to hydrogen dipole formation at the Pd/i-diamond interface and a subsequent change in the voltage distribution across the junction. The oxygen and carbon monoxide sensitivity of the CAIS device is attributed to the modification of the oxygen vacancies in the SnOsb{x} layer and the subsequent change in the voltage drop across the oxide. The current transport mechanisms of the sensors have been studied and gas adsorption effects on sensor parameters have been modeled. The current conduction mechanism of the sensors is Space Charge Limited, distinctively different from Si- and GaAs-based diodes. While no significant change was observed on the ideality factor, a change in the barrier height and tunneling factor of the sensors was found upon gas adsorption. The findings of this study form the basis for the utilization of microelectronic devices in wide range of gas sensor applications, requiring large sensitivity, fast, repeatable, and reproducible response, wider operating temperature range, and stability in harsh environments. Furthermore, this study contributes a fundamental knowledge in the operating principles and sensing mechanisms of the high temperature-tolerant microelectronic gas sensors.

Gurbuz, Yasar

245

A Polycrystalline Diamond Thin Film Based Hydrogen Sensor  

Microsoft Academic Search

A new microelectronic gas sensor utilizing polycrystallinediamondfilm in conjunction with a catalytic metal has been developed for hydrogen detection. The sensor is fabricated in a layered Pd\\/i-diamond\\/p-diamond metal-insulator-semiconductor (MIS) Schottky-diode configuration on a tungsten substrate. The performance of the sensor for H2 detection has been examined in the temperature range 27-300°C. The analysis of the steady-state reaction kinetics has confirmed

David V. Kerns; W P Kang; Y Gurbuz; J L Davidson

2002-01-01

246

Metal–diamond semiconductor interface and photodiode application  

Microsoft Academic Search

Carrier transport mechanism at p-diamond\\/metal interfaces are studied by analyzing dependencies of specific contact resistance (?c) on measurement temperature and acceptor concentration (NA). A variety of metals, such as Ti, Mo, Cr (carbide-forming metals), Pd, and Co (carbon-soluble metals), are deposited on boron-doped polycrystalline diamond layers, and the ?c values are measured by a transmission line method. Thermal annealing which

Yasuo Koide

2008-01-01

247

Optical Properties of Nanocrystalline Diamond\\/Amorphous Carbon Composite Films  

Microsoft Academic Search

Thin nanocrystalline diamond\\/amorphous carbon (NCD\\/a?C) composite films were prepared by microwave plasma chemical vapor deposition (MWCVD) from methane\\/nitrogen gas mixtures. The investigation of the basic films properties (crystallinity, morphology, composition, structure, etc.) showed that the layers are composed of diamond nanocrystallites with a size of 3–5 nm, which are embedded in an amorphous carbon matrix. The ratio of the two fractions

S. Boycheva; C. Popov; W. Kulisch; J. Bulir; A. Piegari

2005-01-01

248

Polycrystalline Diamond and Boron Nitride Cutting Tools.  

National Technical Information Service (NTIS)

The problems of diamond synthesis and the problems of bonding diamond are intimately related. No one has ever succeeded in achieving a decent polycrystalline diamond compact, bonded outside of the stability field of diamond. Further, all bonding not only ...

1976-01-01

249

Amorphous diamond films  

DOEpatents

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

Falabella, S.

1998-06-09

250

Ekati Diamond Mine  

NSDL National Science Digital Library

The page on the Ekati Diamond Mine, which is located in the Northwest Territories and is North America's only operating diamond mine, presents a satellite image and informational text. A detailed map of the region is also included which will allow users to compare the satellite image to what the area looks like on a map. The CCRS was last mentioned in the May 24, 2000 Scout Report for Science and engineering.

2001-01-01

251

Dynamic synthesis of diamonds  

Microsoft Academic Search

Nanometer-size diamonds were produced by firing of high explosive mixtures in water confinement. This simple method avoids the use of inert gas and is efficient enough to prevent the oxidation and graphitization of recovered diamonds. Studies of thermal and luminous phenomena were performed to examine eventually post-combustion phase. Condensed carbon yields of 30–55% were achieved for different explosive compositions, some

J. B. Donnet; E. Fousson; T. K. Wang; M. Samirant; C. Baras; M. Pontier Johnson

2000-01-01

252

Characterization of ZnO\\/diamond SAW devices elaborated on the smooth nucleation side of MPACVD diamond  

Microsoft Academic Search

We designed a SAW filter in this work by combining the piezoelectric ZnO film with a freestanding double layer diamond film deposited using CH4-H2 pulsed MPACVD process through two growth stages. The AFM measurements on the nucleation side of the diamond film has shown that this side is smooth enough to perform photolithography process in the SAW device elaboration, while

L. Le Brizoual; T. Lamara; F. Sarry; M. Belmahi; O. Elmazria; J. Bougdira; M. Remy; P. Alnot

2005-01-01

253

Diamond rotating bit  

SciTech Connect

An improved rotating diamond bit for earth boring is devised by incorporating generally triangular, prismatically shaped synthetic polycrystalline diamond elements in the teeth of the boring bit. The polycrystalline diamond elements are set on lands defined on the bit face such that two opposing triangular faces of the prismatic diamond element form a dihedral angle in the direction of travel of the element defined by the bit rotation. The polycrystalline diamond element is thus inclined with respect to the direction of linear travel of the element when the bit rotates. In other words, the normal to the parallel opposing triangular faces of the diamond element is acutely inclined with respect to the direction of travel of the element. A shoulder-to-gage transition pattern of the junk slot, waterway and collector is arranged to uniformly distribute the flow of fluid across the shoulder to guage transition. Further, the distribution of fluid from the central conduit within the longitudinal core of the bit to a plurality of nozzles which merge with corresponding waterways on the bit face is arranged such that fluid is preferentially delivered to a radially innermost nozzle and thereafter in a graduated series of steps in lesser amounts to a series of sequenced nozzles more radially disposed from the center of the rotating bit.

Link, H. D.

1985-11-05

254

A New Hydrogen Sensor Using a Polycrystalline Diamond-Based Schottky Diode  

Microsoft Academic Search

A new hydrogen sensor utilizing plasma-enhanced chemical vapor deposited diamond in conjunction with palladium(Pd) metal has been developed. The device is fabricated in a layered Pd\\/undoped diamond\\/p-doped diamond Schottkydiode configuration. Hydrogensensing characteristics of the device have been examined in termsof sensitivity, linearity,response rate, and response time as a function of temperature and hydrogen partial pressure. Hydrogen adsorption activation energy is

David V. Kerns; W P Kang; Y Gurbuz; J L Davidson

1994-01-01

255

Influence of Bias-Enhanced Nucleation on Thermal Conductance Through Chemical Vapor Deposited Diamond Films  

Microsoft Academic Search

This work describes an experimental study of the cross-plane thermal conductance of plasma-enhanced chemical vapor deposited (PECVD) diamond films grown as a result of bias-enhanced nucleation (BEN). The diamond films are grown on silicon wafers using a two-step process in which a nucleation layer of amorphous or diamond like (DLC) carbon is first deposited on the silicon under the influence

Baratunde A. Cola; Ratnakar Karru; Changrui Cheng; Xianfan Xu; Timothy S. Fisher

2008-01-01

256

Residual stress in polycrystalline diamond\\/Ti?6Al?4V systems  

Microsoft Academic Search

Polycrystalline diamond coatings were deposited on Ti?6Al?4V alloy by HF-CVD, at fixed temperature (650 C) for different deposition times. During the process, thick titanium carbide layers were formed at the metal\\/diamond interface. X-ray diffraction (XRD) methods were used to assess coating quality, phase composition, texture, and residual macrostress of the diamond\\/TiC\\/Ti system. For a better evaluation of the residual stress

Paolo Scardi; Matteo Leoni; Giorgio Cappuccio; Vito Sessa; Maria Letizia Terranova

1997-01-01

257

Interfacial structure, residual stress and adhesion of diamond coatings deposited on titanium  

Microsoft Academic Search

The interfacial structures of diamond coatings deposited on pure titanium substrate were analyzed using scanning electron microscopy and grazing incidence X-ray diffraction. Results showed that beneath the diamond coating, there was one titanium carbide and hydride interlayer, followed by a heat-affected and carbon\\/hydrogen diffused Ti layer. Residual stress in the diamond coating and TiC interlayer under different process parameters were

Yongqing Fu; Hejun Du; Chang Q. Sun

2003-01-01

258

CVD diamond coating of steel on a CVD-TiBN interlayer  

Microsoft Academic Search

Adherent and homogeneous diamond films were deposited on 41Cr4 steel substrates employing chemical vapor deposited (CVD) TiBN interlayers. The suitability of CVD-TiBN interlayers for diamond deposition was investigated. The CVD intermediate layers showed excellent barrier properties against the diffusion of iron from the bulk substrate to the surface and against diffusion of carbon from gas phase during diamond deposition. Various

J. C. Barei?; G. Hackl; N. Popovska; S. M. Rosiwal; R. F. Singer

2006-01-01

259

Nano-tribological properties of topographically undulated nanocrystalline diamond patterns.  

PubMed

Surface roughness-controlled nanocrystalline diamond film was fabricated as an undulated line and space pattern on a silicon oxide surface. To simulate a MEMS (Micro-/Electro-Mechanical System) and NEMS (Nano-/Electro-Mechanical System) patterned surface, 800 nm and 1 microm wide lines with a 200 nm wide space pattern were prepared on the substrate using E-beam lithography and an ESAND (Electrostatic Self-assembly of NanoDiamond) seeding layer lift-off process. Through this process, an undulated pattern of a nanocrystalline CVD diamond successfully formed by a conventional micro crystalline diamond growth system. The roughness of the deposited surface was controlled by regulating the size of the seeding nanodiamond particles. Crushing of the nanodiamond aggregates and dispersion of the nanodiamond solution was performed in an attrition milling system. An AFM (Atomic Force Microscopy) probe was used for the wear test and surface profiling of nanocrystalline diamond coatings. 2-D friction coefficient mapping by LFM (Lateral Force Microscopy) scanning showed a low friction coefficient (< 0.1) on the line-patterned diamond surface, and a higher friction coefficient (< 0.3) on a narrow area adjacent to the undulated pattern edges. With prolonged LFM scanning, the high coefficient of friction was reduced to less than 0.1. The bonding status of the nanocrystalline diamond was analyzed with Raman spectroscopy. PMID:21446453

Kim, J H; Lee, S K; Hwang, K S; Kwon, O M; Lim, D S

2011-01-01

260

Ion-Implanted Diamond Films and Their Tribological Properties  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

261

Simulation of 1550-nm diamond VECSEL with high contrast grating  

NASA Astrophysics Data System (ADS)

In the following paper a simulation of optically pumped vertical external cavity surface emitting lasers (VECSEL) with a novel approach for the improvement of the heat management is presented. In recent VECSEL structures, it was common to use one top diamond heat spreader in order to decrease the thermal resistance of the device by redistributing the heat flow to the lateral regions and thus transporting heat down to the copper heat sink more efficiently. We present here further improvement of the heat management by eliminating the bottom DBR from the heat flow path and substituting it for a diamond with a High Contrast Grating (HCG). Hence the active region, which consists of 5 pairs of AlGaInAs quaternary alloy quantum wells, is sandwiched between two diamond heat spreading layers. The structure of Si HCG deposited on a diamond provides broad wavelength range in which reflectivity is close to 100% for the emitted beam for perpendicular mode polarization with respect to the direction of the HCG trenches. The HCG assures less than 20% reflection and near zero absorption of pumping light, hence it allows for on-axis bottom pumping scheme and integration of the VECSEL with the pumping laser. According to the simulations 300 ?m thick top diamond heat spreader is enough to assure effective heat dissipation mechanism. Replacing the bottom DBR with the diamond heat spreader will provide additional 10% reduction of the thermal impedance. The minimum of thermal impedance is achieved for about 450 ?m thick bottom diamond heat spreader.

Walczak, Jaroslaw; Czyszanowski, Tomasz; Dems, Maciej; Sarzala, Robert P.; Sokol, Adam; Wasiak, Michal; Iakovlev, Vladimir

2012-05-01

262

Facts about Diamond Blackfan Anemia  

MedlinePLUS

... message, please visit this page: About CDC.gov . Diamond Blackfan Anemia (DBA) Facebook Recommend Twitter Tweet Share ... Favorites Delicious Digg Google Bookmarks Facts About DBA Diamond Blackfan anemia (DBA) is a rare blood disorder ...

263

Shock Diamonds and Mach Disks  

NSDL National Science Digital Library

The article presents and explains the diamond-shaped pattern that appears in the rocket engine and jet engine exhausts. Several photographs illustrate this phenomenon, and images show how crisscrossing shock waves produce the diamond shapes.

2010-06-03

264

Growth of single crystal diamond  

Microsoft Academic Search

The subject of the research presented in this dissertation is the growth of single crystal diamond by microwave plasma chemical vapor deposition (CVD). Both heteroepitaxial and homoepitaxial growth methods have been examined, with emphasis on producing large diamond crystals of high structural and chemical perfection. By heteroepitaxy, epitaxial growth on a foreign substrate, diamond was grown on (001) Ir thin-film

Murari Regmi

2007-01-01

265

Diamond Brazed to a Metal.  

National Technical Information Service (NTIS)

A unitary article that is solid at a temperature in excess of about 1100 deg C which includes a diamond, a metal, and a brazing material brazing the diamond and the metal. The brazing material includes a metal carbide adhering to the diamond and a platinu...

T. P. Thorpe L. A. Snail

1993-01-01

266

Diamond collecting in northern Colorado.  

USGS Publications Warehouse

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.

Collins, D. S.

1982-01-01

267

Experimental study of diamond resorption during mantle metasomatism  

NASA Astrophysics Data System (ADS)

Many of kimberlite-derived diamonds are partially dissolved to various degree but show similar resorption style. This resorption style has been observed in experiments with aqueous fluid at the conditions corresponding to kimberlite emplacement (1-2 GPa). At the same time, each diamond population has more than ten percent of diamond crystals with several drastically different resorption styles, which have not been observed in experiments, and may represent partial dissolution of diamonds during metasomatism in different mantle domains. Metasomatic processes modify the composition of subcratonic mantle, may trigger the formation of kimberlite magma, and result in the growth and partial dissolution of diamonds. Composition of metasomatic agents as constrained from studies of the reaction rims on mantle minerals (garnet, clinopyroxene) and experimental studies vary between carbonatitic melt, aqueous silicate melt, and CHO fluid. However, complex chemical pattern of mantle minerals and estimates of redox regime in subcratonic mantle allow different interpretations. Here we explore diamond dissolution morphology as an indicator of the composition of mantle metasomatic agents. Towards this end we examine diamond dissolution morphologies developed in experiments at the conditions of mantle metasomatism in different reacting media and compare them to the mantle-derived dissolution features of natural diamonds. The experiments were conducted in multi-anvil (Walker-Type) apparatus at 6 GPa and 1200-1500oC. Dissolution morphology of natural octahedral diamond crystals (0.5 mg) was examined in various compositions in synthetic system MgO-CaO- SiO2-CO2-H2O. The runs had the following phases present: solid crystals with fluid (various ratio of H2O-CO2-SiO2, and in the air), carbonate melt, carbonate-silicate melt, and carbonate melt with CHO fluid. Experiments produced three different styles of diamond resorption. In the presence of a fluid phase with variable proportions of H2O and CO2 diamond crystals develop ditrigonal outline of {111} faces, striation or hillocks along the edges, and shallow negatively oriented trigonal etch pits with flat or pointed bottom. Presence of SiO2 in the fluid resulted in multi-corner morphology, layering and / or more intensive etching of {111} faces. Dissolution in carbonate melt in the absence of water produced deep stepped-wall hexagonal and trigonal etch pits with negative orientation. The three resorption styles show strong resemblance to the secondary morphology of natural diamonds. This suggests that CHO fluid, aqueous silicate melt, and carbonatatitic melt are metasomatic agents reacting with natural diamonds in subcratonic mantle. The comparison of the experimentally-induced resorption styles to those on natural diamonds show that mantle metasomatism induced by CHO fluid develop morphologies similar to those developed in kimberlite magma. This indicates that significant proportion of kimberlite-hosted diamonds may show resorption features of mantle origin. Aqueous silicate melt induces step-faced multi-corner resorption morphology, similar to natural diamonds with nitrogen aggregation corresponding to eclogitic diamonds. Dissolution in carbonatitic melt results in complex morphologies with deep hexagonal pits similar to natural diamonds with nitrogen data corresponding to peridotitic diamonds.

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

2014-05-01

268

Diamond deposition on hardmetal substrates after pre-treatment with boron or sulfur compounds  

Microsoft Academic Search

Diamond coatings on WC-Co hardmetal tools are widely used for cutting non-ferrous materials. Until now adhesion problems of the diamond layers on the substrates are the limitation for heavy duty wear applications. The reduced adhesion is mainly caused by cobalt used as a binder phase in the hardmetal. Applying surface treatments the amount of metallic cobalt on the substrate surface

R. Haubner; A. Köpf; B. Lux

2002-01-01

269

Heteroepitaxial growth of diamond thin films on silicon: information transfer by epitaxial tilting  

Microsoft Academic Search

High resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) have been used to study diamond thin films on silicon. The diamond films were deposited by bias-enhanced microwave plasma assisted chemical vapour deposition. At the interface an amorphous layer of up to several nanometers in thickness was observed to be present over large areas of the interface. In other regions

J. Plitzko; M. Rösler; K. G. Nickel

1997-01-01

270

Process for making diamonds  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

271

Fluidized bed deposition of diamond  

DOEpatents

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.

Laia, Jr., Joseph R. (Los Alamos, NM); Carroll, David W. (Los Alamos, NM); Trkula, Mitchell (Los Alamos, NM); Anderson, Wallace E. (Los Alamos, NM); Valone, Steven M. (Santa Fe, NM)

1998-01-01

272

Diamond/AlN Thin Films for Optical Applications  

SciTech Connect

In this work we report on membranes made of nanocrystalline diamond (NCD) and AlN for the use in tunable micro-optics. For the growth of the AlN and NCD thin films, magnetron sputtering and chemical vapor deposition techniques have been used, respectively. A chemical-mechanical polishing process of NCD layers has been introduced, which is crucial for the growth of c-oriented, fiber textured AlN films. AlN layers deposited on as grown and polished nanocrystalline diamond along with free standing membranes have been compared by studying microstructure, surface morphology, piezoelectrical response as well as optical properties.

