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Showing papers on "Diamond published in 2003"


Journal ArticleDOI
06 Feb 2003-Nature
TL;DR: Surprisingly, this synthesized polycrystalline diamond is ultrahard and so could be useful in the manufacture of scientific and industrial tools.
Abstract: Polycrystalline diamonds are harder and tougher than single-crystal diamonds and are therefore valuable for cutting and polishing other hard materials, but naturally occurring polycrystalline diamond is unusual and its production is slow. Here we describe the rapid synthesis of pure sintered polycrystalline diamond by direct conversion of graphite under static high pressure and temperature. Surprisingly, this synthesized diamond is ultrahard and so could be useful in the manufacture of scientific and industrial tools.

617 citations


Journal ArticleDOI
TL;DR: The surfactant-mediated shape evolution of titanium dioxide anatase nanocrystals in nonaqueous media was studied and the modulation of surface energies of the different crystallographic faces through the use of a surface selective surfactants is the key parameter for the shape control.
Abstract: The surfactant-mediated shape evolution of titanium dioxide anatase nanocrystals in nonaqueous media was studied. The shape evolves from bullet and diamond structures to rods and branched rods. The modulation of surface energies of the different crystallographic faces through the use of a surface selective surfactant is the key parameter for the shape control.

556 citations


Journal ArticleDOI
TL;DR: By combining the volume and the frequency pressure shifts, it is deduced that diamond remains very stable under pressure: it is a Gruneisen solid up to at least 140 GPa, and the covalent bond is even slightly strengthened under pressure.
Abstract: Diamond is the archetypal covalent material. Each atom in an sp3 configuration is bonded to four nearest neighbours. Because of its remarkable properties, diamond has been extensively studied1. And yet our knowledge of the properties of diamond under very high pressure is still incomplete. Although diamond is known to be the preferred allotrope of carbon at high pressure, the possibility of producing under pressure high-density polymorphs of diamond, including metallic forms, has been discussed2,3,4. Structural changes have already been reported in diamond under non-hydrostatic pressures around 150 GPa and large deformation5. However, measurements6,7,8 of the properties of diamond under hydrostatic pressure have been limited to below 40 GPa. Here, we report accurate measurements of the volume and of the optical phonon frequency of diamond under hydrostatic pressure up to 140 GPa. We show that diamond is more compressible than currently expected. By combining the volume and the frequency pressure shifts, we deduce that diamond remains very stable under pressure: it is a Gruneisen solid up to at least 140 GPa, and the covalent bond is even slightly strengthened under pressure. Finally, the optical phonon frequency versus pressure is calibrated here to be used as a pressure gauge for diamond anvil cell studies in the multi-megabar range.

405 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present x-ray absorption and emission experiments and ab initio calculations showing that the size of carbon diamond must be reduced to at least 2 nm in order to observe an increase of its optical gap, at variance with Si and Ge where quantum confinement effects persist up to 6-7 nm.
Abstract: We present x-ray absorption and emission experiments and ab initio calculations showing that the size of carbon diamond must be reduced to at least 2 nm, in order to observe an increase of its optical gap, at variance with Si and Ge where quantum confinement effects persist up to 6-7 nm. In addition, our calculations show that the surface of nanodiamond particles larger than approximately 1 nm reconstructs in a fullerenelike manner, giving rise to a new family of carbon clusters: bucky diamonds. Signatures of these surface reconstructions are compatible with pre-edge features observed in measured absorption spectra.

341 citations


Journal ArticleDOI
TL;DR: In this article, a review summarizes some of the recent work aimed at applying conductive (boron-doped) diamond electrodes to improve procedures in electroanalysis, including the application of boron-coated diamond electrodes.
Abstract: Diamond as a high performance material occupies a special place due to its in many ways extreme properties, e.g., hardness, chemical inertness, thermal conductivity, optical properties, and electric characteristics. Work mainly over the last decade has shown that diamond also occupies a special place as an electrode material with interesting applications in electroanalysis. When made sufficiently electrically conducting for example by boron-doping, ‘thin film' and ‘free–standing' diamond electrodes exhibit remarkable chemical resistance to etching, a wide potential window, low background current responses, mechanical stability towards ultrasound induced interfacial cavitation, a low ‘stickiness' in adsorption processes, and a high degree of ‘tunability' of the surface properties. This review summarizes some of the recent work aimed at applying conductive (boron-doped) diamond electrodes to improve procedures in electroanalysis.

326 citations


Journal ArticleDOI
TL;DR: Diamond electrodes offer superb properties for a variety of electrochemical technologies, properties that include corrosion resistance, low background current, good responsiveness without pretreatment, resistance to fouling, and optical transparency.

