Diamond Components Research Articles

Structural nonuniformity of detonation-produced diamond-containing material

Raman backscattering spectra (RBS), infrared spectra, and X-ray diffraction intensity curves for various fractions of ultradispersed diamond-containing material (UDDCM) were recorded. The RBS and XRD curves obtained suggest that UDDCM is characterized by sharp variations in the ratio between the diamond and nondiamond components, a factor that makes it possible to consider this phase as an individual product and determines the scale of variations in the main characteristics. Fine UDDCM fractions contain only small amounts diamond-like (sp3 carbon) grains, if any. One possible reason for changes in the ratio between the phases is density fluctuations under nonequilibrium conditions of synthesis.

Structural heterogeneity of diamond-containing detonation material

Diamond-containing material (DCM) synthesized by detonation was separated into fractions. Raman and infrared spectra and X-ray diffraction patterns of the individual fractions were measured. The particles of this material were characterized by the variable ratio of the diamond (sp 3 ) and non-diamond components. The distribution of sp 3 -grains in the particles was of complicated character. The fine DCM particles contained an insignificant amount of diamond. The influence of density fluctuations on the DCM formation is discussed.

Fast Polishing of Single Crystal Diamond

This paper investigates the polishing of single crystal diamond using the dynamic friction method. It was found that by selecting a proper polishing pressure and sliding speed, a very high polishing rate at 10,300 µm/h (or 2.8 X 10-2 mg/s) with a high quality surface finish can be reached, which is hundreds times faster than the other polishing process reported in the literature. This method can be used to manufacture diamond products and to repair worn diamond components such as diamond cutting tools and diamond dressers for grinding wheels.

Formation of diamond-like carbon by fs laser irradiation of organic liquids

The high intensities generated in femtosecond (fs) laser interactions offers the possibility of novel formation routes for diamond and diamond-like carbon materials. Coulomb explosion, a common phenomenon in intensive fs irradiation, has recently been shown to lead to a direct graphite–diamond phase transition on the surface of graphite. In this paper we report the results of fs irradiation of a variety of liquid organic compounds at intensities in the Coulomb explosion regime. The products of laser-induced chemistry under these conditions have been studied using visual/surface enhanced Raman and transmission electron microscopy (TEM). Surface enhanced Raman spectra/TEM show that an intermediate diamond phase, trans-polyacetylene chains and amorphous carbon are present after fs irradiation of liquid alkanes. We also find that the diamond component can be enhanced by irradiation in the presence of certain transition metals; however the origin of this effect is still uncertain. Diamond films deposited in this way are found to exhibit a nano-assembled structure involving individual nanodiamonds extending over an area of about 1 cm 2. This process represents a wet chemical method for room temperature formation of diamond-like carbon films

Diamond components with integrated abrasion sensor for tribological applications

Tribological components made from CVD diamond are commonly used for protection against abrasion in rough environments. Such components can be used e.g. in textile industry as thread guiding devices provided that surface roughness and resultant friction are low. In this work we report on the fabrication of CVD diamond components of non-planar shape. These devices were fabricated in a negative replication approach on mechanically structured substrates. Using this technique cylindrically shaped diamond devices with smooth surfaces were produced by using the nucleation side of the diamond layers as the exposed surface, thus making subsequent polishing steps unnecessary. Applying an improved two-step nucleation method further reduced surface roughness. Sensing elements in the form of resistors made from boron-doped CVD diamond were integrated into the device surface. Device performance was characterized with respect to the temperature dependence of the resistors and the suitability as abrasion sensor.

Comparative study of diamond films grown on silicon substrate using microwave plasma chemical vapor deposition and hot-filament chemical vapor deposition technique

Diamond films on the p-type Si(111) and p-type(100) substrates were prepared by microwave plasma chemical vapor deposition (MWCVD) and hot-filament chemical vapor deposition (HFCVD) by using a mixture of methane CH4 and hydrogen H2 as gas feed. The structure and composition of the films have been investigated by X-ray Diffraction, Raman Spectroscopy and Scanning Electron Microscopy methods. A high quality diamond crystalline structure of the obtained films by using HFCVD method was confirmed by clear XRD-pattern. SEM images show that the prepared films are poly crystalline diamond films consisting of diamond single crystallites (111)-orientation perpendicular to the substrate. Diamond films grown on silicon substrates by using HFCVD show good quality diamond and fewer non-diamond components.

