Novel Phenomenon of Scintillation Performances with the Component Variation in the Mg Co-/Nondoped GAGG:Ce Crystal

Gd3Al2Ga3O12:Ce (GAGG:Ce) shows potential application in the next-generation positron emission tomography material due to its high light yield and excellent energy resolution. The main method currently available to accelerate the scintillation decay time of GAGG:Ce is mainly through the codoping of low valence ions such as Mg2+, which partially converts Ce3+ to Ce4+ through a charge compensation mechanism. However, there is no clear and reasonable explanation for the deterioration of light yield by codoping with Mg2+ in GAGG:Ce. Therefore, further study of the Mg2+ codoping GAGG:Ce crystal is of great importance for improving the scintillation properties of GAGG:Ce. In this study, two sets of GAGG crystal samples containing different Ce concentrations without or with 0.5 atom % of Mg2+ ion codoping were grown by the micropulling down method. The optimal Ce concentration decreases after Mg2+ codoping, whereas the light yield degenerates significantly. This novel phenomenon suggests that the reduction of light yield after Mg2+ codoping is not only due to the reduction of the luminescence center but also the formation of {Ce3+–Mg2+} and {Ce4+–Mg2+} associates affects the luminescence emission. This work can provide a novel and significant view for high-performance codoped GAGG:Ce component design and performance modification.