CRYSTAL-FIELD STUDIES OF FE2+ BY MOSSBAUER EFFECT - FEF2

Mössbauer experiments on FeF2 in the paramagnetic state are reported. The temperature dependence of the quadrupole splitting is studied experimentally, and interpreted in terms of the variations with temperature of the populations of the energy levels of the ferrous ion. From this analysis, values for the crystal-field splittings of the T2g orbital levels of the Fe2+ ion are extracted. The best fit with experiment is obtained for E2-E1=1150A°K, E3-E1=1300A°K, with a certain spread in the acceptable values for these energy separations. The results agree well with values deduced previously by magnetic and optical techniques. It is shown, however, that all these results, though consistent among themselves, cannot be explained in terms of a conventional crystalline potential. © 1969 The American Physical Society.