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Article type: Cover
2011 Volume 38 Issue 1 Pages
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Article type: Index
2011 Volume 38 Issue 1 Pages
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2011 Volume 38 Issue 1 Pages
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2011 Volume 38 Issue 1 Pages
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Article type: Index
2011 Volume 38 Issue 1 Pages
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Article type: Appendix
2011 Volume 38 Issue 1 Pages
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Shin-ichi Hirano
Article type: Article
2011 Volume 38 Issue 1 Pages
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Masashi Hasegawa, Kiyoshi Shimamura
Article type: Article
2011 Volume 38 Issue 1 Pages
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Masashi Hasegawa, Ken Niwa
Article type: Article
2011 Volume 38 Issue 1 Pages
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The system for the crystal growth in supercritical fluid at ultra-high pressure and temperature using a diamond anvil cell and infra-red laser-heating (Laser-DAC) is described. Well crystalline fine crystals of GaN in the wultzite-type structure have been grown from gallium/aluminium and supercritical nitrogen fluid at about 10GPa and 3000K. They have hexagonal platelet or prismatic morphology, indicating a solution growth using supercritical nitrogen fluid as a solvent. Rectangular hollow tube single crystals of the rutile-type GeO_2 having a structure equivalent to that of TiO_2, a well-known photocatalyst, have been grown for the first time in supercritical oxygen fluid at about 5GPa and 3000K within 1sec. They are in submicron sizes (cross section with sides of 500nm, wall thickness of 20nm, and longitudinal length of 5μm) and grown along the c-axis surrounded by the (110) faces. These results open us a new way of synthesis and crystal growth of various kinds of nitrides and oxides in supercritical fluid in ultra-high pressures and temperatures using diamond anvil cell and infra-red laser heating.
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Hitoshi Sumiya
Article type: Article
2011 Volume 38 Issue 1 Pages
12-18
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Good-quality diamond crystals can be synthesized by the temperature gradient method at high pressure and high temperature. Progressive improvements of the technique and the development of an originative mass-production process enabled the commercial production of the synthetic diamond crystals (type Ib). In addition, systematic technological developments, which includes the enlargement of crystal size, the elimination of impurities and the improvement of crystalline quality, have made it possible to synthesize high-quality large-size diamond crystals (type IIa) up to 10 carats (12mm in diameter) successfully.
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Takashi Taniguchi
Article type: Article
2011 Volume 38 Issue 1 Pages
19-26
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In this paper, synthesis of boron nitride single crystals by using temperature gradient method under high pressure was described. Single crystal of cubic boron nitride (cBN), known as next hard material after diamond, was synthesized with highly pure quality as nearly colorless feature by using Ba base solvent, showing cBN' s band-edge luminescence properties. There is, however, still space for the improvement for the size and purity in the cBN crystals. Other kind of solvents, such as Ni-base alloys, was studied so as to clarify the growth feature of obtained cBN crystals as compared to those with conventional alkali base solvent system. On the other hands, it is found that high quality hBN single crystals were obtained by using the Ba base solvent. The crystals exhibit promising feature for the deep ultraviolet light source and also for high quality substrate of graphene electronic devices.
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Yuji Kagamitani, Toru Ishiguro, Chiaki Yokoyama, Tsuguo Fukuda
Article type: Article
2011 Volume 38 Issue 1 Pages
27-30
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The ammonothermal method, which uses supercritical ammonia fluid instead of supercritical water in the cases of hydrothermal growths of quarts and ZnO, is one of the promising techniques for a mass-production of GaN wafers. Especially, recently, bulk GaN crystal growth by the ammonothermal method is reported from several research laboratories. The expectation for practical use of it becomes higher. In this report, element technologies of the ammonothermal method, development situation in the world and recent results of Tohoku University are introduced.
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Daisuke Tomida, Chiaki Yokoyama
Article type: Article
2011 Volume 38 Issue 1 Pages
31-35
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The solubility of GaN in supercritical ammonia with acidic mineralizer was measured, and compared with the solubility of GaN in supercritical ammonia with basic mineralizer. With acidic mineralizer, the GaN solubility increased with increasing temperature. By contrast, the solubility of GaN with basic mineralizer decreased with increasing temperature. These results indicate the temperature dependence of GaN solubility in supercritical ammonia is quite different from that with different types of mineralizer. Because the solubility of GaN in supercritical ammonia changes with the type of mineralizer and with mineralizer concentration, further solubility data will need to be measured to understand GaN solubility.
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Katsumi Maeda, Takao Suzuki, Hayato Sasaki, Shigeaki Sugimura
Article type: Article
2011 Volume 38 Issue 1 Pages
36-44
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Zinc oxide (ZnO) bulk single crystals were grown by the hydrothermal method, which has been used for the synthesis of quartz single crystals. We evaluated crystallinity, impurit concentration, electric and optical characteristics of ZnO single crystals. The impurity concentration of ZnO was different in each crystal area. Because of that, the electric characteristic was different in the crystal area. And recently we succeeded in the growth of 2inch non-polar ZnO single crystals substrates for the green LED.
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Shigeo Sasaki, Takuo Okuchi, Tetsuji Kume, Hiroyasu Shimizu
Article type: Article
2011 Volume 38 Issue 1 Pages
45-54
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It is well known that gas hydrates are non-stoichiometric compounds which cause experimental difficulty in determining the intrinsic physical and chemical properties of gas hydrates. Therefore, microscopic observation and high-pressure light scattering spectroscopy for single crystalline gas hydrates become ideal methods to investigate the pressure-induced phase trans-formation and the cage occupancy of guest gas molecules in gas hydrate structures. In this article, we present the technique of growing single crystalline gas hydrates and the applications of microscopic observation and light scattering measurements to methane hydrate as an example.
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Hiroyuki Saitoh, Akihiko Machida, Yoshinori Katayama, Katsutoshi Aoki
Article type: Article
2011 Volume 38 Issue 1 Pages
55-61
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Structural information of specimens can be obtained in situ at high pressures and temperatures using a cubic-type multi-anvil press and synchrotron radiation x-ray diffraction measurements. This system enables us to clarify reaction mechanism at high pressures. In the present paper, energy dispersive and angle dispersive in situ x-ray diffraction measurement systems are explained. Hydrogenation reaction of aluminum has been investigated via these methods, and the results are described. These methods are expected to be useful for crystal growth studies at high pressures and temperatures.
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Koichi Kakimoto
Article type: Article
2011 Volume 38 Issue 1 Pages
62-63
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Hiroyasu Katsuno, Masahide Sato
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2011 Volume 38 Issue 1 Pages
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Gen Sazaki, Yoshinori Furukawa
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2011 Volume 38 Issue 1 Pages
65-66
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Article type: Appendix
2011 Volume 38 Issue 1 Pages
67-75
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2011 Volume 38 Issue 1 Pages
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2011 Volume 38 Issue 1 Pages
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2011 Volume 38 Issue 1 Pages
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2011 Volume 38 Issue 1 Pages
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