Hexagonal close-packed iron hydride, hcp FeH, 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 FeH 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) Å/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.

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6707217PMC
http://dx.doi.org/10.1038/s41598-019-48817-7DOI Listing

Publication Analysis

Top Keywords

hexagonal close-packed
8
close-packed iron
8
iron hydride
8
conventional phase
8
phase diagram
8
hydride conventional
4
diagram hexagonal
4
hydride hcp
4
hcp feh
4
feh absent
4

Similar Publications

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!