[S-IT22] [EE] 核-マントルの相互作用と共進化

[SIT22-P39] Sound velocity of hcp-Fe at multi-megabar pressures

*坂巻 竜也¹、福井 宏之²、大谷 栄治¹、田中 遼介¹、バロン アルフレッド³ (1.東北大学、2.兵庫県立大学、3.理化学研究所)

キーワード：core, sound velocity, high pressure

Earth’s inner core consists of mainly hexagonal close-packed iron (hcp-Fe). Therefore, the physical properties of hcp-Fe can provide significant knowledge about the core. Despite seismological observations providing density-sound velocity data of Earth’s core, there are few experimental reports about the sound velocity of hcp-Fe at ultrahigh pressure. Direct comparison of the sound velocity of hcp-Fe with that of observed inner core can provide a clear difference between them, which is an important information to determine the core composition. Here, we report the compressional sound velocity (V_P) of hcp-Fe up to 250 GPa using an inelastic X-ray scattering technique at BL43LXU of SPring-8. Based on the data, we can provide a standard of hcp-Fe (a linear relation of V_P with density: Birch’s law), which enables us to indicate a better constraint on the composition of the Earth's core.