Charge Transfer Luminescence in Ce-Doped Fluorides

Abstract

New emission bands were found in Ce3☎ doped SrF2 and BaF2 crystals under excitation into the charge transfer region. The bands at 4.85 eV in BaF2 and 4.35 eV SrF2 were found in all crystals with Ce-concentration from 0.001 to 1 mol.%, most prominent in 0.01% samples. Decay of luminescence was simple exponential in BaF2, decay time decreased from 1.3 ms at 65 K to 0.41 μs at 523 K. The decay curve in SrF2 shows t−0.3 dependence at room temperature. All experimental results were naturally explained by assumption that new emission belongs to radiative charge transfer recombination in Ce2☎—Fio pairs with different distances between them.