Showing papers on "Diamond published in 1992"
TL;DR: The diamonds and diamondiferous rocks of Dabie Shan are interpreted to be the products of ultrahigh pressure metamorphism in the und�rthrust basement of the Yangtze continental plate during the early Mesozoic, at greater than 4.0 gigapascals and 900�C.
Abstract: Diamond occurs in ultrahigh pressure metamorphic rocks from Dabie Shan, Anhui Province, eastern China. Diamond-bearing rocks include eclogite, gamet-pyroxenite, and jadeitite. Diamond occurs in a mineral assemblage with coesite and jadeite. The diamonds and diamondiferous rocks of Dabie Shan are interpreted to be the products of ultrahigh pressure metamorphism in the underthrust basement of the Yangtze continental plate during the early Mesozoic, at greater than 4.0 gigapascals and 900°C. This interpretation is based on the distribution of rock units, the stability field of diamond, and isotopic data indicating a crustal origin for the rocks. Most diamonds occur as euhedral inclusions in garnets and are 10 to 60 micrometers across, although some are up to 700 micrometers across.
768 citations
Book•
01 Jan 1992
TL;DR: The main forms are diamond and graphite, and they exhibit markedly different properties from other forms of carbon as mentioned in this paper, such as the properties of carbon nanotubes and carbon nano-graphs.
Abstract: The performance of a single-crystal diamond detector, grown by chemical vapour deposition, as an energy (2) Pierson H. O., Handbook of Carbon, Graphite. Diamonds and Fullerenes: Processing, Properties. Applications. Handbook of carbon, graphite, diamond and fullerenes 1993 Pierson.pdf 4.72 MB Handbook of preparative inorganic chemistry 1963 Vol 1,2 Brauer.pdf. but in other areas, less-ordered graphitic or amorphous carbon shells were also Pierson, H. O. in Handbook of Carbon, Graphite, Diamond and Fullerenes:. At high temperature, Mg can reduce not only carbon in the oxidation state of +4 in Pierson, H. O. Handbook of carbon, graphite, diamonds and fullerenes:. nanotoxicity of carbon nanotubes and graphene in biomedicine. Pierson, H.O. Handbook of Carbon, Graphite, Diamond, and Fullerenes: Properties. Section 4 of the article is devoted towards discussing the role of carbon and its (7) H O Pierson, Handbook of carbon, graphite, diamonds and fullerenes:. The main forms are diamond and graphite, and they exhibit markedly di erent Books Handbook of Carbon, Graphite, Diamond and Fullerenes Properties. Four different forms of carbon namely, Graphite, Activated H. O. Pierson, Handbook of Carbon, Graphite, Diamonds and Fullerenes: Processing, Properties. The growth of multi-walled carbon nanotube (MWCNT) and carbon nano (13) H. O. Pierson, Handbook of Carbon, Graphite, Diamond and Fullerenes:.
575 citations
TL;DR: A model is proposed to help explain bias-enhanced nucleation on silicon, in hopes that this will improve the understanding of diamond nucleation, in general, and eventually result in the nucleation and growth of better-quality diamond films.
Abstract: An in-depth study has been performed of the nucleation of diamond on silicon by bias-enhanced microwave plasma chemical vapor deposition. Substrates were pretreated by negative biasing in a 2% methane-hydrogen plasma. The bias pretreatment enhanced the nucleation density on unscratched silicon wafers up to ${10}^{11}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$ as compared with ${10}^{7}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$ on scratched wafers. In vacuo surface analysis including x-ray photoelecton spectroscopy (XPS), Auger electron spectroscopy, and combined XPS and electron-energy-loss spectroscopy were used to study systematically both the initial-nucleation and growth processes. High-resolution cross-sectional transmission electron microscopy (TEM) was used to study the physical and structural characteristics of the diamond-silicon interface as well as to complement and enhance the in vacuo surface-analytical results. Raman spectroscopy confirmed that diamond was actually nucleating during the bias pretreatment. Scanning electron microscopy has shown that once the bias is turned off, and conventional growth is conducted, diamond grows on the existing nuclei and no continued nucleation occurs. If the bias is left on throughout the entire deposition, the resulting film will be of much poorer quality than if the bias had been turned off and conventional growth allowed to begin. Intermittent surface analysis showed that a complete silicon carbide layer developed before diamond could be detected. High-resolution cross-sectional TEM confirmed that the interfacial layer was amorphous and varied in thickness from 10 to 100 \AA{}. A small amount of amorphous carbon is detected on the surface of the silicon carbide and it is believed to play a major role in the nucleation sequence. A model is proposed to help explain bias-enhanced nucleation on silicon, in hopes that this will improve the understanding of diamond nucleation, in general, and eventually result in the nucleation and growth of better-quality diamond films.
