Investigations of EPR parameters and local lattice distortions for both Co2+ centers in La2Mg3(NO3)12.24H2O crystal

The EPR g factors, g parallel and g perpendicular, of Co2+ and hyperfine structure constants (A parallel, A perpendicular) of 59Co2+ and 60Co2+ isotopes in both trigonal Mg2+ sites of La2Mg3(NO3)12.24H2O crystal are calculated from the high-order perturbation formulas of EPR parameters based on the cluster approach for 3d7 ion. It is found that to explain reasonably all these EPR parameters, the local relaxation effects (particularly, those related to the trigonal distortion angles thetai) in the vicinity of both Co2+ impurities should be considered. The local angles thetai are obtained from the calculations and the results are discussed.