材料期刊网

The EPR parameters (zero-field splitting D and g factors g(parallel to) and g(perpendicular to)) and the local structure for the tetragonal Fe+ center in KTaO3 are theoretically studied by using the perturbation formulas of the EPR parameters for a 3d(7) ion in tetragonally distorted dodecahedra. Based on these studies, we find that the impurity Fe+ may not locate on the regular dodecahedral K+ site but suffer a large off-center displacement Delta Z (approximate to 0.43 angstrom) along one of the < 100 > (or C-4) axes, which is responsible for the large tetragonal distortion of the impurity center. The displacement Delta Z obtained in this work is comparable with that (approximate to 0.46 angstrom) of a similar monovalent Li+ on K+ site of KTaO3 obtained from the nuclear quadrupole shift and can be regarded as reasonable. The calculated g factors, particularly the anisotropy Delta g (= g(perpendicular to) - g(parallel to)) based on the above displacement, agree with the observed values.