Abstract
The phase relations of Fe-6.4 wt% Si and Fe-9.9 wt% Si have been investigated up to 130 GPa and 2,600 K based on in situ synchrotron X-ray diffraction measurements in a laser-heated diamond-anvil cell along with chemical analysis of the quenched samples using a field-emission electron probe microanalyzer. We found that the maximum solubility of silicon in solid hcp-iron increases with increasing pressure. Linear extrapolation of the phase boundary between hcp + B2 and hcp phases for Fe-9.9 wt% Si suggests that the solid hcp-iron can include more than 9.9 wt% Si at the Earth’s inner-core conditions. If silicon is a major light element in the outer core, a substantial amount of silicon may be incorporated into the inner core during inner-core solidification.
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Acknowledgments
The authors thank Y. Tatsumi and R. Sinmyo for their help and discussions. We acknowledge H. Terasaki, M. Matsui and anonymous referee for their constructive reviews. In situ XRD measurements were conducted at SPring-8 (proposal no. 2005A5013-LD2-np, 2005B0010, and 2006-2008A0099). Y.K. was supported by the Japan Society for the Promotion of Science (JSPS) Research Fellowships for Young Scientists.
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Kuwayama, Y., Sawai, T., Hirose, K. et al. Phase relations of iron–silicon alloys at high pressure and high temperature. Phys Chem Minerals 36, 511–518 (2009). https://doi.org/10.1007/s00269-009-0296-0
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DOI: https://doi.org/10.1007/s00269-009-0296-0