Theoretical studies of the local structures and EPR parameters for Cu^{2+} center in Cd_{2}(NH_{4})_{2}(SO_{4})_{3} single crystal

Abstract

The electron paramagnetic resonance (EPR) parameters (g factors g i and the hyperfine structure constants A i , i = x, y, z) are interpreted by using the perturbation formulae for a 3d 9 ion in rhombically (D 2h ) elongated octahedra. In the calculated formulae, the crystal field parameters are set up from the superposition model, and the contribution to the EPR parameters from the admixture of d -orbitals in the ground state wave function of the Cu 2+ ion was taken into account. Based on the calculation, local structural parameters of the impurity Cu 2+ center in Cd 2 (NH 4 ) 2 (SO 4 ) 3 (CAS) crystal were obtained (i.e., R x ≈ 2.05 Å, R y ≈ 1.91 Å, R z ≈ 2.32 Å). The theoretical EPR parameters based on the above Cu 2+ -O 2− bond lengths in CAS crystal show a good agreement with the observed values. The results are discussed.