Energy Transfer and Scintillation Properties of Ce3+ Doped (LuYGd)(3)(AlGa)(5)O-12 Multicomponent Garnets
Abstract
Photoluminescence, X-ray excited radioluminescence and photoelectron yield characteristics were studied in multicomponent GdGaYAG:Ce and GdGaLuAG:Ce garnet films grown by liquid phase epitaxy. Nonradiative energy transfer from Gd3+ to activator Ce3+ ions was evidenced.
At low Gd doping, < 5%, two virtually independent emission centers coexist, which compete for intensity: Ce3+ with fast 5d-4f emission and Gd3+ with slow 4f-4f emission. At higher Gd concentrations, the Ce3+ emission retrieves intensity due to the energy transferred from Gd3+ donors.
At Gd concentration similar to 50% and above, the Gd3+ emission is suppressed due to energy migration and transfer to Ce3+ centers. In these samples, the host emission is also completely quenched and the best scintillator performance is achieved.
Contrary to melt-grown crystals, no positive role of Ga substitution was found in epitaxial films.