Spin-Hamiltonian parameters and defect structures for two tetragonal Gd3+ centers in Gd3+-dpoed Tl2ZnF4 crystal

Seven spin-Hamiltonian parameters (g factors g//, g⊥ and zero-field splittings b 2 0 , b 4 0 , b 4 4 , b 6 0 , b 6 4 ) of two tetragonal Gd3+ centers, denoted A and B, in layered perovskite fluoride Tl2ZnF4 crystals doped only with Gd3+ ion and co-doped with Gd3+ and Li+ are calculated using the diagonalization (of energy matrix) method based on the one-electron crystal-field mechanism. In the calculations, the defect models suggested in the previous paper that center A is due to Gd3+ ion at the octahedral Zn2+ site without any local charge compensation and center B is due to Gd3+ ion at the nine-coordinated Tl2+ site associated with a Li+ ion at the nearest Zn2+ site along C4 axis for charge compensation are applied. The calculated results are in reasonable agreement with the experimental values. The suggested defect models of both Gd3+ centers are therefore confirmed and the respective defect structural data are obtained. The results, including the validity of defect structural data, are discussed.