High-efficiency SiO2:Ce3+ glass scintillators

We present the effect of a rapid thermal treatment (RTT) at high temperature (1800degreesC) on the radio-luminescence properties of Ce-doped SiO2 glasses prepared by the sol-gel method and previously densified at 1050degreesC. Cerium concentrations ranging from 0.05 up to 1 mol % were considered. We found that, for all concentrations, the RTT induces a strong increase of the Ce3+ radio-luminescence efficiency; the x-ray-induced luminescence intensity of the SiO2:0.1% Ce is about twice that of Bi3Ge4O12. The decay time of the scintillation response, evaluated as approximate to50 ns, is not affected by RTT. Infrared absorption measurements indicate that the luminescence increase cannot be related to significant release of OH groups during RTT. The conversion of Ce4+ ions into Ce3+ ions can also be ruled out since an increase of about 20% of the intensity of the 4.8 eV optical absorption band related to Ce4+ was observed after RTT. The occurrence of dissolution of rare-earth aggregates is suggested. (C) 2002 American Institute of Physics.