Knoebber, F.; Bludau, O.; Williams, O. A.; Sah, R. E.; Kirste, L.; Baeumler, M.; Nebel, C. E.; Ambacher, O.; Cimalla, V.; Lebedev, V. [Fraunhofer Institute for Applied Solid State Physics, Tullastr. 72, 79108 Freiburg (Germany); Leopold, S.; Paetz, D. [IMN MacroNano registered , Ilmenau University of Technology, PF 100565, 98684 Ilmenau (Germany)

2010-11-01

273

Nucleation and growth of chemical vapor deposited diamond films  

NASA Astrophysics Data System (ADS)

This research involves a study of the nucleation and growth processes during diamond chemical vapor deposition (CVD) via numerical modeling and simulations. Numerical models have been developed: (1) to examine the chemistry of the intermediate layer that forms at the interface between diamond and non-diamond substrate, (2) to understand the nucleation, size and structure of diamond phase carbon clusters on Si(111) substrates, (3) to study the morphological instabilities associated with diamond growth during chemical vapor deposition. The chemistry of the intermediate layer that develops at the interface between diamond and non-diamond substrate during chemical vapor deposition is analyzed using a thermodynamic quasiequilibrium model. Substrates of Si, Mo, W, Ti, Ta, Fe and Ni are examined, and operating parameters such as the substrate temperature, reactor pressure, and CHsb4:Hsb2 ratio in the gas phase required for the growth of the respective metal carbides/solid carbon are predicted. It is shown that the quasiequilibrium approach is advantageous in that it minimizes the use of kinetics to the degree that rate expressions are obtained without requiring the knowledge of the detailed kinetic models of the processes. A theoretical study of the nucleation, size, and structure of diamond-phase carbon clusters on Si(111) substrates is presented. Silicon is chosen as the non-diamond substrate in this work as it is a common substrate material for diamond deposition. Molecular mechanics analysis has been utilized to predict energetically and entropically feasible pathways for nucleation of carbon clusters. Several mechanistic pathways for nucleation of carbon clusters are examined with Csb2Hsb2 and/or CHsb3 as the nucleation precursors. A possible model for the nucleation mechanism of diamond-phase carbon clusters on beta-SiC(111) surface, which forms epitaxially on Si(111) substrates, is presented. The critical size of the carbon clusters is calculated based on the atomistic theory of nucleation and the proposed nucleation mechanisms. The diamond CVD process has been examined theoretically and the morphological instabilities associated with the growth of diamond films have been investigated with a model based on the continuum species conservation equations coupled to surface reaction kinetics. An analytical model is developed to study the morphological instabilities of the diamond-gas interface during the diamond CVD process based on the linear and nonlinear perturbation theories. Linear stability analysis cannot be used to analyze the evolution of the unstable planar interface to a nonplanar cellular interface. Nonlinear analysis is carried out to study the growth behavior of an interface more accurately over a longer period of time. A two-dimensional numerical model describes the evolution of the gas-solid interface. The numerical and analytical models determine the critical parameters affecting the diamond deposition layer morphology. A dispersive relation is derived which relates the effects of species diffusive transport towards the growing interface, surface diffusion, surface tension, and geometrical factors with the stability of perturbations on the interface. (Abstract shortened by UMI.)

Mahalingam, Pushpa

274

Loss of electrical conductivity in boron-doped diamond due to ion-induced damage  

SciTech Connect

The response of B-ion-implanted type-IIa diamond to light ion (H, He) irradiation is investigated by monitoring the sample resistance as a function of dose. It is found that the resistivity of the layer increases rapidly with increasing dose, and reaches the resistivity of the undoped diamond for irradiation doses much less than those required for the onset of damage related electrical conductivity in pristine diamond. It is shown that defects created by the nuclear stopping process act as compensating centers for the B acceptors. The present findings are of importance for the design of radiation hard diamond based electronic devices and suggests a method for the isolation of B-doped devices on a diamond chip. The results of the present work also explain why the collection distance in intrinsic nondoped diamond radiation detectors actually increases with increasing ion dose. {copyright} {ital 1997 American Institute of Physics.}

Kalish, R.; Uzan-Saguy, C.; Philosoph, B.; Richter, V. [Solid State Institute and Physics Department, Technion-Israel Institute of Technology, Haifa 32000 (Israel)] [Solid State Institute and Physics Department, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Prawer, S. [School of Physics, University of Melbourne, Parkville, Victoria 3052 (Australia)] [School of Physics, University of Melbourne, Parkville, Victoria 3052 (Australia)

1997-02-01

275

Optical properties of laser-modified diamond surface  

NASA Astrophysics Data System (ADS)

The results of laser polishing of 350 micrometers thick free- standing diamond films are reported. The polishing was performed with a grazing beam of a copper vapor laser. It is shown that the laser polishing conditions and the resulting surface roughness are controlled by varying an angle of incidence of a scanning laser beam during polishing. The surface roughness of the as-grown films was reduced by an order of magnitude and a minimum roughness of Ra equals 0.38 micrometers was achieved as a result of the two-step polishing. Optical transmission in the UV-visible spectral range of the diamond films polished under the optimized conditions was found to be close to the optical transmission of the mechanically polished diamond film. Properties of the laser-graphitized layer at the diamond surface were studied with optical spectroscopy techniques in the process of oxidative removal of the layer with increasing temperature of the oxidation in ambient air. The optical properties and oxidation stability of the laser-modified surface layer were found to change throughout its thickness from the surface to the diamond interface, depending on the laser polishing regime.

Khomich, A. V.; Kononenko, V. V.; Pimenov, Sergej M.; Konov, Vitaly I.; Gloor, S.; Luethy, Willy A.; Weber, Heinz P.

1998-10-01

276

Lower pressure synthesis of diamond material  

DOEpatents

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.

Lueking, Angela (State College, PA); Gutierrez, Humberto (State College, PA); Narayanan, Deepa (Redmond, WA); Burgess Clifford, Caroline E. (State College, PA); Jain, Puja (King Of Prussia, PA)

2010-07-13

277

DIAMOND AMPLIFIED PHOTOCATHODES.  

SciTech Connect

High-average-current linear electron accelerators require photoinjectors capable of delivering tens to hundreds of mA average current, with peak currents of hundreds of amps. Standard photocathodes face significant challenges in meeting these requirements, and often have short operational lifetimes in an accelerator environment. We report on recent progress toward development of secondary emission amplifiers for photocathodes, which are intended to increase the achievable average current while protecting the cathode from the accelerator. The amplifier is a thin diamond wafer which converts energetic (few keV) primary electrons into hundreds of electron-hole pairs via secondary electron emission. The electrons drift through the diamond under an external bias and are emitted into vacuum via a hydrogen-terminated surface with negative electron affinity (NEA). Secondary emission gain of over 200 has been achieved. Two methods of patterning diamond, laser ablation and reactive-ion etching (RIE), are being developed to produce the required geometry. A variety of diagnostic techniques, including FTIR, SEM and AFM, have been used to characterize the diamonds.

SMEDLEY,J.; BEN-ZVI, I.; BOHON, J.; CHANG, X.; GROVER, R.; ISAKOVIC, A.; RAO, T.; WU, Q.

2007-11-26

278

Diamond Telephone Corporation  

Microsoft Academic Search

Management is examining the performance of a maquiladora operation being used to outsource manufacture of subassemblies for an aging product line. The maquiladora's performance is far below projections; no cost savings are being enjoyed. Diamond is considering four options: move subassembly production back to their main plant, outsource some subassemblies to an Asian electronics firm, revitalize the existing Sheletermex facility,

Edward Davis; Michael Melloy

279

Rockford Diamond Technology.  

National Technical Information Service (NTIS)

Diamond growth in our microwave lamp has been successfully demonstrated. The samples grown for six hours show the crystalline structure with the grain sizes of 1 to approx. 3 micrometers by an optical microscope. X-ray diffraction (XRD) also indicated the...

L. Ballinger

1995-01-01

280

Thermoluminescence of Semiconducting Diamonds.  

National Technical Information Service (NTIS)

The thermoluminescence (TL) of semiconducting diamonds was found to be composed of blue-emitting (at 150 and 260K) and red-emitting peaks (at 175 and 285K). The red peaks could be excited by light of wavelengths up to about650 millimicrons (1.8 ev), the b...

A. Halperin R. Chen

1966-01-01

281

Fracture of synthetic diamond  

SciTech Connect

The fracture behavior of synthetic diamond has been investigated using indentation methods and by the tensile testing of pre-notched fracture-mechanics type samples. Specifically, the fracture toughness of free-standing diamond plates, grown by chemically-vapor deposited (CVD) methods, was measured using Vickers indentations and by the use of disk-shaped compact-tension specimens; the latter method provides an evaluation of the through-thickness fracture properties, whereas the indentation method was performed on the nucleation surface of the sample. Measured fracture toughness ({ital K}{sub c}) values were found to be approximately 5--6 MPa{radical}m by both methods, indicating that the fracture resistance of CVD diamond does not vary appreciably with grain size (within the certainty of the testing procedures). Complications, however, arose with the fracture-mechanics testing regarding crack initiation from a relatively blunt notch; further work is needed to develop pre-cracking methods to permit more reliable fracture toughness testing of diamond. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Drory, M.D. [Crystallume, 3506 Bassett Street, Santa Clara, California 95054 (United States)] [Crystallume, 3506 Bassett Street, Santa Clara, California 95054 (United States); Dauskardt, R.H.; Kant, A.; Ritchie, R.O. [Center for Advanced Materials, Materials Sciences Division, Lawrence Berkeley Laboratory and Department of Materials Science and Mineral Engineering, University of California, Berkeley, California 94720 (United States)] [Center for Advanced Materials, Materials Sciences Division, Lawrence Berkeley Laboratory and Department of Materials Science and Mineral Engineering, University of California, Berkeley, California 94720 (United States)

1995-09-01

282

Multiplying Electrons With Diamond  

NASA Technical Reports Server (NTRS)

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.

2003-01-01

283

Development of Designer Diamond Anvils for High Pressure-High-Temperature Experiments in Support of the Stockpile Stewardship Program  

SciTech Connect

The focus of this program at the University of Alabama at Birmingham (UAB) is to develop the next generation of designer diamond anvils that can perform simultaneous joule heating and temperature profile measurements in a diamond anvil cell. A series of tungsten-rhenium thermocouples will be fabricated onto to the anvil and encapsulated by a chemical vapor deposited diamond layer to allow for a complete temperature profile measurement across the anvil. The tip of the diamond anvil will be engineered to reduce the thermal conductivity so that the tungsten-heating coils can be deposited on top of this layer. Several different approaches will be investigated to engineer the tip of the diamond anvil for reduction in thermal conductivity (a) isotopic mixture of 12C and 13C in the diamond layer, (b) doping of diamond with impurities (nitrogen and/or boron), and (c) growing diamond in a higher concentration of methane in hydrogen plasma. Under this academic alliance with Lawrence Livermore National Laboratory (LLNL), PI and his graduate students will use the lithographic and diamond polishing facility at LLNL. This proposed next generation of designer diamond anvils will allow multi-tasking capability with the ability to measure electrical, magnetic, structural and thermal data on actinide materials with unparallel sensitivity in support of the stockpile stewardship program.

Yogesh K. Vohra

2005-05-12

284

Magnetic Inclusions in Diamonds  

NASA Astrophysics Data System (ADS)

Iron sulfide inclusions in diamonds may provide a new source of paleointensity data from key geological intervals. Pyrrhotite and monosulfide solid solutions (Mss between FeS and NiS, and with minor Cu) are the primary mineral inclusions in diamonds [Deines and Harris, 1995]. Through the courtesy of DeBeers we have obtained eleven diamonds from the Orapa kimberlite pipe (intruded at 92 Ma) in Botswana. The diamonds are all octahedra with slightly rounded or rounded edges and have diameters ranging between 2 and 4 mm. Average mass is 0.03734 grams. The diamonds have abundant internal metallic black disc or rosette fracture systems in the centers of which lie the opaque sulfide inclusions which are 20-50 microns in size. The inclusions are strongly magnetic. The magnetic moments range from 0.8 to 13 x 10-5Am2. This corresponds to minimum estimates of the remanent magnetization of the inclusions of 1 to 8 x10-2Am2/kg (based on estimated masses of the inclusions). The stability of the inclusions' magnetizations is remarkable given the large size of the inclusions (larger than the single-domain grain size of pyrrhotite). Progressive alternating field demagnetization of the natural remanent magnetization yields well-defined magnetization components that demagnetize with peak field values of 90 mT or higher. Isothermal remanent magnetizations saturate in fields of 0.2 to 0.8 Tesla. The strong remanent magnetizations and low coercivities are consistent with a sulfide remanence carrier. Ongoing experiments using thermal demagnetization of orthogonal isothermal remanent magnetizations, hysteresis loop measurements and low temperature measurements, will further constrain the role of iron sulfides as the carrier of these magnetizations. These results will determine if sulfide inclusions in diamonds may provide much needed paleointensity data from the Cretaceous and late Proterozoic. Deines, P. and Harris, J. W. (1995). Sulfide inclusion chemistry and carbon isotopes of African diamonds: Geochimica et Cosmochimica Acta, v. 59, p. 3173-3188.

Clement, B. M.; Haggerty, S. E.; Harris, J. W.

2005-12-01

285

TEM study of superconducting polycrystalline diamond  

NASA Astrophysics Data System (ADS)

Heavily Boron-doped MPCVD-grown (Microwave Plasma Chemical Vapour Deposition) polycrystalline diamond layers were observed to have a superconducting character depending exclusively on the growth time, i.e. grown under identical experimental conditions. To elucidate such behavior, morphology aspects are investigated using Transmission Electron Microscopy (TEM). Diffraction contrasts and High Angle Annular Dark Field (HAADF) observations show that grains are thicker and boron enrichment occur at grain boundary in the superconducting samples. Interfacial effects are the main difference between the two samples, in the non-superconducting ones descohesion effect is observed. In both samples boron concentration is nearly constant except in isolated grains and twins, where their crystal orientation probably influences boron incorporation during growth. In summary, as grain configuration changes along the growth, a threshold thickness should be over passed to allow an optimum transport between the diamond grains.

Alegre, M. P.; Villar, M. P.; Araújo, D.; Bustarret, E.; Capron, T.; Williams, O. A.

2010-11-01

286

Diamond growth by chemical vapour deposition  

Microsoft Academic Search

This paper reviews the growth of diamond by chemical vapour deposition (CVD). It includes the following seven parts: (1) Properties of diamond: this part briefly introduces the unique properties of diamond and their origin and lists some of the most common diamond applications. (2) Growth of diamond by CVD: this part reviews the history and the methods of growing CVD

J. J. Gracio; Q. H. Fan; J. C. Madaleno

2010-01-01

287

Surface Design and Engineering Toward Wear-Resistant, Self-Lubricant Diamond Films and Coatings. Chapter 10  

NASA Technical Reports Server (NTRS)

This chapter describes three studies on the surface design, surface engineering, and tribology of chemical-vapor-deposited (CVD) diamond films and coatings toward wear-resistant, self-lubricating diamond films and coatings. Friction mechanisms and solid lubrication mechanisms of CVD diamond are stated. Effects of an amorphous hydrogenated carbon on CVD diamond, an amorphous, nondiamond carbon surface layer formed on CVD diamond by carbon and nitrogen ion implantation, and a materials combination of cubic boron nitride and CVD diamond on the adhesion, friction, and wear behaviors of CVD diamond in ultrahigh vacuum are described. How surface modification and the selected materials couple improved the tribological functionality of coatings, giving low coefficient of friction and good wear resistance, is explained.

Miyoshi, Kazuhisa

1999-01-01

288

Diamond film growth on the Mo-Re alloy foil  

NASA Astrophysics Data System (ADS)

Nanocrystalline diamond film was deposited on the substrate of Mo-Re alloy foil by using a hot filament chemical vapor deposition (HFCVD) method. The morphology, band structures and crystalline structure of the film were analysed by scanning electron microscopy (SEM), Raman spectroscopy and X-ray diffractometer (XRD), respectively. The results show that the thickness of the diamond film is about 300 nm after 1 h deposition. There is a 2H-Mo 2C layer between the diamond film and the Mo-Re substrate. The values of a and the ratio c/ a of Mo 2C are 3.003 and 1.579 Å, respectively. This Mo 2C layer might be formed due to carbon atoms in the gas phase diffusing into the Mo-Re alloy.

Wu, Xiaobin; Yu, Zhiming; Gong, Yilun; Wang, Jian; Tian, Mengkun

2011-01-01

289

Thermal diffusivity of diamond films using a laser pulse technique  

NASA Technical Reports Server (NTRS)

Polycrystalline diamond films were deposited using a microwave plasma-enhanced chemical vapor deposition process. A laser pulse technique was developed to measure the thermal diffusivity of diamond films deposited on a silicon substrate. The effective thermal diffusivity of a diamond film on silicon was measured by observing the phase and amplitude of the cyclic thermal waves generated by laser pulses. An analytical model is presented to calculate the effective in-plane (face-parallel) diffusivity of a two-layer system. The model is used to reduce the effective thermal diffusivity of the diamonds/silicon sample to a value for the thermal diffusivity and conductivity of the diamond film. The average effective diffusivity values are 1.47 + or - 0.03 and 1.83 + or - 0.10 yielding thermal diffusivity values of 7.46 + or - 0.90 and 7.33 + or - 0.70 sq cm/s respectively, for the two samples; the calculated thermal con ductivity values are 13.50 and 13.28 W/cmK, which are better than that of type 1a natural diamond. The phase and amplitude measurements give similar results.

Albin, Sacharia; Winfree, William P.; Crews, B. Scott

1990-01-01

290

Thermal diffusivity of diamond films using a laser pulse technique  

NASA Astrophysics Data System (ADS)

Polycrystalline diamond films were deposited using a microwave plasma-enhanced chemical vapor deposition process. A laser pulse technique was developed to measure the thermal diffusivity of diamond films deposited on a silicon substrate. The effective thermal diffusivity of a diamond film on silicon was measured by observing the phase and amplitude of the cyclic thermal waves generated by laser pulses. An analytical model is presented to calculate the effective in-plane (face-parallel) diffusivity of a two-layer system. The model is used to reduce the effective thermal diffusivity of the diamonds/silicon sample to a value for the thermal diffusivity and conductivity of the diamond film. The average effective diffusivity values are 1.47 + or - 0.03 and 1.83 + or - 0.10 yielding thermal diffusivity values of 7.46 + or - 0.90 and 7.33 + or - 0.70 sq cm/s respectively, for the two samples; the calculated thermal con ductivity values are 13.50 and 13.28 W/cmK, which are better than that of type 1a natural diamond. The phase and amplitude measurements give similar results.

Albin, Sacharia; Winfree, William P.; Crews, B. Scott

1990-06-01

291

Progress on Diamond-Based Cylindrical Dielectric Accelerating Structures  

NASA Astrophysics Data System (ADS)

The development of a high gradient diamond-based cylindrical dielectric loaded accelerator (DLA) is presented. A diamond-loaded DLA can potentially sustain accelerating gradients far in excess of the limits experimentally observed for conventional metallic accelerating structures. The electrical and mechanical properties of diamond make it an ideal candidate material for use in dielectric accelerators: high rf breakdown level, extremely low dielectric losses and the highest available thermoconductive coefficient. We used the hot-filament Chemical Vapor Deposition (CVD) process to produce high quality 5-10 cm long cylindrical diamond layers. Our collaboration has also been developing a new method of CVD diamond surface preparation that reduces the secondary electron emission coefficient below unity. Special attention was paid to the numerical optimization of the waveguide to structure rf coupling section, where the surface magnetic and electric fields were minimized relative to the accelerating gradient and within known metal surface breakdown limits. We conclude with a brief overview of the use of diamond microstructures for use in compact rf sources.

Kanareykin, A.; Schoessow, P.; Conde, M.; Gai, W.

2006-11-01

292

South Africa, Namibia Diamond Deposits  

NASA Technical Reports Server (NTRS)

This radar image covers a portion of the Richtersveld National Park and Orange River (top of image) in the Northern Cape Province of the Republic of South Africa. The Orange River marks the boundary between South Africa to the south and Namibia to the north. This is an area of active mining for diamonds, which were washed downstream from the famous Kimberley Diamond Area, millions of years ago when the river was much larger. The mining is focused on ancient drainages of the Orange River which are currently buried by think layers of sand and gravel. Scientists are investigating whether these ancient drainages can be seen with the radar's ability to penetrate sand cover in extremely dry regions. A mine, shown in yellow, is on the southern bank of the river in an abandoned bend which is known as an 'oxbow.' The small bright circular areas (left edge of image) west of the mine circles are fields of a large ostrich farm that are being watered with pivot irrigation. The large dark area in the center of the image is the Kubus Pluton, a body of granite rock that broke through the surrounding rocks about 550 million years ago. North is toward the upper right. The area shown is about 55 by 60 kilometers (34 by 37 miles) centered at 28.4 degrees south latitude, 16.8 degrees east longitude. Colors are assigned to different radar frequencies and polarizations as follows: red is L-band horizontally transmitted and horizontally received; green is L-band horizontally transmitted and vertically received; blue is C-band horizontally transmitted and vertically received. The image was acquired on April 18, 1994 by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture (SIR-C/X-SAR) imaging radar when it flew aboard the space shuttle Endeavour. SIR-C/X-SAR is a joint mission of the U.S./German and Italian space agencies.

