SOUND VELOCITY MEASUREMENT BY INELASTIC X-RAY SCATTERING AT HIGH PRESSURE AND TEMPERATURE BY RESISTIVE HEATING DIAMOND ANVIL CELL
E. Ohtani1,2, K. Mibe3, T. Sakamaki1, S. Kamada1, S. Takahashi1, H. Fukui4, S. Tsutsui5, A.Q.R. Baron6
1Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
2V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, ul. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
3Earthquake Research Institute, University of Tokyo, Tokyo 113-0032, Japan
4Graduate School of Material Science, University of Hyogo, Hyogo 678-1297, Japan
5Research and Utilization Division, SPring-8, JASRI, Sayo, Hyogo, 679-5198, Japan
6Materials Dynamics Laboratory, RIKEN SPring-8 Center, RIKEN, Sayo, Hyogo 679-5148, Japan
Keywords: Sound velocity, hcp-iron, high pressure and temperature, inner core, inelastic X-ray scattering, diamond anvil cell, resistive heating
Abstract
We determined the compressional velocity of hcp-Fe in a wide pressure and temperature range using high-resolution inelastic X-ray scattering (IXS) combined with in situ X-ray powder diffraction (XRD) on samples in resistively heated diamond anvil cells: Our measurements extend up to 174 GPa at room temperature, to 88 GPa at 700 K, and to 62.5 GPa at 1000 K. Our data obtained at room temperature and high temperature are well described by a linear relation to density, extending the range of verification of Birch’s law beyond previous work and suggesting only a small temperature dependence up to 1000K. When we compare the present results with the preliminary reference Earth model (PREM), we can conclude that there is either a strong temperature effect on Birch’s law at temperatures above 1000 K or the composition of the core is rather different from that commonly expected, i.e., containing heavy elements.
DOI: http://dx.doi.org/10.1016/j.rgg.2015.01.012
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