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"Katsura, Tomoo*; Funakoshi, Kenichi*; Kubo, Atsushi*; Nishiyama, Norimasa*; Tange, Yoshinori*; Sueda, Yuichiro*; Kubo, Tomoaki*; Utsumi, Wataru
Physics of the Earth and Planetary Interiors, 143-144, p.497 - 506, 2004/06
Times Cited Count：109 Percentile：86.75(Geochemistry & Geophysics)no abstracts in English
Katsura, Tomoo*; Funakoshi, Kenichi*; Nishiyama, Norimasa*; Kubo, Atsushi*; Tange, Yoshinori*; Sueda, Yuichiro*; Kubo, Tomoaki*; Utsumi, Wataru
Hoshako, 16(6), p.352 - 357, 2003/11
no abstracts in English
Katayama, Yoshinori; Hattori, Takanori; Saito, Hiroyuki; Aoki, Katsutoshi; Funakoshi, Kenichi*; Tange, Yoshinori*
no journal, ,
Liquid water at ambient conditions shows unique properties because of hydrogen-bonded network structure. We conducted high-pressure high-temperature X-ray diffraction experiments up to 17 GPa at the SPring-8 synchrotron radiation facility and reported that the local structure changed towards a simple liquid-like structure through an increase of coordination number. We have extended the pressure range to 20 GPa and the results will be reported. However these data were measured just above the melting temperature at each pressure so that the effect of pressure (density) and that of temperature could not be separated. In this work, we have conducted X-ray diffraction measurement at various temperatures near 1 GPa. The shoulder of the first peak in S(Q) vanished at 200 
C and the first peak became symmetric at 600 C. This result suggests a structural change from a low coordinated structure to a simple liquid-like structure.
Katayama, Yoshinori; Hattori, Takanori; Saito, Hiroyuki; Ikeda, Takashi; Aoki, Katsutoshi; Fukui, Hiroshi*; Tange, Yoshinori*; Funakoshi, Kenichi*
no journal, ,
We have measured X-ray diffraction of liquid water under high-pressure and high- temperature conditions up to 9 GPa using a cubic-type press on BL14B1 and up to 17 GPa using a Kawai-type press on BL04B1 at SPring-8. The pressure range has been extended to 20 GPa using sintered diamond anvils. The P-T range where the local structure transforms from an ice-like structure to a simple-liquid-like structure has been revealed with a help of first-principles molecular dynamics simulations.
Katayama, Yoshinori; Ikeda, Takashi; Hattori, Takanori; Saito, Hiroyuki; Aoki, Katsutoshi; Fukui, Hiroshi*; Tange, Yoshinori*; Funakoshi, Kenichi*
no journal, ,
Liquid water shows unique properties and they are related to the network structure formed by hydrogen bonds between water molecules. To study pressure dependence of structure of water, we measured X-ray diffraction of water up to 20 GPa using multi-anvil type presses in SPring-8. The coordination number of water molecules increased rapidly up to 4 GPa while maintaining the intermolecular distance. First-principles molecular dynamics simulations were also performed for high-density water. The obtained oxygen-oxygen radial distribution functions were in excellent agreement with the experimental results. Results of the simulations revealed that temperature was more important factor for the structural change. We have performed additional measurements at high temperatures. The calculated oxygen-oxygen radial distribution functions were again consistent with our experimental results. These studies clarified a pressure-temperature region where the significant structural change occurred.
Katayama, Yoshinori; Yagafarov, O.; Ikeda, Takashi; Saito, Hiroyuki; Aoki, Katsutoshi; Hattori, Takanori; Fukui, Hiroshi*; Tange, Yoshinori*; Funakoshi, Kenichi*
no journal, ,
Liquid water at ambient pressure shows unique properties and they are related to the network structure formed by hydrogen bonds between water molecules. To study structural change in the liquid water under high-pressure and high-temperature conditions, we have measured X-ray diffraction of liquid water just above the melting line up to 20 GPa. Up to 4 GPa, the coordination number increased rapidly while the intermolecular distance changed slightly. First-principles molecular dynamics simulations were also performed for high-density water. Results of the simulations in a wide pressure- temperature range revealed that temperature was more important factor for the crossover between the hydrogen-bonded and simple liquid-like liquids. We have measured X-ray diffraction of water as a function of temperature. The experimental results supported the results of the simulation.
