Structure of the fluorine states in cadmium molybdate host studied by the electronic band structure calculations of CdMoO4, CdMoO4:F and CdMoO3F2 crystals

Abstract The electronic structures of CdMoO 4 , CdMoO 3 F 2 and the fluorine-doped CdMoO 4 :F crystals are calculated by the Full-Potential Linear Augmented Plane Wave method. The energy dispersion curves, partial densities of electronic states and spatial distributions of electronic densities are calculated and analyzed in comparison with published experimental data. Relaxation of the crystal structure around the F O impurity in cadmium molybdate is revealed in geometry-optimization calculations carried out for CdMoO 4 :F. It is found that CdMoO 3 F 2 crystal is as a direct-gap material. The Cd d , F p and O p states electronic states form the top of the Valence band and mainly Mo d states form the bottom of the Conduction band of CdMoO 3 F 2 and all these states are involved into the lowest-energy band-to-band electronic transitions. The low-energy shift of the main bands in intrinsic luminescence emission and excitation spectra of CdMoO 3 F 2 with respect to CdMoO 4 may be a consequence of the lower E g value of the oxyfluoromolybdate. Calculations suggest more complex structure of the luminescence centers in CdMoO 3 F 2 in comparison with CdMoO 4 .