Extending the afterglow of Tb3+ doped CaAl2O4 to 8 hours via the control of doping concentration

With doping concentration varying from 0.1 to 8.0 mol%, a series of Tb3+ doped CaAl2O4 phosphors were prepared via the technique of solution combustion, and the influences of doping concentration on the afterglow of Tb3+ doped CaAl2O4 were investigated. The green afterglow of Tb3+ doped CaAl2O4 is found to heavily depend on the doping concentration and 8-h-long afterglow is achieved at optimal doping concentration of 2.0 mol%. Analysis of the thermoluminescence glow curves reveals that the trap depth in Tb3+ doped CaAl2O4 varies in the range of 0.692–0.728 eV as the doping concentration increases from 0.1 to 8.0 mol%. The large scale extension of the afterglow of Tb3+ doped CaAl2O4 is discussed in terms of the effective manipulation of the trap depth by the variation of Tb3+ concentration. These results demonstrate that tailoring of the trap depth offers a promising approach for controlling the afterglow lifetime of other materials. The finding helps in designing better afterglow materials by optimizing the doping concentration.