Redox reactions and thermoluminescence in some europium-doped phosphates

Abstract

Rare earth (RE) ions in solids can exist in different valencies. Exposure to ionizing radiations and/or thermal treatment can change the valence state of the RE ions. RE3+ to or from RE2+ conversion has been assumed to play an important role in thermoluminescence (TL) processes. Experiments have been performed on TL and photoluminescence for several Eu-doped phosphates. It was found that there is no correlation between glow peaks and Eu3+ to or from Eu2+ conversion. These findings place in doubt whether the accepted models for TL in RE-doped solids can be applied to phosphates.