Optical Absorption Study of Co-Doped Oxide Systems. II

Abstract

The optical absorptionspectra of several Co‐doped oxide systems (MgO, ZnO, aluminum spinel, yttriumgalliumgarnet, and germaniumgarnets) have been studied at room temperature, 78°, and 4.2°K, and analyzed using the formalism of the crystal‐field theory. Oscillator strengths and cubic‐field parameters have been derived. The observed data for tetrahedrally coordinated Co2+ are found to agree satisfactorily with the theoretical predictions. The effect of the spin‐orbit coupling on the cubic‐field terms has been calculated and the predicted splitting compared with the structure of the absorption bands of MgO:Co and ZnO:Co. The optical absorption properties of MgO:Co and ZnO:Co are used to infer the site symmetry of Co2+ in systems (spinels and garnets) in which the cations occupy sites of different symmetry.