448 citations
TL;DR: The correlation energy of diamond is determined by means of increments obtained in ab initio calculations for localized C-C bond orbitals and for pairs and triples of such bonds.
Abstract: The correlation energy of diamond is determined by means of increments obtained in ab initio calculations for localized C-C bond orbitals and for pairs and triples of such bonds. The resulting correlation contribution to the cohesive energy is -0.129 a.u., which is approximately 85% of the experimental value.
365 citations
TL;DR: In this article, the authors analyzed the thermal conductivity of the ZnS-diamond interface with different values of α, defined to be equal to the Kapitza radius divided by the particle radius.
Abstract: We have observed that the thernal conductivity of zincsulphide is increased by adding large particles of highly conducting diamond, but lowered by the addition of sub-micron size particles of diamond. This effect is explained in terms of the interfacial thermal resistance which becomes increasingly dominant as the particles becomes smaller (because that increases their surface to volume ratio). A phenomonological model in which the interface resistance is expressed as an effective Kapitza radius, ak, is presented. The conductivity of the composite is analyzed for different values of α, which is defined to be equal to the Kapitza radius divided by the particle radius. If α = 1, that is, the actual particle radius is equal to ak then the effective thermal conductivity of the particles is equal to that of the matrix. If α > 1, that is the particles are very small, then the contribution of the particles to the thermal conductivity of the composite is dominated by interfaces; if α < 1 then the bulk property of the particles is important. Our measurements yield ak ≈ 1.5 μm for the ZnS-diamond interface.
355 citations
TL;DR: The diamond was characterized by Raman spectroscopy and scanning electron microscopy as discussed by the authors, showing that approximately 50% of the initial diamond nuclei appear to be aligned with the C(001) planes parallel to the SiC(001), and C[110] directions parallel to SiC within 3°.
Abstract: Textured diamond films have been deposited on β‐SiC via microwave plasma chemical vapor deposition preceded by an in situ bias pretreatment that enhances nucleation. Approximately 50% of the initial diamond nuclei appear to be aligned with the C(001) planes parallel to the SiC(001), and C[110] directions parallel to the SiC[110] within 3°. The diamond was characterized by Raman spectroscopy and scanning electron microscopy.
336 citations
TL;DR: In this paper, it was shown that rapid, non-hydrostatic compression of C60 to pressures of 20 ± 5 GPa transforms it instantaneously into bulk polycrystal-line diamond at room temperature.
Abstract: C6o MOLECULES are extremely stable, withstanding hydrostatic pressures of up to at least 20 GPa (ref. 1). It has been proposed that at high pressures they could form a solid harder than diamond2. On the other hand, electrical resistivity measurements3 have revealed the formation of an insulating phase above 20 GPa, which was attributed to the low-symmetry state found in X-ray diffraction studies under nonhydrostatic compression1. Here we report that rapid, nonhydrostatic compression of C60 to pressures of 20 ±5 GPa transforms it instantaneously into bulk polycrystal-line diamond at room temperature. Our measurements place a limit on the stability of the C60molecular phase under nonhydrostatic pressure. The high efficiency and fast kinetics at room temperature suggest the possibility of using this transformation for fabrication of industrial diamonds.
231 citations
TL;DR: A directional dependence to the friction coefficient is found; that for certain crystallographic sliding directions μ increases with increasing load and as the temperature decreases; and that for the sliding speeds investigated here, μ is approximately independent of sliding velocity.