1998-01-01

293

Porous Silicon Coated With Ultrathin Diamond-Like Carbon Film Cathodes.  

National Technical Information Service (NTIS)

The main requirements to electron field emission cathodes are their efficiency, stability and uniformity. In this work we combined the properties of porous silicon layers and diamond-like carbon (DLC) film to obtain emission cathodes with improved paramet...

A. A. Evtukh V. G. Litovchenko Y. M. Litvin D. V. Fedin Y. V. Rassamakin

2001-01-01

294

Metastable carbon allotropes in picosecond-laser-modified diamond  

NASA Astrophysics Data System (ADS)

In this paper, we report on the bulk modifications of type IIa single-crystal diamond with visible 10-ps pulses (at ? = 532 nm) and microstructural changes characterized by the appearance of several `unidentifiable' vibrational modes in the frequency range of 1000-1400 cm-1 in the Raman spectra of laser-modified diamond. It is found that the new Raman modes are strongly pronounced in the spectra of high-stress regions in immediate proximity to the bulk microstructures in the absence of the G mode at ~1580 cm-1 characteristic of the sp2 phase. The high internal stresses are determined from the splitting of the triply degenerate diamond Raman line. The revealed structure transformation is localized within a narrow bulk layer near the bulk microstructures formed, and the stress relaxation is found to result in disappearance of the detected vibrational modes in the spectra. It is suggested that the formation of bulk regions with a sp3 carbon structure consisting of Z-carbon and hexagonal diamond is responsible for the appearance of new Raman modes in the spectra of laser-modified diamond. These findings evidence that the stress-assisted formation of novel metastable carbon phases or defect structures occur in the course of bulk modification of diamond with ps-laser pulses. In addition, we report the results of simulations of internal stresses in the system `graphitized cylinder-in-diamond' to show (1) the effect of the mechanical properties of laser-modified diamond on the resulting stresses and (2) formation of bulk microscopic regions with high stresses of >10 GPa, i.e., the conditions at which various sp3 carbon allotropes and defect structures become more stable than graphite.

Pimenov, Sergei M.; Khomich, Andrey A.; Vlasov, Igor I.; Zavedeev, Evgeny V.; Khomich, Alexander V.; Neuenschwander, Beat; Jäggi, Beat; Romano, Valerio

2014-06-01

295

Iron oxide modified diamond blends containing ultradispersed diamond.  

PubMed

Iron oxide modified diamond blends containing different amounts of ultradispersed diamond were prepared and characterized by nitrogen physisorption, X-ray diffraction, temperature programmed reduction, Mössbauer and IR spectroscopy. The catalytic behavior of these composite materials in methanol decomposition to hydrogen, carbon monoxide, and methane has been also studied. The initial state and phase transformations of the supported highly dispersed iron oxide particles in various pretreatment media, as well as their reductive and catalytic properties, strongly depend on the ultradispersed diamond content in the diamond blends. PMID:16616929

Tsoncheva, Tanya; Dimitrov, Momtchil; Ivanova, Ljubomira; Paneva, Daniela; Mitev, Dimitar; Tsintsarski, Boiko; Mitov, Ivan; Stavrev, Stavri; Minchev, Christo

2006-08-01

296

Forty Years of Development in Diamond Tools.  

National Technical Information Service (NTIS)

The growth of the diamond industry in Western Countries since the First World War is surveyed. The articles described deal specifically with the development of the industrial diamond and diamond tool sector in different countries. All data point to contin...

1983-01-01

297

Low Temperature Growth of Nanostructured Diamond Films on Metals  

NASA Technical Reports Server (NTRS)

The field of nanocrystalline diamond and tetrahedral amorphous carbon films has been the focus of intense experimental activity in the last few years for applications in field emission display devices, optical windows, and tribological coatings, The choice of substrate used in most studies has typically been silicon. For metals, however, the thermal expansion mismatch between the diamond film and substrate gives rise to thermal stress that often results in delamination of the film. To avoid this problem in conventional CVD deposition low substrate temperatures (less than 700 C) have been used, often with the incorporation of oxygen or carbon monoxide to the feedgas mixture. Conventionally grown CVD diamond films are also rough and would require post-deposition polishing for most applications. Therefore, there is an obvious need to develop techniques for deposition of well-adhered, smooth nano-structured diamond films on metals for various tribological applications. In our work, nanostructured diamond films are grown on a titanium alloy substrate using a two-step deposition process. The first step is performed at elevated temperature (820 C) for 30 minutes using a H2/CH4/N2 gas mixture in order to grow a thin (approx. 600 nm) nanostructured diamond layer and improve film adhesion. The remainder of the deposition involves growth at low temperature (less than 600 C) in a H2/CH4/O2 gas mixture. Laser reflectance Interferometry (LRI) pattern during growth of a nanostructured diamond film on Ti-6Al-4V alloy. The first 30 minutes are at a high temperature of 820 C and the rest of the film is grown at a low temperature of 580 T. The fringe pattern is observed till the very end due to extremely low surface roughness of 40 nm. The continuation of the smooth nanostructured diamond film growth during low temperature deposition is confirmed by in-situ laser reflectance interferometry and by post-deposition micro-Raman spectroscopy and surface profilometry. Similar experiments performed without the starting nanostructured diamond layer resulted in poorly adhered films with a more crystalline appearance and a higher surface roughness. This low temperature deposition of nanostructured diamond films on metals offers advantages in cases where high residual thermal stress leads to delamination at high temperatures.

Baker, Paul A.; Catledge, Shane A.; Vohra, Yogesh K.

2001-01-01

298

Surface damage on diamond membranes fabricated by ion implantation and lift-off  

SciTech Connect

Thin membranes with excellent optical properties are essential elements in diamond based photonic systems. Due to the chemical inertness of diamond, ion beam processing must be employed to carve photonic structures. One method to realize such membranes is ion-implantation graphitization followed by chemical removal of the sacrificial graphite. The interface revealed when the sacrificial layer is removed has interesting properties. To investigate this interface, we employed the surface sensitive technique of grazing angle channeled Rutherford backscattering spectroscopy. Even after high temperature annealing and chemical etching a thin layer of damaged diamond remains, however, it is removed by hydrogen plasma exposure.

Drumm, V. S.; Alves, A. D. C.; Fairchild, B. A.; Ganesan, K.; McCallum, J. C.; Jamieson, D. N.; Prawer, S. [School of Physics, University of Melbourne, 3010 Victoria (Australia); Rubanov, S. [Electron Microscopy Unit, Bio21 Institute, University of Melbourne, 3010 Victoria (Australia); Kalish, R. [Department of Physics, Solid State Institute, Technion, 32000 Haifa (Israel); Feldman, L. C. [Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Tennessee 37240 (United States); Institute of Advanced Materials, Devices and Nanotechnology, Rutgers University, New Jersey 08854-8065 (United States)

2011-06-06

299

Diamond films for laser hardening  

NASA Technical Reports Server (NTRS)

Laser-damage experiments were performed on free-standing polycrystalline diamond films prepared by plasma-enhanced CVD. The high laser-induced stress resistance found for this material makes it useful for thin-film coatings for laser optics. Results for diamond-coated silicon substrates demonstrate the enhanced damage threshold imparted by diamond thin-film coatings to materials susceptible to laser damage.

Albin, S.; Watkins, L.; Ravi, K.; Yokota, S.

1989-01-01

300

Conversion of fullerenes to diamond  

DOEpatents

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.

Gruen, Dieter M. (1324 59th St., Downers Grove, IL 60515)

1993-01-01

301

Conversion of fullerenes to diamond  

DOEpatents

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.

Gruen, Dieter M. (1324 59th St., Downers Grove, IL 60515)

1994-01-01

302

Ultrafast laser processing of diamond  

NASA Astrophysics Data System (ADS)

Ultrashort pulsed lasers are used to fabricate 3D structures in single crystal CVD diamond. The interaction of the laser with diamond lattice leads to a permanent structural modification, which is highly localized at the focus. Severe spherical aberrations compromise fabrication precision below the diamond surface. We implement adaptive aberration compensation to ensure optimum fabrication performance. The nature of the structural modification is analysed for both surface and subsurface laser fabrications.

Salter, P. S.; Booth, M. J.

2014-03-01

303

The structure of diamond nanoclusters  

Microsoft Academic Search

A model describing the structure of diamond nanoclusters produced by explosive shocks is proposed. The model is based on experimental\\u000a data obtained from x-ray diffraction and small-angle x-ray scattering. This model considers the diamond nanocluster as a crystalline\\u000a diamond core coated by a carbon shell having a fractal structure. The shell structure depends both on the cooling kinetics\\u000a of the

A. E. Aleksenskii; M. V. Baidakova; A. Ya. Vul’; V. I. Siklitskii

1999-01-01

304

Diamond Ages and Lithosphere Evolution - Applications to Diamond Exploration  

NASA Astrophysics Data System (ADS)

Combinations of studies on diamonds, diamond inclusions, diamond bearing mantle and ultra-high pressure (UHP) metamorphic crustal rocks, kimberlites and lamproites have been successful in delivering insights into major processes such as plate tectonics, craton accretion, the effects of large magmatic events as well as contributing to a better understanding of diamond formation and preservation over an extended period of earth history. The crystal structure of diamond ensures that mineral inclusions in natural diamonds, whether fluid or solid, may be maintained as closed systems over extended periods of geological time and provide useful information about key processes in the mantle, as far back as 3.5 Ga and possibly further. Available diamond ages suggest that all macrodiamonds in economically significant kimberlites and lamproites are xenocrystic and have formed in pre-existing upper mantle assemblages, predominantly peridotite, eclogite and websterite in the sub-continental lithospheric mantle (SCLM) and occasionally in higher-pressure equivalents of such rocks, for example majorite. Diamond ages also suggest that conditions favorable for diamond formation in the SCLM have been episodic, can be repeated in the same pre-existing host rocks at significantly different times and that all investigated ore bodies have more than one population of xenocrystic diamonds contributing to run-of-mine production. Evidence is accumulating as well that diamond forming processes are metasomatic, though this is more conclusively demonstrated for young rather than old diamonds. Given that both diamond formation events and transportation into the crust are episodic and span from the Paleoarchean to the Cenozoic, diamond geology, mineralogy, and chemistry provide a unique opportunity to contribute to knowledge about the evolution of the earth's continental lithosphere through a major part of earth history. While the processes of formation and preservation of diamonds in the cratonic roots are a function of Archean and post-Archean craton evolution and have operated worldwide, the timing of individual diamond-forming events and of their transport to the surface are craton specific. The formation of diamondiferous carbonated, G- 10 garnet-bearing harzburgitic domains in Mesoarchean mantle roots represents the earliest lithospheric- diamond-forming event so far discovered in the Kaapvaal, Zimbabwe, Slave, and Siberian diamond fields. Not only is it the earliest, it remains of primary importance as a contributor to the diamond budget in many of the on-craton deposits. Ideally, exploration for kimberlites containing the G-10 bearing harzburgitic diamond component should concentrate on the Mesoarchean nuclei of Archean cratons or tectonically buried parts thereof. The ancient harzburgitic component makes a lesser or no contribution to the diamond budget of craton-margin and off-craton primary deposits (e.g., the Argyle and Ellendale lamproites, the Colorado/Wyoming State Line kimberlites, the Carolina kimberlite in northwestern Brazil, the kimberlites of the North Lesotho area, and Jagersfontein. This is in accord with the low grade of all these deposits, except Argyle. The presentation will stress that modern exploration should make use of the increasing evidence that diamond formation ages can be correlated with Archean and Proterozoic craton evolution events.

Helmstaedt, H. H.; Gurney, J. J.; Richardson, S. H.

2009-05-01

305

Oxidation behavior of diamond-like carbon films  

Microsoft Academic Search

Diamond-like carbon (DLC) films were synthesized by a combined PVD and PECVD process to produce a multilayered structure consisting of a Ti interlayer, a graded transition layer, and the carbon film. The oxidation behavior of DLC films was investigated using thermogravimetric (TGA) and differential thermal analyses (DTA). The phase identification and microstructural examinations were conducted by XRD, Raman, and SEM\\/EDS.

Da-Yung Wang; Chi-Lung Chang; Wei-Yu Ho

1999-01-01

306

DIAMOND SECONDARY EMITTER  

SciTech Connect

We present the design and experimental progress on the diamond secondary emitter as an electron source for high average power injectors. The design criteria for average currents up to 1 A and charge up to 20 nC are established. Secondary Electron Yield (SEY) exceeding 200 in transmission mode and 50 in emission mode have been measured. Preliminary results on the design and fabrication of the self contained capsule with primary electron source and secondary electron emitter will also be presented.

BEN-ZVI, I.; RAO, T.; BURRILL, A.; CHANG, X.; GRIMES, J.; RANK, J.; SEGALOV, Z.; SMEDLEY, J.

2005-10-09

307

DIAMOND PEAK WILDERNESS, OREGON.  

USGS Publications Warehouse

No metallic mineral resources were identified during a mineral survey of the Diamond Peak Wilderness in Oregon. Cinder cones within the wilderness contain substantial cinder resources, but similar deposits that are more accessible occur outside the wilderness. The area could have geothermal resources, but available data are insufficient to evaluate their potential. Several deep holes could be drilled in areas of the High Cascades outside the wilderness, from which extrapolations of the geothermal potential of the several Cascade wilderness could be made.

Sherrod, David, R.; Moyle, Phillip, R.

1984-01-01

308

Black and White Diamonds  

Microsoft Academic Search

This study of the semantics of UML’s shared aggregation and composition (black and white diamonds) is based on previous detailed\\u000a analyses of the semantics of aggregation in object modelling in which primary axioms were identified. All forms of aggregation\\u000a must comply with these primary axioms. We conclude that both kinds of UML Aggregation do not possess the full complement of

Brian Henderson-sellers; Franck Barbier

1999-01-01

309

Microwave plasma enhanced chemical vapor deposition of nanocrystalline diamond films by bias-enhanced nucleation and bias-enhanced growth  

NASA Astrophysics Data System (ADS)

Effects of biasing voltage-current relationship on microwave plasma enhanced chemical vapor deposition of ultrananocrystalline diamond (UNCD) films on (100) silicon in hydrogen diluted methane by bias-enhanced nucleation and bias-enhanced growth processes are reported. Three biasing methods are applied to study their effects on nucleation, growth, and microstructures of deposited UNCD films. Method A employs 320 mA constant biasing current and a negative biasing voltage decreasing from -490 V to -375 V for silicon substrates pre-heated to 800 °C. Method B employs 400 mA constant biasing current and a decreasing negative biasing voltage from -375 V to -390 V for silicon pre-heated to 900 °C. Method C employs -350 V constant biasing voltage and an increasing biasing current up to 400 mA for silicon pre-heated to 800 °C. UNCD nanopillars, merged clusters, and dense films with smooth surface morphology are deposited by the biasing methods A, B, and C, respectively. Effects of ion energy and flux controlled by the biasing voltage and current, respectively, on nucleation, growth, microstructures, surface morphologies, and UNCD contents are confirmed by scanning electron microscopy, high-resolution transmission-electron-microscopy, and UV Raman scattering.

Chu, Yueh-Chieh; Tzeng, Yonhua; Auciello, Orlando

2014-01-01

310

Diamond tool machining of materials which react with diamond.  

National Technical Information Service (NTIS)

This invention is comprised of an 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 ch...

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

1991-01-01

311

Stable metallization for diamond and other materials  

NASA Technical Reports Server (NTRS)

An adherent and metallurgically stable metallization system for diamond is presented. The big improvement in metallurgical stability is attributed to the use of a ternary, amorphous Ti--Si--N diffusion barrier. No diffusion between the layers and no delamination of the metallization was observed after annealing the schemes at 400.degree. C. for 100 hours and at 900.degree. C. for 30 minutes. Thermal cycling experiments in air from -65 to 155.degree. C. and adhesion tests were performed. Various embodiments are disclosed.

Bachli, Andreas (Inventor); Kolawa, Elzbieta (Inventor); Nicolet, Marc-Aurele (Inventor); Vandersande, Jan W. (Inventor)

2000-01-01

312

Extended defects in diamond: The interstitial platelet  

NASA Astrophysics Data System (ADS)

The structure and properties of the {001} planar platelet in diamond are investigated using ab initio theory. We find that a carbonaceous model, based on a layer of self-interstitials, satisfies the requirements of transmission electron microscopy, infrared absorption data, and energetic considerations. The energetics of self-interstitial production during nitrogen aggregation are considered. It is found that the growth mechanism of the platelet involves a thermally activated release of vacancies from platelets. The role of vacant sites and platelet nitrogen are also investigated and it is shown that these defects embedded within the platelet could account for the observed optical activity.

Goss, J. P.; Coomer, B. J.; Jones, R.; Fall, C. J.; Briddon, P. R.; Öberg, S.

2003-04-01

313

Stacking-Fault Based Microscopic Model for Platelets in Diamond  

NASA Astrophysics Data System (ADS)

We propose a new model for {001} platelets in diamond based on the formation of a metastable stacking-fault. The core of the defect is a double layer of threefold coordinated sp2 carbon atoms embedded in the sp3 diamond matrix. The properties of the model were determined using ab initio calculations. All significant experimental signatures attributed to the platelets are fully accounted for. The model is also very appealing from the point of view of kinetics, since naturally occurring shearing processes will lead to the formation of the metastable fault.

Miranda, C. R.; Antonelli, A.; Nunes, R. W.

2004-12-01

314

Friction and Wear Properties of As-Deposited and Carbon Ion-Implanted Diamond Films  

NASA Technical Reports Server (NTRS)

Recent work on the friction and wear properties of as-deposited and carbon ion-implanted diamond films was reviewed. Diamond films were produced by the microwave plasma chemical vapor deposition (CVD) technique. Diamond films with various grain sizes and surface roughnesses were implanted with carbon ions at 60 keV ion energy, resulting in a dose of 1.2 x 10(exp 17) carbon ions per cm(exp 2). Various analytical techniques, including Raman spectroscopy, proton recoil analysis, Rutherford backscattering, transmission and scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, were utilized to characterize the diamond films. Sliding friction experiments were conducted with a polished natural diamond pin in contact with diamond films in the three environments: humid air (40% relative humidity), dry nitrogen (less than 1 percent relative humidity), and ultrahigh vacuum (10(exp -7) Pa). The CVD diamond films indeed have friction and wear properties similar to those of natural diamond in the three environments. The as-deposited, fine-grain diamond films can be effectively used as self-lubricating, wear-resistant coatings that have low coefficients of friction (0.02 to 0.04) and low wear rates (10(exp -7) to lO(exp -8) mm(exp 3) N(exp -1) m(exp -1)) in both humid air and dry nitrogen. However, they have high coefficients of friction (1.5 to 1.7) and a high wear rate (10(exp -4) mm(exp 7) N(exp -1) m(exp -1)) in ultrahigh vacuum. The carbon ion implantation produced a thin surficial layer (less than 0.1 micron thick) of amorphous, non-diamond carbon on the diamond films. In humid air and dry nitrogen, the ion-implanted, fine and coarse-grain diamond films have a low coefficient of friction (around 0.1) and a low wear rate (10(exp -7) mm(exp 3) N(exp -1) m(exp-1)). Even in ultrahigh vacuum, the presence of the non-diamond carbon layer reduced the coefficient of friction of fine-grain diamond films to 0.1 or lower and the wear rate to 10(exp -6) mm(exp 3) N(exp -1) m(exp -1). Thus, the carbon ion-implanted, fine-grain diamond films can be effectively used as wear-resistant, self-lubricating coatings not only in air and dry nitrogen, but also in ultrahigh vacuum.

