Energy spectra and g factors of α-Al2O3:Cr3+ and α-Al2O3:Mn4+

By diagonalizing the complete d(3) energy matrix in a trigonally distorted cubic-field and using the wavefunctions from it, unified calculations of the whole energy spectrum as well as the g factors of the ground state and t(2)(3) E-2 excited states for alpha-Al2O3:Cr3+ and alpha-Al2O3:Mn4+ have been carried out respectively. All the calculated results are in very good agreement with the experimental data. The comparison between the results of the two crystals has been made, which demonstrates that the covalency of alpha-Al2O3:Mn4+ is stronger than the one of alpha-Al2O3:Cr3+. For the zero-field splittings of the ground state and t(2)(3) E-2, their physical origins are revealed; the comparison and analysis of their values of the two crystals have been made.