Wide Concentration Range of Tb Doping Influence on Scintillation Properties of (Ce, Tb, Gd)GaAlO Crystals Grown by the Optical Floating Zone Method.

To obtain a deeper understand of the energy transfer mechanism between Ce and Tb ions in the aluminum garnet hosts, (Ce, Tb, Gd)GaAlO (GGAG:Ce, Tb) single crystals grown by the optical floating zone (OFZ) method were investigated systematically in a wide range of Tb doping concentration (1-66 at.%). Among those, crystal with 7 at.% Tb reached a single garnet phase while the crystals with other Tb 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 Ce and Tb ions can be observed in all crystals. Photoluminescence (PL) spectra show the presence of an efficient energy transfer from the Tb to Ce and the gradually quenching effect with increasing of Tb concentration. GGAG: 1% Ce, 7% Tb 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 Tb can optimize the photoconversion performance of GGAG:Ce.