Miyoshi, Kazuhisa

1996-01-01

315

Diamond and other forms of elemental carbon in Saturn’s deep atmosphere  

NASA Astrophysics Data System (ADS)

The energetic lightning storms in the Saturn atmosphere will dissociate molecules into atoms, ions and plasma. Specifically, methane will be dissociated into elemental carbon, most probably in an amorphous form, such as fluffy turbostratic carbon or irregular soot particles. Once formed, this non-crystalline carbon sinks down through the atmosphere reaching an altitude of similar density. Amorphous carbon is converted to graphite under pressure. Graphite has a density of ~2.2 g/cc at room temperature. The density of diamond is ~3.3 g/cc at STP. However, at much higher pressures, the density of diamond increases dramatically, up to 9 grams/cm3 at P=1500 GPa (15 Mbar). As carbon descends through the atmosphere, amorphous carbon becomes graphite which then is converted into diamond, creating various strata of carbon allotropes according to their densities. Densities of the planets increase with depth. Eventually, at great depths, diamond will melt, forming liquid diamond. The melting point of diamond varies with pressure, reaching a high of ~ 8000 K at 500 GPa (5 Mbar). Using updated adiabats and equation-of-state data from Nettelmann et al. (2011), we determined the altitude at which diamond reaches its melting point on each planet. Combining these adiabats with new data for the carbon phase diagram from high-pressure shockwave experiments indicates that diamond may be a stable layer in the atmospheres of Jupiter and Saturn. Previously, only Uranus and Neptune were thought to have conditions in their interiors that would allow the formation of diamond at their cores. It appears that the interior of Jupiter gets hot enough to reach the liquid diamond region of the carbon phase diagram, whereas the interior of Saturn includes regions of temperature and pressure where carbon could exist as solid diamond. At the boundaries (locations of sharp increases in density) on Jupiter and Saturn, there may be diamond rain or diamond oceans sitting as a layer. However, in Uranus and Neptune, the temperatures never reach as high as 8000 K. The cores are ~5000K, too cold for diamond to melt on these planets. Therefore, it appears that diamonds are forever on Uranus and Neptune but not on Jupiter and Saturn.

Delitsky, M. L.; Baines, K. H.

2013-10-01

316

Conversion of p-type to n-type diamond by exposure to a deuterium plasma  

SciTech Connect

The lack of a shallow donor in diamond with reasonable room temperature conductivity has been a major obstacle, until now, for the realization of many diamond based electronic devices. Most recently it has been shown that exposure of p-type (B doped) homoepitaxial diamond layers to a deuterium plasma can result in the formation of n-type diamond with a shallow donor state (E{sub a}=0.34 eV) and high room temperature mobility (430 cm{sup 2}/V s) [Z. Teukam et al., Nat. Mater. 2, 482 (2003); C. Saguy et al., Diamond Relat. Mater. 13, 700 (2004)]. Experimental results, based on the comparison of secondary ion mass spectrometry profiles of B and D and Hall effect measurements at different temperatures are presented. They confirm the previous speculation that some deuterium related complex is responsible for the donor activity in diamond. These donors are shown to be formed in a two-step process. First, deuterium diffuses into the entire B containing layer rather slowly, being trapped by the boron acceptors and passivating them. Once all B have formed complexes, further exposure to a D plasma results in the formation of a layer that contains about twice as many D atoms as the B content. This step is the one that gives rise to the excellent n-type features observed. The most recent theoretical attempts to explain the donor state by simulations of various boron-hydrogen complexes in diamond are reviewed.

Kalish, R.; Saguy, C.; Cytermann, C.; Chevallier, J.; Teukam, Z.; Jomard, F.; Kociniewski, T.; Ballutaud, D.; Butler, J.E.; Baron, C.; Deneuville, A. [Physics Department, Solid State Institute, Technion, Haifa 32000 (Israel); Laboratoire de Physique des Solides et de Cristallogenese, UMR CNRS 8635, 1 place A.Briand, 92195 Meudon Cedex (France); Naval Research Laboratory, Code 6174, Washington, DC 20375 (United States); Laboratoire d'Etudes des Proprietes Electroniques des Solides, CNRS, Boite Postale 166, 38042 Grenoble Cedex 09 (France)

2004-12-15

317

Diamonds: Exploration, mines and marketing  

Microsoft Academic Search

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%

George H. Read

2009-01-01

318

Rhaetian diamond placers in Siberia  

Microsoft Academic Search

Large diamond placers have been discovered in a Rhaetian basal horizon (Upper Triassic) in the north of the Sakha Republic (Yakutia) in the drainage areas of the Eekit, Nikabyt, Kelimyar, and Bur Rivers. In typomorphic features the found diamonds and indicator minerals of kimberlites are completely similar to those from Carnian basal horizons but, in contrast to them, are well

S. A. Grakhanov; Yu. A. Malanin; V. I. Pavlov; V. P. Afanas’ev; N. P. Pokhilenko; A. V. Gerasimchuk; A. N. Lipashova

2010-01-01

319

Preferential oxidation of diamond {111}  

Microsoft Academic Search

Measurements using TGA, SEM, Raman spectroscopy and XRD reveal that diamond oxidizes at around 750 K through oxygen impinging into the densely packed {111} planes throughout the course of the reaction. It is also found that diamond graphitizes under vacuum at about 1100 K without orientation preference, which also occurs under an Ar inert gas environment. The intriguing oxidation behaviour

Chang Q. Sun; H. Xie; W. Zhang; H. Ye; P. Hing

2000-01-01

320

ATLAS diamond Beam Condition Monitor  

Microsoft Academic Search

The ATLAS experiment has chosen to use diamond for its Beam Condition Monitor (BCM) given its radiation hardness, low capacitance and short charge collection time. In addition, due to low leakage current diamonds do not require cooling. The ATLAS Beam Condition Monitoring system is based on single beam bunch crossing measurements rather than integrating the accumulated particle flux. Its fast

A. Gorisek; V. Cindro; I. Dolenc; H. Frais-Kölbl; E. Griesmayer; H. Kagan; S. Korpar; G. Kramberger; I. Mandi?; M. Meyer; M. Mikuz; H. Pernegger; S. Smith; W. Trischuk; P. Weilhammer; M. Zavrtanik

2007-01-01

321

Applications of piezoelectric ZnO film deposited on diamond-like carbon coated onto Si substrate under fabricated diamond SAW filter  

Microsoft Academic Search

The applications of surface acoustic wave (SAW) devices aim directly at piezoelectric thin films deposited onto amorphous diamond-like carbon (DLC) coated on silicon substrates from target ZnO in this study. Our high-velocity SAW filters are characterized using multi-layer structures of thin films by DLC depositing. However, if propagating velocity of diamond is much higher, then the SAW phase velocity of

I-Tseng Tang; Han-Jan Chen; W. C Hwang; Y. C Wang; Mau-Phon Houng; Yeong-Her Wang

2004-01-01

322

Optical properties of nanodiamond layers  

Microsoft Academic Search

Thin ultradisperse diamond (UDD) layers deposited from a water suspension are studied by optical and x-ray photoelectron spectroscopy\\u000a (XPS). The effective band gap determined by the 104-cm?1 criterion for ozone-cleaned UDD is 3.5 eV. The broad structureless photoluminescence band (380–520 nm) is associated with\\u000a radiative recombination through a system of continuously distributed energy levels in the band gap of diamond

A. E. Aleksenskii; V. Yu. Osipov; A. Ya. Vul’; B. Ya. Ber; A. B. Smirnov; V. G. Melekhin; G. J. Adriaenssens; K. Iakoubovskii

2001-01-01

323

Analysis of temperature distribution and performance of polycrystalline diamond compact bits under field drilling conditions  

SciTech Connect

Analysis of laboratory tests on full-scale fieldworn polycrystalline diamond compact (PDC) bits showed the frictional heat at the rock/bit interface to be largely generated at the diamond cutting edges of the PDCs. Inspection of the observed wear of the PDCs together with the analysis revealed that the diamond layer attacks the formation at a large negative rake angle and that rock flour accumulates under the cutting edge during drilling, forming a stable buildup edge. The results showed that for effective cooling of the PDCs fluid velocities of at least 50 m/s are required along the diamond surfaces when drilling with oil-based fluids. With water-based drilling fluids, higher velocities should be used to prevent bit balling or boiling of the drilling fluid at the diamond surface of the PDCs.

Zijsling, O.H.

1984-09-01

324

A new hydrogen sensor using a polycrystalline diamond-based Schottky diode  

SciTech Connect

A new hydrogen sensor utilizing plasma-enhanced chemical vapor deposited diamond in conjunction with palladium (Pd) metal has been developed. The device is fabricated in a layered Pd/Undoped diamond/p-doped diamond Schottky diode configuration. Hydrogen sensing characteristics of the device have been examined in terms of sensitivity, linearity, response rate, and response time as a function of temperature and hydrogen partial pressure. Hydrogen adsorption activation energy is investigated in the temperature range from 27 to 85 C. Analysis of the steady-state reaction kinetics using the I-V method confirm that the hydrogen adsorption process is responsible for the barrier height change in the diamond Schottky diode. The ability to fabricate diamond-based hydrogen sensor on a variety of substrates makes the device very versatile for gas sensing.

Kang, W.P.; Gurbuz, Y.; Davidson, J.L.; Kerns, D.V. (Vanderbilt Univ., Nashville, TN (United States). Dept. of Applied and Engineering Sciences)

1994-08-01

325

Modelling wafer bow in silicon-polycrystalline CVD diamond substrates for GaN-based devices  

NASA Astrophysics Data System (ADS)

Composite silicon-polycrystalline chemical vapour deposition (CVD) diamond wafers are potential substrates for GaN-based devices for use in harsh environments due to their high thermal conductivity and chemical stability. When cooled from a typical diamond deposition temperature of approximately 800 to 25 °C wafer bowing arises from a mismatch in the coefficients of thermal expansion of silicon and polycrystalline diamond. In this paper 100 mm diameter silicon-polycrystalline diamond wafers have been modelled using ANSYS finite element software to investigate their bowing behaviour as a function of temperature and geometry. The maximum bow of a wafer occurred where the thicknesses of both the silicon and polycrystalline diamond layers was almost identical; this has been confirmed using analytical methods. Strategies are discussed for reducing wafer bow.

Edwards, M. J.; Bowen, C. R.; Allsopp, D. W. E.; Dent, A. C. E.

2010-09-01

326

Interfaces in nano-/microcrystalline multigrade CVD diamond coatings.  

PubMed

The interfaces of multilayered CVD diamond films grown by the hot-filament technique were characterized with high detail using HRTEM, STEM-EDX, and EELS. The results show that at the transition from micro- (MCD) to nanocrystalline diamond (NCD), a thin precursor graphitic film is formed, irrespectively of the NCD gas chemistry used (with or without argon). On the contrary, the transition of the NCD to MCD grade is free of carbon structures other than diamond, the result of a higher substrate temperature and more abundant atomic H in the gas chemistry. At those transitions WC nanoparticles could be found due to contamination from the filament, being also present at the first interface of the MCD layer with the silicon nitride substrate. PMID:24164667

Almeida, Flávia A; Salgueiredo, Ermelinda; Oliveira, Filipe J; Silva, Rui F; Baptista, Daniel L; Peripolli, Suzana B; Achete, Carlos A

2013-11-27

327

The effect of surface treatment on the electrical properties of metal contacts to boron-doped homoepitaxial diamond film  

SciTech Connect

Both doped and undoped homoepitaxial diamond films were fabricated using microwave plasma-enhanced chemical vapor deposition (CVD). The conductivity of the diamond film is strongly affected by the surface treatment. In particular, exposure of film surface to a hydrogen plasma results in the formation of a conductive layer which can be used to obtain linear (ohmic) {ital I-V} characteristics of the Au/diamond contacts, regardless of the doping level. The proper chemical cleaning of the boron-doped homoepitaxial diamond surface allows the fabrication of Au-gate Schottky diodes with excellent rectifying characteristics at temperatures of at least 400{degrees}C.

Grot, S.A.; Gildenblat, G.S.; Hatfield, C.W.; Wronski, C.R. (Pennsylvania State Univ., University Park, PA (USA). Dept. of Electrical Engineering); Badzian, A.R.; Badzian, T.; Messier, R. (Pennsylvania State Univ., University Park, PA (USA). Materials Research Lab.)

1990-02-01

328

Piezoresistive effect of CVD polycrystalline diamond films  

Microsoft Academic Search

Piezoresistive effect of diamond is an attractive property as a strain sensor. Properties of piezoresistive effect for homoepitaxial and polycrystalline diamond films have already been investigated, but the low gauge factor of polycrystalline diamond film compared with homoepitaxial diamond film should be improved for using as sensors. In this report, two ideas were examined to improve the gauge factor of

A. Yamamoto; T. Tsutsumoto

2004-01-01

329

The EKATI - Kimberlite - Diamond - Mine in Canada  

Microsoft Academic Search

This paper deals with the kimberlites and diamonds of the Ekati Diamond Mine, NWT, Canada, which lies in the central part of the canadian slave craton and is operated by the BHP Billiton Diamond Inc.. 150 kimberlites were discovered at Ekati and five of them are mined for diamonds. The most Ekati kimberlites are pipe-like bodies and their age rang

Janine Mundt

330

Diamond genesis — A synthesis of opposing views  

Microsoft Academic Search

Estimates of the pressure and temperature in the region of kimberlite magma generation are compatible with the formation of diamond in its own thermodynamic stability field as deduced from high pressure experimental synthesis of diamond. However, if diamond growth is allowed only within its stability field, preservation during ascent of kimberlite magma and many properties of diamond distribution in kimberlite

R. H. Mitchell; J. H. Crocket

1971-01-01

331

CVD Diamond Films for Tribological Applications.  

National Technical Information Service (NTIS)

Friction and wear behavior of several types of diamond film has been studied using sapphire on diamond film and diamond on diamond film tests. The coefficient of friction of the films was found to be a strong function of film morphology for sapphire on di...

I. Hayward J. Wegand L. S. Plano

1990-01-01

332

Apparatus and Method for Diamond Production.  

National Technical Information Service (NTIS)

An apparatus for producing diamond in a deposition chamber including a heat-sinking holder for holding a diamond and for making thermal contact with a side surface of the diamond adjacent to an edge of a growth surface of the diamond, a noncontact tempera...

C. S. Yan H. K. Mao R. J. Hemley Y. K. Vohra

2005-01-01

333

Diamond Anvil Cell Techniques  

NASA Astrophysics Data System (ADS)

It has often been said that scientific advances are made either in a dramatic and revolutionary way, or, as in the case of the diamond anvil cell (DAC), in a slow and evolutionary manner over a period of several years. For more than 2 decades, commencing in 1958, the DAC developed stepwise from a rather crude qualitative instrument to the sophisticated quantitative research tool it is today, capable of routinely producing sustained static pressures in the multi-megabar range and readily adaptable to numerous scientific measurement techniques because of its optical accessibility, miniature size, and portability.

Piermarini, Gasper J.

334

Chemical Vapor-Deposited (CVD) Diamond Films for Electronic Applications  

NASA Technical Reports Server (NTRS)

Diamond films have a variety of useful applications as electron emitters in devices such as magnetrons, electron multipliers, displays, and sensors. Secondary electron emission is the effect in which electrons are emitted from the near surface of a material because of energetic incident electrons. The total secondary yield coefficient, which is the ratio of the number of secondary electrons to the number of incident electrons, generally ranges from 2 to 4 for most materials used in such applications. It was discovered recently at the NASA Lewis Research Center that chemical vapor-deposited (CVD) diamond films have very high secondary electron yields, particularly when they are coated with thin layers of CsI. For CsI-coated diamond films, the total secondary yield coefficient can exceed 60. In addition, diamond films exhibit field emission at fields orders of magnitude lower than for existing state-of-the-art emitters. Present state-of-the-art microfabricated field emitters generally require applied fields above 5x10^7 V/cm. Research on field emission from CVD diamond and high-pressure, high-temperature diamond has shown that field emission can be obtained at fields as low as 2x10^4 V/cm. It has also been shown that thin layers of metals, such as gold, and of alkali halides, such as CsI, can significantly increase field emission and stability. Emitters with nanometer-scale lithography will be able to obtain high-current densities with voltages on the order of only 10 to 15 V.

1995-01-01

335

Numerical analysis of Nd:YAG pulsed laser polishing CVD self-standing diamond film  

NASA Astrophysics Data System (ADS)

Chemical vapor deposited (CVD) diamond film has broad application foreground in high-tech fields. But polycrystalline CVD self-standing diamond thick film has rough surface and non-uniform thickness that adversely affect its extensive applications. Laser polishing is a useful method to smooth self-standing diamond film. At present, attentions have been focused on experimental research on laser polishing, but the revealing of theoretical model and the forecast of polishing process are vacant. The paper presents a finite element model to simulate and analyze the mechanism of laser polishing diamond based on laser thermal conduction theory. The experimental investigation is also carried out on Nd:YAG pulsed laser smoothing diamond thick film. The simulation results have good accordance with the results of experimental results. The temperature and thermal stress fields are investigated at different incidence angles and parameters of Nd:YAG pulsed laser. The pyramidal-like roughness of diamond thick film leads to the non-homogeneous temperature fields. The temperature at the peak of diamond film is much higher than that in the valley, which leads to the smoothing of diamond thick film. The effect of laser parameters on the surface roughness and thickness of graphite transition layer is also carried out. The results show that high power density laser makes the diamond surface rapid heating, evaporation and sublimation after its graphitization. It is also found that the good polish quality of diamond thick film can be obtained by a combination of large incident angle, moderate laser pulsed energy, large repetition rate and moderate laser pulse width. The results obtained here provide the theoretical basis for laser polishing diamond film with high efficiency and high quality.

Xu, Feng; Hu, Haifeng; Zuo, Dunwen; Xu, Chun; Qing, Zhenghua; Wang, Min

2013-01-01

336

Diamonds in the Sky  

NASA Astrophysics Data System (ADS)

My first science fiction novel, Star Dragon, just recently available in paperback from Tor, features a voyage to the cataclysmic variable star system SS Cygni. My second novel, Spider Star, to appear early in 2006, takes place in and around a dark matter ``planet'' orbiting a neutron star. Both novels are ``hard'' science fiction, relying on accurate physics to inform the tales. It's possible to bring to life abstract concepts like special relativity, and alien environments like accretion disks, by using science fiction. Novels are difficult to use in a science class, but short stories offer intriguing possibilities. I'm planning to edit an anthology of hard science fiction stories that contain accurate science and emphasize fundamental ideas in modern astronomy. The working title is Diamonds in the Sky. The collection will be a mix of original stories and reprints, highlighting challenging concepts covered in a typical introductory astronomy course. Larry Niven's classic story, ``Neutron Star," is an excellent demonstration of extreme tidal forces in an astronomical context. Diamonds in the Sky will include forewards and afterwards to the stories, including discussion questions and mathematical formulas/examples as appropriate. I envision this project will be published electronically or through a print-on-demand publisher, providing long-term availabilty and keeping low cost. I encourage interested parties to suggest previously published stories, or to suggest which topics must be included.

Brotherton, M.

2004-12-01

337

Chemical-Vapor-Deposited Diamond Film  

NASA Technical Reports Server (NTRS)

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.

