Radio- and thermoluminescence and energy transfer processes in Ce3+(Tb3+)-doped phosphate scintillating glasses

Ce3+ and Tb3+-doped Na(K)-Gd phosphate glasses were synthesized and their radio-, photo- and thermoluminescence properties were investigated. Increased radioluminescence efficiency with respect to Gd-free glass matrix has been achieved at Gd concentrations above 20 mol%. This is explained by efficient capture of thermalised electrons and holes in the Gd3+-sublattice resulting in the formation of Gd3+ excited states followed by Gd3+-Gd3+ energy transfer and single-step transfer to the Ce3+(Tb3+) emission centres. In such a way non-radiative losses in the phosphate glass matrix are reduced. Energy migration in Gd-sublattice becomes frozen below 10-15 K due to local field fluctuations in the glass matrix. Thermoluminescence measurements above room temperature show the presence of two groups of traps with concentrations strongly dependent on the glass composition. (C) 2001 Elsevier Science Ltd. All rights reserved.