Wide Concentration Range of Tb3+ Doping Influence on Scintillation Properties of (Ce, Tb, Gd)(3)Ga2Al3O12 Crystals Grown by the Optical Floating Zone Method

To obtain a deeper understand of the energy transfer mechanism between Ce3+ and Tb3+ ions in the aluminum garnet hosts, (Ce, Tb, Gd)(3)Ga2Al3O12 (GGAG:Ce, Tb) single crystals grown by the optical floating zone (OFZ) method were investigated systematically in a wide range of Tb3+ doping concentration (1-66 at.%). Among those, crystal with 7 at.% Tb reached a single garnet phase while the crystals with other Tb3+ concentrations are mixed phases of garnet and perovskite. Obvious Ce and Ga loss can be observed by an energy dispersive X-ray spectroscope (EDS) technology. The absorption bands belonging to both Ce3+ and Tb3+ ions can be observed in all crystals. Photoluminescence (PL) spectra show the presence of an efficient energy transfer from the Tb3+ to Ce3+ and the gradually quenching effect with increasing of Tb3+ concentration. GGAG: 1% Ce3+, 7% Tb3+ crystal was found to possess the highest PL intensity under excitation of 450 nm. The maximum light yield (LY) reaches 18,941 pho/MeV. The improved luminescent and scintillation characteristics indicate that the cation engineering of Tb3+ can optimize the photoconversion performance of GGAG:Ce.