Miyoshi, Kazuhisa

1999-01-01

338

Friction and wear properties of as-deposited and carbon ion-implanted diamond films  

NASA Technical Reports Server (NTRS)

Recent work on the friction and wear properties of as-deposited and carbon ion-implanted diamond films was reviewed. Diamond films were produced by the microwave plasma chemical vapor deposition (CVD) technique. Diamond films with various grain sizes and surface roughnesses were implanted with carbon ions at 60 ke V ion energy, resulting in a dose of 1.2310(exp 17) carbon ions/cm(exp 2). Various analytical techniques, including Raman spectroscopy, proton recoil analysis, Rutherford backscattering, transmission and scanning electron microscopy, x-ray photoelectron spectroscopy, and x-ray diffraction, were utilized to characterize the diamond films. Sliding friction experiments were conducted with a polished natural diamond pin in contact with diamond films in the three environments: humid air (40 percent relative humidity), dry nitrogen (less than 1 percent relative humidity), and ultrahigh vacuum (10(exp -7) Pa). The CVD diamond films indeed have friction and were properties similar to those of natural diamond in the three environments. The as-deposited, fine-grain diamond films can be effectively used as self-lubricating, wear-resistant coatings that have low coefficients of friction (0.02 to 0.04) and low wear rates (10(exp -7) to 10(exp -8)mm(exp 3)/N-m) in both humid air and dry nitrogen. However, they have high coefficients of friction (1.5 to 1.7) and a high wear rate (10(exp -4)mm(exp 3/N-m) in ultrahigh vacuum. The carbon ion implanation produced a thin surficial layer (less than 0.1 micron thick) of amorphous, nondiamond carbon on the diamond films. In humid air and dry nitrogen, the ion-implanted, fine- and coarse-grain diamond films have a low coefficient of friction (around 0.1) and a low wear rate (10(exp -7)mm(exp 3/N-m). Even in ultrahigh vacuum, the presence of the nondiamond carbon layer reduced the coefficient of friction of fine-grain diamond films to 0.1 or lower and the wear rate to 10(exp -6)mm(exp 3)/N-m. Thus, the carbon ion-implanted, fine-grain diamond films can be effectively used as wear-resistant, self-lubricating coatings not only in air and dry nitrogen, but also in ultrahigh vacuum. The wear mechanism of diamond films is that of small fragments chipping off the surface. The size of wear particles is related to the extent of wear rates.

Miyoshi, Kazuhisa

1994-01-01

339

Properties of chemical vapor infiltration diamond deposited in a diamond powder matrix.  

National Technical Information Service (NTIS)

Densifying non-mined diamond powder precursors with diamond produced by chemical vapor infiltration (CVI) is an attractive approach for forming thick diamond deposits that avoids many potential manufacturability problems associated with predominantly chem...

J. K. G. Panitz D. R. Tallant C. R. Hills D. J. Staley

1993-01-01

340

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

National Technical Information Service (NTIS)

Densifying non-mined diamond powder precursors with diamond produced by chemical vapor infiltration (CVI) is an attractive approach for forming thick diamond deposits that avoids many potential manufacturability problems associated with predominantly chem...

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

1995-01-01

341

Recent Development in Diamond Synthesis  

NASA Astrophysics Data System (ADS)

The high pressure-high temperature (HPHT) method led to wide applications of artificial diamonds in industry. Low temperature coating of diamonds has been studied for some time, and chemical vapor deposition has been developed. In this contribution, we will focus on the most recent developments in diamond synthesis, and especially the important progress upon hydrothermal synthesis and the reduction of carbide (HSRC), which has attracted more and more attention due to its great commercial potential. Especially, we will discuss the synthesis of colorless, large diamond crystals from the reduction of carbon dioxide or carbonates. In addition, some recent progress on the theoretical studies of the metastable nucleation and growth of diamonds will also be reviewed. Finally, theories about the genesis of natural diamond were briefly reviewed, and a new theory based on our experimental results was proposed, which suggests that diamond within the Earth could be produced from carbon dioxide wherever carbon dioxide existed and the conditions (e.g., temperature, pressure, and reducing environment) are satisfied.

Chen, Changle; Chen, Qianwang

342

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

NASA Technical Reports Server (NTRS)

The nucleation and growth of plasma enhanced chemical vapor deposited (PECVD) 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) 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 films cross-section and interface however were not affected by tip convolution, and the images indicate that the surface of the silicon substrate is initially covered by 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 spectroscoy (XPS) spectra indicates that some silicon carbide is present in the precursor layer.

George, M. A.; Burger, A.; Collins, Warren E.; Hu, Z.

1995-01-01

343

Materials Design of Ferromagnetic Diamond  

NASA Astrophysics Data System (ADS)

We propose materials design of ferromagnetic diamond without any transition metal elements based on first principles calculations. The electronic structure and the magnetic properties of impurities-doped diamond are calculated by using the Korringa-Kohn-Rostoker method within the local spin density approximation with taking into account disorder using coherent potential approximation. It is found that H atoms which are doped into tetrahedral interstitial sites show finite local magnetic moments. Moreover, the impurities-doped diamond show ferromagnetism with half-metallic density of states.

Kenmochi, Kazuhide; Sato, Kazunori; Yanase, Akira; Katayama-Yoshida, Hiroshi

2005-02-01

344

Tailoring nanocrystalline diamond film properties  

DOEpatents

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.

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

2003-07-15

345

Diamond and Diamond-Like Materials as Hydrogen Isotope Barriers  

SciTech Connect

This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The purpose of this project was to develop diamond and diamond-like thin-films as hydrogen isotope permeation barriers. Hydrogen embrittlement limits the life of boost systems which otherwise might be increased to 25 years with a successful non-reactive barrier. Applications in tritium processing such as bottle filling processes, tritium recovery processes, and target filling processes could benefit from an effective barrier. Diamond-like films used for low permeability shells for ICF and HEDP targets were also investigated. Unacceptable high permeabilities for hydrogen were obtained for plasma-CVD diamond-like-carbon films.

Foreman, L.R.; Barbero, R.S.; Carroll, D.W.; Archuleta, T.; Baker, J.; Devlin, D.; Duke, J.; Loemier, D.; Trukla, M.

1999-07-10

346

Diamond film ultraviolet detectors with different diamond grain size  

NASA Astrophysics Data System (ADS)

Diamond films with different grain sizes from 1.8 ?m to 3.1 ?m were prepared using the bias-enhanced hot-filament chemical vapor deposition (HFCVD) technique. The film structure and morphology were characterized using the optical microscope and Raman spectrometer. Ultra-violet (UV) detectors with interdigital patterns were fabricated using above diamond films. I-V measurement results showed that the performance of the detector was closely related with the grain size of the diamond film. With increasing the grain size, the photo-current, the ratio of photo-current to dark-current and the net photo-current all increased. The above results indicate that diamond films with larger grain size are more suitable for being fabricated as UV detectors.

Tang, K.; Wang, L. J.; Huang, J.; Ma, Y.; Hu, G.; Zhu, X. F.; Xia, Y. B.

2009-03-01

347

``Compressed Graphite'' Formed During C60 to Diamond Transformation as Revealed by Scattering Computed Tomography  

NASA Astrophysics Data System (ADS)

The collapsing of C60 into polycrystalline diamond has been studied after nonhydrostatic pressurization at ambient temperature using x-ray scattering computed tomography. Using this selective structural probe we provide evidence of concentric coexistence of “compressed graphite” (d00l˜3.09-3.11Å), sp2-graphitelike phase (d00l˜3.35-3.42Å), and sp3-like amorphous carbon surrounding polycrystalline diamond (a˜3.56-3.59Å). The so-called “compressed graphite” exhibits a collapsed c axis and is textured with disordered layers. This latter phase is better described as a short interlayered carbon phase with buckled sp2-sp3 layers with possible interlayer bonding. Additionally, our 3D maps of phase distribution and of the residual stress retained in the polycrystalline diamond phase support the importance of stressed synthesis conditions for diamond formation.

Álvarez-Murga, M.; Bleuet, P.; Garbarino, G.; Salamat, A.; Mezouar, M.; Hodeau, J. L.

2012-07-01

348

"Compressed graphite" formed during C60 to diamond transformation as revealed by scattering computed tomography.  

PubMed

The collapsing of C60 into polycrystalline diamond has been studied after nonhydrostatic pressurization at ambient temperature using x-ray scattering computed tomography. Using this selective structural probe we provide evidence of concentric coexistence of "compressed graphite" (d(00l)?3.09-3.11??Å), sp2-graphitelike phase (d(00l)?3.35-3.42??Å), and sp3-like amorphous carbon surrounding polycrystalline diamond (a?3.56-3.59??Å). The so-called "compressed graphite" exhibits a collapsed c axis and is textured with disordered layers. This latter phase is better described as a short interlayered carbon phase with buckled sp2-sp3 layers with possible interlayer bonding. Additionally, our 3D maps of phase distribution and of the residual stress retained in the polycrystalline diamond phase support the importance of stressed synthesis conditions for diamond formation. PMID:23030177

Álvarez-Murga, M; Bleuet, P; Garbarino, G; Salamat, A; Mezouar, M; Hodeau, J L

2012-07-13

349

Diamond-like carbon\\/epoxy low-friction coatings to replace electroplated chromium  

Microsoft Academic Search

A series of layered structures based on epoxy resins coated with diamond-like carbon (DLC) are examined as potential replacements for electroplated chromium in aerospace applications. Diamond-like carbon coatings can offer superior mechanical properties and tribological performance; however, in some applications high internal stresses and poor adhesion limit their practical use. A DLC\\/epoxy system is developed and studied utilising pin-on-disk testing,

S. Podgoric; B. J. Jones; R. Bulpett; G. Troisi; J. Franks

2009-01-01

350

The electrochemical activity of boron-doped polycrystalline diamond thin film electrodes  

SciTech Connect

The electrochemical activity of [open quotes]as grown[close quotes] boron-doped polycrystalline diamond thin film electrodes has been studied using cyclic voltammetry, chronoamperometry, and ac impedance without external illumination. The resistivity of these materials after doping is ca. 10 ohm-cm. The diamond electrodes possess a low double layer capacitance and a relatively high polarization resistance toward surface oxidation. Slow electrode kinetics are observed for Fe(CN)[sub 6][sup 3[minus]/4[minus

Swain, G.M.; Ramesham, R. (Auburn Univ., AL (United States))

1993-02-15

351

Diamond-like carbon metal-semiconductor-metal switches for active matrix displays  

Microsoft Academic Search

Metal-Semiconductor-Metal (MSM) layer structures of diamond-like carbon (DLC) are investigated for possible use as the switching elements in active matrix displays. Their high field conductivity is found to obey the Poole-Frenkel law for field-assisted hopping out of traps. The conduction parameters are studied as a function of the band gap of diamond-like carbon. The on- and off-currents of DLC MSM

S. Egret; J. Robertson; W. I. Milne; F. J. Clough

1997-01-01

352

Pseudomorphic Stabilization of Diamond on Non-Diamond Substrates. Part 1. Diamond Grown on Single Crystal Beryllium Oxide. Part 2. Anomalous Band Gap Behavior and Phase Stability of c-BN/Diamond Alloys.  

National Technical Information Service (NTIS)

Diamond was grown on single crystal beryllium oxide by hot-filament chemical vapor deposition. Individual diamond crystals grew epitaxially on the basal plane of BeO with the epitaxial relationship: (111)diamond // (0001) and diamond rotated by l...

A. Argoitia J. C. Angus L. Wang X. I. Ning P. Pirouz

1992-01-01

353

Industrial Diamond: A Materials Survey.  

National Technical Information Service (NTIS)

The survey on industrial diamonds summarizes the supply-demand position in the United States and include information on production, imports, consumption, exports, substitutes, and pertinent history, usually in some detail, back to 1925. The properties of ...

H. P. Chandler

1964-01-01

354

Microwave Studies of Semiconducting Diamonds.  

National Technical Information Service (NTIS)

An initially non-conducting diamond treated with boron under high temperature - high pressure conditions was shown to have semiconducting properties. By means of successive experiments in which portions of the specimen were removed by cleaving and polishi...

M. H. Sirvetz

1965-01-01

355

Fabrication of amorphous diamond films  

DOEpatents

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

Falabella, S.

1995-12-12

356

33 CFR 110.6 - Portland Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island).  

Code of Federal Regulations, 2013 CFR

...Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island). 110.6 Section 110.6 Navigation and...Harbor, Portland, Maine (between Little Diamond Island and Great Diamond Island). Beginning at...

2013-07-01

357

Growth of twin-free heteroepitaxial diamond on Ir/YSZ/Si(111)  

NASA Astrophysics Data System (ADS)

Heteroepitaxial nucleation and growth of twin-free diamond on Ir(111) is reported. The bias enhanced nucleation (BEN) technique was applied in a microwave plasma chemical vapor deposition setup to induce diamond nucleation on the new multilayer stack Ir/YSZ/Si(111). We demonstrate that the gathering of the diamond nuclei in so-called ``domains,'' a pattern formation process unique for diamond nucleation on iridium, is also present on Ir(111). The 1-2 nm thick carbon layer deposited by BEN does not show any crystalline diamond structures in electron diffraction and high resolution lattice imaging microscopy. In contrast, x-ray photoelectron diffraction (XPD) measurements yield C 1s diffractograms with clear threefold symmetry. The main features are comparable to measurements on diamond (111) single crystal surfaces. The weaker fine structure in the XPD patterns of the BEN layers is attributed to some disorder due to the harsh ion bombardment. However, this ion bombardment did not induce any measurable amount of twinning as deduced from the threefold symmetry. After 3 h diamond growth, the signal due to twins in the x-ray diffraction pole figures is still below the noise level of ~1%. Negligible twinning and the low mosaic spread of 0.96° (tilt) and 1.85° (twist) indicate that these films mark a breakthrough toward heteroepitaxial diamond films with (111) orientation. They provide interesting growth substrates, e.g., for phosphorous doped diamond or for the formation of heterojunction devices by deposition of wurtzite-type wide band gap semiconductor materials.

Fischer, M.; Brescia, R.; Gsell, S.; Schreck, M.; Brugger, T.; Greber, T.; Osterwalder, J.; Stritzker, B.

2008-12-01

358

Surface Design and Engineering Toward Wear-Resistant, Self-Lubricating Diamond Films and Coatings  

NASA Technical Reports Server (NTRS)

The tribological properties of chemical-vapor-deposited (CVD) diamond films vary with the environment, possessing a Jekyll-and-Hyde character. CVD diamond has low coefficient of friction and high wear resistance in air but high coefficient of friction and low wear resistance in vacuum. Improving the tribological functionality of materials (such as achieving low friction and good wear resistance) was an aim of this investigation. Three studies on the surface design, surface engineering, and tribology of CVD diamond have shown that its friction and wear are significantly reduced in ultrahigh vacuum. The main criteria for judging whether diamond films are an effective wear-resistant, self-lubricating material were coefficient of friction and wear rate, which must be less than 0.1 and on the order of 10(exp 6) cu mm/N(dot)m, respectively. In the first study the presence of a thin film (less than 1 micron thick) of amorphous, nondiamond carbon (hydrogenated carbon, also called diamondlike carbon or DLC) on CVD diamond greatly decreased the coefficient of friction and the wear rate. Therefore, a thin DLC film on CVD diamond can be an effective wear-resistant, lubricating coating in ultrahigh vacuum. In the second study the presence of an amorphous, nondiamond carbon surface layer formed on CVD diamond by ion implantation significantly reduced the coefficient of friction and the wear rate in ultrahigh vacuum. Therefore, such surface layers are acceptable for effective self-lubricating, wear-resistant applications of CVD diamond. In the third study CVD diamond in contact with cubic boron nitride exhibited low coefficient of friction in ultra high vacuum. Therefore, this materials combination can provide an effective self-lubricating, wear-resistant couple in ultrahigh vacuum.

Miyoshi, Kazuhisa

1999-01-01

359

3D neutron and X-ray imaging of diamondiferous eclogites, Siberia: Evidence for the secondary origin of diamonds  

NASA Astrophysics Data System (ADS)

Non-destructive, 3D tomography of diamondiferous eclogites (Siberia) has effectively imaged diamonds and their spatial and textural relationships in situ. A rare suite of 17 diamondiferous eclogites have been analyzed, representing the largest collection outside of Siberia. New innovations in X-ray imaging, in combination with the first effective use of neutron imaging techniques, allow for the identification of secondary metasomatic minerals and the delineation of metasomatic pathways through the eclogites. Combining observations from both imaging techniques provides first-order characterizations and textural descriptions critical for understanding diamond genesis that has heretofore been absent in the literature. Eclogitic diamonds are generally octahedral in morphology, but dodecahedral diamonds are also observed, completely enclosed within the eclogites, implying in situ resorption. Diamonds are never observed in contact with primary minerals - i.e., always surrounded by secondary phases. Primary garnet and clinopyroxene show varying degrees of alteration, discerning the delineation of metasomatic pathways. In general, such pathways are observed as interconnected networks of veinlets, commonly cross-cutting the eclogites. Furthermore, clinopyroxene-rich layers observed show higher degrees of alteration, relative to garnet-rich layers within the same sample, highlighting clinopyroxene as more susceptible to metasomatic alteration than garnet. Diamonds are always observed within such metasomatic pathways. For example, eclogite U-112 contains ~22 macro-diamonds, all of which are contained within an altered clinopyroxene-rich layer. In addition, no spatial relationship is observed between diamonds and sulfide phases. The ubiquitous association of diamonds with metasomatic minerals and pathways provides compelling evidence for the secondary origin of diamonds, in agreement with current interpretations on the origin of diamonds [1,2]. However, diamonds are generally believed to be ancient (1-3 Ga) [3], whereas the metasomatic mineral assemblages observed within eclogites are interpreted to have formed much later, perhaps just prior to incorporation into the rising kimberlite magma [4]. This age dichotomy indicates that either the metasomatic pathways have remained open for billions of years or that diamond growth is significantly younger than previously believed. We suggest that diamond growth may be related to metasomatic fluids circulating just prior to kimberlite emplacement and that diamonds may be significantly younger than previously believed. [1] T. Stachel, J.W. Harris, Ore. Geol. Rev. 34, 5 (2008). [2] Y. Liu et al., Lithos 112S, 1014 (2009). [3] S.B. Shirey, S.H. Richardson, Science 333, 434 (2011). [4] K.C. Misra et al., Contrib. Mineral. Petrol. 146, 696 (2004).

Howarth, G. H.; Pernet-Fisher, J. F.; Sobolev, N. V.; Penumadu, D.; Puplampu, S.; Ketcham, R. A.; Maisano, J. A.; Taylor, D.; Taylor, L. A.

2013-12-01

360

Thermal and fast neutron detection in chemical vapor deposition single-crystal diamond detectors  

SciTech Connect

Recently, a compact solid-state neutron detector capable of simultaneously detecting thermal and fast neutrons was proposed [M. Marinelli et al., Appl. Phys. Lett. 89, 143509 (2006)]. Its design is based on a p-type/intrinsic/metal layered structure obtained by Microwave Plasma Chemical Vapor Deposition (CVD) of homoepitaxial diamond followed by thermal evaporation of an Al contact and a {sup 6}LiF converting layer. Fast neutrons are directly detected in the CVD diamond bulk, since they have enough energy to produce the {sup 12}C(n,{alpha}){sup 9}Be reaction in diamond. Thermal neutrons are instead converted into charged particles in the {sup 6}LiF layer through the {sup 6}Li(n,{alpha})T nuclear reaction. These charged particles are then detected in the diamond layer. The thickness of the {sup 6}LiF converting layer and the CVD diamond sensing layer affect the counting efficiency and energy resolution of the detector both for low- (thermal) and high-energy neutrons. An analysis is carried out on the dynamics of the {sup 6}Li(n,{alpha})T and the {sup 12}C(n,{alpha}){sup 9}Be reactions products, and the distribution of the energy released inside the sensitive layer is calculated. The detector counting efficiency and energy resolution were accordingly derived as a function of the thickness of the {sup 6}LiF and CVD diamond layers, both for thermal and fast neutrons, thus allowing us to choose the optimum detector design for any particular application. Comparison with experimental results is also reported.

