Molecular orbital calculations of Eu-doped SrAl2O4 clusters

The electronic structures of undoped and Eu2+-doped SrAl2O4 clusters are evaluated from the relativistic molecular orbital (RMO) calculation. The calculated forbidden gaps between the highest and lowest unoccupied molecular orbitals of [SrAl6O21]22− and [Sr3Al12O38]34− clusters are calculated to be 8.3 and 7.3 eV, respectively. When a Eu atom replaces a Sr atom, the Eu 4f states appear in the forbidden gap of the SrAl2O4 and the Eu 5d states are distributed widely in the conduction band. Combining the RMO calculation and the configuration interaction method for [EuO7]12− and [EuO8]14− clusters produces three or two theoretical peaks respectively for the transition 4f7→4f6 5d1 in Eu2+-doped SrAl2O4, respectively.