Electric field properties at cationic sites in normal, incommensurate and commensurate K2ZnCl4 crystals

The local electric properties at K and Zn sites in the normal, incommensura te and commensurate phases of K2ZnCl4, as derived from a numerical computat ion of the lattice contributions to the electric potential V(r), electric f ield intensity E(r) and electric field gradient tensor V-alpha beta(r) are reported. The numerical data obtained at each cationic position were correl ated with the experimental K-39 NMR, Cu2+ and Mn2+ EPR and Fe-57 Mossbauer results in pure and doped K2ZnCl4. A proportionality between crystal field and zero-field splitting was taken into account for Mn2+, whereas for K+, C u2+ and Fe3+ ions the electric field gradient is directly related to the cr ystal field parameter. By this comparison, on computations done in the ioni c fractional charge and relaxed lattice approximations, the insertion of pr obe-species of iron, copper and manganese ions on off-center Zn sites is pr oposed. The K-39 electric field gradient tensor calculations in the incomme nsurate phase fit well with the NMR data reported recently.