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Yamauchi, Hiroki; Sari, D. P.*; Yasui, Yukio*; Sakakura, Terutoshi*; Kimura, Hiroyuki*; Nakao, Akiko*; Ohara, Takashi; Honda, Takashi*; Kodama, Katsuaki; Igawa, Naoki; et al.
Physical Review Research (Internet), 6(1), p.013144_1 - 013144_9, 2024/02
Kajimoto, Ryoichi; Nakamura, Mitsutaka; Murai, Naoki; Shamoto, Shinichi; Honda, Takashi*; Ikeda, Kazutaka*; Otomo, Toshiya*; Hata, Hiroto*; Eto, Takahiro*; Noda, Masaaki*; et al.
Scientific Reports (Internet), 8(1), p.9651_1 - 9651_8, 2018/06
Times Cited Count:6 Percentile:30.3(Multidisciplinary Sciences)Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Ikeda, Kazutaka*; Oshita, Hidetoshi*; Kaneko, Naokatsu*; Otomo, Toshiya*; Suzuya, Kentaro; Hoshikawa, Akinori*; Ishigaki, Toru*
JPS Conference Proceedings (Internet), 8, p.034002_1 - 034002_6, 2015/09
Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Ikeda, Kazutaka*; Oshita, Hidetoshi*; Kaneko, Naokatsu*; Otomo, Toshiya*; Suzuya, Kentaro; Hoshikawa, Akinori*; Ishigaki, Toru*
JPS Conference Proceedings (Internet), 3, p.013012_1 - 013012_6, 2014/06
Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Ikeda, Kazutaka*; Oshita, Hidetoshi*; Kaneko, Naokatsu*; Otomo, Toshiya*; Suzuya, Kentaro
Journal of the Physical Society of Japan, 82(9), p.094601_1 - 094601_6, 2013/09
Times Cited Count:11 Percentile:58.33(Physics, Multidisciplinary)Naito, Hiroyuki; Itagaki, Wataru; Okazaki, Yoshihiro; Imaizumi, Kazuyuki; Ito, Chikara; Nagai, Akinori; Kitamura, Ryoichi; Shamoto, Naoki*; Takeshima, Yoshiyuki*
JAEA-Technology 2012-009, 100 Pages, 2012/05
The radiation characteristics of image fiber and light guide fiber were evaluated to develop a high radiation resistant fiberscope for the fast reactor in-vessel observation. It is known that a pure silica core fiber has a high radiation resistance and radiation resistance is influenced with impurities in silica. Moreover it is necessary to change the clad material of the light guide fiber because that of the current light guide fiber is acrylate, which is weak against radiation. Hence the improved fibers consist of a pure silica core with 1,000 ppm OH and fluorine-doped silica clad. As a result of a irradiation test, we confirm that OH inhibits the generation of the precursor by irradiation. About the clad material, we confirmed that the transmission loss of the fluorine-doped silica clad fiber is smaller than that of the acrylate clad fiber. About the mechanical strength of a fiber, we confirmed that there is no weakening the strength of the fiber and no exfoliation of the coating from the glass. In this study, we discovered the fiber which consists of a pure silica core with 1,000 ppm OH and fluorine-doped silica clad has a high radiation resistance and it is possible to observe using this fiber under the 200 C after 510 Gy irradiation.
Taguchi, Tomitsugu; Igawa, Naoki; Shamoto, Shinichi
IOP Conference Series; Materials Science and Engineering, 18, p.062020_1 - 062020_4, 2011/10
Times Cited Count:3 Percentile:76.97(Nanoscience & Nanotechnology)SiC nanowires and nanotubes sheathed with BN were synthesized by annealing C-SiC and SiC nanotubes at 1600 and 1700 C for 5 h with BN powder in Ar gas. According to TEM observation, the BN coating was very thin and the layer number of BN coating was less than 10. The BN coating on the surface of SiC nanotubes was not produced by the heat treatment at 1500 C. This result revealed that BN on the surface of SiC nanomaterials produced by heat treatment of higher than 1600 C. After the heat treatment of higher than 1600 C, many nanotubes transformed to nanowires because the inner space of nanotubes was occluded due to the SiC grain growth by heat treatment.
Hanna, Taku*; Muraba, Yoshinori*; Matsuishi, Satoru*; Igawa, Naoki; Kodama, Katsuaki; Shamoto, Shinichi; Hosono, Hideo*
Physical Review B, 84(2), p.024521_1 - 024521_7, 2011/07
Times Cited Count:102 Percentile:94.65(Materials Science, Multidisciplinary)Kodama, Katsuaki; Wakimoto, Shuichi; Igawa, Naoki; Shamoto, Shinichi; Mizoguchi, Hiroshi*; Hosono, Hideo*
Physical Review B, 83(21), p.214512_1 - 214512_5, 2011/06
Times Cited Count:19 Percentile:61.3(Materials Science, Multidisciplinary)Belik, A. A.*; Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Kosuda, Kosuke*; Muromachi, Eiji*
Journal of the American Chemical Society, 132(23), p.8137 - 8144, 2010/05
Times Cited Count:49 Percentile:74.59(Chemistry, Multidisciplinary)Belik, A. A.*; Iikubo, Satoshi; Yokosawa, Tadahiro*; Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Azuma, Masaki*; Takano, Mikio*; Kimoto, Koji*; Matsui, Yoshio*; et al.
