Mössbauer Study of the SmFe2Hydride through149Sm and57Fe

Abstract

We have applied the nuclear resonant forward scattering of synchrotron radiation by 149 Sm and 57 Fe Mossbauer spectroscopy to SmFe 2 and c -SmFe 2 H x (\(x\lesssim 3\)), to study the effect of hydrogen absorption on local electronic states. The averages of the parameters of the hyperfine structure of SmFe 2 and c -SmFe 2 H x at 20 K are as follows: the electric quadrupole splitting parameters of 149 Sm are -10.3±0.3 and -8.3±0.3 mm/s, the magnetic hyperfine fields of 149 Sm are 299±8 and 326±8 T, the isomer shifts of 57 Fe are 0.07±0.03 and 0.41±0.03 mm/s, the electric quadrupole splitting parameters of 57 Fe are 0 and 0.15±0.03 mm/s, and the magnetic hyperfine fields of 57 Fe are 20.4±0.1 and 19.3±0.1 T, respectively. The differences in these parameters between SmFe 2 and c -SmFe 2 H x are discussed in connection with the modulation of local electronic states induced by lattice expansion and chemical effect of hydrogenation. The differences also imply the screening of interactions between Sm and Fe by i...