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Chimi, Yasuhiro; Iwase, Akihiro*; Ishikawa, Norito; Kobiyama, Mamoru*; Inami, Takashi*; Kambara, Tadashi*; Okuda, Shigeo*
Nuclear Instruments and Methods in Physics Research B, 245(1), p.171 - 175, 2006/04
Times Cited Count：16 Percentile：72.85(Instruments & Instrumentation)We have studied effects of irradiation with energetic particles on defect accumulation in nanocrystalline gold (nano-Au). The specimens of nano-Au foil (3-5 
m thickness) with various grain sizes (23-156 nm) are prepared by the gas deposition method and subsequent thermal annealings. Irradiations of the specimens with 60-MeV 
C ions, 3.54-GeV 
Xe ions or 2.0-MeV electrons are performed at low temperature. The defect accumulation behavior is observed by measuring the electrical resistivity change during irradiation. Through an analysis of defect accumulation behavior, cross-sections for defect production, 
, and annihilation, 
, in nano-Au increase monotonically as the grain size decreases. These results are considered to be caused by the existence of a large volume fraction of the regions near grain boundaries in nano-Au where the threshold energy for atomic displacements, E, becomes lower than in polycrystalline gold. The possibility of electronic excitation effects in nano-Au is also discussed.
Hiura, Nobuo*; Yamaura, Takayuki; Motohashi, Yoshinobu*; Kobiyama, Mamoru*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 1(2), p.202 - 208, 2002/06
The purpose of this study is to develop oxygen sensor which can measure the oxygen potential of the fuel in a nuclear reactor. The oxygen sensor with CaO stabilized zirconia solid electrolyte has been specially designed in order to prolong its life time. Electromotive force (EMF) of solid galvanic cell Ni/NiO|ZrO
-CaO|Fe/FeO was measured in both the out-pile tests and the in-situ tests using Japan Material Testing Reactor (JMTR), and the characteristics of EMF was discussed. In the out-pile test, it was found that the EMF was almost equal to the theoretical values at temperatures ranging from 700 to 1,000
, and the life span of the sensor was very long up to 980h at 800. In the in-situ test, it was found that the EMF showed almost the reliable values up to 300 h (neutron fluence (E 
1 MeV) 1.5
10
m
), at temperatures from 700 to 900. The imprecision of the EMF was found to be within 6% of the theoretical values up to 1,650 h irradiation time (neutron fluence (E 1 MeV) 8.010 m) at 800. The oxygen sensors were found to be applicable for the oxygen potential measurement of the fuels in a reactor.
Matsunami, Noriaki*; Sataka, Masao; Iwase, Akihiro; Inami, Takashi*; Kobiyama, Mamoru*
Journal of Nuclear Materials, 302(2-3), p.206 - 210, 2002/04
Times Cited Count：8 Percentile：47.9(Materials Science, Multidisciplinary)no abstracts in English
Chimi, Yasuhiro; Iwase, Akihiro; Ishikawa, Norito; Kobiyama, Mamoru*; Inami, Takashi*; Okuda, S.*
Journal of Nuclear Materials, 297(3), p.355 - 357, 2001/09
Times Cited Count：217 Percentile：98.84(Materials Science, Multidisciplinary)no abstracts in English
