Electron paramagnetic resonance parameters of V2+ ions in both Cd2+ sites of CsCdCl3 crystal

Theoretical investigation of optical and paramagnetic resonance spectra of [NiF6](4-) clusters with orthorhombic symmetry

The ground state absorption spectra of [NiF6](4-) clusters with orthorhombic symmetry (Ni(2+) in NiF2 crystal and Ni(2+)-doped ZnF2 crystal, D2h point group) are theoretically calculated and assigned by diagonalization of 45×45 complete energy matrix for 3d(8) configuration and the spin-Hamiltonian (SH) parameters (zero-field splitting D and E, and g factors gx, gy, gz) are studied by use of high-order perturbation method, in the frame of semi-empirical molecular orbital (MO) scheme based on strong crystal field framework. In those energy matrix, all the configuration interactions though the cubic crystal field (CF), the orthorhombic crystal field, the Coulomb interaction are taken into account. The calculated results are in good agreement with the experimental data. The local structure (bond length and bond angle) of [NiF6](4-) clusters are determined, and the results shows that the structure data given by Stout are more plausible than those given by Baur.

EPR parameters and local geometry for Cr3+ and V2+ ions in HfS2 crystals

From the high-order perturbation formulas of EPR parameters (zero-field splitting D, g factors gparallel, gperpendicular and hyperfine structure constants Aparallel, Aperpendicular) based on the two spin-orbit coupling parameter model for 3d3 ions in trigonal symmetry, the EPR parameters of Cr3+ and V2+ ions in HfS2 crystals are calculated. From the calculations, it is found that the local trigonal distortion angle theta of impurity center in HfS2:Cr3+ is smaller than that in HfS2:V2+. The dominant cause of the small zero-field splitting |D| and g-anisotropy |Deltag|=|gparallel-gperpendicular| in HfS2:Cr3+ (compound to HfS2:V2+) is due to the small local trigonal distortion angle theta rather than to the small impurity-ligand distance R in HfS2:Cr3+.