Abstract: The friction which occurs when two diamond (111) hydrogen-terminated surfaces are placed in sliding contact is investigated for sliding in different crystallographic directions, as a function of applied load, temperature, and sliding velocity. We find a directional dependence to the friction coefficient, μ; that for certain crystallographic sliding directions μ increases with increasing load and as the temperature decreases; and that for the sliding speeds investigated here, μ is approximately independent of sliding velocity
231 citations
217 citations
TL;DR: The observed orientation relation satisfies the previously proposed martensitic transition mechanism from graphite to hexagonaliamond, but this hexagonal diamond formed at room temperature is unquenchable upon the release of pressure, and how it differs from the quenched phase formed under high pressure and temperature remains to be clarified.
Abstract: High-pressure in situ x-ray diffraction was carried out to clarify the nature of the pressure-induced phase transformation in graphite at room temperature. The combined use of a Drickamer-type high-pressure apparatus with sintered diamond as an anvil material and very intense x rays from synchrotron radiation made it possible to obtain high-quality x-ray-diffraction data, as well as information on the orientation relation, for this phase transformation. It was found that the transition starts at 14 GPa at room temperature, although this onset pressure is sensitive to the nature of the sample and of the applied pressure. X-ray-diffraction profiles obtained on the high-pressure phase are well explained by the hexagonal diamond structure, but the observed c/a ratio is slightly larger than that of ideal packing. The observed orientation relation satisfies the previously proposed martensitic transition mechanism from graphite to hexagonal diamond. But this hexagonal diamond formed at room temperature is unquenchable upon the release of pressure, and how it differs from the quenched phase formed under high pressure and temperature remains to be clarified.
211 citations
AT&T1
TL;DR: In this paper, the authors measured thermal conductivity in the experimentally difficult direction perpendicular to the plane of the diamond film and showed that the local conductivity near the top growth surface of a synthetic diamond film is, surprisingly, at least as high as that of gem-quality diamond single crystals.
Abstract: AS high-power electronic devices are packed to progressively higher densities, synthetic diamond films are being considered as heat spreaders for the prevention of thermal damage (see ref. 1 for example). Although diamond single crystals are known to have the highest thermal conductivity for any material at room tem-perature (22 W cm−1 K−1 for diamond with natural isotopic abundance, compared with 4 W cm-1 K-1 for copper), the dependence of conductivity on the microstructure of polycrystalline diamond films is not understood. Using a newly developed laser technique2, we have measured thermal conductivity in the experimentally difficult direction perpendicular to the plane of the diamond film. Taken together with earlier in-plane measurements3, this gives a complete description of the local thermal conductivity, showing a significant gradient and anisotropy correlated with the inhomogeneous grain structure. Despite phonon scattering at lattice defects and grain boundaries, we find that the local conductivity near the top growth surface of a synthetic diamond film is, surprisingly, at least as high as that of gem-quality diamond single crystals.
TL;DR: In this paper, the threshold energy for displacement of atoms from their lattice sites was determined for three principal crystallographic directions by observing the formation of defect clusters during irradiation in a transmission electron microscope.
Abstract: A type IIa natural diamond was irradiated at room temperature with energetic electrons. The threshold energy for displacement of atoms from their lattice sites was determined for three principal crystallographic directions by observing the formation of defect clusters during irradiation in a transmission electron microscope. The displacement‐threshold energies were found to be 37.5±1.2 eV for the electron incident in the [100] direction, 45.0±1.3 eV in the [111] direction, and 47.6±1.3 eV in the [110] direction.
TL;DR: In this paper, two major methods for generating the emission, photoluminescence and cathodoluminecence, are considered, and the defects responsible for the most significant luminescence bands are discussed in detail.
TL;DR: Simulations of the reaction of small hydrocarbon molecules adsorbed on a reconstructed diamond {001}(2x1) surface suggest that these hydrocarbons are highly reactive species and that initial stages of diamond growth proceed through a dimer-opening mechanism.
