A complete diagonalization (of energy matrix) method based on the cluster approach (where the covalence effect due to the admixture between the orbitals of the central d n ion and that of ligands was considered) was applied to calculate the spin-Hamiltonian parameters (g factors, g| and g﬩, and hyperfine structure constants, A| and A﬩) for two Cu2+ centers in ZnGa2O4 spinel at the temperature T ≈ 110K. In both Cu2+ centers, Cu2+ ions occupy the trigonally-distorted octahedral sites 16d and the octahedrons undergo the static Jahn-Teller distortions from trigonal to tetragonally-elongated and tetragonally-compressed, respectively. The calculated spin-Hamiltonian parameters of the elongated Cu2+ center show good agreement with the experimental values and those of the compressed Cu2+ center were close to the observed values. The better agreement of spin-Hamiltonian parameter between calculation and experiment for the compressed Cu2+ center can be acquired by considering a small admixture of |dx2-y2> state to the |dz2> ground state due to the vibrational motion of ligands. The defect structures of both Cu2+ centers (characterized by the ligand displacements a1 and a2, respectively) in ZnGa2O4 spinel were also determined from the calculation.

Studies on the Spin-Hamiltonian Parameters of Two Cu2+ Centers and Their Defect Structures due to Jahn-Teller Effect for Cu2+-Doped ZnGa2O4 Spinel. W.C.Zheng, Y.Mei, Y.G.Yang, H.G.Liu: Philosophical Magazine, 2012, 92[6], 760-7