Preparation and characterization of (1 0 0)-textured diamond films obtained by hot-filament CVD

(1 0 0)-textured chemival vapor deposited (CVD) diamond films were deposited on both ultrasonically roughened and manually scratched silicon substrates using hot-filament chemical vapor deposition (HFCVD). Scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and thermally stimulated current (TSC) were used to characterize the structure, morphology, residual stress, impurities and/or defects and other properties of CVD diamond films. The results indicate that manual scratching results in (1 0 0)-texturing of the diamond films and these have improved properties due to larger grain size, fewer grain boundaries, increased fraction of diamond components and lower residual stress. The TSC results suggest two possible electronic conduction mechanisms corresponding to an activation energy E a of about 1.68 eV in the high-temperature region ( T > 500 K ) and about 0.31 eV in the low-temperature region ( T < 500 K ), respectively.

Field emission of polycrystalline diamond films grown by microwave-plasma chemical vapor deposition. I. Effects of surface morphology of diamond

The effects of surface morphology on the field emission of non-doped polycrystalline diamond films with thicknesses ranging from 5 to 55 μm were studied. Diamond films grown by a microwave-plasma chemical vapor deposition technique had both the diamond and non-diamond components with pyramidal and angular crystalline structures. Although the average crystallite size increased with increasing the film thickness ( d), the volume fraction of the non-diamond components in the films was insensitive to the film thickness. However, the turn-on electric field, F T, (defined as the low-end electric field to emit electrons) showed a U-shape dependence on the film thickness. This U-shape dependence was explained by a model in which the emission current was controlled by Fowler–Norheim tunneling of electrons at surface of the pyramids when d was thinner than 20 μm and by carrier transport in the polycrystalline diamond film when d was thicker than 20 μm. The lowest field of 4 V/μm was obtained in the film with 20 μm thick.

Infrared Absorption and Emission Spectra of Hydrogenated Amorphous Carbon Prepared in the Presence of Oxygen, Nitrogen, Ammonia, and Carbon Monoxide

The formation of carbonaceous condensates in the atmospheres of asymptotic giant branch (AGB) carbon stars and in the nebulae of post-AGB objects occurs in a chemical environment that also contains oxygen and nitrogen. The extent of incorporation of chemical groups containing these elements in carbonaceous solids will depend on the ratios C/O and C/N. The presence of chemical groups containing O and N can have a significant effect on the infrared spectrum of this material through the introduction of new absorption and emission features and by perturbing spectral lines arising from CH and other hydrocarbon groups. To simulate some aspects of this chemistry, we have prepared samples of hydrogenated amorphous carbon (HAC) containing these elements by laser ablation of graphite in mixed H2/N2, H2/O2, and H2/CO gases and in NH3. Absorption and emission spectra are reported for these materials in the 2.5-20 μm region. We find that the inclusion of oxygen has a profound effect on both 3.4 μm and longer wavelength absorption in HAC even at low concentration. Condensation of HAC in the presence of N2, CO, and NH3 produces changes in the profile and relative intensity of components of the 3.4 μm CH2, 3 hydrocarbon band, but some of these effects can be reversed by heating to higher temperature. We find that the condensation of a crystalline diamond component is greatly facilitated in the presence of O2 or NH3. A number of sharp spectral features attributable to diamond have been observed in these spectra.

Recognition and Grading of Severely Distorted Geometric Shapes from within a Complex Figure

A novel method is presented for the location of highly distorted geometric shapes from within a complex free hand line drawing, such as those generated in neuropsychological figure copying tests. With such high levels of distortion, a shape can no longer be crisply categorised as either present or not, and so a grade of perceptual distortion is generated. Candidate shapes are located from within a graph representation of the pre-processed line drawing. These are then rated by a set of fuzzy rules based upon Gestalt principles of human visual perception. This produces a very flexible process that can be adapted to the required application. Test data was acquired from patient attempts at a specific neuropsychological test (the Rey Osterrieth Complex Figure), with the aim of locating certain rectangular, triangular and diamond components. These are the first steps of the automation of the traditional, clinical scoring of the test. Of the 140 test shapes used to evaluate the system, all but one was successfully located from within patient drawings of figure and of these only two were graded with an error greater than 10% of manually generated grades by independent raters.

