The structure of Fe-Ni alloy in Earth's inner core

Shigehiko Tateno, Kei Hirose, Tetsuya Komabayashi, Haruka Ozawa, Yasuo Ohishi

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The crystal structure of Fe-10%Ni was investigated up to 340 GPa and 4700 K, corresponding to the Earth's inner core conditions by synchrotron X-ray diffraction measurementsin-situat ultrahigh pressure and temperature in a laser-heated diamond-anvil cell. The results show that hexagonal closed-packed (hcp) structure is stable throughout the experimental conditions investigated with no evidence for a phase transition to body-centered cubic (bcc) or face-centered cubic (fcc) phases. The axialc/a ratio of the hcp crystal obtained around 330 GPa has a small temperature dependence similar to the axial ratio of pure Fe. Iron alloy with less than 10% Ni crystallizes to an hcp structure with c/a ratio of ∼1.61 at inner core conditions, although the effect of small amount of light elements remains to be examined by experiments.
Original languageEnglish
Article numberL12305
Pages (from-to)1-4
Number of pages4
JournalGeophysical Research Letters
Issue number12
Publication statusPublished - 1 Jun 2012


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