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Suekuni, Koichiro*; Lee, C. H.*; Tanaka, Hiromi*; Nishibori, Eiji*; Nakamura, Atsushi*; Kasai, Hidetaka*; Mori, Hitoshi*; Usui, Hidetomo*; Ochi, Masayuki*; Hasegawa, Takumi*; et al.
Advanced Materials, 30(13), p.1706230_1 - 1706230_6, 2018/03
Times Cited Count：62 Percentile：89.45(Chemistry, Multidisciplinary)Thermoelectric materials for highly efficient devices must satisfy conflicting requirements of high electrical conductivity and low thermal conductivity. In this paper, we studied the crystal structure and phonon dynamics of tetrahedrites (Cu,Zn)
(Sb,As)
S
. The results revealed that the Cu atoms in a planar coordination are rattling, which effectively scatter phonons. These findings provide a new strategy for the development of highly efficient thermoelectric materials with planar coordination.
Okamoto, Yoshihiro; Shiwaku, Hideaki; Nakada, Masami; Komamine, Satoshi*; Ochi, Eiji*; Akabori, Mitsuo
Journal of Nuclear Materials, 471, p.110 - 115, 2016/02
Times Cited Count：6 Percentile：45.30(Materials Science, Multidisciplinary)Extended X-ray Absorption Fine Structure (EXAFS) analyses were performed to evaluate REDOX (REDuction and OXidation) state of platinoid elements in simulated high-level nuclear waste glass samples prepared under different conditions of temperature and atmosphere. At first, EXAFS functions were compared with those of standard materials such as RuO
. Then structural parameters were obtained from a curve fitting analysis. In addition, a fitting analysis used a linear combination of the two standard EXAFS functions of a given elements metal and oxide was applied to determine ratio of metal/oxide in the simulated glass. The redox state of Ru was successfully evaluated from the linear combination fitting results of EXAFS functions. The ratio of metal increased at more reducing atmosphere and at higher temperatures. Chemical form of rhodium oxide in the simulated glass samples was RhO unlike expected RhO
. It can be estimated rhodium behaves according with ruthenium when the chemical form is oxide.
Tokuhisa, Atsushi*; Arai, Junya*; Jochi, Yasumasa*; Ono, Yoshiyuki*; Kameyama, Toyohisa*; Yamamoto, Keiji*; Hatanaka, Masayuki*; Gerofi, B.*; Shimada, Akio*; Kurokawa, Motoyoshi*; et al.
Journal of Synchrotron Radiation, 20(6), p.899 - 904, 2013/11
Times Cited Count：5 Percentile：27.91(Instruments & Instrumentation)Okamoto, Yoshihiro; Nakada, Masami; Akabori, Mitsuo; Komamine, Satoshi*; Fukui, Toshiki*; Ochi, Eiji*; Nitani, Hiroaki*; Nomura, Masaharu*
Denki Kagaku Oyobi Kogyo Butsuri Kagaku, 81(7), p.543 - 546, 2013/07
Times Cited Count：8 Percentile：19.15(Electrochemistry)The molten state of simulated high-level waste glass and the behavior of ruthenium element in the melt were investigated by using synchrotron radiation based X-ray imaging technique. Melting, generating and moving of bubbles, condensation and sedimentation of ruthenium element were observed dynamically in continuous 12-bit gray-scale images from the CCD camera. X-ray intensity was obtained easily by digitizing gray-scale values in the image. The existence of ruthenium element is emphasized as a black color in the CCD image at X-ray energy higher than the Ru K-absorption edge. Position sensitive imaging X-ray absorption fine structure (XAFS) measurement was also performed to clarify the chemical state of ruthenium element in the melt.
Okamoto, Yoshihiro; Nakada, Masami; Akabori, Mitsuo; Komamine, Satoshi*; Fukui, Toshiki*; Ochi, Eiji*; Nitani, Hiroaki*; Nomura, Masaharu*
Proceedings of 4th Asian Conference on Molten Salt Chemistry and Technology & 44th Symposium on Molten Salt Chemistry, Japan, p.47 - 52, 2012/09
The molten state of the simulated high-level waste glass and the behavior of ruthenium element in the melt were investigated by using synchrotron radiation based X-ray imaging technique. Melting, generating and moving of bubbles, condensation and sedimentation of ruthenium element were observed dynamically in continuous 12-bit gray-scale images from the CCD camera. The existence of ruthenium in the X-ray CCD image was emphasized over the energy of Ru K-absorption edge. X-ray intensity was obtained easily by digitalizing gray-scale values in the image. Position sensitive imaging X-ray absorption fine structure (XAFS) measurement was performed to clarify the chemical state of ruthenium element in the melt.
