[S-IT39_2PO1] Deep Earth science: Dynamics of plate, mantle, and core

[SIT39-P10] Sound velocities of laser-shocked Fe-Ni alloys under Earth core conditions

*Tatsuhiro SAKAIYA¹, Naoya YOKOYAMA¹, Ryota HOSOGI¹, Tadashi KONDO¹, Hidenori TERASAKI¹, Keisuke SHIGEMORI², Yoichiro HIRONAKA² (1.Graduate School of Science, Osaka University, 2.Institute of Laser Engineering, Osaka University)

Keywords:sound velocity, laser, shock wave, iron alloy, Earth's core, experiment

When we consider the structure of Earth's interior, the sound velocity is one of the important physical properties of the interior materials because it can be directly compared with the seismological data (1) which can yield the physical properties of the Earth's interior. Cosmochemical data and the composition of iron meteorites suggest that Earth's core contains mainly Fe-Ni alloy with 5-25 wt.% Ni. Although Lin et al. (2) and Kantor et al. (3) measured compressional sound velocities of Fe-Ni alloys at room temperature by inelastic x-ray scattering (IXS) at diamond anvil cell (DAC), the sound velocity data of liquid Fe-Ni alloys is very few (4).We performed laser-shock experiments of liquid Fe-Ni alloys at HIPER system of Gekko-XII laser in Institute of Laser Engineering, Osaka University (5). Sound velocities were measured by side-on radiography (6, 7). We obtained sound velocities of Fe-Ni alloys at pressures up to 770 GPa. The sound velocity of Fe-Ni alloy was about 10% lower than that of liquid Fe at inner core boundary (ICB) pressure. Part of this work was performed under the joint research project of the Institute of Laser Engineering, Osaka University.References1. A.M. Dziewonski, D.L. Anderson, Phys. Earth Planet. Inter. 25, 297 (1981).2. J.F. Lin et al., Geophys. Res. Lett. 30, 2112 (2003).3. A.P. Kantor et al., Phys. Earth Planet. Inter. 164, 83 (2007).4. P.M. Nasch, M.H. Manghnani, Geophys. Monograph Ser. 101, 307 (1998).5. C. Yamanaka et al., Nucl. Fusion 27, 19 (1987).6. K. Shigemori et al., Rev. Sci. Instrum. 83, 10E529 (2012).7. T. Sakaiya et al., Earth Planet. Sci. Lett. in press (2014).