Almaviva, S.; Marinelli, M.; Milani, E.; Prestopino, G.; Tucciarone, A.; Verona, C.; Verona-Rinati, G. [Dipartimento di Ingegneria Meccanica, Universita di Roma 'Tor Vergata', Via del Politecnico 1, I-00133 Roma (Italy); Angelone, M.; Lattanzi, D.; Pillon, M. [Associazione EURATOM-ENEA sulla Fusione, Via E. Fermi 45, I-00044 Frascati (Roma) (Italy); Montereali, R. M.; Vincenti, M. A. [ENEA-FIS C.R. Frascati, Via E. Fermi 45, I-00044 Frascati (Roma) (Italy)

2008-03-01

361

Diamonds: Exploration, mines and marketing  

NASA Astrophysics Data System (ADS)

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

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

2009-11-01

362

Low surface energy coatings covalently bonded on diamond-like carbon films  

Microsoft Academic Search

In the present work, a chemical treatment with perfluorinated peroxides is proposed to obtain protective layers covalently linked to a diamond-like carbon (DLC) surface. The lubricant properties of perfluorinated compounds and the stability of the chemical modification of DLC surface simultaneously cooperate in this technical approach. Each fluorinated layer is deposed on an bare DLC surface by a dip coating

Walter Navarrini; Claudia L. Bianchi; Luca Magagnin; Luca Nobili; Gabriella Carignano; Pierangelo Metrangolo; Giuseppe Resnati; Maurizio Sansotera

2010-01-01

363

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

364

Tensile properties of amorphous diamond films  

SciTech Connect

The strength and modulus of amorphous diamond, a new material for surface micromachined MEMS and sensors, was tested in uniaxial tension by pulling laterally with a flat tipped diamond in a nanoindenter. Several sample designs were attempted. Of those, only the single layer specimen with a 1 by 2 {micro}m gage cross section and a fixed end rigidly attached to the substrate was successful. Tensile load was calculated by resolving the measured lateral and normal forces into the applied tensile force and frictional losses. Displacement was corrected for machine compliance using the differential stiffness method. Post-mortem examination of the samples was performed to document the failure mode. The load-displacement data from those samples that failed in the gage section was converted to stress-strain curves using carefully measured gage cross section dimensions. Mean fracture strength was found to be 8.5 {+-} 1.4 GPa and the modulus was 831 {+-} 94 GPa. Tensile results are compared to hardness and modulus measurements made using a nanoindenter.

Lavan, D.A.; Hohlfelder, R.J.; Sullivan, J.P.; Friedmann, T.A.; Mitchell, M.A.; Ashby, C.I.

1999-12-02

365

CVD diamond nucleation enhanced by ultrasonic pretreatment using diamond and mixture of diamond and TaC powders  

Microsoft Academic Search

Effects of ultrasonic pretreatment on chemical vapor deposition (CVD) diamond nucleation on Si substrates were systematically studied. Pure 1.5–40 ?m-diamond powder and mixtures of 1.5–5 ?m-diamond as well as 5–20 ?m-Tantalum Carbide (TaC) powder were used in ultrasonic pretreatment. The root-mean-square (Rms) surface roughness of the pretreated substrates, residual diamond and TaC powders left on the substrates were examined using

S. G Wang; Qing Zhang; S. F Yoon; J Ahn; Q Wang; D. J Yang; Q. F Huang; Rusli; W. Z Tang; F. X Lu

2002-01-01

366

Properties of chemical vapor infiltration diamond deposited in a diamond powder matrix  

Microsoft Academic Search

Densifying nonmined diamond powder precursors with diamond produced by chemical vapor infiltration is an attractive approach for forming thick diamond deposits that avoids many potential manufacturability problems associated with predominantly chemical vapor deposition (CVD) processes. We have developed two techniques: electrophoretic deposition and screen printing, to form diamond powder precursors on substrates. We then densify these precursors in a hot

Janda K. G. Panitz; D. R. Tallant; C. R. Hills; D. J. Staley

1994-01-01

367

Properties of chemical vapor infiltration diamond deposited in a diamond powder matrix  

Microsoft Academic Search

Densifying non-mined diamond powder precursors with diamond produced by chemical vapor infiltration (CVI) is an attractive approach for forming thick diamond deposits that avoids many potential manufacturability problems associated with predominantly chemical vapor deposition (CVD) processes. The authors have developed two techniques: electrophoretic deposition and screen printing, to form nonmined diamond powder precursors on substrates. They then densify these precursors

J. K. G. Panitz; D. R. Tallant; C. R. Hills; D. J. Staley

1993-01-01

368

Improvement of mechanical properties of electroplated diamond tools by microwave plasma CVD diamond process  

Microsoft Academic Search

The growth and surface modification of irregular diamond grains of electroplated diamond tools have been developed successfully. Results show that the adherence, cutting ability, and wear resistance of diamond grains are improved by this process. In this study, the crystallization and quality of diamond grains were determined by SEM (SE and BSE), Raman spectroscopy, and XRD determination. Tests using a

C. R Lin; C. T Kuo

1998-01-01

369

Simplified Monte Carlo simulations of chemical vapour deposition diamond growth  

NASA Astrophysics Data System (ADS)

A simple one-dimensional Monte Carlo model has been developed to simulate the chemical vapour deposition (CVD) of a diamond (100) surface. The model considers adsorption, etching/desorption, lattice incorporation, and surface migration along and across the dimer rows. The top of a step-edge is considered to have an infinite Ehrlich-Schwoebel potential barrier, so that mobile surface species cannot migrate off the edge. The reaction probabilities are taken from experimental or calculated literature values for standard CVD diamond conditions. The criterion used for the critical nucleus needed to form a new layer is considered to be two surface carbon species bonded together, which forms an immobile, unetchable step on the surface. This nucleus can arise from two migrating species meeting, or from direct adsorption of a carbon species next to a migrating species. The analysis includes film growth rate, surface roughness, and the evolving film morphology as a function of varying reaction probabilities. Using standard CVD diamond parameters, the simulations reveal that a smooth film is produced with apparent step-edge growth, with growth rates (~1 µm h-1) consistent with experiment. The ?-scission reaction was incorporated into the model, but was found to have very little effect upon growth rates or film morphology. Renucleation events believed to be due to reactive adsorbates, such as C atoms or CN groups, were modelled by creating random surface defects which form another type of critical nucleus upon which to nucleate a new layer. These were found to increase the growth rate by a factor of ~10 when the conditions were such that the rate-limiting step for growth was new layer formation. For other conditions these surface defects led to layered 'wedding cake' structures or to rough irregular surfaces resembling those seen experimentally during CVD of nanocrystalline diamond.

May, Paul W.; Allan, Neil L.; Ashfold, Michael N. R.; Richley, James C.; Mankelevich, Yuri A.

2009-09-01

370

Chemical gases sensing properties of diamond nanocone arrays formed by plasma etching  

SciTech Connect

A uniform diamond nanocone array was formed by plasma etching of diamond film in a hot filament chemical vapor deposition (HFCVD) system. A surface amorphous carbon coating layer, which is formed during CH{sub 4}/H{sub 2} plasma-etching process, was removed by Ar plasma in a reactive ion etching system. The hydrogenation of diamond nanocones was performed in H{sub 2} ambience by using the same HFCVD system. The air-diluted NH{sub 3} and NO{sub 2} gases sensing properties of the diamond cone arrays had been studied by using electric current versus measurement time characteristics at room temperature. The repeatable chemical sensing properties of the hydrogenated diamond cone array sensor are enhanced, in comparison with as-formed diamond film. Surface two-dimensional hole gas structure and greatly increased surface-to-volume ratio both play a key role for the excellent detection performance. As-formed diamond nanocone arrays show a promising prospect for applications as chemical sensor for both reducing (NH{sub 3}) and oxidizing (NO{sub 2}) gases.

Wang, Q.; Qu, S. L.; Fu, S. Y.; Liu, W. J.; Li, J. J.; Gu, C. Z. [Department of Optics and Electronics Science, Harbin Institute of Technology at Wei Hai, Weihai 264209 (China); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)

2007-11-15

371

Thermal Diffusivity Measurement of Diamond Materials.  

National Technical Information Service (NTIS)

The thermal wave/mirage effect technique is applied to the determination of thermal properties of polycrystalline diamond slabs and single crystal diamonds of different isotopic compositions. This method is well-suited for these kind of materials.

L Wei P. K. Kuo R. L. Thomas

1992-01-01

372

Boron carbide coatings on diamond particles  

Microsoft Academic Search

Boron carbide (B4C) coatings on diamond offer potential for obtaining homogeneous B4C-diamond composites with improved properties. A method was developed for coating diamond particles with B4C at 1150°C under argon atmosphere for dwell times of 2–6hours in a powder mixture of boric acid (H3BO3) and amorphous boron. The B4C coating showed very good adhesion to the diamond substrate, and an

A. H. Ras; F. D. Auret; J. M. Nel

2010-01-01

373

Ultimate Atomic Bling: Nanotechnology of Diamonds  

SciTech Connect

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.

Dahl, Jeremy

2010-05-25

374

Ultimate Atomic Bling: Nanotechnology of Diamonds  

ScienceCinema

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.

375

The tribology of nano-crystalline diamond  

Microsoft Academic Search

Nano-crystalline diamond is the hardest diamond-like carbon (DLC) with properties very close to true diamond. Among such properties is the low frictional coefficient and high wear resistance. Cemented WC disks were coated by nano-crystalline diamond deposited by cathodic arc. These disks were rubbed cyclically by pins made of aluminum–silicon alloy (4032), carbon steel (52100), and alumina ceramics (Al2O3). It was

Shenq Y. Luo; Jui-Kang Kuo; Brian Yeh; James C. Sung; Chuang-Wen Dai; Tsung J. Tsai

2001-01-01

376

High pressure annealing of CVD diamond films  

Microsoft Academic Search

CVD diamond films were annealed from 600 to 1900 °C at 7.7 GPa in a toroidal high pressure (HP) apparatus, always inside the diamond-phase stability region. The annealed films were analyzed by Raman and infrared (IR) spectroscopy and the results showed that the diamond grains remained stable while the non-diamond carbon phases and impurities, responsible for the intricate film structure,

N. M. Balzaretti; J. A. H. da Jornada

2003-01-01

377

Self-assembled GaN nanowires on diamond.  

PubMed

We demonstrate the nucleation of self-assembled, epitaxial GaN nanowires (NWs) on (111) single-crystalline diamond without using a catalyst or buffer layer. The NWs show an excellent crystalline quality of the wurtzite crystal structure with m-plane faceting, a low defect density, and axial growth along the c-axis with N-face polarity, as shown by aberration corrected annular bright-field scanning transmission electron microscopy. X-ray diffraction confirms single domain growth with an in-plane epitaxial relationship of (10 ?10)(GaN) [parallel] (01 ?1)(Diamond) as well as some biaxial tensile strain induced by thermal expansion mismatch. In photoluminescence, a strong and sharp excitonic emission reveals excellent optical properties superior to state-of-the-art GaN NWs on silicon substrates. In combination with the high-quality diamond/NW interface, confirmed by high-resolution transmission electron microscopy measurements, these results underline the potential of p-type diamond/n-type nitride heterojunctions for efficient UV optoelectronic devices. PMID:22506554

Schuster, Fabian; Furtmayr, Florian; Zamani, Reza; Magén, Cesar; Morante, Joan R; Arbiol, Jordi; Garrido, Jose A; Stutzmann, Martin

2012-05-01

378

A study on graphitization of diamond in copper–diamond composite materials  

Microsoft Academic Search

The graphitization of diamond particles in the copper–diamond composite materials used for low voltage electro-contacts was investigated by SEM, TEM and X-ray diffraction (XRD) analyses. The results show that although diamond is a metastable allotropic modification of carbon, the diamond particles are not graphitized to an apparent extent after sintering at 1150–1220 K in the copper–diamond composite. The reason for

W. Z. Shao; V. V. Ivanov; L. Zhen; Y. S. Cui; Y. Wang

2004-01-01

379

Diamond Drilling Specification Manual and Course Outline.  

ERIC Educational Resources Information Center

This publication presents the standards required of a person practicing diamond drilling in western Canada and provides an outline for teaching the skills and knowledge. It is divided into two parts. The Diamond Drilling Specification Manual establishes the levels of skill and knowledge required in the four certified levels of diamond drilling.…

British Columbia Dept. of Education, Victoria.

380

Study of porosity in permeable diamond membranes  

Microsoft Academic Search

As reported previously, porous diamond membranes can be fabricated using a method based on growing diamond on a patterned silicon surface. Protrusions on the silicon surface act as molds for forming the pores on the diamond films. This method leads to a non-negligible pore size non-uniformity. The present work is concerned with identifying the process that accounts for this, so

V. P. Mammana; M. C. Salvadori; I. G. Brown

1997-01-01

381

Tribological properties of partly polished diamond coatings  

Microsoft Academic Search

Extremely low friction coefficient was achieved with “partly polished diamond coatings”. Diamond coatings were deposited onto Si substrates by MWCVD with the mixture of CH4 and H2. Deposited films were characterized by X-ray diffraction (XRD), Raman spectroscopy and Electron Spectroscopy for Chemical Analysis (ESCA). Sharp peak derived from polycrystalline diamond was observed by XRD. Whereas Raman profile of partly polished

T. Takeno; T. Komoriya; I. Nakamori; H. Miki; T. Abe; T. Uchimoto; T. Takagi

2005-01-01

382

Deep Level Transient Spectroscopy on Polycrystalline Diamond  

Microsoft Academic Search

We have used deep level transient spectroscopy (DLTS) to study the defect levels in polycrystalline diamond films, which have been grown by hot filament chemical vapor deposition (HFCVD). The polycrystalline diamond used in this study is p-type (boron doped) grown on p-type [100] silicon. Schottky diodes were fabricated by sputtering gold onto the diamond. The parameters of trapping centers in

H. Karbasi; J. W. Farmer; J. M. Meese; H. Golestanian; I. St. Omer; J. E. Charleson

1998-01-01

383

Ultradispersity of diamond at the nanoscale  

Microsoft Academic Search

Nanometre-sized diamond has been found in meteorites, protoplanetary nebulae and interstellar dusts, as well as in residues of detonation and in diamond films. Remarkably, the size distribution of diamond nanoparticles seems to be peaked around 2-5 nm, and to be largely independent of preparation conditions. We have carried out ab initio calculations of the stability of nanodiamond as a function

Jean-Yves Raty; Giulia Galli

2003-01-01

384

Ellipsometric study of CVD diamond films prepared with various grain sizes  

NASA Astrophysics Data System (ADS)

Diamond films with various grain sizes are grown on silicon substrates by hot-filament chemical vapor deposition method. Scanning electron microscopy (SEM) measurement shows that the films consist of diamond grain with an average crystallite size of 1.4-0.1?m. The optical and structural properties of diamond films are investigated by spectroscopic phase modulated ellipsometer in the energy range of 0.8-1.5eV. A three-layer model, Si/diamond film/diamond film + void/, is applied to diamond film based on Bruggeman effective-medium approximation and New Amorphous dispersion formula which is a rewrite of Forouhi-Bloomer formulation. By fitting spectroscopic characteristics (?,?) with Levenberg-Marquardt regression algorithm, the energy band gap and refractive index are obtained, along with the film thickness, bulk void fraction and roughness layer. The study indicates that both energy band gap and refractive index decrease when grain size reduces due to the raise of disorder sp2 bonded carbon. The result on the Raman scattering measurement is consistent with the fitting result of spectroscopic ellipsometer.

Lou, Yanyan; Wang, Linjun; Ma, Hongliang; Deng, Hongmei; Lu, Bo; Xia, Yiben

2008-03-01

385

Diamond and diamond-like films for transportation applications  

SciTech Connect

This section is a compilation of transparency templates which describe the goals of the Office of Transportation Materials (OTM) Tribology Program. The positions of personnel on the OTM are listed. The role and mission of the OTM is reviewed. The purpose of the Tribology Program is stated to be `to obtain industry input on program(s) in tribology/advanced lubricants areas of interest`. The objective addressed here is to identify opportunities for cost effective application of diamond and diamond-like carbon in transportation systems.

Perez, J.M.

1993-01-01

386

A new method for fabrication of diamond-dust blocking filters  

NASA Technical Reports Server (NTRS)

Thermal embedding of diamond dust onto a polyethylene-coated Al plate has been used to make a blocking filter for FIR applications. The Al plate is sandwiched between two Mylar 'blankets' and the air between the layers is removed by means of a small vacuum pump. After the polyethylene is heated and softened, the diamond dust is applied to the polyethylene coating using a brush. The optimum diamond dust grain sizes corresponding to polyethylene layer thicknesses of 9-12 microns are given in a table, and the application of the blocking filter to spectrometric measurements in the FIR is described. An exploded view diagram of the layered structure of the blocking filter is provided.

Collard, H. R.; Hogan, R. C.

1986-01-01

387

Diamond nanowires for highly sensitive matrix-free mass spectrometry analysis of small molecules.  

PubMed

This paper reports on the use of boron-doped diamond nanowires (BDD NWs) as an inorganic substrate for matrix-free laser desorption/ionization mass spectrometry (LDI-MS) analysis of small molecules. The diamond nanowires are prepared by reactive ion etching (RIE) with oxygen plasma of highly boron-doped (the boron level is 10(19) B cm(-3)) or undoped nanocrystalline diamond substrates. The resulting diamond nanowires are coated with a thin silicon oxide layer that confers a superhydrophilic character to the surface. To minimize droplet spreading, the nanowires were chemically functionalized with octadecyltrichlorosilane (OTS) and then UV/ozone treated to reach a final water contact angle of 120°. The sub-bandgap absorption under UV laser irradiation and the heat confinement inside the nanowires allowed desorption/ionization, most likely via a thermal mechanism, and mass spectrometry analysis of small molecules. A detection limit of 200 zeptomole for verapamil was demonstrated. PMID:22080363

Coffinier, Yannick; Szunerits, Sabine; Drobecq, Hervé; Melnyk, Oleg; Boukherroub, Rabah

2012-01-01

388

Diamond nanowires for highly sensitive matrix-free mass spectrometry analysis of small molecules  

NASA Astrophysics Data System (ADS)

This paper reports on the use of boron-doped diamond nanowires (BDD NWs) as an inorganic substrate for matrix-free laser desorption/ionization mass spectrometry (LDI-MS) analysis of small molecules. The diamond nanowires are prepared by reactive ion etching (RIE) with oxygen plasma of highly boron-doped (the boron level is 1019 B cm-3) or undoped nanocrystalline diamond substrates. The resulting diamond nanowires are coated with a thin silicon oxide layer that confers a superhydrophilic character to the surface. To minimize droplet spreading, the nanowires were chemically functionalized with octadecyltrichlorosilane (OTS) and then UV/ozone treated to reach a final water contact angle of 120°. The sub-bandgap absorption under UV laser irradiation and the heat confinement inside the nanowires allowed desorption/ionization, most likely via a thermal mechanism, and mass spectrometry analysis of small molecules. A detection limit of 200 zeptomole for verapamil was demonstrated.

