Stress-Induced Trigonal Crystal-Field Parameters in Some Oxide Lattices

Numerical perturbation methods are used to express trigonal stress splittings in terms of two phenomenological parameters, vₛ and vₛ^_^', for many levels of Cr³⁺, V²⁺, Ni²⁺ in MgO, and Cr³⁺ in ruby and emerald. Values of vₛ and vₛ^_^' for ruby and for Cr³⁺ and V²⁺ in MgO have been determined from published data. Point-charge calculations using Hartree-Fock free-ion radial wave functions give useful estimates of the stress-induced crystal-field parameters.