Zero-Field Splitting and g-Values of d8 Ions in a Trigonal Crystal Field

On the basis of the crystal-field theory the zero-field splitting and g-values of the 3A2 ground state for d8 impurity ions in a trigonally distorted octahedral field are calculated. Using perturbation theory the analytical expressions connecting the spin-Hamiltonian parameters with the crystal-field parameters are obtained. It is shown that experimental data for Cu3+ in Al2O3, and Ni2+ in Al2O3, α-LiIO3, LiNbO3 can be explained taking into account the influence of all the excited levels on the ground state. [Russian Text Ignored].