Optical spectra and energy levels of the Cr3+ ions in MWO4 (M=Mg, Zn, Cd) and MgMoO4 crystals

Single crystals of MWO4 (M=Mg, Zn, Cd) and MgMoO4 doped with Cr3+ have been grown by the flux growth method. Their optical spectra have been systematically measured and assigned on the basis of the classical Ligand Field Theory. The exchange charge model of the crystal field has then been applied to calculate the crystal field parameters (CFPs) and the energy levels of the Cr3+ ion in all studied crystals. These are in reasonable agreement with the experimental data. Systematic trends in the CFPs values, crystal field splittings and Racah parameters have been evidenced and their relation with sizes and symmetry properties of the host cavities occupied by Cr3+ has been pointed out.