Hexagonal Close-packed Iron Hydride behind the Conventional Phase Diagram.
Sci Rep
; 9(1): 12290, 2019 Aug 23.
Article
em En
| MEDLINE
| ID: mdl-31444386
ABSTRACT
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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Bases de dados:
MEDLINE
Idioma:
En
Revista:
Sci Rep
Ano de publicação:
2019
Tipo de documento:
Article
País de afiliação:
Japão