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Endo, Naruki; Ishikawa, Kazuhiro*; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori
no journal, ,
no abstracts in English
CuH
Saito, Hiroyuki; Takagi, Shigeyuki*; Endo, Naruki; Machida, Akihiko; Aoki, Katsutoshi; Orimo, Shinichi*; Katayama, Yoshinori
no journal, ,
no abstracts in English
Hattori, Takanori; Sano, Asami; Inamura, Yasuhiro; Funakoshi, Kenichi*; Abe, Jun*; Machida, Shinichi*; Okazaki, Nobuo*; Katayama, Yoshinori; Yagafarov, O.*; Chiba, Ayano*
no journal, ,
SiO glass consists of SiO
tetrahedra. This glass is easily densified by applying pressure, due to its relatively sparse network ring formed by the linkage of tetrhaera. The density increase amounts to 20% by room temperature compression to 8 GPa. This increase is, however, released after decompression because of insufficient structural relaxation. On the other hand, the heating at high pressures promotes the structural relaxation, resulting in permanent densification of 20% at most. The mechanism of this densification has been investigated so far, but the microscopic origin is still to be revealed. So, we performed in-situ high-pressure neutron experiments at newly constructed high-pressure neutron beamline PLANET in J-PARC. We will discuss the origin of the reversibility in the densification.
Katayama, Yoshinori; Hattori, Takanori; Saito, Hiroyuki; Sano, Asami; Suzuya, Kentaro; Yagafarov, O.*; Chiba, Ayano*; Otomo, Toshiya*
no journal, ,
Liquid water at ambient conditions has an ice-like, characteristic structure due to the hydrogen bonds between molecules. To study pressure and temperature dependence of the structure of water, we have carried out in-situ high-temperature high-pressure measurements on liquid water using synchrotron radiation at the SPring-8 and molecular dynamics simulations. The results revealed transformation from the ice-like structure to a simple-liquid-like structure. To investigate change in hydrogen bonds, neutron is an important probe. We carried out neutron diffraction measurements on heavy water at room temperature, 100
C and 200C at 0.8 GPa using newly-built high-pressure diffractometer, PLANET, at J-PARC/MLF. Significant temperature dependence of diffraction pattern was observed.
Machida, Akihiko; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Oshita, Hidetoshi*; Ikeda, Kazutaka*; Otomo, Toshiya*
no journal, ,
no abstracts in English
Watanuki, Tetsu; Machida, Akihiko; Kawana, Daichi*; Tanaka, Yukinori*; Ishimasa, Tsutomu*
no journal, ,
no abstracts in English