Radiophotoluminescence Phenomenon of CaF₂ Ceramics Doped with Li

The objective of this study is to examine the impact of Li-doping on the radiophotoluminescent (RPL) properties of CaF2. Before ionizing irradiation, Li-doped CaF2 exhibited no photoluminescence (PL) under excitation in the range of 250–700 nm. After ionizing irradiation, Li-doped CaF2 displayed PL at 800 nm when excited at 390 and 610 nm. The decay time constant for this luminescence was determined to be 20 ns, which suggests that it is attributed to (F2+)A centers. All the Li-doped CaF2 showed higher PL intensity than the non-doped CaF2 did, with the highest intensity observed in the 0.5% Li-doped CaF2. The 0.5% Li-doped CaF2 was also found to have a minimum measurable dose of 14 μGy as an RPL dosimeter, and the RPL response monotonically increased to 10 Gy. As for radiation-induced luminescence other than RPL, the scintillation peak and the thermally stimulated luminescence (TSL) glow peak were mainly observed at 300 nm and 140 °C, respectively