Fe57Mössbauer effect in ScFe2and ScFe2H2

Abstract

The intermetallic compound Sc${\mathrm{Fe}}_2$ is able to absorb large quantities of hydrogen gas without a change in crystal structure. The ternary hydride has the composition Sc${\mathrm{Fe}}_2$ ${\mathrm{H}}_2$. Its lattice constants are $a=5.279\mathrm{}$ Å and $c=8.507\mathrm{}$ Å (C14 type). By means of magnetic measurements we found that the moment per Fe atom changes from $1.4{\mu }_B$ to $2.2{\mu }_B$. Using ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ Mössbauer-effect spectroscopy we observed that an increase of the same magnitude (about 60%) also occurs in the hyperfine splitting. On the other hand, only a rather small change in isomer shift was observed to accompany the hydrogen absorption. Arguments are presented that it is difficult to explain the moment change in terms of a simple $3d$-band picture and charge-transfer effects.