Abstract: Computer simulations of hydrocarbon and related molecules using empirical force fields have become important tools for studying a number of biological and related processes at the atomic scale. Traditional force fields, however, cannot be used to simulate dynamic chemical reactivity that involves changes in atomic hybridization. Application of a many-body potential function allows such reactivity to occur in a computer simulation. Simulations of the reaction of small hydrocarbon molecules adsorbed on a reconstructed diamond {001}(2x1) surface suggest that these hydrocarbons are highly reactive species and that initial stages of diamond growth proceed through a dimer-opening mechanism. Rates estimated from transition state theory of two interconversions between states where the dimer is open and closed are given.
Book•
01 Aug 1992
TL;DR: In this paper, the authors present a detailed analysis of the properties of graphite-based graphite and diamond-like carbon films, including the following properties: 1.1.1 Lattice properties, 2.2.3 Optical properties, 3.3.4 Thermal properties, 4.4 Energy Loss, 5.5 Electronic Transport Measurements, 6.5 Modification of Mechanical Properties, 7.6 Implantation-Enhanced Intercalation, 8.7.
Abstract: 1. Introduction.- 2. Carbon Materials: Graphite, Diamond and Others.- 2.1 Structure and Materials.- 2.1.1 Graphite.- 2.1.2 Graphite-Related Materials.- 2.1.3 Carbon Fibers.- 2.1.4 Glassy Carbon.- 2.1.5 Graphite Intercalation Compounds.- 2.1.6 Diamond.- 2.1.7 CVD Diamond Films.- 2.1.8 Diamond-Like Carbon Films.- 2.2 Properties of Graphite.- 2.2.1 Lattice Properties.- 2.2.2 Electronic and Transport Properties.- 2.2.3 Optical Properties.- 2.2.4 Thermal Properties.- 2.2.5 Mechanical Properties.- 2.3 Properties of Diamond.- 2.3.1 Lattice Properties.- 2.3.2 Electronic and Transport Properties.- 2.3.3 Optical Properties.- 2.3.4 Thermal Properties.- 2.3.5 Mechanical Properties.- 2.3.6 Chemical Properties.- 3. Ion Implantation.- 3.1 Energy Loss Mechanisms.- 3.2 Parameters of Implantation.- 3.2.1 Energy of Implantation.- 3.2.2 Implantation Range.- 3.2.3 Implantation Fluence (Dose) and Beam Current (Dose Rate).- 3.3 Radiation Damage.- 3.4 Energy Loss Simulations.- 4. Ion Beam Analysis Techniques.- 4.1 Rutherford Backscattering Spectroscopy.- 4.2 Nuclear Reaction Analysis.- 4.3 Particle Induced X-Ray Emission (PIXE).- 4.4 Channeling.- 4.5 Elastic Recoil Detection (ERD).- 4.6 Secondary Ion Mass Spectroscopy (SIMS).- 4.7 Channeling Studies in Graphite-Based Materials.- 4.8 Stoichiometric Characterization of GICs by RBS.- 4.9 Ion Channeling in GICs.- 5. Other Characterization Techniques.- 5.1 Raman Spectroscopy.- 5.2 Other Optical and Magneto-Optical Techniques.- 5.3 Electron Microscopies and Spectroscopies.- 5.4 X-Ray-Related Characterization Techniques.- 5.5 Electronic Transport Measurements.- 5.6 Electron Spin Resonance (ESR).- 5.7 Hyperfine Interactions.- 5.7.1 Mossbauer Spectroscopy.- 5.7.2 Perturbed Angular Correlations (PAC).- 5.8 Mechanical Properties.- 6. Implantation-Induced Modifications to Graphite.- 6.1 Lattice Damage.- 6.2 Regrowth of Ion-Implanted Graphite.- 6.3 Structural Modification.- 6.4 Modification of the Electronic Structure and Transport Properties.- 6.5 Modification of Mechanical Properties.- 6.6 Implantation with Ferromagnetic Ions.- 6.7 Implantation-Enhanced Intercalation.- 6.8 Implantation with Hydrogen and Deuterium.- 7. Implantation-Induced Modifications to Graphite-Related Materials.- 7.1 Glassy Carbon.- 7.2 Carbon Fibers.- 7.3 Disordered Graphite.- 7.4 Carbon-Based Polymers.- 8. Implantation-Induced Modifications to Diamond.- 8.1 Structural Modifications and Damage-Related Electrical Conductivity.- 8.2 Volume Expansion.- 8.3 Lattice Damage.- 8.4 Damage Annealing and Implantations at Elevated Temperatures.- 8.5 Electrical Doping.- 8.6 Impurity State Identification.- 8.7 Electronic Device Realization.- 8.8 New Materials Synthesis.- 8.9 Improving Mechanical Properties.- 9. Implantation-Induced Modifications to Diamond-Related Materials.- 9.1 Diamond-Like Carbon (a-C:H) Films.- 9.1.1 DC Conductivity.- 9.1.2 Optical Characterization.- 9.1.3 Structural Modifications and Hydrogen Loss.- 9.1.4 Attempts to Dope a-C:H by Ion-Implantation.- 9.1.5 Discussion of Implantation-Induced Effects in DLC.- 9.2 Diamond Films.- 10. Concluding Remarks.- References.
