A Mössbauer spectral study of the NdMn 6− xFe xGe 6 solid solutions

Abstract

The Mössbauer spectra of the NdMn 6− x Fe x Ge 6 solid solutions, with x = 0.5, 1.0 and 1.5 have been obtained at 4.2, 78 and 295 K. They are analyzed in terms of a binomial distribution of environments for the iron 3 g sites. The 78 K weighted average hyperfine fields vary between 14.7 and 15.3 T. The hyperfine field increases with increasing number of iron near neighbours. The isomer shift decreases with increasing x, in agreement with the concomitant unit-cell contraction. The 78 K quadrupole shift of NdMn 5.5Fe 0.5Ge 6 is different from those of NdMn 5FeGe 6 and NdMn 4.5Fe 1.5Ge 6 and indicates that the iron magnetic moments have a different orientation in the former compound, i.e., they lie in the basal plane of the hexagonal unit cell.