305 citations


Journal ArticleDOI
TL;DR: In this article, a simplified mechanism involving hydroxyl radicals formed by water discharge has been proposed for water oxidation on boron-doped diamond anodes, where small amounts of O3 and H2O2 are formed.
Abstract: Electrolysis in aqueous 1 M HClO4 and 1 M H2SO4 solutions has been carried out under galvanostatic conditions using boron-doped diamond electrodes (BDD). Analyses of the oxidation products have shown that in 1 M HClO4 the main reaction is oxygen evolution, while in H2SO4 the main reaction is the formation of H2S2O8. In both electrolytes small amounts of O3 and H2O2 are formed. Finally, a simplified mechanism involving hydroxyl radicals formed by water discharge has been proposed for water oxidation on boron-doped diamond anodes.

278 citations


Journal ArticleDOI
TL;DR: In this article, columnar-structured diamond films with column diameters less than 100 nm and thickness in the range of 1-5 μm were grown on silicon substrates by chemical vapor deposition (CVD) in a microwave plasma reactor with purified methane and hydrogen used as the reactants.
Abstract: Nanocrystalline columnar-structured diamond films with column diameters less than 100 nm and thicknesses in the range of 1–5 μm were grown on silicon substrates by chemical vapor deposition (CVD) in a microwave plasma reactor with purified methane and hydrogen used as the reactants. Uniform conformal nucleation densities in excess of 1012 cm−2 were accomplished prior to growth by seeding with explosively formed nanodiamonds, which resulted in good optical quality films. The film thickness was measured in situ by the laser reflectometry method. The grain size and optical quality of the films were characterized by scanning electron microscopy and Raman measurements. Broadband surface acoustic wave pulses were used to measure the anomalous dispersion in the layered systems. The experimental dispersion curves were fitted by theory, assuming the diamond film as an isotropic layer on an anisotropic silicon substrate, to determine mean values of the density and Young’s modulus of the diamond films. The density w...

266 citations


Journal ArticleDOI
TL;DR: In this article, the laser-induced periodic surface structure (LIPSS) with periodicity about a quarter of the laser wavelength on unpolished diamond film treated by a P-polarized femtosecond laser was observed.
Abstract: We report the laser-induced periodic surface structure (LIPSS) with periodicity about a quarter of the laser wavelength on unpolished diamond film treated by a P-polarized femtosecond laser. The short period LIPSS is parallel to the laser polarization and independent on the incidence angle. The LIPSS perpendicular to the laser polarization with periodicity shorter than a third of the laser wavelength slightly dependent on the incidence angle is also observed as well as the LIPSS perpendicular to the laser polarization with periodicity dependent on the incidence angle. The results are explained by interference of the incident laser and surface scattered wave related to the excited electrons during laser interactions with diamond, being in excellent agreement with a previously developed theory.

243 citations


Journal ArticleDOI
TL;DR: In this paper, nitrogen-doped ultrananocrystalline diamond (UNCD), Raman scattering, near edge xray absorption fine structure (NEXAFS), soft x-ray fluorescence (SXF), and secondary ion mass spectroscopy (SIMS) measurements were performed.
Abstract: The transport properties of diamond thin films are well known to be sensitive to the sp2/sp3-bonded carbon ratio, the presence of the grain boundaries and other defects, and to the presence of various impurities. In order to clarify the roles these factors play in the conduction mechanisms of nitrogen-doped ultrananocrystalline diamond (UNCD), Raman scattering, near edge x-ray absorption fine structure (NEXAFS), soft x-ray fluorescence (SXF), and secondary ion mass spectroscopy (SIMS) measurements were performed. Transmission electron microscopy analysis of nitrogen doped UNCD has previously indicated that the films are composed of crystalline diamond nano-grains with boundaries of amorphous carbon, and NEXAFS measurements reveal that the global amount of sp2-bonded carbon in these films increases slightly with nitrogen doping. The nitrogen content is quantified with high-resolution SIMS analysis, while NEXAFS and SXF indicates that the nitrogen exists primarily in tetrahedrally coordinated sites. These m...

243 citations


Journal ArticleDOI
TL;DR: In this paper, the position of the ν 1 mode of trans-polyacetylene using a vibronic model for resonance Raman scattering and compared the results with the measured positions of the 1150 cm−1 mode for diamond samples on different substrates and found a very good agreement.

