Novel scintillators based on cerium-doped garnets in amorphous silica: crystal quality at the cost of glass

A two-step sol-gel procedure is proposed to fabricate low-cost composite scintillators consisting of microcrystalline cerium-doped garnets embedded in a silica matrix. Scintillators containing yttrium aluminum garnet (YAG:Ce) and garnets with partial or complete substitution of Y by Lu (LuYAG:Ce and LuAG:Ce) to improve the stopping power of the scintillator were fabricated and studied. X-ray diffraction (XRD) patterns show that the microcrystals exhibit a garnet structure without significant traces of other crystalline phases. Time-resolved photo- and cathodoluminescence spectroscopy revealed that the luminescence is dominated by the emission of unperturbed Ce³⁺ ions, although a small fraction of the emission centers are modified in LuYAG:Ce and LuAG:Ce. The agglomeration of microcrystals with their increasing content in the composite positively influences the luminescence intensity. Despite the relatively low fabrication temperatures, the microcrystals contain trapping centers that reduce the luminescence rate, as observed in the corresponding bulk crystals.