Photoluminescence and radioluminescence properties of (Gd8Ca2)(SiO4)6O2 crystals with different concentrations of Ce

Abstract

(Gd8Ca2)(SiO4)6O2 apatite crystals doped with different concentrations of Ce were synthesized by the Floating Zone (FZ) method, and we have evaluated the photoluminescence (PL) and radioluminescence (RL) properties. In PL, an emission band appeared around 400 nm under excitation at 300 nm due to the 5d-4f transitions of Ce3+. The PL decay curves were approximated by a second-order exponential decay function, and the derived decay time constants ranged around 20–25 ns and 40–480 ns. Similar emission was observed in RL, but the decay time constants were much longer than those in PL. The RL afterglow was the lowest in the 1.0% Ce-doped sample. The 1.0% and 2.0% Ce-doped samples showed a full-energy peak in the pulse height spectrum measured under 241Am 5.5 MeV α-ray irradiation, and the absolute scintillation light yields were estimated to be around 55 and 36 ph/5.5 MeV-α, respectively.