Luminescence quenching processes in Gd sub(2)O sub(2)S:Pr super(3+),Ce super(3+) scintillating ceramics

Temperature dependent radioluminescence under X-ray excitation (XRL) and luminescence decay time measurements following 430 nm laser excitation have been performed in the 10-775 K range on Gd sub(2)O sub(2)S:Pr super(3+),Ce super(3+) scintillating ceramics. From 200 K to both low and high temperature, XRL light yield decreases by 60%. High temperature luminescence quenching has been revisited. Temperature dependent lifetime measurements imply non-radiative de-excitation mechanism at electronic defects spatially correlated to Pr super(3+) emitting ions. At low temperatures, decreasing XRL light yield with irradiation time is linked to very intense thermoluminescence (TL) peak around 120 K ascribed to sulfur vacancies. These traps cause efficient electron trapping which competes with the prompt recombination mechanism.