Journal ArticleDOI
TL;DR: The results showed that a spatial resolution up to 13 μm can be achieved without the use of infrared microscope objectives, which is the first time that FT-IR imaging is reported using such a versatile accessory based on a diamond ATR crystal.
Abstract: New opportunities exist to obtain chemical images using attenuated total reflection infrared (ATR-IR) spectroscopy. This paper shows the feasibility of obtaining FT-IR images with a spatial resolution of at least 3-4 μm using a Ge ATR objective coupled with an infrared microscope. The improved spatial resolution compared to FT-IR images obtained by the transmission method is due to the high refractive index of the ATR crystal, which gives a high numerical aperture and hence, a higher spatial resolution. FT-IR imaging with a conventional diamond ATR accessory has been investigated. This is the first time that FT-IR imaging is reported using such a versatile accessory based on a diamond ATR crystal. These results showed that a spatial resolution up to 13 μm can be achieved without the use of infrared microscope objectives. One advantage of the diamond element is that it allows pressure to be applied and hence, good contact to be obtained over the whole field of view.

Journal ArticleDOI
TL;DR: In this paper, the authors used microwave plasma chemical vapour deposition to grow epitaxial diamond layers with low boron doping, from 5 × 1014 to 1 × 1016 cm−3, and the compensating n-type impurities are the lowest reported for any semiconducting diamond, 700 °C for 1 s in air.
Abstract: Exceptionally pure epitaxial diamond layers have been grown by microwave plasma chemical vapour deposition, which have low boron doping, from 5 × 1014 to 1 × 1016 cm−3, and the compensating n-type impurities are the lowest reported for any semiconducting diamond, 700 °C for ~1 s in air. Schottky diodes made on these epitaxial diamond films have breakdown voltages >6 kV, twelve times the highest breakdown voltage reported for any diamond diode and higher than any other semiconductor Schottky diode.

Journal ArticleDOI
TL;DR: In this paper, phase-memory times as long as 58μs at 300 K for nitrogen-vacancy centers in CVD single crystals were studied. But it is not clear whether these phase-modes represent a fundamental limit or are limited by an external source of decoherence.
Abstract: Electron-spin-echo experiments reveal phase-memory times as long as 58 μs at 300 K for nitrogen-vacancy centers in chemical vapor deposition (CVD) single crystals. The spins were optically polarized and optically detected. Two high-quality CVD samples were studied. From the current results, it is not clear whether these phase-memory times represent a fundamental limit or are limited by an external source of decoherence.

Journal ArticleDOI
TL;DR: It is found that at about 3 nm, and for a broad range of pressures and temperatures, particles with bare, reconstructed surfaces become thermodynamically more stable than those with hydrogenated surfaces, thus preventing the formation of larger grains.
Abstract: Nanometre-sized diamond has been found in meteorites1, protoplanetary nebulae2 and interstellar dusts3, as well as in residues of detonation4 and in diamond films5,6. Remarkably, the size distribution of diamond nanoparticles seems to be peaked around 2–5 nm, and to be largely independent of preparation conditions. We have carried out ab initio calculations of the stability of nanodiamond as a function of surface hydrogen coverage and of size. We have found that at about 3 nm, and for a broad range of pressures and temperatures, particles with bare, reconstructed surfaces become thermodynamically more stable than those with hydrogenated surfaces, thus preventing the formation of larger grains. Our findings provide an explanation of the size distribution of extraterrestrial and of terrestrial nanodiamond found in ultradispersed and ultracrystalline diamond films. They also provide an atomistic structural model of these films, based on the topology and structure of 2–3-nm dimond clusters consisting of a diamond core surrounded by a fullerene-like carbon network7.

Journal ArticleDOI
TL;DR: The present work reports on the use of diamond anodes for the chemical oxygen demand (COD) removal from several industrial wastewater and from two synthetic wastewaters with malic acid and ethylenediaminetetraacetic (EDTA) acid.

Journal ArticleDOI
TL;DR: In this article, the electrochemical incineration of organic pollutants on a boron-doped diamond (BDD) thin film electrode was examined by bulk electrolysis, and the mechanism of oxidation was investigated.
Abstract: The electrochemical incineration of organic pollutants on a boron-doped diamond (BDD) thin film electrode was examined by bulk electrolysis, and the mechanism of oxidation was investigated. A compa...

