Micro–Raman Spectroscopy of Diamonds from JaH 054 and Sahara 98505 Ureilites, Statistic Research

In this paper Raman spectra of diamonds from two different ureilites, JaH 054 and Sahara 98505, were measured. Obtained results for both ureilites showed the Raman shift ranged between 1321 cm -1 and 1336 cm -1 for JaH 054 and between 1329 cm -1 and 1336 cm -1 for Sahara 98505. FWHM parameter (full width at half maximum) varied also in wide range especially for Sahara 98505. Raman imaging was done for JaH 054 sample and diamonds of different Raman shifts (1321 cm-1, 1328 cm-1, 1330 cm-1) were found in few tens (im sized area of carbon vein. Raman peaks of ureilitic diamonds were compared with literature data of laboratory diamonds produced under high pressure, under low pressure with MW PACVD method and with other ureilites. Presented research showed that even in highly shocked ureilites Raman shift versus FWHM parameter plots are similar with CVD diamonds for ureilites. However, the origin of diamonds in ureilites is not explained based on the obtained results, close coexistence of different diamonds in investigated ureilites suggests that the mechanism of diamond creation in meteorites was very complex and could be multi-step process

Micro-Raman study of nanodiamonds from the Allende meteorite

We have studied the Raman spectroscopic signatures of nanodiamonds from the Allende meteorite in which some portions must be of presolar origin as indicated by the isotopic compositions of various trace elements. The spectra of the meteoritic nanodiamond show a narrow peak at 1326 cm‑1 and a broad band at 1590 cm‑1. Compared to the intensities of these peaks, the background fluorescence is relatively high. A significant frequency shift from 1332 to 1326 cm‑1, peak broadening, and appearance of a new peak at 1590 cm‑1 might be due to shock effects during formation of the diamond grains. Such changes may have several origins: an increase in bond length, a change in the electron density function or charge transfer, or a combination of these factors. However, Raman spectroscopy alone does not allow distinguishing between a shock origin of the nanodiamonds and formation by a CVD process as is favored by most workers

Microstructures Manufactured in Diamond by Use of Laser Micromachining.

Different microstructures were created on the surface of a polycrystalline diamond plate (obtained by microwave plasma-enhanced chemical vapor deposition-MW PECVD process) by use of a nanosecond pulsed DPSS (diode pumped solid state) laser with a 355 nm wavelength and a galvanometer scanning system. Different average powers (5 to 11 W), scanning speeds (50 to 400 mm/s) and scan line spacings ("hatch spacing") (5 to 20 µm) were applied. The microstructures were then examined using scanning electron microscopy, confocal microscopy and Raman spectroscopy techniques. Microstructures exhibiting excellent geometry were obtained. The precise geometries of the microstructures, exhibiting good perpendicularity, deep channels and smooth surfaces show that the laser microprocessing can be applied in manufacturing diamond microfluidic devices. Raman spectra show small differences depending on the process parameters used. In some cases, the diamond band (at 1332 cm-1) after laser modification of material is only slightly wider and shifted, but with no additional peaks, indicating that the diamond is almost not changed after laser interaction. Some parameters did show that the modification of material had occurred and additional peaks in Raman spectra (typical for low-quality chemical vapor deposition CVD diamond) appeared, indicating the growing disorder of material or manufacturing of the new carbon phase

Nanocrystalline diamond coatings for dental implants : [abstract]

