57Fe Mössbauer spectroscopy on hydrogenated ScFe2

Abstract

The intermetallic compound ScFe₂ is capable of absorping large amounts of hydrogen, which can be derived from the measured absorption isotherm and from the lattice constant before and after charging. The magnetic properties of ScFe₂ are sensitive to small variations in the stoichiometry and are changed significantly after hydrogen absorption. Magnetization measurements and ⁵⁷Fe Mössbauer spectroscopy have been performed on the stoichiometric composition and a composition somewhat excessive in iron. The increase in magnetic moment and hyperfine field at the iron nuclei are much smaller for the off‐stoichiometric compound. From the temperature dependence of the Mössbauer spectra it is concluded that this effect is due to a difference between the two compositions in the occupation of the various interstitial holes by the hydrogen atoms. In the stoichiometric compounds an efficient shielding of the iron sublattice from the scandium sublattice results from a preferential, symmetric filling of the interstitial holes. In the off‐stoichiometric composition the shielding is much less effective, since a fraction of the iron atoms occupy scandium positions and thereby affect the occupation of many interstitial holes.