GSAG:Ce scintillator: insights from yttrium admixture

The GSAG:Ce scintillator represents a promising and cost-effective alternative to the expensive GGAG:Ce. Recent studies have attributed its low light yield to the thermal quenching effect. In this study, we employed the strategy of adding an yttrium (Y) admixture to the GSAG matrix to increase the thermal activation energy of thermal quenching. The scintillation, optical, and luminescence properties of Gd_(3-Y Sc₂Al₃O₁₂:Ce (x = 0, 0.2, 0.5, 0.8) grown using the micro-pulling-down method are thoroughly studied and reported. We further investigated the correlation between the Y content and other characteristics (scintillation rise time, light yield, decay, etc.). The magnitude of thermal quenching was evidenced by combination of the temperature-dependent photoluminescence decay kinetics and thermally stimulated luminescence. Excitation spectra were measured down to 30 nm in the VUV range under the synchrotron radiation at DESY to monitor the energy transfer efficiency from the host under excitation above the band gap. Results suggested that thermal ionization was not the primary reason for the low performance of the GSAG:Ce composition, and other defects related to the presence of scandium (Sc) must play a role. Furthermore, it was found that the stoichiometric GSAG host provided a noticeably higher light yield than the previously studied congruent one. This research provides valuable insights into the characteristics of GSAG:Ce scintillators.