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Liss, K.-D.*; Han, J.-K.*; Blankenburg, M.*; Lienert, U.*; Harjo, S.; Kawasaki, Takuro; Xu, P. G.; Yukutake, Eitaro*; Kawasaki, M.*
Journal of Materials Science, 23 Pages, 2024/00
Times Cited Count：0 Percentile：0.01(Materials Science, Multidisciplinary)Hirano, Tatsumi*; Maeda, Takehiro*; Murata, Tetsuyuki*; Yamamoto, Takahiro*; Matsubara, Eiichiro*; Shobu, Takahisa; Shiro, Ayumi*; Yasuda, Ryo*; Takamatsu, Daiko*
SPring-8/SACLA Riyo Kenkyu Seikashu (Internet), 11(5), p.345 - 353, 2023/10
no abstracts in English
Liss, K.-D.*; Xu, P. G.; Shiro, Ayumi*; Zhang, S. Y.*; Yukutake, Eitaro*; Shobu, Takahisa; Akita, Koichi*
Advanced Engineering Materials, 9 Pages, 2023/00
Liu, X. J.*; Xu, P. G.; Shiro, Ayumi*; Zhang, S. Y.*; Shobu, Takahisa; Yukutake, Eitaro*; Akita, Koichi*; Zolotoyabko, E.*; Liss, K.-D.*
Journal of Materials Science, 57(46), p.21446 - 21459, 2022/12
Times Cited Count：3 Percentile：41.53(Materials Science, Multidisciplinary)
-BaTiO solid solutionsYoneda, Yasuhiro; Kim, S.*; Mori, Shigeo*; Wada, Satoshi*
Japanese Journal of Applied Physics, 61(SN), p.SN1022_1 - SN1022_10, 2022/11
Times Cited Count：1 Percentile：17.38(Physics, Applied)Local structural analysis of the (1-
) BiFeO-BaTiO solid solution was performed by PDF analysis of the data obtained in the synchrotron radiation high-energy X-ray diffraction experiment. First, when XAFS experiments were performed and sample screening was performed, it was found that structural fluctuations were large in the BiFeO-rich composition. Therefore, PDF analysis of a sample with BiFeO-rich composition was performed. As a result, it was found that although the average structure is a cubic structure, the local structure can be reproduced with a rhombohedral crystal structure, and there is a displacement that breaks the symmetry of the rhombohedral structure in a composition with a large fluctuation.
Kyono, Atsushi*; Yamamoto, Genichiro*; Yoneda, Yasuhiro; Okada, Satoru*
Isotope News, (783), p.23 - 27, 2022/10
Mineral traps are attracting attention as an underground storage method for carbon dioxide. Carbon dioxide laden groundwater reacts with basalt to form magnesite. The formed magnesium carbonate phase varies in many ways, but we tried to clarify the structure because all of them pass through amorphous magnesium carbonate. Pair distribution function using high-energy X-ray diffraction revealed that amorphous magnesium carbonate has a structure similar to that of hydromagnesite. It can be said that it is a safe sequestration method as a carbon dioxide storage technology.
Shiro, Ayumi*; Shobu, Takahisa; Hagihara, Koji*; Watanabe, Masashi*
SPring-8/SACLA Riyo Kenkyu Seikashu (Internet), 10(5), p.438 - 446, 2022/10
no abstracts in English
Ohashi, Tomonori*; Sakamaki, Tatsuya*; Funakoshi, Kenichi*; Hattori, Takanori; Hisano, Naoki*; Abe, Jun*; Suzuki, Akio*
American Mineralogist, 107(3), p.325 - 335, 2022/03
Times Cited Count：1 Percentile：22.72(Geochemistry & Geophysics)The basaltic glass structure were investigated to 18 GPa using in situ X-ray and neutron diffraction. The O-O coordination number (CN
) starts to rise with maintaining the mean O-O distance (r) above 2-4 GPa, and then CN stops increasing and r begins to shrink along with the increase in the Al-O coordination number (CN
) above 9 GPa. This is interpreted by the change in the contraction mechanism from tetrahedral network bending to oxygen packing ratio increase via the CN increase. The oxygen packing fraction exceeds the value for dense random packing, suggesting that the oxygen-packing hypothesis cannot account for the pressure-induced structural transformations of silica and silicate glasses. The CN increase at 2-4 GPa reflects the elastic softening of silicate glass, which may causes anomalous elastic moduli of basaltic glass at 
