Wide Concentration Range of Tb3+ Doping Influence on Scintillation Properties of (Ce,Tb, Gd)3Ga2Al3O12 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)₃Ga₂Al₃O₁₂ (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.