TL;DR: It is proposed that the dependence is indicative of the resonant inelastic scattering description of these emission spectra, i.e., the absorption-emission process should be described as a single scattering event where the momenta of the photoelectron and the valence hole in the final state are related by momentum conservation.
Abstract: We present carbon K emission spectra of diamond excited with high-resolution undulator radiation The valence-band emission spectra are shown to be strongly dependent on the excitation energy, up to 20--30 eV above the C K edge It is proposed that the dependence is indicative of the resonant inelastic scattering description of these emission spectra, ie, the absorption-emission process should be described as a single scattering event where the momenta of the photoelectron and the valence hole in the final state are related by momentum conservation
TL;DR: The high thermal conductivity of isotopically pure diamond is shown to be consistent with the Klemens-Callaway model, and the new data on the thermal-conductivity temperature dependence k(T) is presented.
Abstract: New data on the thermal-conductivity temperature dependence k(T) of both natural abundance and isotopically enriched synthetic diamond gems are presented. The existing data on the thermal-conductivity temperature dependence k(T) of natural type-IIa diamond have been reanalyzed using a comprehensive Klemens-Callaway model. The high thermal conductivity of isotopically pure diamond is shown to be consistent with the model.
TL;DR: In this paper, a sliding test was performed on polycrystalline diamond coatings with a range of surface roughness, and the results indicated that the wear resistance of the coatings is comparable to that of natural, single-crystal diamond.
TL;DR: In this article, a series of CVD polycrystalline diamond films with a thermal conductivity that is only 25% less than that of high quality single-crystal natural diamond was studied and the observed gradient is attributed mainly to phonon scattering by the roughly cone-shaped columnar microstructure.
Abstract: Chemical‐vapor‐deposited (CVD) polycrystalline diamond films have recently been reported with a thermal conductivity that is only 25% less than that of high quality single‐crystal natural diamond. By studying a series of such films of various thicknesses grown under virtually identical conditions, we have discovered a significant (factor of four) through the thickness gradient in thermal conductivity. The observed gradient is attributed mainly to phonon scattering by the roughly cone‐shaped columnar microstructure. For 350 μm films, the material near the top (growth) surface has a conductivity of at least 21 W/cm °C, i.e., comparable to the best single crystals. This remarkable dependence of thermal conductivity on microstructure has important implications for thermal management of microelectronic devices using CVD diamond.
Patent•
12 Feb 1992TL;DR: A diamond-coated hard material having a diamond-or diamond-like carbon-coating layer with a high bonding strength to a substrate is characterized in this paper, where microscopic roughness is present on the surface of the substrate and at least one protrusive part is present in a standard length when the standard length is 10 µ m in the interface of the diamond and/or diamondlike carbon coated layer and the substrate.