Journal ArticleDOI
TL;DR: The nanocrystallinity is a result of a growth and nucleation mechanism discovered by Gruen, which involves the insertion of C2 carbon dimer into C−H bonds on the growth surface as mentioned in this paper.
Abstract: The deposition, characterization, and electrochemical responsiveness of boron-doped nanocrystalline diamond thin-film electrodes is reported. The films consist of clusters of diamond grains, ∼50−100 nm in diameter, and possess an rms surface roughness of 34 nm over a 5 × 5 μm2 area. The individual and randomly ordered diamond grains are approximately 10−15 nm in diameter, as evidenced by TEM. The ∼4-μm-thick films were deposited by microwave-assisted chemical vapor deposition (CVD) using a CH4/H2/Ar source gas mixture (1%/5%/95%). Under these conditions, C2, rather than CH3•, appears to be the dominant nucleation and growth precursor. The nanocrystallinity is a result of a growth and nucleation mechanism discovered by Gruen, which involves the insertion of C2 carbon dimer into C−H bonds on the growth surface (MRS Bull. 1998, 23, 32). The nanocrystalline morphology results from a high renucleation rate. However, unlike previously reported nanocrystalline diamond thin films that have electrical properties d...

Journal ArticleDOI
TL;DR: Measurements are presented with a low-temperature atomic force microscope with pico-Newton force sensitivity that reveal the hidden surface atom in graphite.
Abstract: Carbon, the backbone material of life on Earth, comes in three modifications: diamond, graphite, and fullerenes. Diamond develops tetrahedral sp3 bonds, forming a cubic crystal structure, whereas graphite and fullerenes are characterized by planar sp2 bonds. Polycrystalline graphite is the basis for many products of everyday life: pencils, lubricants, batteries, arc lamps, and brushes for electric motors. In crystalline form, highly oriented pyrolytic graphite is used as a diffracting element in monochromators for x-ray and neutron scattering and as a calibration standard for scanning tunneling microscopy (STM). The graphite surface is easily prepared as a clean atomically flat surface by cleavage. This feature is attractive and is used in many laboratories as the surface of choice for “seeing atoms.” Despite the proverbial ease of imaging graphite by STM with atomic resolution, every second atom in the hexagonal surface unit cell remains hidden, and STM images show only a single atom in the unit cell. Here we present measurements with a low-temperature atomic force microscope with pico-Newton force sensitivity that reveal the hidden surface atom.

Journal ArticleDOI
TL;DR: Fabrication and evaluation of a subwavelength grating in diamond, designed to reduce the Fresnel reflection, is demonstrated and microlenses in diamond are demonstrated, which show good performance.
Abstract: Fabrication and evaluation of a subwavelength grating in diamond, designed to reduce the Fresnel reflection, is demonstrated. The antireflection (AR) structures are designed to reduce the surface reflection at an illuminating wavelength of 10.6 µm. With this AR-treatment, where no other material is introduced (i.e., no thin film coating), the unique properties of diamond can be fully used. The fabricated AR structures were optically evaluated with a spectrophotometer. The transmission through a diamond substrate with AR structures on both sides was increased from 71% to 97%, with a theoretical value of 99%. Microlenses in diamond are also demonstrated. The lenses are evaluated with interferometers and show good performance. The micro-optical structures were fabricated by electron-beam lithography or photolithographic methods followed by plasma etching.

Journal ArticleDOI
TL;DR: In this article, the formation mechanisms of diamond as well as the transformation of diamond to graphite and onion-like carbon upon heating were analyzed. But the mechanism of diamond formation has not been previously analyzed.
Abstract: Synthesis of nano- and microcrystalline sp3-bonded carbon (diamond) with cubic and hexagonal structure by extraction of silicon from silicon carbide in chlorine-containing gases has been reported recently. This process is attractive because it can produce diamond at ambient pressure and temperatures below 1000 °C. No plasma or other high-energy activation is required, thus providing an opportunity for large-scale synthesis. However, the mechanism of diamond formation has not been previously analyzed. This work reports on the formation mechanisms of diamond as well as the transformation of diamond to graphite and onionlike carbon upon heating. Study of SiC/carbon interfaces showed that direct epitaxial growth of diamond on SiC is possible, in agreement with previous molecular-dynamics simulation. However, random nucleation of diamond from amorphous sp3-bonded carbon produced as the result of extraction of Si from SiC has also been demonstrated. It has been shown that the presence of hydrogen in the environ...

Patent
28 Aug 2003
TL;DR: An articulating diamond-surfaced spinal implant with a concave surface end and a convex surface has been proposed in this article, where the two components form a device with diamond-to-diamond contact at the articulation point.
Abstract: An articulating diamond-surfaced spinal implants having a first component (60074) with a concave surface end and a corresponding second element (60075) having a convex surface. The two components form a device with diamond to diamond contact at the articulation point.

