Tailoring Luminescence and Scintillation Properties of Tb3+-Doped LuYAGG Single Crystals for High-Performance Radiation Detection

In this study, Lu2.5Y0.5(Al2.5Ga2.5)O12 (LuYAGG) single-crystal scintillators doped with terbium ions (Tb3+) at concentrations of 0.5, 1, 5, and 10 mol% were successfully synthesized using the floating zone method. The structural, optical, photoluminescence (PL), and scintillation properties of the Tb3+-doped crystals were systematically investigated with a focus on their potential for high-performance scintillator applications. X-ray diffraction (XRD) confirmed the formation of a pure garnet phase without any secondary phases, indicating the successful incorporation of Tb3+ into the LuYAGG lattice. Optical transmittance spectra revealed high transparency in the visible range. Photoluminescence measurements showed characteristic Tb3+ emission peaks, with the strongest green emission observed from the 5D4 → 7F5 transition, particularly for the 5 mol% sample. The PL decay curves further confirmed that this concentration offers a favorable balance between radiative efficiency and minimal non-radiative losses. Under γ-ray excitation, the 5 mol% Tb3+-doped crystal exhibited the highest light yield, surpassing the performance of other concentrations and even outperforming Bi4Ge3O12 (BGO) in relative comparison, with an estimated yield of approximately 60,000 photons/MeV. Scintillation decay time analysis revealed that the 5 mol% sample also possessed the fastest decay component, indicating its superior capability for radiation detection. Although 10 mol% Tb3+ still showed good performance, slight quenching effects were observed, while lower concentrations (0.5 and 1 mol%) suffered from longer decay and lower emission efficiency due to limited activator density. These findings clearly identify with 5 mol% Tb3+ as the optimal dopant level in LuYAGG single crystals, offering a synergistic combination of high light yield and excellent optical transparency. This work highlights the strong potential of LuYAGG:Tb3+ as a promising candidate for the next-generation scintillator materials used in medical imaging, security scanning, and high-energy physics applications.