Rare earth-doped alkaline earth silicates, Sr2MgSi2O7:Eu2+, Dy3+ and Ca2MgSi2O7:Eu2+, Dy3+, with an akermanite-type structure show bright and long-lasting phosphorescence. After irradiation by a white-color fluorescent lamp (780lm) for 5min, the light blue emission of Sr2MgSi2O7:Eu2+, Dy3+ was observable by naked eye in the dark for over 100min after removal of the excitation light source.
