“…Guo et al [23] reported the enhancement mechanism of luminescent properties of RE 3+ (RE 3+ = Eu 3+ , Sm 3+ , Dy 3+ ) in Y 2 O 2 S phosphor by a trace of Tb 3+ . Aizawa et al [24] reported the SrAl 2 O 4 :Eu 2+ phosphor doped with Nd, Sm, Lu, Gd, Dy and Y, and found that the long afterglow phosphorescence was influenced by the depth and density of the traps. Chen et al [1] reported that the luminescent properties of SrAl 2 O 4 :Eu 2+ , Dy 3+ could be significantly modified by the Yb 3+ ions doping.…”