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Osakabe, Toyotaka
no journal, ,
no abstracts in English
Katayama, Yoshinori; Hattori, Takanori; Fukui, Hiroshi*; Nozawa, Akifumi*; Funakoshi, Kenichi*
no journal, ,
Liquid water shows anomalous properties and these properties are attributed to a network structure formed by hydogen-bonded water molecules. To study the structure of water under high pressure, we have carried out in-situ high-pressure high-temperature X-ray diffraction experiments in SPring-8. In addition to the previous X-ray diffraction measurements using a cubic-type multianvil press installed on BL14B1, measurements up to about 17 GPa were successfully carried out using a Kawai-type double-stage press installed on BL04B1. The stcuture factor, 
, at ambient pressure has two maxima at 2A
and 3A. With increasing pressure, these maxima merged and formed a sharp peak which is resembles that for a simple liquid. Futher compression shifted the peak to larger-Q direction. The increase of density is attributed to an increase of coordination number up to a few GPa and then it is attributed to a decrease of inter-molecular distance at higher pressures.
Katayama, Yoshinori; Kaneko, Hiroshi; Hattori, Takanori
no journal, ,
Energy-despersive X-ray method is commonly used for X-ray diffraction measurements using a cubic-type multi-anvil-press because low background scattering and short data acquisition time can be achieved. However, diffraction intensity is affected by several energy-dependent factors, such as intensity spectrum of synchrotron radiation, sensitivity spectrum of a detector, absorption spectra of sample and surrounding materials. It is difficult to estimate these factors separately, Tsuji et al., proposed a new empirical method to determine structure factor of liquids and glasses. Furthermore, Funakoshi et al., developed a Monte Carlo simulation code to carry out the procedure. But the result is sometimes unstable. We improved the method and reproduce the structure factor of silica glass stably.
Saito, Hiroyuki; Utsumi, Wataru; Kaneko, Hiroshi; Aoki, Katsutoshi
no journal, ,
no abstracts in English
Omura, Ayako; Machida, Akihiko; Watanuki, Tetsu; Aoki, Katsutoshi; Takemura, Kenichi*
no journal, ,
no abstracts in English
Hattori, Takanori; Tomomasa, Masatoshi*; Higaki, Takuya*; Tsuji, Kazuhiko*
no journal, ,
no abstracts in English
Hattori, Takanori; Saito, Hiroyuki; Kaneko, Hiroshi; Okajima, Yuka; Aoki, Katsutoshi; Utsumi, Wataru
no journal, ,
no abstracts in English
Hattori, Takanori
no journal, ,
no abstracts in English
Tateiwa, Naoyuki; Haga, Yoshinori; Matsuda, Tatsuma; Yamamoto, Etsuji; Ikeda, Shugo; Onuki, Yoshichika*
no journal, ,
We report our thermodynamic studies on the heavy fermion superconductors under high pressure. In this talk, I would like to present basic experimental methods and recent data on the pressure induced superconductor UIr. UIr is a ferromagnet with the Curie temperature 46 K. From previous high pressure studies by the resistivity and magnetic susceptibility measurements, it was clarified that the transition temperature decreases with increasing pressure that multiple ferromagnetic phases (FM1, 2,3) exists under high pressure. We determine the phase boundaries of the FM1, 2, 3 phases by the ac heat capacity measurements under pressures. We will discuss the unusual features of the physical properties in the high pressure phase of UIr.
Watanuki, Tetsu; Machida, Akihiko; Aoki, Katsutoshi; Omura, Ayako*; Sato, Taku*; Tsai, A. P.*
no journal, ,
no abstracts in English
Machida, Akihiko; Omura, Ayako*; Watanuki, Tetsu; Aoki, Katsutoshi; Takemura, Kenichi*
no journal, ,
no abstracts in English
under high pressureMachida, Akihiko; Omura, Ayako*; Watanuki, Tetsu; Aoki, Katsutoshi; Takemura, Kenichi*
no journal, ,
no abstracts in English
Machida, Akihiko; Omura, Ayako*; Aoki, Katsutoshi
no journal, ,
no abstracts in English
Nemoto, Kazuaki*; Hirayama, Tomoko*; Matsuoka, Takashi*; Hattori, Takanori
no journal, ,
no abstracts in English