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Kawabata, Kuniaki; Sato, Noritaka*
Keisoku To Seigyo, 62(5), p.276 - 279, 2023/05
no abstracts in English
Teraoka, Yuden; Tode, Mayumi*; Harries, J.; Yoshigoe, Akitaka
Denki Gakkai Rombunshi, C, 134(4), p.473 - 478, 2014/04
Yoshida, Miru*; Zhao, Y.; Fujita, Masahiro*; Ohira, Akihiro*; Takeoka, Yuko*; Koizumi, Satoshi*; Rikukawa, Masahiro*
ECS Transactions, 50(2), p.1045 - 1053, 2012/10
Harries, J.; Teraoka, Yuden; Tode, Mayumi; Yoshigoe, Akitaka
Applied Physics Express, 5(3), p.031802_1 - 031802_3, 2012/03
Times Cited Count:0 Percentile:0(Physics, Applied)Takeda, Masayasu; Suzuki, Junichi*; Akiya, Takahiro*; Kato, Hiroaki*
Nihon Kinzoku Gakkai-Shi, 76(3), p.165 - 176, 2012/03
Times Cited Count:1 Percentile:78.66(Metallurgy & Metallurgical Engineering)Matsuoka, Takahiro*; Fujihisa, Hiroshi*; Hirao, Naohisa*; Oishi, Yasuo*; Mitsui, Takaya; Masuda, Ryo; Seto, Makoto*; Yoda, Yoshitaka*; Shimizu, Katsuya*; Machida, Akihiko; et al.
Physical Review Letters, 107(2), p.025501_1 - 025501_4, 2011/07
Times Cited Count:29 Percentile:77.56(Physics, Multidisciplinary)Europium-hydride EuH exposed to high-pressure H conditions has been found to exhibit structural and valence changes, (=2, divalent) 63/ (=2, 7.2-8.7 GPa) 4/ (2, 8.7-9.7 GPa) 4/ (2, 9.7 GPa-, trivalent). Having trivalent character and distorted cubic fcc structure, the 4/ structure is the -phase which has been commonly observed for other rare-earth metal hydrides. Our study clearly demonstrates that EuH is no longer an "irregular" member of the rare earth metal hydrides.
Kamakura, Nozomu; Takeda, Yukiharu; Saito, Yuji; Yamagami, Hiroshi; Tsubota, Masami*; Paik, B.*; Ichikawa, Takayuki*; Kojima, Yoshitsugu*; Muro, Takayuki*; Kato, Yukako*; et al.
Physical Review B, 83(3), p.033103_1 - 033103_4, 2011/01
Times Cited Count:5 Percentile:25.28(Materials Science, Multidisciplinary)The electronic structure of lithium amide, which is lightweight complex hydride expected as a high-capacity hydrogen storage material, is investigated by N 1 soft X-ray emission spectroscopy (XES) and absorption spectroscopy (XAS). The overall feature of the electronic structure of lithium amide by the XES and XAS is consistent with the band calculation, while the strongly hybridized state with H 1 is located at higher binding energy than the band calculation.
Tode, Mayumi; Harries, J.; Teraoka, Yuden; Yoshigoe, Akitaka
Denki Gakkai Rombunshi, C, 130(10), p.1819 - 1820, 2010/10
In order to study the thermal degradation process of the hydrogen storage materials surface layer and the thermal desorption of hydrogen property, we have used high-resolution synchrotron radiation X-ray photoelectron spectroscopy. The experiments were performed at the JAEA soft X-ray beamline BL23SU at SPring-8, using the "SUREAC2000" surface reaction analysis apparatus. Spectra were recorded for two samples (VCrTi) covered with native oxide layers, one of which was implanted with deuterium ions. For the un-implanted sample, the oxide layer changes dramatically between 373 K and 473 K, for the deuterium-implanted sample, the change occurs between 473 K and 573 K. The implantation of deuterium leads to a stabilization (of approximately 100 K) of the surface oxide layer.