Journal of the American Chemical Society, 129(4), p.971 - 977, 2007/01
Times Cited Count:182 Percentile:95.3(Chemistry, Multidisciplinary)Structural properties of polycrystalline single-phased BiMnO samples prepared at 6 GPa and 1383 K have been studied by selected area electron diffraction (SAED), convergent beam electron diffraction (CBED), and the Rietveld method using neutron diffraction data measured at 300 and 550 K. The SAED and CBED data showed that BiMnO crystallizes in the centrosymmetric space group C2/c at 300 K. The analysis of Mn-O bond lengths suggested that the orbital order present in BiMnO at 300 K melts above T= 474 K. The phase transition at 474 K is of the first order and accompanied by a jump of magnetization and small changes of the effective magnetic moment and Weiss temperature.
Belik, A. A.*; Iikubo, Satoshi; Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Niitaka, Seiji*; Azuma, Masaki*; Shimakawa, Yuichi*; Takano, Mikio*; Izumi, Fujio*; et al.
Chemistry of Materials, 18(3), p.798 - 803, 2006/02
Times Cited Count:278 Percentile:98.63(Chemistry, Physical)The crystal and magnetic structures of polycrystalline BiCoO have been determined by the Rietveldmethod from neutron diffraction data measured at temperatures from 5 to 520 K. BiCoO (space groupP4mm; Z=1; a=3.72937(7) and c=4.72382(15) at room temperature; tetragonality c/a=1.267) is isotypic with BaTiO and PbTiO in the whole temperature range. BiCoO is an insulator with a Neeltemperature of 470 K. A possible model for antiferromagnetic order is proposed with a propagationvector of k=(1/2, 1/2, 0). In this model, magnetic moments of Co ions are parallel to the c directionand align antiferromagnetically in the ab plane. The antiferromagnetic ab layers stack ferromagneticallyalong the c axis, forming a C-type antiferromagnetic structure. Refined magnetic moments at 5 and 300K are 3.24(2) and 2.93(2), respectively. The structure refinements revealed no deviation fromstoichiometry in BiCoO. BiCoO decomposed in air above 720 K to give CoO and sillenite-like BiCoO.
Belik, A. A.*; Iikubo, Satoshi; Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Maie, Makoto*; Nagai, Takuro*; Matsui, Yoshio*; Stefanovich, S. Y.*; Lazoryak, B. I.*; et al.
Journal of the American Chemical Society, 128(3), p.706 - 707, 2006/01
Times Cited Count:114 Percentile:89.99(Chemistry, Multidisciplinary)The crystal structure of BiScO have been determined by neutron diffraction and electron diffraction measurements. All experimental results shows space group of BiScO is C2/c, which has a center of symmetry.
Taguchi, Tomitsugu; Igawa, Naoki; Yamamoto, Hiroyuki; Shamoto, Shinichi; Jitsukawa, Shiro
Physica E, 28(4), p.431 - 438, 2005/09
Times Cited Count:83 Percentile:91.14(Nanoscience & Nanotechnology)Preparation conditions of single-phase SiC nanotubes and C-SiC coaxial nanotubes were investigated. The characterization of single-phase SiC nanotubes and C-SiC coaxial nanotubes were carried out. The SiC nanowires, which were made of the catenated SiC grains of 50-200 nm in diameter, were obtained in carbon nanotubes reacted at 1450 C. The only C-SiC coaxial nanotubes were formed at 1300 C. A few single-phase SiC nantoubes were synthesized at 1200 C for 100 h. More than half number of nanotubes reacted at 1200 C for 100 h were altered to single-phase SiC nantoubes by heat treatment of 600 C for 1h in air since the remained carbon was removed. The energy dispersive X-ray spectroscopy analysis revealed that the atomic ratio of Si to C in single-phase SiC nanotubes was almost 1; these single-phase SiC nanotubes consisted of near-stoichiometric SiC grains.
Shikama, Tatsuo*; Ishihara, Masahiro; Hayashi, Kimio; Kakuta, Tsunemi; Shamoto, Naoki*; Ishino, Shiori*
Proceedings of 1st Information Exchange Meeting on Basic Studies on High-Temperature Engineering, p.379 - 386, 1999/09
no abstracts in English
Kakuta, Tsunemi; Shikama, Tatsuo*; *; ; Shamoto, Naoki*; *
Proc. of Int. Conf. on Optical Technology and Image Processing in Fluid,Thermal and Combustion Flow, p.1 - 5, 1998/00
no abstracts in English
Taguchi, Tomitsugu; Igawa, Naoki; Jitsukawa, Shiro; Yamamoto, Hiroyuki; Shamoto, Shinichi
no journal, ,
no abstracts in English
Taguchi, Tomitsugu; Igawa, Naoki; Yamamoto, Hiroyuki; Shamoto, Shinichi
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Single-phase SiC nanotubes were succeeded in synthesized by the reaction of carbon nanotubes with Si powder at 1200 C for 100 h. The X-ray diffraction patterns indicate that most of the carbon nanotubes reacted with Si at 1200 C for 100 h were transformed to SiC. The results of TEM observation revealed that single-phase SiC nanotubes as well as C-SiC coaxial nanotubes, which are carbon nanotubes sheathed with SiC layer, were synthesized by reacting for 100 h. Furthermore, SiC-SiO nanotubes were succeeded in synthesized by heating SiC nanotube at 1300 C in a low vacuum.
Taguchi, Tomitsugu; Igawa, Naoki; Yamamoto, Hiroyuki; Shamoto, Shinichi
no journal, ,
no abstracts in English
Taguchi, Tomitsugu; Igawa, Naoki; Yamamoto, Hiroyuki; Shamoto, Shinichi
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no abstracts in English