Structure of water under high pressure and high temperature

Katayama, Yoshinori; Hattori, Takanori   ; Saito, Hiroyuki; Ikeda, Takashi; Aoki, Katsutoshi; Fukui, Hiroshi*; Tange, Yoshinori*; Funakoshi, Kenichi*

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.