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Nakano, Satoshi*; Sano, Asami; Hattori, Takanori; Machida, Shinichi*; Komatsu, Kazuki*; Fujihisa, Hiroshi*; Yamawaki, Hiroshi*; Goto, Yoshito*; Kikegawa, Takumi*
Inorganic Chemistry, 60(5), p.3065 - 3073, 2021/03
Times Cited Count：10 Percentile：74.02(Chemistry, Inorganic & Nuclear)X-ray and neutron diffraction analyses of ammonia borane were conducted at ambient and high pressures. The H-H distance in dihydrogen bonds was shorter than twice the van der Waals radius (2.4 
). The half of the dihydrogen bonds were broken on phase transition from AP to the first high pressure phase (HP1) at approximately 1.2 GPa as revealed by an increase in the H-H distances. On further pressure increase, all of the H-H distances became shorter than 2.4 again, implying the pressure-induced reformation of the dihydrogen bonds. Furthermore, the HP1 transformed to the second one with the structure of 
(Z = 2) at about 11 GPa. In this phase transition, the inclination of the molecule axis became larger and the number of types of dihydrogen bonds increased from 6 to 11. Just before the third transition at 18.9 GPa, the shortest dihydrogen bond decreased to 1.65 . The present study experimentally first confirmed the breakage and reformation of the dihydrogen bonds by the structural change under pressure.
AsIkeda, Shugo*; Tsuchiya, Yu*; Zhang, X.-W.*; Kishimoto, Shunji*; Kikegawa, Takumi*; Yoda, Yoshitaka*; Nakamura, Hiroki; Machida, Masahiko; Glasbrenner, J.*; Kobayashi, Hisao*
Physical Review B, 98(10), p.100502_1 - 100502_6, 2018/09
Times Cited Count：6 Percentile：25.82(Materials Science, Multidisciplinary)The interplay between magnetism and superconductivity is one of important subjects to investigate the pairing mechanism in novel superconductors. We have found new coexistence between an antiferromagnetic order in the Fe sublattice and superconductivity of the FeAs-based EuFeAs superconductor in the pressure range from 2.4 to 3.0 GPa by 
Fe nuclear forward scattering (NFS) using a single crystal sample. The magnetic state in the Fe sublattice changes to a new antiferromagnetic one with superconductivity from a stripe-type antiferromagnetic one observed in normal conducting state at 2.7 GPa. Below the superconducting transition temperature, the temperature dependence of Fe NFS spectra reveals that the new antiferromagnetic order develops with the superconductivity. This non-trivial coupling of two ordered states in EuFeAs under pressure demonstrates a new and intriguing relationship between magnetism and superconductivity in Fe-based superconductors.
-type oxide PbZnOMori, Daisuke*; Tanaka, Kie*; Saito, Hiroyuki; Kikegawa, Takumi*; Inaguma, Yoshiyuki*
Inorganic Chemistry, 54(23), p.11405 - 11410, 2015/12
Times Cited Count：28 Percentile：81.65(Chemistry, Inorganic & Nuclear)Hattori, Takanori; Taga, Naohito*; Takasugi, Yukinobu*; Kinoshita, Tomohiro*; Narushima, Takashi*; Tsuji, Kazuhiko*; Kikegawa, Takumi*
Photon Factory Activity Report 2005, Part A, p.42 - 43, 2006/11
no abstracts in English
X-ray diffraction of graphite-diamond transformation using various catalysts under high pressures and high temperaturesUtsumi, Wataru; Okada, Taku; Taniguchi, Takashi*; Funakoshi, Kenichi*; Kikegawa, Takumi*; Hamaya, Nozomu; Shimomura, Osamu
Journal of Physics; Condensed Matter, 16(14), p.S1017 - S1026, 2004/04
Times Cited Count：14 Percentile：54(Physics, Condensed Matter)The graphite-diamond transformation was investigated using in-situ time-resolved X-ray diffraction experiments with a MgO dissolved aqueous fluid as the diamond forming catalyst under conditions of 6.6-8.8 GPa and 1400-1835
C. Experiments were conducted using a 180-ton DIA-type cubic-anvil apparatus installed on the beamline BL14B1 at SPring-8, a third-generation synchrotron radiation facility in Japan. By analyzing the kinetic data using the JMAK rate equation, it was clarified that altering the pressure-temperature conditions drastically changes the nucleation and growth process of diamond.
