Different luminescent behaviors between photoluminescence and persistent luminescence in Tb3+ doped Li2CaGeO4 phosphors

Abstract Different contents of Tb 3+ ions doped Li 2 CaGeO 4 phosphors were prepared successfully by the traditional high temperature solid-state reaction method. The influences of Tb 3+ ions concentrations on photoluminescence (PL), long persistent luminescence (LPL) and thermoluminescence (TL) properties were studied systematically. The cross-relaxation of Tb 3+ in Li 2 CaGeO 4 host was observed in PL when the doping concentration of Tb 3+ exceeded 2% but not in LPL. The optimal concentration of Tb 3+ for LPL was about 1%. The escaped charge carriers from shallower trap can be re-trapped by deeper traps. A tentative schematic was proposed to illuminate the mechanism of LPL. Besides, the different luminescent behaviors of Tb 3+ in Li 2 CaGeO 4 host between PL and LPL were also discussed accordingly.