2:45 PM - 3:00 PM
[SIT35-03] Sound velocities of liquid Fe-Si alloys at Earth's core pressures by laser-shock compression
Keywords:sound velocity, laser, shock wave, Fe-Si alloys, Earth's core, experiment
We conducted shock-compression experiments using a High Intensity Plasma Experimental Research (HIPER) system at the GEKKO-XII laser irradiation facility  at the Institute of Laser Engineering, Osaka University. The samples are Fe-Si alloys (Fe95Si5, Fe90Si10, Fe80Si20 and Fe66Si34 in weight percent). The sound velocities and densities of shock-compressed Fe-Si alloys using the high-power laser were measured by x-ray radiography [7, 11, 12] at pressures up to 960 GPa. The linear relation between the sound velocity and the density for FeSi alloy well follows Birch's law  up to 960 GPa along the Hugoniot. The extrapolated sound velocity of FeSi alloy was about 40% faster than that of PREM at inner core boundary pressure. The outer core is composed of Fe-Si alloy with 5-13 wt.% Si assuming Si is only light element at the core. This Si content is consistent with the results of previous work by sound velocity measurement  and shock-compression experiment .
We thank Naoya Yokoyama for his help with the laser-shock experiments and data analysis. Part of this work was performed under the joint research project of the Institute of Laser Engineering, Osaka University.
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