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

Multicomponent garnets (Y 3− x Gd x Al 5− y Ga y O 12 ) doped with Ce 3+ 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 Ce 3+ activated multicomponent garnet single crystals. Temperature dependence of Gd 3+ emission intensities as well as decay kinetics in Y 3− x Gd x Al 5− y Ga y O 12 ( x , y =1,2,3) crystals point to the Gd 3+ →Gd 3+ nonradiative energy migration, which is diffusion limited. Concentration quenching of Gd 3+ emission occurs by energy migration to accidental impurities and/or structure defects. Temperature dependence of photoluminescence emission intensities and decay time measurements of Gd 3+ as well as Ce 3+ ions in Gd 3 Ga 3 Al 2 O 12 :Ce 3+ single crystal reveal nonradiative energy transfer Gd 3+ →Ce 3+ (including migration through Gd 3+ sublattice) which is responsible for slow Ce 3+ fluorescence decay component.