Kinetics of the graphite-diamond transformation in aqueous fluid determined by in-situ X-ray diffractions at high pressures and temperatures

高温高圧下でのその場観察により決定された水中での黒鉛-ダイヤモンド変換の動力学

岡田 卓; 内海 渉; 金子 洋*; Turkevich, V.*; 浜谷 望; 下村 理*

Okada, Taku; Utsumi, Wataru; Kaneko, Hiroshi*; Turkevich, V.*; Hamaya, Nozomu; Shimomura, Osamu*

MgOを含む水を触媒とした黒鉛からダイヤモンドへの変換過を6.6-8.9GPa, 1400-1850Cの高温高圧条件下で、放射光を用いた時間分割X線回折の手法によりその場観察した。ダイヤモンドへの変換率の時間依存性が種々の条件下で決定され、それらがJMAK式により解析された。

The graphite-diamond transformation was investigated by in situ time-resolved X-ray diffraction experiments using aqueous fluid containing dissolved MgO as the diamond forming catalyst under conditions of 6.6-8.9 GPa and 1400-1835 C. The transformed volume fractions of diamond as a function of time under various pressure-temperature conditions were obtained and analyzed using the JMAK rate equation. Variations in the nucleation and growth processes during diamond formation as a function of pressure and temperature were clarified.