Iron-water reaction at high pressure and temperature, and hydrogen transport into the core

Eiji Otani, Naohisa Hirao, Tadashi Kondo, Masayoshi Ito, Takumi Kikegawa

Research output: Contribution to journalArticlepeer-review

48 Citations (Scopus)


We observed a direct reaction of metallic iron with water to form iron hydride and iron oxide, 3Fe + H2O->2FeHx + FeO, at pressures from 6 GPa to 84 GPa and temperatures above 1,000 K in diamond anvil cell (DAC). Iron hydride is dhcpFeHx or γ-FeHx, and iron oxide has the rhombohedral or B1 structure at pressures at least up to 37 GPa. The formation of an assembly composed of dhcpFeHx and FeO with the B8 structure was observed at 84 GPa. In primordial Earth, water formed by dehydration of the low temperature primitive materials reacts with metallic iron in the high temperature component to form iron hydride FeHx and iron oxide FeO. The former would be incorporated in the iron forming the core. Thus hydrogen could be an important element of the Earth's core. This reaction would be essential for transport of hydrogen into the core in the accretion stage of the Earth.

Original languageEnglish
Pages (from-to)77-82
Number of pages6
JournalPhysics and Chemistry of Minerals
Issue number1
Publication statusPublished - 2005 May 1


  • High pressure
  • High temperature
  • Iron
  • Iron hydride
  • Iron oxide
  • Water
  • X-ray diffraction

ASJC Scopus subject areas

  • Materials Science(all)
  • Geochemistry and Petrology


Dive into the research topics of 'Iron-water reaction at high pressure and temperature, and hydrogen transport into the core'. Together they form a unique fingerprint.

Cite this