Effect of Ce Co-Doping on CaGa2S4:Eu Phosphor: I. Energy Transfer from Ce to Eu Ions

Abstract

The resonance-type energy transfer process has been investigated for the first time in Ce and Eu co-doped CaGa₂S₄ polycrystalline samples with different dopant concentrations in the range from 0.2 at.% to 4 at.%. The energy transfer from Ce to Eu ions increases with increasing Ce and Eu concentrations. The values of the rate determined from measured Ce emission decay time constants with different dopant concentrations showed a reasonable agreement with those obtained from intensity analyses of the Ce emission which takes into account the re-absorption effect by Eu ions. In addition, the observed change of the transfer rate with dopant concentration was discussed in terms of the distance between Ce and Eu ions.