High-temperature long persistent and photo-stimulated luminescence in Tb3+ doped gallate phosphor

Abstract

The formation of suitable defects levels is crucial to the optical performance of the electron trapping materials which provide a wide range of applications from the initial civil uses to life sciences, energy and environmental engineering. SrGa2O4, possessing a one-dimensional chain structure of cations along a crystal direction, exhibits a self-activated blue long persistent luminescence (LPL) related to the intrinsic defects. Different trap depths are generated forming a successive defect structure in this three-dimensional framework of SrGa2O4 containing channels occupied by Sr2+ when Tb3+ ions are introduced. The captured carriers in shallow traps are spontaneously released at room temperature and recombine in the luminescence center of Tb3+, eventually causing characteristic emission of Tb3+. The deeper traps are critically important to prevent the thermal fading of carriers at room temperature, therefore, LPL is achieved in SrGa2O4:Tb3+ phosphor at 328 K. Furthermore, a photo-stimulated luminescence (PSL) originated from Tb3+ ions is realized in SrGa2O4:Tb3+ phosphor induced by 980 nm laser diode with the releasing of the carriers trapped in the deeper traps at room temperature. Our results infer that the existence of a successive defect structure with multiple traps for the incorporation of the shallow and deep ones is conducive to the thermal stability of SrGa2O4:Tb3+ phosphor, which could provide a potential application in a rigorous environment with a higher thermal energy than the room temperature, such as solar energy utilization, and in vivo-imaging.