Investigations on the EPR g factors and local structures for the orthorhombic and tetragonal Cu 2+ centers in Pb[Zr 0.54 Ti 0.46 ]O 3 .

The defect models of the orthorhombical and tetragonal Cu 2+ centers in Pb[Zr 0.54 Ti 0.46 ]O 3 are attributed to Cu 2+ ions occupying the sixfold coordinated octahedral Ti 4+ site with and without charge compensation, respectively. The electron paramagnetic resonance (EPR) g factors g i (i = x, y, z) of the Cu 2+ centers in Pb[Zr 0.54 Ti 0.46 ]O 3 are theoretically studied by using the perturbation formulas of a 3d 9 ion under orthorhombically and tetragonally elongated octahedra. Based on the calculation, the impurity off-center displacements are about 0.253 and 0.162 Å for the orthorhombical and tetragonal Cu 2+ centers, respectively. Meanwhile, the planar Cu 2+ -O 2- bonds are found to experience the relative variation ΔR (≈0.102 Å) along the a- and b-axes for the orthorhombical Cu 2+ center due to the Jahn-Teller (JT) effect. The theoretical EPR g factors based on the above local structures agree well with the observed values.