TY - JOUR
T1 - Stability of fcc phase FeH to 137 GPa
AU - Kato, Chie
AU - Umemoto, Koichiro
AU - Ohta, Kenji
AU - Tagawa, Shoh
AU - Hirose, Kei
AU - Ohishi, Yasuo
N1 - Funding Information:
We thank two anonymous reviewers for their constructive comments that improved the quality of the manuscript. In situ XRD measurements were performed at BL10XU, SPring-8 (proposal no. 2014A0080, 2014B0080, 2015A0080, 2015B0080, and 2016B0080). Calculations were performed at ELSI and supported by JSPS Kakenhi (Grant number: 17K05627).
Publisher Copyright:
© 2020 Walter de Gruyter GmbH, Berlin/Boston 2020.
PY - 2020/6/25
Y1 - 2020/6/25
N2 - 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.
AB - 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.
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U2 - 10.2138/am-2020-7153
DO - 10.2138/am-2020-7153
M3 - Article
AN - SCOPUS:85090879779
VL - 105
SP - 917
EP - 921
JO - American Mineralogist
JF - American Mineralogist
SN - 0003-004X
IS - 6
ER -