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2004 Volume 31 Issue 4 Pages
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Article type: Index
2004 Volume 31 Issue 4 Pages
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2004 Volume 31 Issue 4 Pages
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Shigeyuki Kimura
Article type: Article
2004 Volume 31 Issue 4 Pages
301-302
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Yasunao Oyama, Koichi Kakimoto
Article type: Article
2004 Volume 31 Issue 4 Pages
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Ichiro Sunagawa
Article type: Article
2004 Volume 31 Issue 4 Pages
304-310
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Diamond crystals grow under diamond stable conditions from silicate or carbonate solution in nature and from metal solution in synthesis, as well as under labile conditions by CVD method. How these differences affect the morphologies of diamond crystals (external forms, surface microtopographs, internal perfection and homogeneity, etc.) are critically analyzed. In silicate or carbonate solution, only {111} behaves as a smooth interface, and {100} exclusively behaves as a rough interface, whereas in metal solution, both {111} and {100} behave as smooth interfaces on which spiral growth takes place. Surface reconstruction of {100} in metal solution is the main cause for the observed differences between natural and synthetic diamonds grown under diamond stable conditions. In CVD diamond growth, the order of morphological importance is reversed and {100} becomes more important than {111}. This drastic change in the order of morphological importance is inferred to the change in surface energy term due to hydrogen. Based on morphological features observed on natural diamond crystals, their growth and post-growth histories are analyzed. There are two distinctly different sites for diamond formation; one in ultra high pressure metamorphic rocks (including eclogite), the other in ultramafic magma. Diamond crystals in the former are micron order in size and show high proportion of cuboid and spherulite, with concentration attaining % order, whereas in the latter, crystals are bigger in size but the content is in ppm order. The carbon in the former is organic origin, whereas in the latter inorganic mantle origin. The former crystals subducted deeper into the mantle act as seeds for the growth of diamond under low driving force condition. Crystals formed in the latter are uplifted and fibrous growth took place, forming coated stones and cuboids. In post-growth history, diamonds experience partial dissolution resulting in rounded crystals and trigons, and plastic deformation. Type II diamonds are fractured during this stress history, resulting in irregular forms characteristic to Type II crystals.
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Masao Wakatsuki
Article type: Article
2004 Volume 31 Issue 4 Pages
311-318
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Growth process of diamond in the solvent method is understood on the basis of pseudo-binary eutectic system between the solvent and diamond. In the pressure region where thermodynamic stabilities of graphite and diamond are nearly balanced, nearly perfect graphite is recrystallized in competition with diamond nucleation. This phenomenon is utilized for controlling the nucleation density of diamond in actual production of diamond particles. In the growth of large single crystal under temperature gradient in the solvent, the growth rate is controlled by the carbon transport in the solvent. Large and high quality crystals are grown under consideration of the mechanism of forming inclusion of solvent, reasonable limitation of the growth rate for avoiding the solvent inclusion, suitable crystal direction and lattice perfection of the seed and selection of the solvent composition. Crystals weighing around 10 carats are grown for several hundred hours.
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Hisao Kanda
Article type: Article
2004 Volume 31 Issue 4 Pages
319-325
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It is well known that high pressure diamond grows from conventional solvents such as iron and nickel metals. However, it has been found that diamond can also be grown from non-conventional solvents such as carbonates and copper. Solubility of carbon is negligibly low in the non-conventional solvent. It is not easy to grow large single crystals because of extremely low growth rates, but some of the non-conventional solvents are very powerful for sintering fine diamond powder. Unique surface morphology is observed from the diamond grown from the non-conventional solvents.
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Takahiro Imai, Yoshiyuki Yamamoto, Kiichi Meguro
Article type: Article
2004 Volume 31 Issue 4 Pages
326-329
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Homogeneous growth apparatus for diamond single crystal which improved the uniformity of plasma was developed, and the chemical vapor deposition (CVD) technology of a large single crystal diamond was established. The design of the microwave plasma CVD apparatus which utilized electromagnetic-field analysis can generate uniform plasma now in the diameter range of more than 20mm. By using this CVD apparatus, 16-mm-square homoepitaxial growth was completed over the type Ib mosaic seed-crystal diamond. After 100h growth, the thickness of the epitaxial layer was over 1mm, and it had a jointed mosaic interface.
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Yoichi Hirose, Kohei Hosono
Article type: Article
2004 Volume 31 Issue 4 Pages
330-334
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Diamond crystals have been synthesized by hot-filament CVD method (chemical vapor deposition) using methyl alcohol (CH_3OH) only. The crystals are grown on the substrate at a pressure of 760 torr. The deposited crystals are characterized by SEM observation and Raman spectroscopy. With the view of promoting science education, a diamond synthesis device can be composed of glass-bottles and ruber stoppers; it simply costs several hundred yen. The previous by reported CVD methods have used plasma to decompose the gases (CH_4,C_2H_5OH) containing carbon. It is known that one of a plasma in the atmosphere is the combustion flame. Diamond crystals with good crystallinity have been successfully grown on a substrate using oxyacetylene combustion flame in the atmosphere. The substrate had to place within a inner flame (reducing flame) of combustion flame. The growth rates of the diamond depend on substrate temperatures and gas ratios (O_2/C_2H_2). A reaction chamber is not required and therefore, the diamond synthesis is easily performed.
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Kwang-Soup Song, Yusuke Nakamura, Munenori Degawa, Yoshinori Sasaki, H ...
Article type: Article
2004 Volume 31 Issue 4 Pages
335-340
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The electrolyte-solution-gate diamond field effect transistors (SGFETs) have been fabricated on polycrystalline diamond surface and which are used biosensors worked in electrolyte solution. The hydrogen-terminated diamond surface is sensitive to halogen ions about 30mV/decade, which can be applied to cell biological reaction. The hydrogen-terminated surface channel of the SGFETs was modified into partially aminated and oxygen-terminated (H-A-O-terminated) with irradiation of ultraviolet in an ammonia environment to get pH sensitivity and immobilize enzyme. The pH response of that is obtained about 50mV/pH at pH 2-10. The concentration of substrates (urea or glucose) in the electrolyte solution has been detected by the pH change due to the bio-catalyzed effect of enzyme (urease or glucose oxidase), which is immobilized on the channel of SGFETs. The sensitivity of urea and glucose is approximately 30mV/decade and 20mV/decade respectively.
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Atsushi Mori
Article type: Article
2004 Volume 31 Issue 4 Pages
341-342
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Masahito Watanabe
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2004 Volume 31 Issue 4 Pages
343-344
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Article type: Appendix
2004 Volume 31 Issue 4 Pages
345-354
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Article type: Appendix
2004 Volume 31 Issue 4 Pages
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Article type: Appendix
2004 Volume 31 Issue 4 Pages
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2004 Volume 31 Issue 4 Pages
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Article type: Appendix
2004 Volume 31 Issue 4 Pages
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Article type: Appendix
2004 Volume 31 Issue 4 Pages
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Article type: Cover
2004 Volume 31 Issue 4 Pages
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