Research Articles

High-Pressure Chemistry of Hydrogen in Metals: In Situ Study of Iron Hydride

See allHide authors and affiliations

Science  12 Jul 1991:
Vol. 253, Issue 5018, pp. 421-424
DOI: 10.1126/science.253.5018.421


Optical observations and x-ray diffraction measurements of the reaction between iron and hydrogen at high pressure to form iron hydride are described. The reaction is associated with a sudden pressure-induced expansion at 3.5 gigapascals of iron samples immersed in fluid hydrogen. Synchrotron x-ray diffraction measurements carried out to 62 gigapascals demonstrate that iron hydride has a double hexagonal close-packed structure, a cell volume up to 17% larger than pure iron, and a stoichiometry close to FeH. These results greatly extend the pressure range over which the technologically important iron-hydrogen phase diagram has been characterized and have implications for problems ranging from hydrogen degradation and embrittlement of ferrous metals to the presence of hydrogen in Earth's metallic core.

Stay Connected to Science