The defect structure for Mn2+ in KTaO3 was theoretically studied by using perturbation formulas of the spin Hamiltonian parameters for 3d5 ions in tetragonal symmetry based upon the strong-field scheme. Upon analyzing the electron paramagnetic resonance data of the studied system, it was suggested that the impurity Mn2+ ion occupied the dodecahedral K+ site, rather than the octahedral Ta5+ site. Based upon these studies, it was found that the Mn2+ impurity underwent an off-center displacement away from the ideal K+ site by about 0.60Å along the C4 axis. The above displacement was qualitatively consistent with a recent result that was based upon the generalized gradient approximation, and that obtained from electron paramagnetic resonance and dielectric spectroscopy studies.

Theoretical Studies of the Defect Structure for Mn2+ in KTaO3. S.Y.Wu, H.N.Dong, W.Z.Yan, X.Y.Gao: Materials Research Bulletin, 2005, 40[5], 742-8