[S-IT18] Planetary cores: Structure, formation, and evolution

[SIT18-02] 非弾性散乱法によるhcp Fe-Si合金の音速測定と内核の組成

*大谷 栄治¹、坂入 崇紀¹、坂巻 竜也¹、福井 宏之²、鎌田 誠司⁴、筒井 智嗣⁵、内山 裕士⁵、バロン アルフレッド³ (1.東北大学大学院理学研究科地学専攻、2.兵庫県立大学物質科学専攻、3.理化学研究所、4.東北大学学際科学フロンテイア研究所、5.高輝度光科学研究センター)

キーワード：鉄シリコン合金、縦波、内核

The compressional velocity of hcp Fe0.89Si0.11 (Fe-6wt%Si) alloy was measured at pressures from 45 to 84 GPa and temperatures of 300 and 1800 K using inelsstic X-ray scattering (IXS) from laser-heated samples in diamond anvil cell (DAC). The measurement was made at beamline BL35XU of SPring8. The compressional velocity and density of the alloy are observed to follow a linear relationship at a given temperature. We found Vp=1.03Xrho-1.45+[3.8X10^(-5)X(T-300)X(rho-15.37)] including non-negligible temperature dependence for hcp-Fe0.89S90.11 alloy. The present results of compresssinal velocity and density of the alloy indicates that 3-6 wt.% od silicon in the inner core with the additional amount of nickel can explain the compressional velocity and density of the preliminary Earth reference model (PREM), assuming that the inner core temperature is 5500 K and silicon is the only light element in the inner core.