Compositional regulation of multi-component GYGAG:Ce scintillation ceramics: Self-sintering-aid effect and afterglow suppression

(Gd,Y,Ce)₃(Y_xGa_1-x)₂GaAl₂O₁₂ (GYGAG:Ce) scintillation ceramics with different Y excess, where x=0.005-0.08, were fabricated by the solid-state reaction method. The effects of stoichiometry on the phase composition, optical quality and microstructure of GYGAG:Ce ceramics were analyzed. GYGAG:Ce ceramics have a pure garnet phase and obtain good in-line transmittance when x < 0.04, while more Y excess leads to the creation of the secondary phase. The change of x value influences the sintering behavior of the GYGAG:Ce ceramics: the excess of Y works as the self-sintering aid and significantly reduces the sintering temperature of ceramics. When x=0.01-0.04, the the X-ray excited luminescence (XEL) spectra and light yields of GYGAG:Ce ceramics are similar. The fast scintillation decay time and afterglow intensity of GYGAG:Ce ceramics show a slight decrease with increasing x value. Finally, additional 50-500 ppm MgO and 100-500 ppm CaO were introduced to the GYGAG:Ce ceramic with x=0.04, and both were found to significantly increase the fast scintillation component and reduce the afterglow intensity by two orders of magnitude to 0.01% after X-ray cut-off.