Investigations of the spin-Hamiltonian parameters and tetragonal compression due to the static Jahn–Teller effect for Cr5+ center in cubic SrTiO3 crystal

By using the distortion model that the tetragonal site symmetry of Cr(5+) in cubic phase of SrTiO(3) originates from the static Jahn-Teller effect, the spin-Hamiltonian parameters (g factors g(parallel to), g(perpendicular to) and hyperfine structure constants A(parallel to), A(perpendicular to)) of this tetragonally compressed Cr(5+) center in SrTiO(3) are calculated from the high-order perturbation formulas based on a two-mechanism model. In the model, not only the contribution to spin-Hamiltonian parameters due to the crystal-field mechanism, but also that due to the charge-transfer mechanism (which is omitted in the extensively used crystal-field theory) are included. The calculated results are in reasonable agreement with the experimental values. The tetragonal compression (characterized by Delta R=R(perpendicular to) - R(parallel to), where R(perpendicular to) and R(parallel to) denote the metal-ligand distances perpendicular to and parallel with the C(4) axis) of Cr(5+) center is also obtained from the calculation. The results (including the tetragonal compression and the relative importance of the charge-transfer mechanism) are discussed. (C) 2010 Elsevier B.V. All rights reserved.