“…Compared with the conventional sulphide materials, alkaline earth silicates long afterglow phosphors yield much better characteristics, such as a longer duration of time of the phosphorescence, brighter luminosity, improved chemical and physical stability, especially an excellent water-resistant property [3][4][5][6]. For those phosphors, the phosphorescence is ascribed to the parity-allowed electronic transition of 4f 6 5d 1 -8 S 7/2 of the Eu 2+ ion, which is strongly influenced by the host lattice.…”