Coffinier, Yannick; Szunerits, Sabine; Drobecq, Hervé; Melnyk, Oleg; Boukherroub, Rabah

2011-12-01

389

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

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

390

YBa2Cu3O7 thin films on nanocrystalline diamond films for HTSC bolometer  

NASA Technical Reports Server (NTRS)

Superconducting YBa2Cu3O(7-x) films on nanocrystalline diamond thin films have been fabricated. A composite buffer layer system consisting of diamond/Si3N4/YSZ/YBCO was explored for this purpose. The as-deposited YBCO films were superconducting with Tc of about 84 K and a relatively narrow transition width of about 8 K. SEM cross sections of the films showed very sharp interfaces between diamond/Si3N4 and between Si3N4/YSZ. The deposited YBCO film had a surface roughness of about 1000 A, which is suitable for high-temperature superconductive (HTSC) bolometer fabrication. It was also found that preannealing of the nanocrystalline diamond thin films at high temperature was very important for obtaining high-quality YBCO films.

Cui, G.; Beetz, C. P., Jr.; Boerstler, R.; Steinbeck, J.

1993-01-01

391

Diamond photodiodes for x-ray application  

SciTech Connect

Single crystal high purity CVD diamonds have been metallized and calibrated as photodiodes at the National Synchrotron Light Source (NSLS). Current mode responsivity measurements have been made over a wide range (0.2-28 keV) of photon energies across several beamlines. Linear response has been achieved over ten orders of magnitude of incident flux, along with uniform spatial response. A simple model of responsivity has been used to describe the results, yielding a value of 13.3 {+-} 0.5 eV for the mean pair creation energy. The responsivity vs. photon energy data show a dip for photon energies near the carbon edge (284 eV), indicating incomplete charge collection for carriers created less than one micron from the metallized layer.

Distel, James R [Los Alamos National Laboratory; Smedley, John [BNL; Keister, Jeffrey W [BNL; Muller, Erik [STONY BROOK UNIV.; Jordan - Sweet, Jean [WATSON RESEARCH CENTER; Bohon, Jen [CASE WESTERN RESERVE UNIV.; Dong, Bin [NON LANL

2009-01-01

392

Modal properties of isolated layer longitudinal leaky acoustic wave  

Microsoft Academic Search

In order to fabricate cavityless wafer level packaged devices based on longitudinal leaky surface (LLSAW) waves one has to find a coating with wave velocity approaching that of diamond. As diamond deposition conditions are prohibitive for SAW device technology so far, only the isolated layer acoustic wave (ILAW) approach may be used. We report on the possibility to use acoustic

S. Zhgoon; A. Shvetsov; K. Bhattacharjee

2010-01-01

393

Twin quintuplets in CVD diamond  

NASA Astrophysics Data System (ADS)

The atomic structure of twin quintuplets in a chemical vapor deposited (CVD) diamond film was - investigated by high resolution transmission electron microscopy (HRTEM). We conclude that the twin quintuplets have two main morphologies. The first consists of four Sigma = 3 twin boundaries and one Sigma = 81 twin boundary. The Sigma = 81 twin boundary contains the dislocations needed to accommodate a 7.35 deg misfit angle between a set of (111) planes on opposite sides of the boundary. In the second case, the 7.35 deg misfit angle is accommodated by two or more grain boundaries that are tilted slightly more than the 70.53 deg tilt of a Sigma = 3 boundary. These grain boundaries and the conventional diamond lattice twin boundaries are the only types of boundaries that we have observed in CVD diamond.

Shechtman, D.; Feldman, A.; Hutchison, J. L.

1992-08-01

394

Boron doped nanostructured diamond films  

NASA Astrophysics Data System (ADS)

A chemical vapor deposition hydrogen/methane/nitrogen feed-gas mixture with unconventionally high methane (15% CH4 by volume) normally used to grow ultra-hard and smooth nanostructured diamond films on Ti-6Al-4V alloy substrates was modified to include diborane B2H6 for boron-doping of diamond films. The flow rates for B2H 6 and N2 were varied to investigate their effect on plasma chemistry, film structure, boron incorporation, and mechanical properties. It was found that boron atoms can easily be incorporated into diamond films and change the lattice constant and film structure. Nitrogen, on the other hand, competes with boron in the plasma and acts to prevent boron incorporation into the diamond structure. In addition, with the appropriate choice of deposition conditions, the film structure can be tailored to range from highly crystalline, well faceted diamond to nanocrystalline diamond. Glancing angle X-ray diffraction and Micro-Raman were used as the main tools to investigate the relation between processing and structure. An optimal N2/CH4 ratio of 0.4 was found to result in a film with a minimum in grain size and surface roughness, along with high boron incorporation (˜4 x 1020 cm-3). Mechanical properties and thermal stability of boron doped nanostructured diamond films were examined by means of nanoindentation, open air thermal annealing, and nanotribometry. It was found that the films have high hardness close to that of undoped nanostructured diamond films. Thermal stability of these films was evaluated by heating in an oxygen environment above 700°C. Improved thermal stability of boron doped nanostructured diamond films was observed. Tribological tests show that although both undoped and boron doped nanostructured diamond films show extremely low coefficient of friction and wear rate as compared with uncoated titanium alloys (Ti-6Al-4V) and cobalt chrome alloy (Co-Cr-Mo), a critical failure max stress of 2.2 GPa was observed for boron doped nanostructured diamond films. A FORTRAN Chemical Kinetics Package for the Analysis of Gas Phase Chemical Kinetics, gas-phase thermodynamic equilibrium calculations involving H 2/CH4/N2/B2H6 mixtures was employed to investigate the chemical interactions leading to boron incorporation and crystalline structure variations. The strong influence of the BH 3 in causing the boron incorporation and the role of CN radical in causing the nanocrystallinity are confirmed by the correlation of their modeled compositions in the gas phase with boron content and degree of nanocrystallinity as determined experimentally. A good degree of agreement was obtained between the theoretically predicted gas phase concentration of species and the experimental concentration trends as measured by the optical emission spectroscopy of the microwave plasma. Overall, high film hardness and toughness, combined with good thermal stability and low surface roughness, indicate that nanostructured boron doped diamond films can be used as wear resistant coatings that are able to withstand high temperature oxidizing environments.

Liang, Qi

395

Underground at Black Diamond Mines  

SciTech Connect

Although California is noted for its mining history and annually leads the nation in total monetary value of minerals produced, there a few opportunities for the public to tour underground mines. One reason is that nearly all mining in the state today is done above ground in open pits. Another reason is that active underground mines are not commonly favorable to public tours. There is one place, Black Diamond Mines Regional Preserve, where the public can safely tour a formerly active underground mine. Black Diamond Mines Regional Preserve is a 3,600-acre parkland about 5 miles southwest of Antioch in Contra Costa County. The Preserve was established in the early 1970s and is administered by the East Bay Regional Park District. Black Diamond Mines Preserve is noteworthy for its mining history as well as its natural history, both of which are briefly described here.

Higgins, C.T.

1989-10-01

396

The effects of Ti carbonization on the nucleation and oriented growth of diamond films on cemented carbide.  

PubMed

To better understand the influence of carbonization of the Ti interlayer on diamond nucleation and growth, a series of Ti/diamond composite films were deposited on cemented carbide (WC:Co) substrates using a two-step deposition technique. The microstructural properties of the composite films were then characterized by scanning electron microscopy, X-ray diffractometry, and Raman spectroscopy, and their tribological properties were evaluated using a ball-on-disc tester and a metalloscope. The results showed that differences in carbonization for five Ti interlayers of different thicknesses led to variations in the preferred orientations of the TiC layers and in the subsequent nucleation and oriented growth of diamond. This suggests that Ti carbonization significantly influences the nucleation and growth of diamond and subsequently causes variations in the tribological properties of the produced diamond films. PMID:24625495

Yu, Xiang; Zhao, Xi-an; Liu, Ya-yun; Hua, Meng; Jiang, Xin

2014-04-01

397

Development of Designer Diamond Technology for High Pressure High Temperature Experiments in Support of Stockpile Stewardship Program  

SciTech Connect

The role of nitrogen in the fabrication of designer diamond was systematically investigated by adding controlled amount of nitrogen in hydrogen/methane/oxygen plasma. This has led to a successful recipe for reproducible fabrication of designer diamond anvils for high-pressure high-temperature research in support of stockpile stewardship program. In the three-year support period, several designer diamonds fabricated with this new growth chemistry were utilized in high-pressure experiments at UAB and Lawrence Livermore National Laboratory. The designer diamond anvils were utilized in high-pressure studies on heavy rare earth metals, high pressure melting studies on metals, and electrical resistance measurements on iron-based layered superconductors under high pressures. The growth chemistry developed under NNSA support can be adapted for commercial production of designer diamonds.

Vohra, Yogesh, K.

2009-10-28

398

Laser-based diagnostics of diamond synthesis reactors  

NASA Astrophysics Data System (ADS)

The many existing and potential applications of diamond thin films have created a flurry of activity directed toward the understanding and optimization of diamond synthesis by chemical vapor deposition (CVD). In this thesis, laser-based diagnostic techniques are applied to investigate the gas-phase environment of two diamond CVD reactors. Degenerate four-wave mixing (DFWM) is used to probe the thin reacting boundary layer above the deposition substrate in an atmospheric pressure plasma torch. Cavity ring-down spectroscopy (CRDS) is applied to measure absolute CH3 and CH radical concentrations and temperatures in a hot-filament CVD (HFCVD) reactor. Concentration and temperature profiles obtained by these experiments are compared with modeling predictions. Atmospheric pressure plasmas are an attractive method for diamond thin film synthesis because the inherently high reactant densities lead to large growth rates. DFWM is a technique that enables the in situ measurements of CH and C2 radical concentrations, vibrational and rotational temperatures, in the thin boundary layer above the diamond growth substrate. Measurements are also performed in a HFCVD reactor to gain additional understanding of the diamond growth process. The highly sensitive CRDS technique is used to measure the rotational temperature as well as absolute CH 3 and CH radical concentration profiles inside the HFCVD reactor during film growth. For many operating conditions, the methyl radical concentration is found to peak at a location several millimeters from the filament surface. The peak is the result the effects of steep temperature gradients and thermal diffusion, on the production and destruction of the methyl radical. The CH rotational temperature measurements indicate that the gas temperature near the filament surface is significantly lower than the filament temperature. This temperature discontinuity is due to the breakdown of the continuum energy conduction theory at low pressures, and to the small energy accommodation coefficient between hydrogen and the filament. Random temporal oscillations in the CH concentration are observed when the tungsten filament is replaced with a rhenium filament. The oscillations are attributed to surface reactions, and to the cyclical formation and destruction of a carbon layer on the filament surface.

Wahl, Edward Harmon

2001-07-01

399

Fabrication of GaP disk resonator arrays coupled to nitrogen-vacancy centers in diamond  

NASA Astrophysics Data System (ADS)

Nitrogen-vacancy (NV) centers coupled to scalable optical networks have the potential to realize solid-state quantum information processing platforms. Toward this goal, we demonstrate coupling of near-surface NV- centers to an array of GaP optical resonators. The use of GaP as the optical waveguiding materials is appealing due to the possibility of realizing integrated photonic switches based on the linear electro-optic effect. We explore large-area integration of GaP on diamond through two routes: molecular beam deposition directly onto diamond substrates and layer transfer of single-crystalline sheets. While the direct deposition benefits from simpler, monolithic processing, the layer transfer route benefits from higher material quality. In the latter approach, we demonstrate the transfer of submicrometer thick, mm2-sized GaP sheets from a GaP/AlGaP/GaP substrate to a diamond sample prepared with near-surface NV- centers. We fabricate large arrays of GaP disk resonators with varying diameters (1 to 20 ?m) on the diamond substrate via electron beam lithography and dry etching, and show coupling of the NV- center emission to the cavity structures. Quality factors above 10,000 were observed in 5 ?m diameter disks on the non-etched diamond substrate. Similar quality factors in smaller sized devices are expected with diamond substrate etching to further confine the optical mode. This approach opens a path towards the integration of coupled optical components in the hybrid GaP/diamond system, an essential step towards large-scale photonic networks utilizing NV- centers in diamond.

Thomas, Nicole K.; Barbour, Russell; Song, Yuncheng; Lee, Minjoo L.; Fu, Kai-Mei C.

2014-02-01

400

Thermal Conductivity Of Natural Type IIa Diamond  

NASA Technical Reports Server (NTRS)

Report describes application of flash diffusivity method to measure thermal conductivity of 8.04 x 8.84 x 2.35-mm specimen of natural, white, type-IIa diamond at temperatures between 500 and 1,250 K. Provides baseline for comparison to isotopically pure (12C) diamond. Results used as reference against which diamond films produced by chemical-vapor deposition at low pressures can be compared. High thermal conductivity of diamond exploited for wide variety of applications, and present results also used to estimate heat-conduction performances of diamond films in high-temperature applications.

Vandersande, Jan; Vining, Cronin; Zoltan, Andrew

1992-01-01

401

Diamond cutting element in a rotating bit  

SciTech Connect

An improved tooth for use in rotating diamond bits incorporating a generally triangular prismatic polycrystalline diamond element is devised by integrally forming an oval shaped base about the tooth or element extending from the face of the rotating bit, thereby providing a lateral reinforcing collar. The diamond element is also reinforced by a tapered trailing support having a leading surface contiguous and substantially congruous with the trailing surface of the diamond element. In one embodiment, a prepad provides reinforcement or support for the leading surface of the diamond element.

Grappendorf, R. H.

1985-01-01

402

Fabrication of single-crystal diamond microcomponents  

SciTech Connect

We have combined a technique for the lift-off of thin diamond films from a bulk diamond with a technique for engraving diamond with a focused excimer laser to produce free-standing single-crystal diamond microstructures. One microcomponent that has been produced is a 12 tooth gear [similar to]400 [mu]m in diameter and [similar to]13 [mu]m thick. Other microstructures have also been demonstrated, showing the versatility of this method. This process should be applicable to producing diamond microcomponents down to spatial dimensions (width and thickness) of a few micrometers.

Hunn, J.D.; Withrow, S.P.; White, C.W.; Clausing, R.E.; Heatherly, L. (Oak Ridge National Laboratory, Bldg 5500 MS-6376, Oak Ridge, Tennessee 37831-6376 (United States)); Christensen, C.P. (Potomac Photonics, Lanham, Maryland 20705 (United States))

1994-12-12

403

Diamond Ablators for Inertial Confinement Fusion  

SciTech Connect

Diamond has a unique combination of physical properties for the inertial confinement fusion ablator application, such as appropriate optical properties, high atomic density, high yield strength, and high thermal conductivity. Here, we present a feasible concept to fabricate diamond ablator shells. The fabrication of diamond capsules is a multi-step process, which involves diamond chemical vapor deposition on silicon mandrels followed by polishing, microfabrication of holes, and removing of the silicon mandrel by an etch process. We also discuss the pros and cons of coarse-grained optical quality and nanocrystalline chemical vapor deposition diamond films for the ablator application.

Biener, J; Mirkarimi, P B; Tringe, J W; Baker, S L; Wang, Y M; Kucheyev, S O; Teslich, N E; Wu, K J; Hamza, A V; Wild, C; Woerner, E; Koidl, P; Bruehne, K; Fecht, H

2005-06-21

404

Method for machining steel with diamond tools  

SciTech Connect

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.

Casstevens, John M. (Greenville, TX)

1986-01-01

405

Method for machining steel with diamond tools  

DOEpatents

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.

Casstevens, J.M.

1984-01-01

406

Mechanical properties of diamond and diamond-like films.  

National Technical Information Service (NTIS)

A discussion of the factors influencing hardness and elastic modulus measurements of thin films and hard materials is given with emphasis on DLC and diamond. Hardness values ranging from 5 to 15 GPa and elastic (Young's) modulus of 40 to 130 GPa were foun...

C. J. McHargue

1991-01-01

407

Diamond Wars? Conflict Diamonds and Geographies of Resource Wars  

Microsoft Academic Search

In the late 1990s, natural resources such as oil, diamonds, and timber came under increased scrutiny by conflict analysts and media outlets for their purported role in many contemporary wars. This article discusses some of the limitations of conventional arguments linking wars and resources. Dominated by econometric approaches and rational choice theory interpretations, arguments pertaining to “resource wars” often oversimplify

Philippe Le Billon

2008-01-01

408

Diamond radiation detectors II. CVD diamond development for radiation detectors  

SciTech Connect

Interest in radiation detectors has supplied some of the impetus for improving the electronic properties of CVD diamond. In the present discussion, we will restrict our attention to polycrystalhne CVD material. We will focus on the evolution of these materials over the past decade and the correlation of detector performance with other properties of the material.

Kania, D.R.

1997-05-16

409

Catalytic activity of platinum nanoparticles on highly boron-doped and 100-oriented epitaxial diamond towards HER and HOR.  

PubMed

Platinum nanoparticles supported on boron-doped single-crystalline diamond surfaces were used as a model system to investigate the catalytic activity with respect to the influence of particle morphology, particle density and surface preparation of the diamond substrates. We report on the preparation, characterization and activity regarding hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) of these Pt/diamond electrodes. Two kinds of diamond layers with boron doping above 10(20) cm(-3) were grown epitaxially on (100)-oriented diamond substrates; post-treatments of wet chemical oxidation and radio frequency (rf) oxygen plasma treatments were applied. Electrochemical deposition of Pt was performed using a potentiostatic double-pulse technique, which allowed variation of the particle size in the range between 1 nm and 15 nm in height and 5 nm and 50 nm in apparent radius, while keeping the particle density constant. Higher nucleation densities on the plasma processed surface at equal deposition parameters could be related to the plasma-induced surface defects. Electrochemical characterization shows that the platinum particles act as nanoelectrodes and form an ohmic contact with the diamond substrate. The catalytic activity regarding HER and HOR of the platinum nanoparticles exhibits no dependence on the particle size down to particle heights of ?1 nm. The prepared Pt on diamond(100) samples show a similar platinum-specific activity as bulk platinum. Therefore, while keeping the activity constant, the well-dispersed particles on diamond offer an optimized surface-to-material ratio. PMID:21687867

Brülle, Tine; Denisenko, Andrej; Sternschulte, Hadwig; Stimming, Ulrich

2011-07-28

410

Fabrication of ultra-thin diamond films using hydrogen implantation and Lift-off technique  

NASA Astrophysics Data System (ADS)

The Lift-off technique based on high fluence (>3×1016cm-2) implantation of hydrogen (H-) ions has been developed to increase the structural quality and electro-optical properties of the diamond thin membranes. According to the XTEM study the Vacuum Pressure - High Temperature (VPHT) treatment of the H2+ implanted (111) diamond plates at 1200-1600°C and 10-3Pa forms buried glassy like graphite layers in the implanted areas. High Pressure - High Temperature (HPHT) annealing at the same temperatures but under the pressure 4-8 GPa leads to the epitaxial growth of graphite in the buried implanted layers, which could not be etched chemically, but could be easily removed by etching in the anodic cell. Visible light Raman spectroscopy has shown that the H-Lift-off technique is suitable for formation of ultra-thin (down to 30 nm) high quality single crystal diamond membranes and heterostructures. High concentration of nitrogen-vacancy NV- centres (~1020cm-3) was observed under graphite contacts in thin layer (<=100 nm). Thin, 30 nm single crystal diamond films are the thinnest and largest area single crystal diamond structure produced to date by the Lift-off technique.

Popov, V. P.; Antonov, V. A.; Safronov, L. N.; Kupriyanov, I. N.; Pal'yanov, Yu. N.; Rubanov, S.