Okamoto, Yoshihiro; Nakada, Masami; Akabori, Mitsuo; Shiwaku, Hideaki; Komamine, Satoshi*; Fukui, Toshiki*; Ochi, Eiji*; Nitani, Hiroaki*; Nomura, Masaharu*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 11(2), p.127 - 132, 2012/06
Distribution and the chemical state of Ru element in the simulated high-level waste glass were examined by using the synchrotron radiation based X-ray imaging technique. In this technique, a direct X-ray CCD camera is used in place of an ion chamber. Position sensitive X-ray absorption spectra were obtained by analyzing gray scale in images of the X-ray CCD camera. At first, we measured a test sample containing RuO and Ru metal powder. We successfully obtained information on the Ru distribution in the sample. In addition, the chemical state (oxide or metal ?) of each small Ru-rich spot was evaluated by the corresponding position sensitive XAFS spectrum. The imaging XAFS technique was applied to some simulated high-level waste glass samples. The Ru distribution of the glass sample and their chemical state were confirmed by image analyses. It can be seen that Ru element scattered in the glass sample exists as oxide RuO.
Fukidome, Hirokazu*; Abe, Shunsuke*; Takahashi, Ryota*; Imaizumi, Kei*; Inomata, Shuya*; Handa, Hiroyuki*; Saito, Eiji*; Enta, Yoshiharu*; Yoshigoe, Akitaka; Teraoka, Yuden; et al.
Applied Physics Express, 4(11), p.115104_1 - 115104_3, 2011/11
Times Cited Count：36 Percentile：77.83(Physics, Applied)Inagaki, Yaohiro*; Sakatani, Keiichi*; Yamamura, Yuki*; Mitsui, Seiichiro; Noshita, Kenji*; Miura, Yoshiyuki*; Kanehira, Norio*; Ochi, Eiji*; Mukunoki, Atsushi*; Chiba, Tamotsu*
Dai-7-Kai Saishori, Risaikuru Bukai Semina Tekisuto, p.136 - 137, 2011/01
Conventional static test methods are not appropriate to evaluate glass dissolution behavior at an arbitrarily-fixed condition due to compositional change of the solution with glass dissolution. In this study, we applied a newly-devised micro-channel flow-through test method to measurement of the initial dissolution rates of Japanese simulated waste glasses, JAEA-P0798 and JNFL-KMOC, at arbitrarily-fixed conditions and we evaluated temperature and pH dependence of glass dissolution. The results showed that the initial dissolution rate increased with temperature and had "V-shaped" pH dependence at each temperature.
Tsuji, Hiroshi; Okuno, Kiyoshi*; Thome, R.*; Salpietro, E.*; Egorov, S. A.*; Martovetsky, N.*; Ricci, M.*; Zanino, R.*; Zahn, G.*; Martinez, A.*; et al.
Nuclear Fusion, 41(5), p.645 - 651, 2001/05
Times Cited Count：58 Percentile：83.02(Physics, Fluids & Plasmas)no abstracts in English
Okamoto, Yoshihiro; Nakada, Masami; Akabori, Mitsuo; Komamine, Satoshi*; Fukui, Toshiki*; Ochi, Eiji*; Nitani, Hiroaki*; Nomura, Masaharu*
no journal, ,
Distribution and the chemical state of fission product elements like Zr, Mo and Ru in the simulated high-level waste glass were examined by using the synchrotron radiation based X-ray imaging technique. We used the high resolution imaging system and the high-speed CCD camera for imaging XAFS measurement of the glass sample at molten state. Position sensitive X-ray absorption spectra were obtained by analyzing gray scale in images of the CCD camera.
