Investigation of the electric-field effect in EPR spectra of Fe3+ in KTaO3

The displacements of Fe3+ (at the Ta5+ site) along the [001] direction in KTaO3 crystal, caused by the electric field, have been studied by calculating the electric-field-induced zero-field splittings from the microscopic mechanisms and the empirical superposition model. It is found that the Fe3+ displacements obtained by the two methods at the same electric-field strength and temperature are close to each other. These displacements are also close to that estimated from the force-balance equation. It is suggested that the electric-field-induced zero-field splitting can be attributed primarily to the above displacement and the temperature dependence of the electric-field-induced zero-field splitting is mainly due to the change in the dielectric constant of KTaO3 with temperature.