Abnormal photo-stimulated luminescence in Ba2Ga2GeO7: Tb3+, Bi3+

A novel green-emitting phosphor Ba2Ga2GeO7: Tb3+, Bi3+ was successfully synthesized by solid-state reaction. The photoluminescence (PL), photo-stimulated luminescence (PSL) and long persistent luminescence (LPL) were investigated in detail. After pre-irradiation upon UV light, the PSL spectrum of Ba2Ga2GeO7: Tb3+, Bi3+ exhibits peaks centered at 493, 547, 589, and 627 nm under excitation at 980 nm, ascribed to the transitions of D-5(4)-> F-7(j) (j = 3, 4, 5, 6) by tunneling process. While PL spectrum exhibits peaks related to the transitions of D-5(3), D-5(4) -> F-7(j) (j = 3, 4, 5, 6). Thermo-luminescence (TL) curve shows that a large amount of traps can be in Ba2Ga2GeO7: Tb3+ by induced Bi3+, leading to the improvement of PSL spectra performance. These findings open a vista of possible avenues for the understanding of the PSL process.