Optical performance of chemically vapour-deposited diamond at infrared wavelengths

The optical parameters which determine the performance of chemically vapour-deposited diamond samples as imaging and power-handling windows have been investigated. These parameters include: modulation transfer function, absorption and laser-induced damage threshold at ∼10 μm wavelengths. The diamond component has to be fashioned in an optically accurate form and therefore current geometrical precision capabilities are discussed, including the manufacture of curved samples suitable for laser cavity output couplers.

パルス放電プラズマ化学気相成長によるＡｌ基板上へのダイヤモンドの形成

Diamond particles have been prepared from CH4 H2 gas mixtures on Si and Al substrates by a pulsed discharge (PD) plasma chemical vapor deposition (CVD) method at low substrate temperatures of nearby 500°C, and their structural changes as a function of PD conditions have been investigated to make clear the possibility of the diamond deposition on the Al substrate. The crystalline quality of the diamond deposited on the Si substrate became superior when the discharge time (Td) in the repetition period of the pulse was shortened from 2 to 0.5 ms under the constant non-discharge time (Tn) of 3 ms. The longer Tn at constant Td was also effective to improve the crystalline quality. When the deposition was performed on the Al substrate under the constant Td=0.5 ms, Al4C3 was formed at short Tn of 2 ms, and diamond was formed at longer Tn of 3 ms. The increase of the current at the beginning of the discharge by means of inserting a condenser and a resistor between the electrodes was also effective to deposit diamond component. These results showed PD plasma CVD method was effective to improve the crystalline quality, and could deposit the diamond on the Al substrate at low substrate temperature.

Mechanism of the formation of a diamond nanocomposite during transformations of C60 fullerite at high pressure

The results of an investigation of the transformation of C60 fullerite to diamond under pressure through intermediate three-dimensionally polymerized and amorphous phases are reported. It is found that treatment of fullerite C60 at pressures 12–14 GPa and temperatures ∼1400°C produces a nanocrystalline graphite-diamond composite with a concentration of the diamond component exceeding 50%. At lower temperatures (700–1200°C) nanocomposites consisting of diamondlike (sp 3) and graphitic (sp 2) amorphous phases are formed. The nanocomposites obtained have extremely high mechanical characteristics: hardness comparable to that of best diamond single crystals and fracture resistance two times greater than that of diamond. Mechanisms leading to the transformation of C60 fullerite into diamond-based nanocomposites and the reasons for the high mechanical characteristics of these nanocomposites are discussed.

Carbon, nitrogen, argon and helium study of impact diamonds from Ebeliakh alluvial deposits and Popigai crater

Abstract— Nineteen diamond aggregate specimens (1–2 mm in size) from impactites of Popigai crater and five diamond samples (5–7 mm in size) from Ebeliakh river placers were studied. Our investigations indicate that samples from Ebeliakh were formed in an impact event with the exception of one specimen (Y7).The carbon isotopic composition of diamonds from Popigai varies within the previously reported limits (δ13C, −8 to −22%); whereas, diamonds from Ebeliakh placers show heavier values of δ13C (−7 to −10%). All the specimens studied contain very low amounts of N, mostly &lt;20 ppm, but a few contained up to 60 ppm. For specimens, where the quantity of N allowed reliable analysis, δ15N values were found to be in the range of −3.9 to +11.9%. On the basis of combined Ar and N study, it was concluded that impact diamonds studied here can be a mixture of at least two types of gas carriers (e.g., different diamond components). A possible explanation would be involvement of a carbon vapour deposition (CVD) process or diamond growth in the impact melt in addition to the direct graphite‐diamond shock transformation. The δ13C distributions and different N/36Ar correlations have indicated a difference between impact diamonds from Ebeliakh and diamonds extracted from Popigai crater. This could be explained by the existence of different diamond populations formed during the Popigai impact event. On the other hand, Ebeliakh diamonds could have resulted from a separate impact event to Popigai and an alternative crater is yet to be found.