Abstract: A diamond-coated hard material having a diamond- or diamond-like carbon coated layer with a high bonding strength to a substrate is provided. The coated hard material comprising a diamond- and/or diamond-like carbon-coating layer formed on the surface of a hard material, i.e. substrate is character-ized in that (I) (1) microscopic roughness is present on the surface of the sub-strate and (2) protrusive parts thereof are defined by the surface roughness Rmax within a range of 1.0 to 30 µ m in a standard length when the standard length is 50 µ m in the interface of the diamond- and/or diamond-like carbon coated layer and the substrate, and (II) (1) microscopic roughness is present on the surface of the substrate, (2) at least one protrusive part is present in a standard length when the standard length is 10 µ m in the interface of the diamond- and/or diamond-like carbon coated layer and the substrate, (3) the ratio of sum A of the lengths of dent parts to sum B of the lengths of the pro-trusions is in the rangeof 0.05 <= A/B <= 20 in the standard length in the interface and (4) the protrusive parts are intruded into the diamond-coated layer.
TL;DR: In this article, a new class of amorphous hydrogenated carbon based films is described, which consists of atomic-scale composite random networks of carbon and silicon, and the carbon network is stabilized by hydrogen and the silicon network is stabilised by oxygen.
TL;DR: In this article, a diamond phase carbon film was grown on silicon substrates at temperatures of less than 50°C by using an organic solution, which was negatively biased with sufficient dc potential to simulate ionized deposition conditions used in physical vapor deposition.
Abstract: Diamond phase carbon films have been grown on silicon substrates at temperatures of less than 50 °C by using an organic solution. Substrates were negatively biased with sufficient dc potential to simulate ionized deposition conditions used in physical vapor deposition. The surface morphology, crystal structure, and some physical properties of the films were examined by scanning electron microscopy, transmission electron microscopy, x‐ray photoemission spectroscopy. It was confirmed that the film is composed of small grains of diamond phase or diamondlike structure.
TL;DR: In this paper, the authors used high-energy and low-energy electron diffraction and X-ray photoelectron spectroscopy measurements to show that the natural and synthetic diamond surfaces maintained their crystallinity even after the hydrogenation.
Abstract: Hydrogenation of diamond has been carried out using the electron-cyclotron-resonance microwave plasma chemical-vapor deposition apparatus. According to reflection high-energy and low-energy electron diffraction and X-ray photoelectron spectroscopy measurements, the natural- and synthetic-diamond surfaces maintained their crystallinity even after the hydrogenation. Seebeck effect measurement and the temperature dependence of the resistance revealed an appearance of deep acceptor levels in the hydrogenated diamond layer. The diffusion depth of the hydrogen by the plasma treatment (2 h, 830°C) was roughly estimated to be ~0.6 µm from the drain current-voltage characteristics of a rudimentary MISFET using the hydrogenated diamond.
TL;DR: In this paper, the authors describe a new method for removing thin, large area sheets of diamond from bulk or homoepitaxial diamond crystals, which consists of an ion implantation step, followed by a selective etching procedure.
Abstract: We describe a new method for removing thin, large area sheets of diamond from bulk or homoepitaxial diamond crystals. This method consists of an ion implantation step, followed by a selective etching procedure. High energy (4–5 MeV) implantation of carbon or oxygen ions creates a well‐defined layer of damaged diamond that is buried at a controlled depth below the surface. For C implantations, this layer is graphitized by annealing in vacuum, and then etched in either an acid solution, or by heating at 550–600 °C in oxygen. This process successfully lifts off the diamond plate above the graphite layer. For O implantations of a suitable dose (3×1017 cm−2 or greater), the liftoff is achieved by annealing in vacuum or flowing oxygen. In this case, the O required for etching of the graphitic layer is also supplied internally by the implantation. This liftoff method, combined with well‐established homoepitaxial growth processes, has considerable potential for the fabrication of large area single crystalline dia...
TL;DR: The ability to grow thin films of polycrystalline diamond at atmospheric pressure and below is a relatively new development and has potential electronic applications in thermal management, packaging, lithography and active electronic devices.
TL;DR: In this article, a cathodic arc with beam filter is employed for the deposition of hydrogen-free amorphous carbon films, and a linear filter is used to prevent macroparticles and nonionized carbon atoms from reaching the substrate.
