The effects of applied electric fields on the EPR spectra of Fe3+ ion in tetragonal SrTiO3 crystal

The electric-field-induced zero-field splittings for Fe3+ in tetragonal phase of SrTiO3 are studied from the microscopic mechanisms and the empirical superposition model. From the studies, it is found that the induced zero-field splittings can be reasonably explained by considering suitable Fe3+ displacements along the electric-field direction in the tetragonal (FeO6)(9-) groups in SrTiO3:Fe3+. The electric-field-induced Fe3+ displacements obtained by the above two methods are close to each other and they are also comparable with those obtained from the force-balance equation. The strong temperature dependences of electric-field-induced zero-field splitting and hence of Fe3+ displacement can be attributed mainly to the strong temperature dependence of dielectric constant of SrTiO3 crystal. (C) 2004 Elsevier B.V. All rights reserved.