Theoretical studies of the spin-Hamiltonian parameters and their stress dependences for Ru3+ and Ir4+ ions in Y3Ga5O12 crystals

The spin-Hamiltonian parameters (g factors g(parallel to), g(perpendicular to) and hyperfine structure constants A(parallel to), A(perpendicular to)) and the stress dependence of g(perpendicular to) for 4d(5) ion Ru3+ and 5d(5) ion Ir4+ in Y3Ga5O12 (YGG) crystals are calculated from the perturbation formulas related to the low-spin T-2(2) term subjected to the trigonal symmetry crystal field. The calculated results are in reasonable agreement with the experimental values. Based on the calculations, the signs of hyperfine structure constants are suggested, and the local bonding angles beta (between the metal-ligand bond and C-3 axis) and local angular compressibilities d beta/dP(where P parallel to C-3 axis) are obtained for both systems. It is found that the local angle 6 and local angular compressibility d beta/dP of impurity center are different not only from the corresponding values in the host crystal, but also from impurity to impurity. The results are discussed. (C) 2008 Elsevier B.V. All rights reserved.