Kamakura, Nozomu; Okane, Tetsuo; Takeda, Yukiharu; Fujimori, Shinichi; Saito, Yuji; Yamagami, Hiroshi; Fujimori, Atsushi; Fujita, Asaya*; Fujieda, Shun*; Fukamichi, Kazuaki*
Materials Research Society Symposium Proceedings, Vol.1262, 6 Pages, 2010/10
Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*
Proceedings of 21st International Workshop on Rare-Earth Permanent Magnets and their Applications (REPM 2010), p.161 - 164, 2010/08
We performed small-angle neutron scattering (SANS) measurements of Nd-Fe-B sintered magnets to get information on the averaged internal microstructure of Nd-Fe-B sintered magnets including the interfacial structure which is a key parameter to achieve a high-coercivity Dy-free Nd-Fe-B sintered magnet. SANS patterns from the Nd-Fe-B sintered magnets measured with a two-dimensional detector of a small-angle neutron scattering spectrometer SANS-J-II in the research reactor JRR-3 were sensitive to the sintering and annealing condition of the samples. These results indicate that the SANS measurement is a promising tool to investigate the correlation between the coercivity and the internal microstructure of Nd-Fe-B sintered magnets.
Komeda, Masao; Arai, Masaji; Sagawa, Hisashi; Kusunoki, Tsuyoshi
Proceedings of 12th International Group on Research Reactors (12th IGORR) (USB Flash Drive), 9 Pages, 2009/10
Yagi, Masahiro; Watanabe, Masanori; Oyama, Koji; Yamamoto, Kazuyoshi; Komeda, Masao; Kashima, Yoichi; Yamashita, Kiyonobu
Applied Radiation and Isotopes, 67(7-8), p.1225 - 1229, 2009/07
Times Cited Count:11 Percentile:59.65(Chemistry, Inorganic & Nuclear)Tagawa, Masahito*; Yokota, Kumiko*; Maeda, Kenichi*; Yoshigoe, Akitaka; Teraoka, Yuden
Applied Physics Express, 2(6), p.066002_1 - 066002_3, 2009/06
Times Cited Count:3 Percentile:14.39(Physics, Applied)Hyperthermal (kinetic energy of 10 eV) fluorine atom beam interaction with highly oriented pyrolytic graphite (HOPG) was studied. Surface analytical results of atomic fluorine-exposed HOPG using synchrotron radiation photoelectron spectroscopy showed that the fluorine reaction was limited at the topmost HOPG(0001) layer. This is due to the fact that the kinetic energy of 10 eV is not sufficient to penetrate graphite layer but is enough for breaking C-C bonds and forms CF and CF functional groups through the beam-induced fluorination reactions. It was demonstrated that the use of hyperthermal energy in the range of 10 eV is advantageous for damage-free modification of the topmost surface of carbon-based materials.
Iwase, Hiroki; Koizumi, Satoshi; Iikura, Hiroshi; Matsubayashi, Masahito; Yamaguchi, Daisuke; Maekawa, Yasunari; Hashimoto, Takeji
Nuclear Instruments and Methods in Physics Research A, 605(1-2), p.95 - 98, 2009/06
Times Cited Count:33 Percentile:88.89(Instruments & Instrumentation)We constructed an in-situ and simultaneous observation method as a result of combination between ultra-small-angle neutron scattering and neutron imaging (radiography). With this novel technique, we are able to visualize water distribution or transportation, occurring from micro to macro length scales in a polymer electrolyte fuel cell (PEFC). At a sample position of SANS-J-II at JRR-3, we installed a neutron imaging camera in order to construct an in-situ and simultaneous observation method by USANS and neutron imaging with monochromatized cold neutrons. In addition, in order to selectively observe MEA in a running PEFC by using the in-situ and simultaneous observation method, we need to replace carbon separators which cause strong small-angle scattering as a noise. To reduce this strong background, we replaced the carbon separators with the aluminium ones. As a result, the background scattering was minimized (1/10) as compared to before.
Yokota, Kumiko*; Tagawa, Masahito*; Kitamura, Akira*; Matsumoto, Koji*; Yoshigoe, Akitaka; Teraoka, Yuden
Applied Surface Science, 255(13-14), p.6710 - 6714, 2009/04
Times Cited Count:13 Percentile:50.2(Chemistry, Physical)The densities of hydrogen and carbon atoms in a hydrogenated diamond-like carbon (DLC) film exposed to a hyperthermal atomic oxygen beam were investigated by Rutherford backscattering spectroscopy and elastic recoil detection analysis. The hydrogen density in DLC decreased upon atomic oxygen exposure with collision energy as low as 2 eV, whereas an exposure greater than 3 eV was necessary to remove carbon atoms. A high collision energy also led to hydrogen desorption in the deeper region of DLC. The surface density of hydrogen decreased 6% by atomic oxygen exposure, and was independent of the collision energy. Additionally, the non-bonded hydrogen, which could diffuse in DLC, was desorbed by the energy transfer from the atomic oxygen collisions.
