Theoretical investigations of the local structure and the spin Hamiltonian parameters for Ti2+ in MgCl2

The local structure and spin Hamiltonian parameters (zero-field splitting and g factors) for Ti2+ in MgCl2 are theoretically studied using the perturbation formulas of these parameters for a 3d(2) ion under trigonally distorted octahedra. The contributions from the dynamical Jahn-Teller effect, the configuration interactions and the ligand orbital and spin orbit coupling interactions are quantitatively involved based on the cluster approach in a uniform way. The chlorine polyhedron around the impurity Ti2+ is found to transform from a slightly compressed octahedron in pure MgCl2 to a slightly elongated one, characterized by the local angular decrease of 0.3 degrees related to the host bond angle 54.78 degrees due to the Jahn-Teller effect. The calculated spin Hamiltonian parameters based on the above trigonal elongation show good agreement with the experimental data. The results are discussed. (C) 2013 Elsevier B.V. All rights reserved.