Charge Transfer Luminescence in Ce-Doped Fluorides

Abstract

New emission bands were found in Ce^3☎ 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 Ce^2☎—F_i^o pairs with different distances between them.

Keywords:

• Charge transfer luminescence
• Alkaline earth fluoride
• Decay
• Recombination