Influence of the Jahn-Teller effect on the linewidth of the Mössbauer spectra of natural spinels

The temperature dependence of the Mössbauer doublet linewidth of tetrahedrally coordinated Fe²⁺ions, distorted by the Jahn-Teller effect, was analysed by means of a new mathematical approach. The idea was that the linewidth depends on a distribution of quadrupole splittings that are in turn dependent on temperature. The variation of the quadrupole splitting was supposed to be connected with the temperature dependent population of the ground state E_g orbitals, split by the local Jahn-Teller effect. The model was applied to three sets of experimental data. The barrier splitting between the two E_g electronic states as well as their widths, , were obtained.