Mapping crystalline quality in diamond films by micro-Raman spectroscopy

Abstract It is known that different growth sectors within diamond films grown by chemical vapor deposition can contain different concentrations of defects. The defects in the diamond can be in the form of inclusions of non-diamond carbon. The quality of the diamond can be observed by the change in the ratios of diamond and non-diamond components in the Raman spectrum and in the widths of the Diamond Raman Line. In (001) textured growth, the (001) sectors are observed to be made up of good quality diamond, whereas the neighboring (111) growth sectors have high concentrations of defects and inclusions. Because of the transparency of diamond, it is possible to map the Raman signal with a confocal microscope to depths of hundreds of microns. In this way, it has been possible to show that the regions of relatively defect-free diamond lie within inverted pyramids. The bases of these pyramids correspond to the observed square (001) facets, whereas the sides of the pyramid correspond to (111) planes. This feature of textured diamond films has been observed by transmission electron microscopy of cross-sections of such films, but this is the first time that it has been shown in-situ. The “Blue-Cross” of defect related luminescence [N.C. Burton, J.E. Butler, A.R. Lang, J.W. Steeds, Proc. R. Soc. Lond. A 449 (1995) 555–566] is observed by PL and correlates well with a mapping of the FWHM. The result demonstrates the ability of confocal micro-Raman spectroscopy to map the crystalline quality in diamond films on a micron scale. It is demonstrated for the first time that the pattern of defect densities previously observed by TEM can be observed in particular growth features of diamond films by confocal Raman spectroscopy.

Use of different excitation wavelengths for the analysis of CVD diamond by laser Raman spectroscopy

Abstract Raman spectroscopy has been shown to be an accurate technique for the qualitative characterisation of chemical vapour deposited (CVD) diamond films. The intensities of the diamond and non-diamond components in the spectrum vary with the wavelength of the laser excitation. This shows that laser Raman at different wavelengths can be used as a selective probe for the different constituents of the deposited film. In the present work, this selectivity has been used to examine the effect of methane concentration during growth on the Raman spectra of CVD diamond. Diamond films were deposited on single crystal Si(100) wafer substrates by microwave plasma enhanced, and hot filament assisted CVD. Methane concentrations of 0.36–2.16% in hydrogen were used as the feedstock. Laser wavelengths ranging from the ultraviolet (244 nm) to the infra-red (780 nm) were used to perform Raman spectroscopy on the deposited diamond films. Scanning electron microscopy (SEM) was used to determine the morphology of the films and related to the Raman spectra.

Metallization of CVD diamond films by cathodic arc deposition

Reliable metallization schemes for chemical vapor deposited diamond are critical for expanding the use of diamond components in electronics and optics. We present here the results of our investigation of several metallization schemes produced by cathodic arc deposition. The deposition process also allows the control of the metal ion energy, and this is used to promote good adhesion between film and substrate. Films of Mo, Cu, Ta and W with thickness varying between 50 and 1000 nm were deposited on free-standing smooth diamond substrates and annealed at temperatures between 200°C and 900°C. Interdiffusion and solid state reactions between carbon and the deposited metal were studied using backscattering spectrometry and X-ray diffraction. Of the films tested, W was the only one virtually unaffected by annealing at all temperatures. Upon annealing at 200°C all metal films remained intact and did not delaminate.

Characterization of the diamond growth process using optical emission spectroscopy

In situ optical emission spectroscopy was applied to an electron assisted hot filament diamond growth process. Emission lines from the Balmer series of atomic hydrogen, molecular hydrogen, CH, CH+, and Ar were observed in the visible range when CH4, Ar, and H2 were used as the input gases. The relative concentration of atomic hydrogen was estimated by using the emission line of Ar at 750.4 nm as an actinometer. The effects of deposition conditions, including filament temperature, substrate temperature, bias voltage, and methane concentration in the source gas, on the species distribution, electron temperature, and diamond film growth were investigated. The vertical spatially resolved measurements show that the concentration of atomic hydrogen decreases as the detection point moves far from the filament and suddenly drops near the substrate. The horizontal spatially resolved measurements show that the homogeneous region of reaction species and the electron temperature near the substrate define the homogeneous region of diamond film growth. Increase of filament temperature, substrate temperature, bias voltage, and the decrease of methane concentration in the feed gas increase the atomic hydrogen concentration and diamond deposition. A higher intensity ratio of CH+ to Ar and a lower ratio of CH to Ar are associated with a high quality of diamond film growth. Optical emission spectroscopy showed that atomic hydrogen and CH+ correlate with the formation of the diamond component, whereas the CH relates to the presence of amorphous carbon in the films. The effect of positive bias on the diamond growth results largely from the bombardment of electrons on the substrate.