Teraoka, Yuden; Yoshigoe, Akitaka; Harries, J.
Journal of Surface Analysis, 15(3), p.303 - 306, 2009/03
In order to study correlation between oxide layers on hydrogen storage metals such as V(111), polycrystalline Vanadium, and VCrTa alloy and hydrogen desorption temperature, the surfaces covered by native oxides have been analyzed by photoemission spectroscopy using soft X-ray synchrotron radiation. Depth analyses of the oxide layers were performed by changing synchrotron radiation energy to estimate the oxide thickness. The native oxide layer was disappeared by thermal annealing up to 713 K for the V(111) surface. The oxide layers of the poly V and the VCrTa alloy, however, were remained even at 873 K. Although the oxides of V and Cr were disappeared, Ta oxides were remained. The re-arrangement of oxidation took place in the oxide layer of VCrTa alloy by thermal annealing. The oxidation of Ta controlled oxide thickness in the VCrTa alloy. The formation of an artificial oxide layer could be controlled using supersonic oxygen molecular beams.
Komeda, Masao; Yamamoto, Kazuyoshi; Yagi, Masahiro; Sagawa, Hisashi
JAEA-Technology 2008-064, 77 Pages, 2008/10
We investigated the irradiation method to irradiate 12 inch NTD silicon uniformly in JRR-3, where 6 inch NTD silicon is being irradiated at present, by using MVP of the Monte Carlo calculation code. In the case of irradiating 12 inch NTD silicon, the deviation of the doping distribution in the radial direction becomes 1.17 by the same irradiation method of 6 inch NTD silicon. Therefore the thermal neutron filter was introduced for uniform doping (the deviation is less than 1.10) in the radial direction and the effect was analyzed. As the result, it was indicated that the deviation of the doping distribution in the radial direction became less than 1.1 by using the neutron filter, which was made from aluminum alloy of 2 mm thickness including natural boron of 1%.
Yagi, Masahiro; Watanabe, Masanori; Oyama, Koji; Komeda, Masao; Yamamoto, Kazuyoshi; Kashima, Yoichi
JAEA-Technology 2008-015, 91 Pages, 2008/03
The irradiation experimental device is designed by surveying analytically an irradiation condition to improve the neutron flux distribution of the radial direction on NTD-Si by using neutron transportation calculation Monte Carlo calculation code MCNP5 in order to develop neutron irradiation technology for the large-diameter silicon to 12 inches diameter at the maximum and an irradiation experiment will be performed in JRR-4. Thus the validity of the design technique of the irradiation device will be confirmed by this experiment. The irradiation experimental device is installed in the side of the core tank outer wall. A 12 inches silicon ingot of 60cm in height is irradiated in a reflector cover which surrounds the silicon ingot for increasing the flux. The silicon ingot is rotated during irradiation in order to require the condition of uniformly distributed thermal neutron flux over whole circumferences. A uniform irradiation condition was achieved by the pass-through core method, in which silicon ingot moved up and down with rotating. The condition was satisfied when silicon was covered with the thermal neutron filter, which is made from aluminum alloy of thickness of 2mm with natural boron element ratio of 1.5%, and was moved in the range from -42mm to 22mm for the center of the reactor core. The deviation of the Si-30 neutron absorption reaction rate was range from -3.2% to +5.3% in the intermediate volume of 40cm height and the neutron absorption reaction ratio of the circumference to the center was within 1.09 in the volume.
Yamamoto, Kazuyoshi; Yamashita, Kiyonobu; Sagawa, Hisashi; Isshiki, Masahiko*
no journal, ,
no abstracts in English
Yamashita, Kiyonobu; Isshiki, Masahiko*; Sagawa, Hisashi; Yamamoto, Kazuyoshi
no journal, ,
no abstracts in English