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 3 A 2 ground state for d 8 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 Cu 3+ in Al 2 O 3 , and Ni 2+ in Al 2 O 3 , α‐LiIO 3 , LiNbO 3 can be explained taking into account the influence of all the excited levels on the ground state.