Defect model for a tetragonal Co2+ impurity center in AgCl crystal

The EPR g-factors g//, g⊥ and hyperfine structure constants A//, A⊥ for a tetragonal Co2+ impurity center (i.e. Co2+(II) center) in AgCl crystal are calculated by using the perturbation formulas of EPR parameters for the 3d7 ion in tetragonal symmetry obtained from the cluster approach. Based on the calculations, the defect model for the center is suggested as a substitutional Co2+ ion associated with a nearest neighbour O2− ion.