Thermal quenching of luminescence in (Lu,Gd,Y)3(Ga, Al)5O12:Ce complex garnet ceramics at high and low temperatures

Cerium-doped complex garnets with the general formula (Lu,Y,Gd)3,(Ga,Al)5O12:Ce are promising materials to be used in PET and CT scanners. By modifying garnet composition (bandgap engineering), one can adjust its scintillation properties to fit a specific set of requirements. In certain compositions, Ce3+ luminescence intensity can decrease upon cooling (negative thermal quenching). The reason for that is still a matter of active debate. This article is focused on negative thermal quenching in Ce-doped (Lu,Gd)3(Ga,Al)5O12 garnet ceramics. We have measured thermally stimulated luminescence, temperature dependence of the X-ray excited luminescence intensity, and other scintillation properties of samples which have different Lu and Ga content and were annealed in different conditions. We discuss that negative thermal quenching in our samples can be attributed to the process of charge carrier localization on traps at lower temperatures