Crystal-field levels in the distorted perovskite PrGaO₃

Inelastic neutron scattering has been employed to study the crystalline-electric-field interaction of the distorted perovskite PrGaO ₃. The observed energy spectra show several well defined inelastic peaks of magnetic origin in an energy transfer range up to 86 meV which are attributed to crystalline-electric-field transitions within the ground-state J multiplet ³H₄ of the Pr³⁺ ions. The spectra are analysed in terms of single-particle crystal-field theory based on geometrical coordinations associated with the C_s site symmetry of the Pr ³⁺ ions. J mixing as well as the imaginary part of the crystal-field Hamiltonian are found to be important to reproduce the experimental data. The resulting crystal-field parameters are close to the values extrapolated from a similar study of NdGaO₃. Our approach turns out to constitute a useful extrapolation scheme for other structurally related perovskite-type compounds.