材料期刊网

The perturbation formulas of EPR parameters (g factors g(parallel to), g(perpendicular to) and hyperfine structure constants A(parallel to), A(perpendicular to)) for the lowest Kramers doublet Gamma6 or Gamma(7) of F-2(7/2) of 4f(13) ion in trigonal symmetry are established. In these formulae, the contributions of the covalency effects, the admixture between J = 7/2 and 5/2 states as well as the second-order perturbation (which is not considered in the previous works) are all included. From these formulae, the EPR parameters for two trigonal Yb3+ centers in LiNbO3 and MgO codoping LiNbO3 crystals are reasonably explained by considering suitable defect structures of these centers. The results (including the relative importance of second-order perturbation contribution) are discussed. (C) 2003 Elsevier Science Ltd. All rights reserved.