Optical properties and microstructure of CVD diamond films

Abstract The optical constants n (refractive index) and k (extinction coefficient) of CVD (chemical vapor deposition) diamond thin films are important parameters not only for their optical applications but also provide information concerning the microstructure of the films. Values of n and k as well as the rms surface roughness σ have been extracted from experimental data on transmittance and reflectance for a series of CVD diamond thin films in the visible/UV and infrared ranges and are presented here. The bonded hydrogen contents N(C-H) of these diamond films have also been determined from infrared spectroscopy. A method to effectively extract a weak infrared absorption signal out of a spectrum which is dominated by strong interference fringes has been demonstrated. The changes of n and k as well as of N(C-H) as functions of the reactant gas ratio CH4/H2 are presented. The effective medium approximation is applied to these films in order to provide information concerning film microstructure. Results of SEM, AFM, and Raman spectroscopy are also presented. The correlation between film quality, optical constants, hydrogen content, and volume fractions of diamond and non-diamond components for CVD diamond films has been shown. The analysis indicates that the bonded hydrogen in the films is associated primarily with the inner surface of voids.

Diamonds from the iridium-rich K-T boundary layer at Arroyo el Mimbral, Tamaulipas, Mexico

Research Article| November 01, 1997 Diamonds from the iridium-rich K-T boundary layer at Arroyo el Mimbral, Tamaulipas, Mexico R. M. Hough; R. M. Hough 1Planetary Sciences Research Institute, The Open University, Milton Keynes, MK7 6AA, United Kingdom Search for other works by this author on: GSW Google Scholar I. Gilmour; I. Gilmour 1Planetary Sciences Research Institute, The Open University, Milton Keynes, MK7 6AA, United Kingdom Search for other works by this author on: GSW Google Scholar C. T. Pillinger; C. T. Pillinger 1Planetary Sciences Research Institute, The Open University, Milton Keynes, MK7 6AA, United Kingdom Search for other works by this author on: GSW Google Scholar F. Langenhorst; F. Langenhorst 2Institut für Mineralogie, Museum für Naturkunde, Humboldt-Universität zu Berlin, Invalidenstrasse 43, D-10115 Berlin, Germany Search for other works by this author on: GSW Google Scholar A. Montanari A. Montanari 3Osservatorio Geologico di Coldigioco, I-62020, Frontale di Apiro (MC), Italy4École des Mines de Paris, Boulevard Saint-Michel, 75272, Paris Cedex 06, France Search for other works by this author on: GSW Google Scholar Author and Article Information R. M. Hough 1Planetary Sciences Research Institute, The Open University, Milton Keynes, MK7 6AA, United Kingdom I. Gilmour 1Planetary Sciences Research Institute, The Open University, Milton Keynes, MK7 6AA, United Kingdom C. T. Pillinger 1Planetary Sciences Research Institute, The Open University, Milton Keynes, MK7 6AA, United Kingdom F. Langenhorst 2Institut für Mineralogie, Museum für Naturkunde, Humboldt-Universität zu Berlin, Invalidenstrasse 43, D-10115 Berlin, Germany A. Montanari 3Osservatorio Geologico di Coldigioco, I-62020, Frontale di Apiro (MC), Italy4École des Mines de Paris, Boulevard Saint-Michel, 75272, Paris Cedex 06, France Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1997) 25 (11): 1019–1022. https://doi.org/10.1130/0091-7613(1997)025<1019:DFTIRK>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation R. M. Hough, I. Gilmour, C. T. Pillinger, F. Langenhorst, A. Montanari; Diamonds from the iridium-rich K-T boundary layer at Arroyo el Mimbral, Tamaulipas, Mexico. Geology 1997;; 25 (11): 1019–1022. doi: https://doi.org/10.1130/0091-7613(1997)025<1019:DFTIRK>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Diamonds, up to 30 µm in size, were found in the iridium-rich layer from the K-T boundary site at Arroyo El Mimbral and the spherule bed from Arroyo El Peñon, northeastern Mexico. Stepped heating experiments indicate two or more isotopically distinct diamond components with carbon isotopic compositions characteristic of a mixture of carbon sources. The diamonds' crystal form is cubic—not the hexagonal polymorph of diamond, lonsdaleite, which has been used previously to infer formation due to shock transformation of graphite. The size, crystallography, and mineralogic associations of K-T diamonds are similar to those of impact-produced diamonds from the Ries crater in Germany where both shock transformation of graphite and a mode of formation by condensation from a vapor plume have been inferred. The discovery of impact-produced diamonds in association with high Ir contents for these sediments supports their impact origin, K-T age, and the inference that their source was from the buried impact crater of Chicxulub on the Yucatan peninsula, Mexico. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.