Akabori, Mitsuo; Yamagishi, Isao; Takano, Masahide; Komamine, Satoshi*; Fukui, Toshiki*; Ochi, Eiji*
no journal, ,
no abstracts in English
Okamoto, Yoshihiro; Shiwaku, Hideaki; Nakada, Masami; Takano, Masahide; Akabori, Mitsuo; Komamine, Satoshi*; Fukui, Toshiki*; Ochi, Eiji*
no journal, ,
Synchrotron based X-ray absorption fine structure analysis of Mn, Ce, Zr, Mo, Ru, Rh and Pd was performed to evaluate chemical state and the local structure in the simulated glass samples. Redox state and chemical state were confirmed from X-ray near edge structure (XANES) analysis. Information on the local structure was obtained from the extended X-ray absorption fine structure (EXAFS) analysis.
Akabori, Mitsuo; Takano, Masahide; Nakada, Masami; Kawashima, Hidenori*; Komamine, Satoshi*; Ochi, Eiji*
no journal, ,
no abstracts in English
Nakajima, Masayoshi; Oyama, Koichi; Morikawa, Yo; Miyauchi, Atsushi; Yamashita, Teruo; Komamine, Satoshi*; Ochi, Eiji*
no journal, ,
Noble metal elements (NME) contained in high level liquid waste (HLLW) are distributed in a vitrification melter. Some part of them forms sediment which causes negative effects to steady operation of the melter. The formation process and characteristics of the sediment is useful information for considering methods of removing or discharging them. Thus the sedimentation observation was carried out by using simulated glass. Samples with 1.1wt% of initial NME concentration held at 1100
C indicated zone settling, and the settling rate of interface is constant; 2.4 mm/h. This sedimentation behavior is the type of rapid settling. Following the rapid settling, the settling rate goes slower gradually, this is the type of compressive settling. The samples whose initial NME concentrations are 3.0wt% and 6.1wt% showed compression settling form the beginning. From the settling curve of interface, the maximum concentration of NME in sediment was estimated as around 23-26wt%. This value can specify the properties of sediment to be removed, Also, growth of NME particles was observed by holding at 1100C for up to 2880 hours.
Okamoto, Yoshihiro; Shiwaku, Hideaki; Nakada, Masami; Akabori, Mitsuo; Kawashima, Hidenori*; Komamine, Satoshi*; Ochi, Eiji*
no journal, ,
The EXAFS measurement of simulated waste glass prepared under several heating conditions were performed to clarify redox state of Ru, Rh and Pd elements. The EXAFS functions were fitted by linear combination of standard functions of pure metal and its oxide. A ratio of metallic and oxide components in the simulated glass was obtained from the fitting analysis. We proposed we could evaluate redox state in the process of glass melters.
Okamoto, Yoshihiro; Shiwaku, Hideaki; Nakada, Masami; Takano, Masahide; Akabori, Mitsuo; Komamine, Satoshi*; Fukui, Toshiki*; Ochi, Eiji*
no journal, ,
Chemical properties and behavior of insoluble residue in the cold cap of simulated high-level waste glass was examined by using synchrotron radiation based imaging and XAFS analyses. From XAFS analyses of Zr, Mo and Ce, (1) Zr is in a complex oxide like ZrSiO
or Zr(MoO), (2) The complex MoO
ion is predominant for Mo element, (3) Redox state for cerium element was evaluated from Ce L-edge XAFS, and (4) Chemical state of cerium was determined from Ce K-edge XAFS. Chemical state and bubble growth at molten state was investigated by using X-ray imaging analysis.
Fe M
ssbauer spectroscopyNakada, Masami; Takano, Masahide; Akabori, Mitsuo; Komamine, Satoshi*; Fukui, Toshiki*; Ochi, Eiji*
no journal, ,
no abstracts in English
ssbauer spectroscopyNakada, Masami; Takano, Masahide; Akabori, Mitsuo; Komamine, Satoshi*; Fukui, Toshiki*; Ochi, Eiji*
no journal, ,
no abstracts in English
Oyama, Koichi; Morikawa, Yo; Miyauchi, Atsushi; Nakajima, Masayoshi; Yamashita, Teruo; Komamine, Satoshi*; Ochi, Eiji*
no journal, ,
no abstracts in English
