Crystal field analysis of the ground and excited state absorption of a Cr4+ ion in LiAlO2 and LiGaO2 crystals

The exchange charge model of crystal field theory has been used to analyze the ground and excited state absorption of tetrahedrally coordinated Cr4+ ion in lithium aluminum oxide LiAlO2 (gamma-phase) and lithium dioxogallate LiGaO2. The parameters of the crystal field acting on the Cr4+ ion are calculated from the crystal structure data, taking into account the crystal lattice ions located at distances up to 12.744 angstrom in LiGaO2 and 13.180 angstrom in LiAlO2. The obtained energy level schemes were compared with experimental ground and excited state absorption spectra and literature data on the application of other crystal field models (the angular overlap model and Racah theory) to the considered crystals; a good agreement with experimental data is demonstrated. (C) Central European Science Journals. All rights reserved.