Theoretical studies on the defect structure for Mn2+ in KTaO3

The defect structure for Mn2+ in KTaO3 is theoretically studied by using perturbation formulas of the spin Hamiltonian (SH) parameters for 3d5 ions in tetragonal symmetry based on the strong-field scheme. By analyzing the electron paramagnetic resonance (EPR) data of the studied system, we suggest that the impurity Mn2+ ion occupy the dodecahedral K+ site, rather than the octahedral Ta5+ site. Based on the studies, it is found that the Mn2+ impurity undergoes an off-center displacement away from the ideal K+ site by about 0.60 Å along the C4 axis. The above displacement is qualitatively consistent with the recent result based on the generalized gradient approximation (GGA) and that obtained from EPR and dielectric spectroscopy studies.