2012-11-01

411

Microstructure and tribological performance of self-lubricating diamond/tetrahedral amorphous carbon composite film  

NASA Astrophysics Data System (ADS)

In order to smooth the rough surface and further improve the wear-resistance of coarse chemical vapor deposition diamond films, diamond/tetrahedral amorphous carbon composite films were synthesized by a two-step preparation technique including hot-filament chemical vapor deposition for polycrystalline diamond (PCD) and subsequent filtered cathodic vacuum arc growth for tetrahedral amorphous carbon (ta-C). The microstructure and tribological performance of the composite films were investigated by means of various characterization techniques. The results indicated that the composite films consisted of a thick well-grained diamond base layer with a thickness up to 150 ?m and a thin covering ta-C layer with a thickness of about 0.3 ?m, and sp 3-C fraction up to 73.93%. Deposition of a smooth ta-C film on coarse polycrystalline diamond films was proved to be an effective tool to lower the surface roughness of the polycrystalline diamond film. The wear-resistance of the diamond film was also enhanced by the self-lubricating effect of the covering ta-C film due to graphitic phase transformation. Under dry pin-on-disk wear test against Si 3N 4 ball, the friction coefficients of the composite films were much lower than that of the single PCD film. An extremely low friction coefficient (˜0.05) was achieved for the PCD/ta-C composite film. Moreover, the addition of Ti interlayer between the ta-C and the PCD layers can further reduce the surface roughness of the composite film. The main wear mechanism of the composite films was abrasive wear.

Chen, Xinchun; Peng, Zhijian; Yu, Xiang; Fu, Zhiqiang; Yue, Wen; Wang, Chengbiao

2011-02-01

412

Diamond Nanophotonics and Quantum Optics  

NASA Astrophysics Data System (ADS)

The diamond nitrogen-vacancy (NV) center is an optically active impurity whose ``atom-like'' properties make it a promising solid state qubit, in which well-defined optical transitions are used to control the quantum state of single NV electron and nuclear spins. These properties have led to impressive demonstrations of quantum information storage in single NV nuclear spins, entanglement between NV electron spins and single photons, and implementations of high resolution optical magnetometers using single NVs. A missing ingredient for implementing quantum information processing architectures with NVs is creating scalable coherent coupling between them. Nanophotonic circuits, in which waveguides function as a ``quantum bus'' between NVs embedded in optical microcavities, offer a chip-based solution to this hurdle. In my talk I will review recent advances in realizing nanophotonic devices in diamond based materials. I will present results demonstrating Purcell enhanced coupling between optical nanocavities and NVs in single crystal diamond, and will discuss opportunities and challenges which lay ahead for diamond quantum optics.

Barclay, Paul

2011-10-01

413

Ion implantation doping of diamond  

SciTech Connect

The introduction by ion implantation of electrical dopants into single crystal diamond for the formation of an extrinsic semiconductor has been studied. RBS/channeling and optical absorption have been used to study the radiation damage produced by implantation of carbon ions into single crystal diamond. Damage recovery by thermal annealing has been measured as a function of dose, anneal temperature, and anneal rate. Three dose dependent effects have been observed in the annealed samples. At low dose, recovery of the crystal structure was possible when annealed above 900[degrees]C. At high dose, sufficient amorphization caused a conversion to graphite upon annealing at high temperature. In a medium dose range, a thermally stable damage region was formed at 800[degrees]C which showed no channeling but did not convert to graphite. The results of the annealing studies were applied to minimize the damage accompanying the implantation of boron (p-type), sodium (n-type), and other dopants into single crystal diamond. Implantation of boron successfully reproduced the semiconducting behavior observed in natural, boron doped, semiconducting diamond. A single electrical activation energy of 0.32 eV has been measured over a broader temperature range than previously observed. N-type doping with suitable species has also been attempted. Exponentially activated conduction has been observed but thermal instability points to a damage related mechanism.

Hunn, J.D.

1992-01-01

414

Valleytronics: Electrons dance in diamond  

NASA Astrophysics Data System (ADS)

In addition to manipulating the charge or spin of electrons, another way to control electric current is by using the 'valley' degree-of-freedom of electrons. The first demonstration of the generation, transport and detection of valley-polarized electrons in bulk diamond now opens up new opportunities for quantum control in electronic devices.

Nebel, Christoph E.

2013-08-01

415

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

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

416

High-density data storage using diamond probe technique  

NASA Astrophysics Data System (ADS)

A novel technique for high-density data storage that combines heat-assisted magnetic recording (HAMR) with scanning tunneling microscopy (STM) has been proposed. We use the metal-doped single-crystal diamond STM probe as the magnetic recording head for both heating and magnetization of the local fragment of the magnetic surface by applying pulsing emission current. Data is read using the same probe in the magnetic force measurement mode. Due to the presence of the magnetic inclusions diamond probe acts as a permanent magnet mounted on the flexible membrane capable to deform when subjected to the magnetic field coming from the substrate's magnetic layer. The proposed technique can potentially provide data densities up to 1 Tbit/in2.

Lysenko, O.; Novikov, N.; Grushko, V.; Shcherbakov, A.; Katrusha, A.; Ivakhnenko, S.

2008-03-01

417

Zr/oxidized diamond interface for high power Schottky diodes  

NASA Astrophysics Data System (ADS)

High forward current density of 103 A/cm2 (at 6 V) and a breakdown field larger than 7.7 MV/cm for diamond diodes with a pseudo-vertical architecture, are demonstrated. The power figure of merit is above 244 MW/cm2 and the relative standard deviation of the reverse current density over 83 diodes is 10% with a mean value of 10-9 A/cm2. These results are obtained with zirconium as Schottky contacts on the oxygenated (100) oriented surface of a stack comprising an optimized lightly boron doped diamond layer on a heavily boron doped one, epitaxially grown on a Ib substrate. The origin of such performances are discussed.

Traoré, A.; Muret, P.; Fiori, A.; Eon, D.; Gheeraert, E.; Pernot, J.

2014-02-01

418

Multiple Diamond Anvil (MDA) apparatus using nano-polycrystalline diamond  

NASA Astrophysics Data System (ADS)

Thanks to the great efforts by Dave Mao, Bill Bassett, Taro Takahashi, and their colleagues at the University of Rochester through 1960s-70s, diamond anvil cell (DAC) became a major tool to investigate the deep Earth after its invention by scientists at NBS in 1958. DAC can now cover almost the entire pressure and temperature regimes of the Earth's interior, which seems to have solved the longstanding debate on the crystal structure of iron under the P-T conditions of the Earth's inner core. In contrast, various types of static large-volume presses (LVP) have been invented, where tungsten carbide has conventionally been used as anvils. Kawai-type multianvil apparatus (MA), which utilize 6 first-stage harden steel and 8 tungsten carbide anvils, is the most successful LVP, and has been used for accurate measurements of phase transitions, physical properties, element partitioning, etc. at high pressure and temperature. However, pressures using tungsten carbide as the second-stage anvils have been limited to about 30 GPa due to significant plastic deformation of the anvils. Efforts have been made to expand this pressure limit by replacing tungsten carbide anvils with harder sintered diamond (SD) anvils over the last two decades, but the pressures available in KMA with SD anvils have still been limited to below 100 GPa. We succeeded to produce nano-polycrystalline diamond (NPD or HIME-Diamond) in 2003, which is known to have ultrahigh hardness, very high toughness and elastic stiffness, high transmittance of light, relatively low thermal conductivity. These properties are feasible for its use as anvils, and some preliminary experiments of application of NPD anvils to laser heated DAC have successfully made in the last few years. We are now able to synthesize NPD rods with about 1cm in both diameter and length using a newly constructed 6000-ton KMA at Geodynamics Research Center, Ehime University, and have just started to apply this new polycrystalline diamond as anvils for multianvil apparatus. Various versions of the Multiple Diamond Anvil (MDA) apparatus with NPD anvils (Fig.1), amalgamated forms of MA and DAC, are currently being tested for experiments under Mbar regimes without sacrificing the advantages of MA over DAC.

Irifune, T.; Kunimoto, T.; Tange, Y.; Shinmei, T.; Isobe, F.; Kurio, A.; Funakoshi, K.

2011-12-01

419

Medical applications of diamond particles and surfaces.  

SciTech Connect

Diamond has been considered for use in several medical applications due to its unique mechanical, chemical, optical, and biological properties. In this paper, methods for preparing synthetic diamond surfaces and particles are described. In addition, recent developments involving the use of diamond in prostheses, sensing, imaging, and drug delivery applications are reviewed. These developments suggest that diamond-containing structures will provide significant improvements in the diagnosis and treatment of medical conditions over the coming years. Diamond is an allotrope of carbon that is being considered for use in several medical applications. Ramachandran determined that the crystal structure of diamond consists of two close packed interpenetrating face centered cubic lattices; one lattice is shifted with respect to the other along the elemental cube space diagonal by one-quarter of its length. If one approximates carbon atoms as equal diameter rigid spheres, the filling of this construction is 34%. Due to the carbon-carbon distance (1.54 {angstrom}), diamond crystal exhibits the highest atomic density (1.76 x 10{sup 23} cm{sup -3}) of any solid. The very high bond energy between two carbon atoms (83 kcal/mol) and the directionality of tetrahedral bonds are the main reasons for the high strength of diamond. Diamond demonstrates the highest Vickers hardness value of any material (10,000 kg/mm{sup 2}). The tribological properties of diamond are also impressive; the coefficient of friction of polished diamond is 0.07 in argon and 0.05 in humid air. Diamond is resistant to corrosion except in an oxygen atmosphere at temperatures over 800 C. In addition, type IIa diamond exhibits the highest thermal conductivity of all materials (20 W cm{sup -1} K{sup -1} at room temperature).

Narayan, R. J.; Boehm, R. D.; Sumant, A. V. (Center for Nanoscale Materials); (Univ. of California)

2011-04-01

420

Diamond-coated ATR prism for infrared absorption spectroscopy of surface-modified diamond nanoparticles  

NASA Astrophysics Data System (ADS)

Linear antenna microwave chemical vapor deposition process was used to homogeneously coat a 7 cm long silicon prism by 85 nm thin nanocrystalline diamond (NCD) layer. To show the advantages of the NCD-coated prism for attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) of nanoparticles, we apply diamond nanoparticles (DNPs) of 5 nm nominal size with various surface modifications by a drop-casting of their methanol dispersions. ATR-FTIR spectra of as-received, air-annealed, plasma-oxidized, and plasma-hydrogenated DNPs were measured in the 4000-1500 cm-1 spectral range. The spectra show high spectral resolution, high sensitivity to specific DNP surface moieties, and repeatability. The NCD coating provides mechanical protection against scratching and chemical stability of the surface. Moreover, unlike on bare Si surface, NCD hydrophilic properties enable optically homogeneous coverage by DNPs with some aggregation on submicron scale as evidenced by scanning electron microscopy and atomic force microscopy. Compared to transmission FTIR regime with KBr pellets, direct and uniform deposition of DNPs on NCD-ATR prism significantly simplifies and speeds up the analysis (from days to minutes). We discuss prospects for in situ monitoring of surface modifications and molecular grafting.

Remes, Z.; Kozak, H.; Rezek, B.; Ukraintsev, E.; Babchenko, O.; Kromka, A.; Girard, H. A.; Arnault, J.-C.; Bergonzo, P.

2013-04-01

421

Pt-polyaniline nanocomposite on boron-doped diamond electrode for amperometic biosensor with low detection limit  

Microsoft Academic Search

Boron-doped diamond electrodes covered with a nanostructured Pt nanoparticle-polyaniline composite have been fabricated and\\u000a employed as sensitive amperometric sensors with low detection limit. A highly conductive boron-doped diamond thin film (BDD)\\u000a was prepared by chemical vapor deposition, and its morphology was characterized by scanning electron microscopy and transmission\\u000a electron microscopy. The nanostructured composite layer was grown on the BDD electrode

Min-Jung Song; Jong Hoon Kim; Seung Koo Lee; Jae-Hyun Lee; Dae Soon Lim; Sung Woo Hwang; Dongmok Whang

2010-01-01

422

Study of polycrystalline and single crystal diamond detectors irradiated with pions and neutrons up to 3×1015 cm?2  

Microsoft Academic Search

Polycrystalline CVD (pCVD) diamond detectors are a viable candidate for the innermost tracking layer of experiments at the SLHC, where lifetime fluences are expected to exceed 1016 particles\\/cm2. Irradiation data of diamonds in this fluence range are scarce, and mostly rely on high-energy protons. According to recent NIEL simulations radiation damage induced by fast reactor neutrons might be representative of

M. Mikuz; V. Cindro; S. Cline; I. Dolenc; A. Gorisek; H. Kagan; G. Kramberger; I. Mandic; S. Smith; M. Zavrtanik

2007-01-01

423

Synthesizing Diamond from Liquid Feedstock  

NASA Technical Reports Server (NTRS)

A relatively economical method of chemical vapor deposition (CVD) has been developed for synthesizing diamond crystals and films. Unlike prior CVD methods for synthesizing diamond, this method does not require precisely proportioned flows of compressed gas feedstocks or the use of electrical discharges to decompose the feedstocks to obtain free radicals needed for deposition chemical reactions. Instead, the feedstocks used in this method are mixtures of common organic liquids that can be prepared in advance, and decomposition of feedstock vapors is effected simply by heating. The feedstock used in this method is a solution comprising between 90 and 99 weight percent of methanol and the balance of one or more other oxyhydrocarbons that could include ethanol, isopropanol, and/or acetone. This mixture of compounds is chosen so that dissociation of molecules results in the desired proportions of carbon-containing radicals (principally, CH3) and of OH, H, and O radicals. Undesirably, the CVD temperature and pressure conditions thermodynamically favor the growth of graphite over the growth of diamond. The H radicals are desirable because they help to stabilize the growing surface of diamond by shifting the thermodynamic balance toward favoring the growth of diamond. The OH and O radicals are desirable because they preferentially etch graphite and other non-diamond carbon, thereby helping to ensure the net deposition of pure diamond. The non-methanol compounds are included in the solution because (1) methanol contains equal numbers of C and O atoms; (2) an excess of C over O is needed to obtain net deposition of diamond; and (3) the non-methanol molecules contain multiple carbon atoms for each oxygen atom and thus supply the needed excess carbon A typical apparatus used in this method includes a reservoir containing the feedstock liquid and a partially evacuated stainless-steel reaction chamber. The reservoir is connected to the chamber via tubing and a needle valve or other suitable flow controller. When the liquid enters the low-pressure environment inside the chamber, it evaporates to form a vapor mixture of the same chemical composition. In addition to the inlet for the feedstock liquid, the chamber is fitted with an outlet connected to a vacuum pump (not shown) through a throttle valve (also not shown) that is automatically controlled to keep the pressure at or near the required value throughout the deposition process. Inside the chamber, a spiral filament made of tungsten, tantalum, graphite, or other high-melting-temperature material is electrically heated to a temperature >2,000 C high enough to cause dissociation of vapor molecules into the aforementioned radicals. A deposition substrate typically, a diamond-polished silicon wafer about 2.5 cm square is positioned about 2 cm away from the filament. The exact location of the substrate is chosen so that the substrate becomes heated by the filament to a deposition temperature in the approximate range of 800 to 1,000 C.

Tzeng, Yonhua

2005-01-01

424

Measurements and Studies of Secondary Electron Emission of Diamond Amplified Photocathode  

SciTech Connect

The Diamond Amplified Photocathode (DAP) is a novel approach to generating electrons. By following the primary electron beam, which is generated by traditional electron sources, with an amplifier, the electron beam available to the eventual application is increased by 1 to 2 orders of magnitude in current. Diamond has a very wide band gap of 5.47eV which allows for a good negative electron affinity with simple hydrogenation, diamond can hold more than 2000MV/m field before breakdown. Diamond also provides the best rigidity among all materials. These two characters offer the capability of applying high voltage across very thin diamond film to achieve high SEY and desired emission phase. The diamond amplifier also is capable of handling a large heat load by conduction and sub-nanosecond pulse input. The preparation of the diamond amplifier includes thinning and polishing, cleaning with acid etching, metallization, and hydrogenation. The best mechanical polishing available can provide high purity single crystal diamond films with no less than 100 {micro}m thickness and <15 nm Ra surface roughness. The ideal thickness for 700MHz beam is {approx}30 {micro}m, which requires further thinning with RIE or laser ablation. RIE can achieve atomic layer removal precision and roughness eventually, but the time consumption for this procedure is very significant. Laser ablation proved that with <266nm ps laser beam, the ablation process on the diamond can easily achieve removing a few microns per hour from the surface and <100nm roughness. For amplifier application, laser ablation is an adequate and efficient process to make ultra thin diamond wafers following mechanical polishing. Hydrogenation will terminate the diamond surface with monolayer of hydrogen, and form NEA so that secondary electrons in the conduction band can escape into the vacuum. The method is using hydrogen cracker to strike hydrogen atoms onto the bare diamond surface to form H-C bonds. Two independent experiments were carried out to determine the transport of the electrons within the diamond and their emission at the surface. In transmission mode measurements, the diamond amplifier was coated with metal on both sides, so results simply depend only on the electron transport within the diamond. The SEY for this mode provides one secondary electron per 20eV energy, which gives the gain of more than 200 for 4.7keV (effective energy) primary electrons under 2MV/m. Laser detrapping can help the signal maintain the gain with lops pulse and duty cycle of 1.67 x 10{sup -7}. In emission mode measurements, in which the diamond is prepared as in the actual application, the SEY is {approx}20 for 700eV (effective energy) primary electrons under 1.21MV/m. The electric field applied and the primary electron energy is limited by the experiment setup, but the results show good trend toward large gain under high field. Thermal emittance of the diamond secondary emission is critical for the beam application. A careful design is setup to measure with very fine precision and accuracy of 0.01eV.

Wu,Q.

2008-10-01

425

Hydrogen-doped cubic diamond and the crystal structure of n-diamond  

NASA Astrophysics Data System (ADS)

A comprehensive analysis of the crystal structure of n-diamond has been carried out based on a hydrogen-doped (H-doped) diamond model using first principles calculations. In particular, hydrogen concentration dependent elastic constants and lattice parameters for the H-doped diamond have been analyzed. Our results indicate that when the hydrogen concentration is less than 19 at.%, the H-doped diamond is mechanically stable. When the hydrogen concentration is about 4 at.%, the optimized lattice parameter, simulated XRD pattern and electronic properties for the H-doped diamond are all agree well with the corresponding experimental values of n-diamond. The results imply that the n-diamond is likely to be an H-doped diamond.

Wen, Bin; Melnik, Roderick; Yao, Shan; Li, Tingju

2011-11-01

426

Adhesive bonding and brazing of nanocrystalline diamond foil onto different substrate materials  

NASA Astrophysics Data System (ADS)

Diamond coatings are used in heavily stressed industrial applications to reduce friction and wear. Hot-filament chemical vapour deposition (HFCVD) is the favourable coating method, as it allows a coating of large surface areas with high homogeneity. Due to the high temperatures occurring in this CVD-process, the selection of substrate materials is limited. With the desire to coat light materials, steels and polymers a new approach has been developed. First, by using temperature-stable templates in the HFCVD and stripping off the diamond layer afterwards, a flexible, up to 150 ?m thick and free standing nanocrystalline diamond foil (NCDF) can be produced. Afterwards, these NCDF can be applied on technical components through bonding and brazing, allowing any material as substrate. This two-step process offers the possibility to join a diamond layer on any desired surface. With a modified scratch test and Rockwell indentation testing the adhesion strength of NCDF on aluminium and steel is analysed. The results show that sufficient adhesion strength is reached both on steel and aluminium. The thermal stress in the substrates is very low and if failure occurs, cracks grow undercritically. Adhesion strength is even higher for the brazed samples, but here crack growth is critical, delaminating the diamond layer to some extent. In comparison to a sample directly coated with diamond, using a high-temperature CVD interlayer, the brazed as well as the adhesively bonded samples show very good performance, proving their competitiveness. A high support of the bonding layer could be identified as crucial, though in some cases a lower stiffness of the latter might be acceptable considering the possibility to completely avoid thermal stresses which occur during joining at higher temperatures.

Lodes, Matthias A.; Sailer, Stefan; Rosiwal, Stefan M.; Singer, Robert F.

2013-10-01

427