TY - JOUR
T1 - Hexagonal Close-packed Iron Hydride behind the Conventional Phase Diagram
AU - Machida, Akihiko
AU - Saitoh, Hiroyuki
AU - Hattori, Takanori
AU - Sano-Furukawa, Asami
AU - Funakoshi, Ken ichi
AU - Sato, Toyoto
AU - Orimo, Shin ichi
AU - Aoki, Katsutoshi
N1 - Funding Information:
Neutron diffraction experiments were performed under proposal no. 2014B0017 at J-PARC. Synchrotron X-ray diffraction experiments were performed under proposal numbers 2015A3602 and 2016B3651 at SPring-8. This work was performed under the Inter-university Cooperative Research Program of the Institute for Materials Research, Tohoku University, proposal numbers 16K0075 and 17K0018, and supported partially by the Grants-in-aid for Scientific Research, grant numbers 24241032, 25220911 and 18H05224 of Japan Society for the Promotion of Science. We thank T. Yagi and H. Kagi for their polite discussions.
Publisher Copyright:
© 2019, The Author(s).
PY - 2019/12/1
Y1 - 2019/12/1
N2 - Hexagonal close-packed iron hydride, hcp FeHx, is absent from the conventional phase diagram of the Fe–H system, although hcp metallic Fe exists stably over extensive temperature (T) and pressure (P) conditions, including those corresponding to the Earth’s inner core. In situ X-ray and neutron diffraction measurements at temperatures ranging from 298 to 1073 K and H pressures ranging from 4 to 7 GPa revealed that the hcp hydride was formed for FeHx compositions when x < 0.6. Hydrogen atoms occupied the octahedral interstitial sites of the host metal lattice both partially and randomly. The hcp hydride exhibited a H-induced volume expansion of 2.48(5) Å3/H-atom, which was larger than that of the face-centered cubic (fcc) hydride. The hcp hydride showed an increase in x with T, whereas the fcc hydride showed a corresponding decrease. The present study provides guidance for further investigations of the Fe–H system over an extensive x–T–P region.
AB - Hexagonal close-packed iron hydride, hcp FeHx, is absent from the conventional phase diagram of the Fe–H system, although hcp metallic Fe exists stably over extensive temperature (T) and pressure (P) conditions, including those corresponding to the Earth’s inner core. In situ X-ray and neutron diffraction measurements at temperatures ranging from 298 to 1073 K and H pressures ranging from 4 to 7 GPa revealed that the hcp hydride was formed for FeHx compositions when x < 0.6. Hydrogen atoms occupied the octahedral interstitial sites of the host metal lattice both partially and randomly. The hcp hydride exhibited a H-induced volume expansion of 2.48(5) Å3/H-atom, which was larger than that of the face-centered cubic (fcc) hydride. The hcp hydride showed an increase in x with T, whereas the fcc hydride showed a corresponding decrease. The present study provides guidance for further investigations of the Fe–H system over an extensive x–T–P region.
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U2 - 10.1038/s41598-019-48817-7
DO - 10.1038/s41598-019-48817-7
M3 - Article
C2 - 31444386
AN - SCOPUS:85071383292
SN - 2045-2322
VL - 9
JO - Scientific Reports
JF - Scientific Reports
IS - 1
M1 - 12290
ER -