Jahn-Teller configurations in natural spinels

The local configurations and related hyperfine interactions of the tetrahed rally coordinated Fe2+ in two natural spinels were investigated. A special fitting procedure of the Mossbauer spectra is proposed in order to cover th e involved mechanisms over the whole temperature range. The behavior of the quadrupole splitting vs temperature was successfully explained in terms of the split of the electronic 3d ground state doublet under a non-cooperativ e Jahn-Teller effect also providing estimates of the splitting energy for e ach configuration.