Investigations on the EPR g factors and local structures for the orthorhombic and tetragonal Cu2+ centers in Pb[Zr0.54Ti0.46]O3

The defect models of the orthorhombical and tetragonal Cu2+ centers in Pb[Zr0.54Ti0.46]O3 are attributed to Cu2+ ions occupying the sixfold coordinated octahedral Ti4+ site with and without charge compensation, respectively. The electron paramagnetic resonance (EPR) g factors gi (i = x, y, z) of the Cu2+ centers in Pb[Zr0.54Ti0.46]O3 are theoretically studied by using the perturbation formulas of a 3d9 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 Cu2+ centers, respectively. Meanwhile, the planar Cu2+–O2− bonds are found to experience the relative variation ΔR (≈0.102 Å) along the a‐ and b‐axes for the orthorhombical Cu2+ 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. Local structure of Cu2+ centers (site 1 and site 2) in Pb[Zr0.54Ti0.46]O3. Local structure of Cu2+ center with one oxygen vacancies (VO) along the C4‐axis (site 1). Local structure of Cu2+ center with [CuO6]10− cluster without charge compensation (site 2).