2 GPa.
synchrotron radiation observation of deformation and annealing processes of aluminum single crystalShiro, Ayumi*; Okada, Tatsuya*; Shobu, Takahisa
Mechanical Engineering Journal (Internet), 8(6), p.21-00106_1 - 21-00106_8, 2021/12
The objective of the present study was to carry out observations of deformation and annealing processes of aluminum single crystals using a synchrotron radiation X-rays at SPring-8. Al single-crystalline samples having a 111 orientation parallel to the longitudinal direction were grown by a Bridgman method. The samples were deformed in tension to a nominal strain of 0.08 at room temperature using an in-line tensioning apparatus. Post-deformation annealing at 480 
C was subsequently carried out in the same apparatus. A two-dimensional detector was used to detect multiple diffracted beams from the sample during the deformation and annealing processes. The volume irradiated by the X-ray beam was found to be composed of three regions having a small orientation difference, which was attributable to sub-grained microstructures of the sample. Detailed analyses of a diffraction spot intensity showed that the sub-grained microstructures were surpassed by dislocated microstructures with the increase in the tensile strain. During the post-deformation annealing, diffraction spots from a recrystallized grain first appeared at 180 s after the temperature reached 480 C. Coexistence of diffraction spots from the deformation matrix and recrystallized grain lasted only for about 22 s in the irradiated volume. The migration rate of the boundary between the deformation matrix and recrystallized grain was estimated to be of the order of several micrometers/s.
Nb
)OYoneda, Yasuhiro; Taniguchi, Hiroki*; Noguchi, Yuji*
Journal of Physics; Condensed Matter, 33(3), p.035401_1 - 035401_8, 2021/01
Times Cited Count：4 Percentile：33.7(Physics, Condensed Matter)Nanoscale structural analysis of relaxor Pb(MgNb)O (PMN) was performed using synchrotron high-energy X-ray diffraction measurements. Although PMN is a well-known relaxor ferroelectric material, the average structure is a cubic structure, and various models have been proposed to explain the ferroelectric microstructure. We performed a wide-range local structure analysis up to 20 nm using the pair distribution function (PDF). As a result, it was found that the structure of PMN changed depending on the distance and it was a glass-like structure.
Hojo, Tomohiko*; Akiyama, Eiji*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Kinugasa, Junichiro*; Yuse, Fumio*
Corrosion Science, 177, p.108957_1 - 108957_9, 2020/12
Times Cited Count：18 Percentile：76.44(Materials Science, Multidisciplinary)Hydrogen assisted cracking on hemispherically-stretch-formed specimens of transformation induced plasticity-aided martensitic steel was investigated. Hydrogen charging induced cracking around the foot of the impression formed on the steel sheet, and the cracks propagated along the radial direction toward the hillside and the plains. Distributions of stress, plastic strain and volume fraction of retained austenite were analyzed employing the energy-dispersive X-ray diffraction method utilizing the synchrotron X-ray radiation at SPring-8. It was notable that the crack initiation took place in the region where the measured tensile stress was the highest. Influences of plastic strain and resulted martensitic transformation were also suggested.
Sumi, Tatsuya*; Nagai, Kazuki*; Bao, J.*; Terasawa, Tomoo; Norimatsu, Wataru*; Kusunoki, Michiko*; Wakabayashi, Yusuke*
Applied Physics Letters, 117(14), p.143102_1 - 143102_5, 2020/10
Times Cited Count：4 Percentile：26.53(Physics, Applied)A systematic structural study of epitaxial graphene samples on the SiC (0001) surface has been performed by the surface X-ray diffraction method, which is a non-contact technique. For samples with only a buffer layer, one layer graphene, and multilayer graphene, the distances between the buffer layer and the surface Si atoms were found to be 0.23 nm. This value is the same as reported values. For quasi-free-standing graphene samples prepared by the rapid cooling method, there was no buffer layer and the distance between the quasi-free-standing graphene and the surface Si atoms was 0.35 nm, which is significantly shorter than the value in hydrogen-intercalated graphene and slightly longer than the interplane distance in graphite. The Si occupancy deviated from unity within 1 nm of the SiC surface. The depth profile of the Si occupancy showed little sample dependence, and it was reproduced by a simple atomistic model based on random hopping of Si atoms.
Nagashima, Mariko*; Sano, Yuko*; Kochi, Takako*; Akasaka, Masahide*; Sano, Asami
Journal of Mineralogical and Petrological Sciences, 115(5), p.391 - 406, 2020/10
Times Cited Count：0 Percentile：0.02(Mineralogy)The crystal chemistry of Sr-rich piemontite from a layered manganese ore deposit of the Tone mine, Nishisonogi Peninsula, Japan, was studied using methods of electron microprobe analysis, single crystal X-ray structural refinement, 
Fe M
ssbauer spectroscopy, and X-ray and Time-of-Flight neutron Rietveld analyses to elucidate the intracrystalline distributions of Sr, Mn and Fe and the general and individual features on the structural changes with Sr contents in piemontite and epidotes.