Abstract: A cathodic arc with beam filter is employed for the deposition of hydrogen‐free amorphous carbon films. A linear filter is used to prevent macroparticles and nonionized carbon atoms from reaching the substrate. The deposited films are characterized by their optical and mechanical behavior. Depending on the deposition conditions, optical band gaps in the range 2.1–2.4 eV are measured. Mechanical properties are investigated using the nanoindentation method and are shown to approach those of natural diamond. To our knowledge, the data obtained thus far reveal these films to be more diamondlike than those prepared using any other method for the deposition of nonhydrogenated amorphous diamond.
TL;DR: Amorphous carbon thin films were prepared at 30, 200, and 450 C by magnetron sputtering of a graphite target as mentioned in this paper, and the surface structure and chemical bonding (sp2/sp3) of the carbon films were characterized by scanning tunneling microscopy (STM) and Raman spectroscopy.
Abstract: Amorphous carbon thin films were prepared at 30, 200, and 450 °C by magnetron sputtering of a graphite target. The surface structure and chemical bonding (sp2/sp3) of the carbon films were characterized by scanning tunneling microscopy (STM) and Raman spectroscopy. STM images show that graphite microcrystallites of 20–40 A in size are present at the surfaces of all the films and the number of the microcrystallites increases with increasing substrate temperature. The microcrystallites often contain structural defects. Raman measurements show that increasing the substrate temperature results in an increase in the sp2‐bonded fraction of carbon atoms and a decrease in the microstructural defects. These results indicate that the microstructural changes are correlated with changes in the chemical bonding ratio (sp3/sp3) and no diamond microcrystallites are present in the amorphous carbon. A three‐dimensional atomic structure of the graphite microcrystallites is discussed in terms of turbostratic graphite.
TL;DR: In this article, the microhardness of polycrystalline diamond films and several amorphous diamond-like carbon (DLC) films were determined from force-displacement curves obtained using an ultralowload micro-hardness instrument (UMIS‐2000).
Abstract: The microhardness, H, and Young’s modulus, E, of a polycrystalline diamond film and several amorphous diamondlike carbon (DLC) films were determined from force‐displacement curves obtained using an ultralow‐load microhardness instrument (UMIS‐2000). Measurements were made at a constant loading rate of 3 mN/s, to a maximum applied force of 67 and 100 mN with contact force of 0.06 and 1.07 mN, respectively. The diamond film had a surface morphology typical of microwave plasma chemical vapor deposition films (crystallite size 0.5–3 μm), and the force‐displacement curves showed nearly complete elastic behavior. The average values of hardness (80–100 GPa) and modulus (500–533 GPa) are comparable to those of natural (001) diamond reference standards (H=56–102 GPa, E=1050 GPa). The DLC films were prepared by low‐energy ion‐assisted unbalanced magnetron sputtering. By varying the bombarding ion energy, five films were prepared having different sp3/sp2 bonding ratios (3–6), optical gaps (1.2–1.6 eV), and hydrogen ...
TL;DR: The Kapitza conductance between isotopically enriched synthetic diamond and Ti, Al, Au, and Pb has been studied using picosecond optical techniques and suggests the existence of a second conductance mechanism.
Abstract: The Kapitza conductance between isotopically enriched synthetic diamond and Ti, Al, Au, and Pb has been studied using picosecond optical techniques. For Ti and Al, which have Debye temperatures roughly 1/5 of that of diamond, the measured heat flow is in reasonable agreement with calculations of the phonon heat transport based on a simple lattice dynamical model. However, for Au and Pb, which have Debye temperatures 0.07 and 0.04 times that of diamond, the measured Kapitza conductances are as much as 100 times larger than expected, suggesting the existence of a second conductance mechanism.
TL;DR: Two super-Gaussian output resonators of orders 4 and 6 have been designed by using the inverse-propagation method for the calculation of the graded-phase feedback mirrors using the diamond cutting technique on a copper substrate.
Abstract: Two super-Gaussian output resonators of orders 4 and 6 have been designed by using the inverse-propagation method for the calculation of the graded-phase feedback mirrors. The graded-phase mirrors were made by using the diamond cutting technique on a copper substrate. An increase of 40% and 50% of monomode energy extraction has been measured compared with that of a semiconfocal resonator of the same dimension in a TEA CO2 laser.