Fabrication and Scintillation Performance of Nonstoichiometric LuAG:Ce Ceramics

Nonstoichiometric LuAG:Ce Ceramics ([Lu(1-x)Cex](3)Al5O12, x=0.005) with different excess of Lu3+ were designed on the basis of Lu2O3-Al2O3 phase diagram and fabricated by a solid-state reaction method. Without using any traditional sintering aids, pure phase and good optical performance were obtained in such a Lu-rich LuAG:Ce ceramics. In addition, scintillation efficiency and light yield of 1% excess of Lu3+ ceramic sample were found 16 times and 1.82 times higher than that of commercial Bi4Ge3O12 (BGO) single crystals, respectively. Such values are comparable or even better than those in most of LuAG:Ce single crystals. However, antisite defects were also induced by excess of Lu doping, whose luminescence was found at 350-410nm in Lu-rich LuAG:Ce ceramics. The relationship of excess content of Lu and the microstructure, optical quality, and scintillation performance were clarified and discussed. Furthermore, by utilizing X-ray absorption near edge spectroscopy technique, the charge state stability of cerium in Lu-rich LuAG:Ce ceramics was examined. It appears that the excess of isovalence Lu3+ doping has a negligible effect on the cerium valence instability and creation of stable Ce4+ center.