A comparative study on the local structures of the V⁴⁺ and Cu²⁺ centers in WO₃

Abstract

The local structures and electron paramagnetic resonance (EPR) parameters (the g factors g i and the hyperfine structure constants A i , with i = x, y, z) of the V4+ and Cu2+ centers in WO3 were theoretically investigated based on the perturbation formulas of the EPR parameters for 3d1 and 3d9 ions under rhombically compressed and elongated octahedra, respectively. In these formulas, the adopted crystal-field parameters (CFPs) are obtained from the superposition model which enables connection of the CFPs and hence the EPR parameters to the rhombic distortion. Based on the calculations, the impurity-ligand distances of the studied [VO6]8− (or [CuO6]10−) cluster are found to suffer the axial compression (or elongation) δz of about 0.098 Å (or 0.132 Å) along the z-axis, and the additional planar bond length variation δr (≈0.052 or 0.047 Å) along x- and y-axis, respectively, due to the Jahn–Teller (JT) effect.