[S-MP38] 鉱物の物理化学

[SMP38-10] C_ijs of single crystal Pt under high pressure based on IXS and primary pressure scale

*鎌田 誠司^1,2、福井 宏之^3,4、米田 明⁵、前田 郁也²、筒井 智嗣⁶、内山 裕士^4,6、平尾 直久⁶、石川 大介⁶、バロン アルフレッド⁴ (1.東北大学学際科学フロンティア研究所、2.東北大学大学院理学研究科地学専攻、3.兵庫県立大学大学院物質理学研究科、4.理化学研究所物質ダイナミクス研究室、5.岡山大学惑星物質研究所、6.高輝度光科学研究センター)

キーワード：単結晶弾性、白金一次圧力スケール、非弾性X線散乱法、ダイヤモンドアンビルセル

There have been conflicts between previously proposed equations of state of platinum (Pt) in spite of importance of precise pressures under high pressure conditions. In order to determine independently EOS, the elastic constants of Pt, C₁₁, C₁₂, and C₄₄, were obtained based on inelastic X-ray scattering from ambient condition to ca. 20 GPa. The lattice parameters under high pressure conditions were measured simultaneously. Adiabatic bulk moduli and shear moduli were obtained from C_ijs and experimental pressures were calculated by integrating K_T(V). The EOS of Pt as a primary pressure scale was determined based on the experimental pressures. The pressures by our scale are 5 to 10 % lower than those of previous studies up to 200 GPa. Above 200 GPa, the present pressure scale shows up to 5 % higher pressures than pressures by the scales determined by XRD. On the other hand, our pressure scale shows 10 % lower pressures than those by the scales determined by shock data. In addition, the pressures based on the current scale show a good agreement those by Au scale obtained the same method, when pressures are calculated by using volumes of Pt and Au obtained simultaneously up to 140 GPa. On the other hand, the difference between pressures by previous Pt and Au scales become remarkable above 100 GPa.