Japan Geoscience Union Meeting 2019

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[E] Oral

S (Solid Earth Sciences ) » S-IT Science of the Earth's Interior & Techtonophysics

[S-IT25] Planetary cores: Structure, formation, and evolution

Thu. May 30, 2019 9:00 AM - 10:30 AM A09 (TOKYO BAY MAKUHARI HALL)

convener:Hidenori Terasaki(Graduate School of Science, Osaka University), Eiji Ohtani(Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University), William F McDonough(University of Maryland College Park), George Helffrich(Earth-Life Science Institute, Tokyo Institute of Technology), Chairperson:George Helffrich(ELSI, Tokyo Institute of Technology), Hidenori Terasaki

9:30 AM - 9:45 AM

[SIT25-03] P-wave velocity of Fe3S under high pressure and temperature

*Seiji Kamada1,2, Hidenori Terasaki3, Hiroshi Fukui4,5, Tatsuya Sakamaki2, Hiroshi Uchiyama6, Satoshi Tsutsui6, Eiji Ohtani2, Alfred Q.R. Baron5 (1.Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 2.Department of Earth Science, Graduate School of Science, Tohoku University, 3.Department of Earth and Space Science, Graduate School of Science, Osaka University, 4.Graduate School of Material Science, University of Hyogo, 5.RIKEN, 6.JASRI)

Keywords:Inelastic X-ray scattering, diamond anvil cell, laser heateting

Martian cores have been thought to include a certain amount of sulfur as a light element. Sohl and Spohn (1997) proposed seismic wave velocity and density profiles of the interior of Mars based on equations of state of core matrials although seismic wave velocities of core materials are needed for presice estimation. However, there have been only a limited number of works for VP of Fe alloys with sulfur. In the Fe-FeS system, VP of FeS and FeS2 have been studied (e.g. Badro et al. 2007) but these compounds are not appropriate for the core materials of Mars because Fe3S is a stable phase above 20 GPa corresponding to Martian core conditions (Fei et al., 1997, 2000) up to at least 200 GPa (Kamada et al., 2010, 2012). Therefore, Fe3S is a subsolidus phase together with ε-Fe in the Fe-Fe3S system at Martian core conditions and it is essential to study VP of Fe3S to understand seismic properties of the Martian core. We have measured sound VP of Fe3S under high temperature and pressure at BL35XU of SPring-8.
In this study, a synthesized Fe3S was used as a starting material. A symmetric diamond anvil cell was used to generate high pressures. IXS(Inelastic X-ray Scattering) and XRD experiments were performed at the beamline 35XU of SPring-8, Japan (Baron et al., 2000). VP of Fe3S were measured up to 100 GPa and 2000 K. We will discuss temperature effect on the VP of Fe3S and the Birch's law and seismic wave velocity profile of the Martian core.