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GEOPHYSICAL RESEARCH LETTERS,
VOL. 35,
L12307,
4 PP., 2008
doi:10.1029/2008GL033863
Phase relations of Fe-Si alloy up to core conditions: Implications for the Earth inner core
Department of Earth Science, School of Science, Tohoku University, Sendai, Japan
Department of Earth Science, School of Science, Tohoku University, Sendai, Japan
International Advanced Research and Education Organization, Tohoku University, Sendai, Japan
Department of Earth Science, School of Science, Tohoku University, Sendai, Japan
Department of Earth Science, School of Science, Tohoku University, Sendai, Japan
Spring-8, Japan Synchrotron Research Institute, Sayo, Japan
Institute for Frontier Research on Earth Evolution, Yokosuka, Japan
Spring-8, Japan Synchrotron Research Institute, Sayo, Japan
X-ray diffraction experiments were conducted to 257 GPa and high temperature in situ on an iron-silicon alloy containing 3.4 wt% silicon, a candidate for the Earth's inner core forming material. The results revealed that fcc and hcp phases coexist up to 104 GPa. A single hcp phase is stable at higher pressures at least up to 3600 K at 242 GPa and to 2400 K at 257 GPa. Dissolution of silicon in the liquid outer core following reaction with the silicate mantle during core formation strongly suggests the existence of silicon in the solid inner core. Our results revealed that the iron-3.4 wt% silicon alloy in the inner core is likely to possess an hcp structure, which can explain the inner core anisotropy observed in seismology.
Received 5 March 2008; accepted 24 April 2008; published 25 June 2008.
Citation: (2008), Phase relations of Fe-Si alloy up to core conditions: Implications for the Earth inner core, Geophys. Res. Lett., 35, L12307, doi:10.1029/2008GL033863.
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