Journal ArticleDOI
TL;DR: In this paper, a shapely beautiful AlN nanotube with a uniform diameter has been obtained in this work, which even rivals the carbon nanotubes, which is expected to find novel applications in the nanotechnology area.

Journal ArticleDOI
TL;DR: The only dopant available for bulk diamond with good controllability is boron, which acts as an acceptor and can be incorporated in relatively high concentrations, allowing the design of devices for electronic applications.
Abstract: To date, the only dopant available for bulk diamond with good controllability is boron, which acts as an acceptor and can be incorporated in relatively high concentrations, allowing the design of devices for electronic applications. This paper summarizes data on doping procedures and on optical and electrical properties.

Journal ArticleDOI
07 Feb 2003-Langmuir
TL;DR: It is shown that hybridization on DNA-modified polycrystalline diamond is specific, with strong binding of perfectly matched 16-mer complements and little or no binding to 16-mers with 4 mismatched nucleotides.
Abstract: Preparation and hybridization of DNA-modified polycrystalline diamond substrates with fluorescently labeled complementary and noncomplementary oligonucleotide sequences were investigated. Hydrogen-terminated, free-standing diamond substrates were photochemically modified to produce amine-terminated surfaces. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were used to characterize the initial attachment of a protected amine and the subsequent deprotection chemistry. Thiol-terminated DNA oligonucleotides were then linked to the amine-terminated diamond surfaces using a heterobifunctional linker. It is shown that hybridization on DNA-modified polycrystalline diamond is specific, with strong binding of perfectly matched 16-mer complements and little or no binding to 16-mers with 4 mismatched nucleotides. A direct comparison of DNA hybridization on DNA-modified diamond and DNA-modified surfaces of crystalline silicon shows that the diamond surfaces exhibit superior chemical stabil...

Journal ArticleDOI
TL;DR: In this article, the Raman spectra of heavily boron doped polycrystalline diamond films were used as a non-destructive technique to deduce easily and without contact the BORON concentration of diamond films in the range 2×1020 to 1022 cm−3.

Journal ArticleDOI
01 Aug 2003-Wear
TL;DR: In this paper, a molecular dynamics simulation approach is proposed to model the wear of the diamond tool in nanometric cutting, which includes the effects of the cutting heat on the workpiece property.

Journal ArticleDOI
TL;DR: It is demonstrated that heteroepitaxial c-BN films can be prepared at 900 °C on highly (001)-oriented diamond films, formed by chemical vapour deposition, using ion-beam-assisted deposition as a low-pressure technique.
Abstract: Cubic boron nitride (c-BN), although offering a number of highly attractive properties comparable to diamond, like hardness, chemical inertness and a large electronic bandgap, up to now has not found the attention it deserves. This mostly has to do with preparational problems, with easy chemical routes not available and, instead, the necessity to apply ion-bombardment-assisted methods. Hence, most of the c-BN samples prepared as thin films have been nanocrystalline, making the prospect of using this material for high-temperature electronic applications an illusion. Although heteroepitaxial nucleation of c-BN on diamond substrates has been demonstrated using the high-pressure-high-temperature technique, none of the low-pressure methods ever succeeded in the epitaxial growth of c-BN on any substrate. Here, we demonstrate that heteroepitaxial c-BN films can be prepared at 900 degrees C on highly (001)-oriented diamond films, formed by chemical vapour deposition, using ion-beam-assisted deposition as a low-pressure technique. The orientation relationship was found to be c-BN(001)[100]||diamond(001)[100]. High-resolution transmission electron microscopy additionally proved that epitaxy can be achieved without an intermediate hexagonal BN layer that is commonly observed on various substrates.

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

Journal ArticleDOI
TL;DR: In this article, the authors investigated the process monitoring and mechanics of fixed abrasive diamond wire saw machining and developed a signal processing technique for measuring the cutting forces, wire speed, down feed rate, and wire bow angle.
Abstract: The process monitoring and mechanics of fixed abrasive diamond wire saw machining are investigated in this study. New techniques to affix diamond particles to a steel wire core have advanced to make this process feasible for the machining of ceramics, wood, and foam materials. Developments in fixed abrasive diamond wire machining are first reviewed. Advantages of using fixed abrasive diamond wire machining are then introduced. The process monitoring and signal processing techniques for measuring the cutting forces, wire speed, down feed rate, and wire bow angle in diamond wire saw machining are developed. The application of a capacitance sensor to measure the wire bow and a procedure to convert the wire bow to vertical cutting force in a rocking motion wire saw machine are developed. The tension force of the wire during cutting is also derived and discussed.