Comparison study of the luminescent properties of the white-light long afterglow phosphors: CaxMgSi2O5+x:Dy3+(x=1, 2, 3)

A series of Dy3+-doped calcium magnesium silicate phosphors: CaMgSi2O6:Dy3+, Ca2MgSi2O7:Dy3+, and Ca3MgSi2O8:Dy3+ with white long-lasting afterglow were prepared and investigated. The characteristic intra-configurational 4f emissions of Dy3+ were observed in the emission spectra as well as the afterglow spectra under ultraviolet excitation. The combination of the 480 nm blue emission corresponding to the 4F9/2→6H15/2 transition and the 575 nm yellow emission corresponding to the 4F9/2→6H13/2 transition yielded white-light emission. The white-coloured afterglow emission can last more than 1 h for most of the samples under study. The concentration dependence of the ratio of the yellow emission intensity with blue emission intensity was also examined and found to be varied for the different hosts. The thermoluminescence spectra above room temperature are employed for the discussion of the origin of the traps and the mechanism of the persistent luminescence.