Hojo, Tomohiko*; Kumai, B.*; Koyama, Motomichi*; Akiyama, Eiji*; Waki, Hiroyuki*; Saito, Hiroyuki*; Shiro, Ayumi*; Yasuda, Ryo*; Shobu, Takahisa; Nagasawa, Akihiko*
International Journal of Fracture, 224(2), p.253 - 260, 2020/08
Times Cited Count：14 Percentile：67.28(Materials Science, Multidisciplinary)In the study, the pre-strain effect on hydrogen embrittlement property of the ultra-high-strength transformation-induced plasticity -aided bainitic ferrite steel was investigated towards application for automobile frame parts. 3-10% tensile pre-strain suppressed hydrogen-induced mechanical degradation relative to total elongation while 12-15% pre-strained specimen did not exhibit elongation after hydrogen charging. The advantageous effect of the 3-10% pre-strain was attributed to the suppression of crack initiation related to retained austenite. The TRIP by pre-straining decreased the volume fraction of retained austenite before hydrogen charging, thereby reducing existing probabilities of preferential crack initiation sites and propagation paths. Conversely, high pre-strain such as 12-15% does not effectively work due to work hardening resulting in increases in hydrogen embrittlement susceptibility and a significant increase in hydrogen content due to the multiplication of dislocations.
glass up to 10 GPaUrakawa, Satoru*; Inoue, Toru*; Hattori, Takanori; Sano, Asami; Kohara, Shinji*; Wakabayashi, Daisuke*; Sato, Tomoko*; Funamori, Nobumasa*; Funakoshi, Kenichi*
Minerals (Internet), 10(1), p.84_1 - 84_13, 2020/01
Times Cited Count：9 Percentile：64.36(Geochemistry & Geophysics)The structure of hydrous amorphous SiO is fundamental to investigate the effects of water on the physicochemical properties of oxide glasses and magma. The hydrous SiO glass with 13 wt.% DO was synthesized under high-pressure and high-temperature conditions and its structure was investigated by small angle X-ray scattering, X-ray diffraction, and neutron diffraction experiments at pressures of up to 10 GPa and room temperature. This hydrous glass is separated into a SiO rich major phase and a DO rich minor phase. Medium-range order of the hydrous glass shrinks compared to the anhydrous SiO glass due to disruption of SiO
linkage by formation of Si-OD deuterioxyl, while the pressure response is similar. Most of DO molecules are in the small domains and hardly penetrate into SiO major phase.
Suzuki, Kenji*; Shobu, Takahisa; Shiro, Ayumi*
Zairyo, 68(4), p.312 - 317, 2019/04
Materials after thermal processing such as welding often have coarse grains. To understand the residual stress after processing is very important from the viewpoint of the soundness of the structure. In this study, we proposed a double exposure method that combines a two-dimensional detector and high-energy synchrotron radiation as an X-ray stress measurement method for materials with coarse grains, and confirmed its practicality. As a result of measuring the residual stress of the plastic bending specimen and the indentation specimen of the aluminum alloy (A5052), the effectiveness of this measurement method was clarified because the residual stress distribution was in good agreement with the finite element analysis.
Akita, Koichi; Nakatani, Hayato*; Ogihara, Shinji*; Shobu, Takahisa; Shiro, Ayumi*; Igawa, Naoki; Shimojo, Yutaka
SPring-8/SACLA Riyo Kenkyu Seikashu (Internet), 6(1), p.105 - 108, 2018/01
no abstracts in English
K
Li
)NbO synthesized by malic acid complex solution methodYoneda, Yasuhiro; Takada, Eri*; Nagai, Haruka*; Kikuchi, Takeyuki*; Morishita, Masao*; Kobune, Masafumi*
Japanese Journal of Applied Physics, 56(10S), p.10PB07_1 - 10PB07_7, 2017/10
Times Cited Count：3 Percentile：15.1(Physics, Applied)A monoclinic phase was discovered in (NaKLi)NbO solid solution ceramics grown by a malic acid complex solution method. The average and local structures of this monoclinic phase were analyzed by synchrotron X-ray measurements. The local structure can be reproduced by assuming a rhombohedral model, that is the same local structure of KNbO. The results demonstrate that the monoclinic average structure is observed as a disordered rhombohedral structure.
Ojima, Mayumi*; Shiro, Ayumi*; Suzuki, Hiroshi; Inoue, Junya*; Shobu, Takahisa; Xu, P. G.; Akita, Koichi; Nambu, Shoichi*; Koseki, Toshihiko*
Zairyo, 66(6), p.420 - 426, 2017/06
Tomota, Yo*; Sato, Shigeo*; Harjo, S.
Tetsu To Hagane, 103(2), p.73 - 85, 2017/01
Times Cited Count：17 Percentile：62.95(Metallurgy & Metallurgical Engineering)