Theoretical studies on the Spin Hamiltonian parameters and the local structure for Cu2+ in rutile

The spin Hamiltonian parameters (SHPs) (the g factors g(i) and the hyperfine structure constants A(i), i = x, y, z) and the local structure of the substitutional Cu2+ center in rutile (TiO2) are theoretically studied from the perturbation formulas of these parameters for a 3d(9) ion in rhombically elongated distorted octahedra. The related molecular orbital coefficients are quantitatively determined from the cluster approach in a uniform way, and the required crystal-field parameters are estimated from the superposition model which enables correlation of the crystal-field parameters and hence the studied SHPs with the local structure of the Cu2+ center. Based on the studies, the Cu-O bond lengths parallel and perpendicular to the C-2-axis are found to be R-parallel to(') approximate to 2.030 angstrom and R-perpendicular to(') approximate to 1.924 angstrom, respectively, with the planar bond angle theta approximate to 87.21 degrees. The calculated SHPs are in agreement with the experimental data and the results are discussed. (C) 2020 Elsevier B.V. All rights reserved.