Różne rodzaje warstw węglowych otrzymanych różnymi sposobami, między innymi warstwy diamentopodobne (DLC) oraz warstwy nanokrystalicznego diamentu (NCD) otrzymane w procesie rozkładu metanu w polu wysokiej częstotliwości RFPACVD, są w wysokim stopniu biokompatybilne. W zależności od parametrów nanoszenia, różnią się one bio-fizycznymi oraz mechanicznymi właściwościami, DLC są amorficzne i zawierają około 60% diamentu oraz 40% grafitu, NCD składają się niemalże całkowicie z czystego diamentu. Zastosowanie warstw węglowych w medycynie jest znane od wielu lat. Prace nad implantami stomatologicznymi rozpoczęły się ponad dziesięć lat temu.Different kinds of carbon coatings, obtained by different methods are highly biocompatible, among them both diamond-like carbon (DLC) and nanocrystailine diamond (NCD) coatings obtained with the radio frequency plasma activated chemical vapour deposition (RFPACVD) process. They have different bio-physical and mechanical properties, in dependence of the parameters of deposition; DLC are amorphous coatings consisting of about 60% diamond and 40% graphite, NCD contains almost pure diamond. The application of carbon coatings in medicine is investigated for many years. Research on dental implants has begun more that decade ago. Otborska and all has explained the good mechanical properties of amorphous carbon coatings - DLC. Amorphous carbon (a-C) coatings, obtained by RFPACVD method, were deposited on implants used in maxillofacial surgery and on the dental prostheses. In all cases the substrate was the medical steel AISI 316L. After that the coating was investigated by Auger electron spectroscopy (AES). AES results show that the surface layer consists of carbon and the interface layer consisting of the substrate carbides (i.e. Cr, Ni, Mo, Fe) makes the coating more adhesive and improves its quality. However, the next generation coatings-NCD, improved in many ways the mechanical properties of the first carbon coatings. Nanocrystailine diamond coatings (NCD), posses the unique bio-medical and mechanical properties and so have found many applications in medicine. NCD is about 1mim thin coating with a very high adhesion to substrate thanks to the interface layer containing substrate carbides. It consists almost pure diamond, the crystals are of the sizes of nanometers. The small amount of graphite, on the grain baundries, even improves the mechanical quality of the coating, it is less brittle. NCD can be coated on different materials, such as titanium and its alloys or medical steel AISI316L, especially interesting are its applications as the coatings for medical implants. Investigations, lasting for many years, show the high biocompatibility of NCD and its good mechanical and physico-chemical properties, it is also resistant to bacterial colonization. Nanocrystailine diamond is also used as the coating for artificial heart valve because of its heamocompatibility and for dental implants. Dental implants have been coated with nanocrystailine diamond by RFPACVD method. Then their surface was analyzed by Raman Spectroscopy, Atomic Force Microscopy and Scanning Electron Microscopy. The good quality, uniform NCD coating, obtained on the dental implants surface, is a promising material in this area of research

Diamonds in ureilites

The presence of diamonds in meteorites was confirmed for the first time in the Novo-Ureiureilite in 1888. Ureilites are a rare class of achondrites, often referred to as primitive achondrites. They are composed of olivine and pyroxene (pygeonite), as well as graphite inclusions often coexisting with diamonds. The following three main hypotheses of diamond origin in ureilites have been proposed: the HPHT process, graphite-to-diamond conversion under shock compression due to impact on the parent body (the most popular theory, as of the time of publication), and the CVD process in the solar nebula. The samples of all types of ureilites, from less shocked up to highly shocked, were examined using Raman Spectroscopy and Scanning Electron Microscopy. The results show the presence of diamonds in all of our samples. Of particular significance is the comparison of Raman spectra of diamonds and graphite phases of different ureilites

3D simulations of diamond microfluidic devices

The aim of this study was to optimize the diamond microfluidic device with four microchannels. The temperature distributions in electrophoretic microchips of different geometries and different materials have been analyzed by the Coventor software. Diamond microfluidic devices are very advantageous over glass or polymer microfluidic devices; they dissipate Joule heat much more efficiently because of the highest thermal conductivity coefficient of diamond

Diamonds from ureilites – CL study of meteorites

Analiza katodoluminescencyjna (CL) została wykorzystana do zbadania czterech różnych meteorytów należących do grupy ureilitów: Dhofar 1303, DaG 868, DaG 999 oraz NWA. We wszystkich próbkach odkryte zostały diamenty o różnych barwach luminescencji i widmach CL. Świadczy to o zróżnicowaniu rodzajów centrów luminescencji w sieci krystalicznej badanych ziaren. Głównymi liniami emisyjnymi w diamentach z ureilitów są: 433 ±5 nm, 615 ±5 nm i 520 ±5 nm. Badane diamenty należy zaliczyć do typu Ia. Są to diamenty zawierające podstawienia węgla przez atomy azotu (>1018 N/cm3) występujące w formie agregatów, a nie pojedynczych atomów.Four different meteorites of the ureilite group have been examined with cathodoluminescence method: Dhofar 1303, DaG 868, DaG 999 and NWA. Diamonds differing both in luminescence colours and CL spectra have been discovered in all the samples. They show diversity of luminescence centres in the crystalline lattice of the grains. Main emission lines in diamonds from ureilites are 433 ±5 nm, 615 ±5 nm and 520 ±5 nm. The diamonds should be classified as Type Ia. They contain substitutions of carbon by nitrogen atoms (>1018 N/cm3) occurring in the form of aggregates rather than individual atoms

Meteoritic nanodiamond: a micro-raman spectroscopical overview

Introduction: There are two hypotheses on the formation processes of the meteoritic nanodiamonds: (1) Chemical Vapor Deposition (CVD) and (2) Shock metamorphism. The purpose of this study is to investigate the crystalline background of the meteoritic nanodiamond from different meteorite separates and understand more about formation mechanism of these samples. This method is not only of great help in elucidating crystal structures, but can also be used as a method of qualitative analysis (finger print), e.g., in determining the phases of small thin section areas without destroying them. This tecnique is potentially useful for study of nanodiamonds