Theoretical investigations of the g factors and the local structure for the trigonal Zr3+ center in X-ray irradiated YSZ

The electron paramagnetic resonance (EPR) g factors g// and g⊥ and the local structure for the trigonal Zr3+ center in X-ray irradiated yttria-stabilized zirconia (YSZ) are theoretically investigated from the perturbation formulas of the g factors for a 4d1 ion in trigonally distorted octahedra. Based on the studies, in this trigonal center (characterized as [ZrO6]9− cluster associated with two oxygen vacancies VO along the [1 1 1] axis), the O2− ions in the ligand triangles are found to displace towards the neighbouring VO by about 0.42 Å due to the electrostatic attraction of the VO. The above displacement is comparable with that (≈0.36 Å) obtained from neutron diffraction measurements and those (≈0.24-0.37 Å) based on the optical spectral analysis and crystal-field calculations in the previous works. Particularly, partial quenching of the spin-orbit (SO) coupling interaction (i.e., γ(SO) ≈ 0.44) due to the dynamic Jahn-Teller effect (DJTE) and its influence on the g factors, which were ignored by the previous authors, are taken into account in the present work. The validity of the results is discussed.