Static compression of Fe0.83Ni0.09Si0.08 alloy to 374GPa and Fe0.93Si0.07 alloy to 252GPa: Implications for the Earth's inner core

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

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


The pressure-volume equations of state of iron-nickel-silicon alloy Fe0.83Ni0.09Si0.08 (Fe-9.8wt.% Ni-4.0wt.% Si) and iron-silicon alloy Fe0.93Si0.07 (Fe-3.4wt.% Si) have been investigated up to 374GPa and 252GPa, respectively. The present compression data covered pressures of the Earth's core. We confirmed that both Fe0.83Ni0.09Si0.08 and Fe0.93Si0.07 alloys remain in the hexagonal close packed structure at all pressures studied.We obtained the density of these alloys at the pressure of the inner core boundary (ICB), 330GPa at 300K by fitting the compression data to the third order Birch-Murnaghan equation of state. Using these density values combined with the previous data for hcp-Fe, hcp-Fe0.8Ni0.2, and hcp-Fe0.84Si0.16 alloys and comparing with the density of the PREM inner core, we estimated the Ni and Si contents of the inner core. The Si content of the inner core estimated here is slightly greater than that estimated previously based on the sound velocity measurement of the hcp-Fe-Ni-Si alloy at high pressure.

Original languageEnglish
Pages (from-to)113-118
Number of pages6
JournalEarth and Planetary Science Letters
Issue number1-2
Publication statusPublished - Oct 1 2011
Externally publishedYes


  • Compression
  • Hcp structure
  • Inner core
  • Iron-nickel-silicon alloy
  • Iron-silicon alloy

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science


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