FE-57 MOSSBAUER STUDY OF NICKEL HYDRIDE UNDER HIGH-PRESSURE

Nickel hydride was studied by Mossbauer measurements with the 14.4 keV resonance in Fe-57 at temperatures between 4.2 K and 450 K and hydrog en-to-metal ratios near unity in absorber experiments with 0.1 5 and 1 .0 at.% Fe-57 in NiH(x), and in source experiments with Co-57 in NiH(x ). To avoid hydrogen losses during measurements at temperatures above 200 K, the hydride was subjected to a pressure of about 2.5 GPa. A com parison of the Mossbauer spectra of the source and the absorber experi ments reveals differences in the local hydrogen distribution around Fe and Co impurities in NiH(x).