Energy migration processes in undoped and Ce-doped multicomponent garnet single crystal scintillators

Multicomponent garnets (Y3−xGdxAl5−yGayO12) doped with Ce3+ ions are promising scintillators with a high density, fast response time and high light yield. To deepen the knowledge about the transfer stage of scintillation mechanism we discuss the energy migration and energy transfer processes in the set of undoped and Ce3+ activated multicomponent garnet single crystals. Temperature dependence of Gd3+ emission intensities as well as decay kinetics in Y3−xGdxAl5−yGayO12 (x,y=1,2,3) crystals point to the Gd3+→Gd3+ nonradiative energy migration, which is diffusion limited. Concentration quenching of Gd3+ emission occurs by energy migration to accidental impurities and/or structure defects. Temperature dependence of photoluminescence emission intensities and decay time measurements of Gd3+ as well as Ce3+ ions in Gd3Ga3Al2O12:Ce3+ single crystal reveal nonradiative energy transfer Gd3+→Ce3+ (including migration through Gd3+ sublattice) which is responsible for slow Ce3+ fluorescence decay component.