Stability of fcc phase FeH to 137 GPa

Chie Kato, Koichiro Umemoto, Kenji Ohta, Shoh Tagawa, Kei Hirose, Yasuo Ohishi

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12 Citations (Scopus)

Abstract

We examined the crystal structure of FeHX (X~1) (FeH hereafter) at high pressure and temperature by Xâ'ray diffraction up to 137 GPa. Results show that FeH adopts a face-centered cubic (fcc) structure at pressures of 43 to 137 GPa and temperatures of ~1000 to 2000 K. Our study revises a phase diagram of stoichiometric FeH in which fcc has a wider-than-expected stability field at high pressure and temperature. Based on our findings, the FeH end-member of the Fe-FeH system is expected to be stable in the fcc structure at the P-T conditions of the Earth's core, rather than in the double-hexagonal close packed (dhcp) structure as previously reported. We compared the experimentally determined unit-cell volumes of FeH with those from ab initio calculations. Additionally, we observed a change in compressibility at ~60 GPa, which could be attributed to a magnetic transition- A n interpretation supported by our ab initio computations.

Original languageEnglish
Pages (from-to)917-921
Number of pages5
JournalAmerican Mineralogist
Volume105
Issue number6
DOIs
Publication statusPublished - Jun 25 2020
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology

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