The axial Ti2+ center in a nearly wholly cubic ZnS crystal was attributed to the Ti2+ ion on the hexagonal site of wurtzite structure caused by stacking faults. On the ground of the assignment, the electron paramagnetic resonance parameters (zero-field splitting D, g factor g|| and g-anisotropy Δg = g||−g) of the axial Ti2+ center were calculated from the high-order perturbation formulas based on the cluster approach for the electron paramagnetic resonance parameters of 3d2 ion in trigonal symmetry. From the calculations, the local atom-position parameter (which was different to the corresponding parameter in the host wurtzite structure) and hence the defect structure of the Ti2+ center were estimated.

EPR Parameters and Defect Structure of the Trigonal Ti2+ Center in ZnS. W.C.Zheng, M.Yang, X.X.Wu: Spectrochimica Acta A, 2005, 61[11-12], 2720-3