Ultrafast GGAG:Ce X-ray scintillation ceramics with Ca2+and Mg2+co-dopants

Among the aluminate garnet materials, cerium-doped gadolinium gallium aluminum garnet ceramics (GGAG:Ce) show fast scintillation properties, which suggests that they have promising applications in medical imaging, highenergy ray detection and high-power LED lighting. In this study, Gd3Ga3Al2O12:Ce scintillation ceramics codoped with Me2+ (Me = Mg, Ca) are fabricated using a two-steps route: a solid-state reaction followed by annealing in air. The optical and scintillation properties, including the absorption, radio luminescence (RL), light yield, and decay time, of these co-doped ceramics are studied in detail. Doping with Mg2+ and Ca2+ leads to the oxidation of Ce3+ to Ce4+, which accelerates the scintillation process and decreases the light yield. Co-doping with Ca2+ and Mg2+ shows a synergistic effect on this phenomenon. Compared with 0.2 at% Ca2+ or 0.2 at% Mg2+ single-doped GGAG:Ce, the GGAG:Ce co-doped with 0.1 at% Ca2+ and 0.1 at% Mg2+ has the fastest decay time (-31 ns) and maintains a relatively high light yield (-27400 +/- 1600 ph/MeV, 77% of undoped GGAG:Ce). These findings shed new light on designing Ce-activated garnet scintillator materials with ultra-fast decay time for applications in time-of-flight (TOF) PET technology.