Phase relations of Fe-Si alloy up to core conditions: Implications for the Earth inner core

Hidetoshi Asanuma, Eiji Ohtani, Takeshi Sakai, Hidenori Terasaki, Seiji Kamada, Naohisa Hirao, Nagayoshi Sata, Yasuo Ohishi

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33 Citations (Scopus)

Abstract

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.

Original languageEnglish
Article numberL12307
JournalGeophysical Research Letters
Volume35
Issue number12
DOIs
Publication statusPublished - 2008 Jun 28

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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    Asanuma, H., Ohtani, E., Sakai, T., Terasaki, H., Kamada, S., Hirao, N., Sata, N., & Ohishi, Y. (2008). Phase relations of Fe-Si alloy up to core conditions: Implications for the Earth inner core. Geophysical Research Letters, 35(12), [L12307]. https://doi.org/10.1029/2008GL033863