Otaka, Osamu*; Utsumi, Wataru; Kikegawa, Takumi*
Mirai O Hiraku Koatsuryoku Kagaku Gijutsu Semina Shirizu, 27, p.52 - 62, 2003/07
no abstracts in English
and HfO under high-temperature and high-pressureOtaka, Osamu*; Fukui, Hiroyuki*; Funakoshi, Kenichi*; Utsumi, Wataru; Irifune, Tetsuo*; Kikegawa, Takumi*
High Pressure Research, 22(1), p.221 - 226, 2002/01
Times Cited Count：30 Percentile：76.07(Physics, Multidisciplinary)no abstracts in English
SiO
Kubo, Tomoaki*; Otani, Eiji*; Kato, Takumi*; Urakawa, Satoru*; Suzuki, Akio*; Kambe, Yuichi*; Funakoshi, Kenichi*; Utsumi, Wataru; Kikegawa, Takumi*; Fujino, Kiyoshi*
Physics of the Earth and Planetary Interiors, 129(1-2), p.153 - 171, 2002/01
Times Cited Count：50 Percentile：66.4(Geochemistry & Geophysics)no abstracts in English
under high pressure and high peratureOtaka, Osamu*; Fukui, Hiroyuki*; Kunisada, Taichi*; Fujisawa, Tomoyuki*; Funakoshi, Kenichi*; Utsumi, Wataru; Irifune, Tetsuo*; Kuroda, Koji*; Kikegawa, Takumi*
Physical Review B, 63(17), p.174108_1 - 174108_8, 2001/05
Times Cited Count：127 Percentile：96.62(Materials Science, Multidisciplinary)no abstracts in English
Yagi, Takehiko*; Kondo, Tadashi*; Watanuki, Tetsu; Shimomura, Osamu; Kikegawa, Takumi*
Review of Scientific Instruments, 72(2), p.1293 - 1297, 2001/02
Times Cited Count：28 Percentile：78.2(Instruments & Instrumentation)no abstracts in English
under high-temperature and high-pressure conditionsFukui, Hiroyuki*; Otaka, Osamu*; Katsura, Tomoo*; Nagai, Takaya*; Funakoshi, Kenichi*; Utsumi, Wataru; Kikegawa, Takumi*
Science and Technology of High Pressure, p.554 - 557, 2000/00
no abstracts in English
Irifune, Tetsuo*; Kuroda, Koji*; Nishiyama, Norimasa*; Inoue, Toru*; Funamori, Nobumasa*; Uchida, Takeyuki*; Yagi, Takehiko*; Utsumi, Wataru; Miyajima, Nobuyoshi*; Fujino, Kiyoshi*; et al.
Geophysical Monograph 101 (Properties of Earth and Planetary Materials at High Pressure and Temperature), p.1 - 8, 1998/00
no abstracts in English
Taniguchi, Takashi*; Sato, Masashi*; Utsumi, Wataru; Kikegawa, Takumi*; Shimomura, Osamu
Diamond and Related Materials, 6(12), p.1806 - 1815, 1997/12
Times Cited Count：17 Percentile：69.66(Materials Science, Multidisciplinary)no abstracts in English
Taniguchi, Takashi*; Sato, Masashi*; Utsumi, Wataru; Kikegawa, Takumi*; Shimomura, Osamu
Applied Physics Letters, 70(18), p.2392 - 2394, 1997/05
Times Cited Count：25 Percentile：74.65(Physics, Applied)no abstracts in English
OOH oxyhydroxide and implication for hydrogen bond symmetrizationSano, Asami; Yagi, Takehiko*; Okada, Taku*; Goto, Hirotada*; Kagi, Hiroyuki*; Nagai, Takaya*; Kikegawa, Takumi*
no journal, ,
