Effects of Ln3+ (Ln=Ce, Pr, Tb and Lu) doping on the persistent luminescence properties BaMg2(PO4)2:Eu2+ phosphor

The photoluminescent and persistent luminescence properties of BaMg2(PO4)(2):Eu2+, Ln(3+) (Ln=Ce, Pr, Tb and Lu) were investigated. These phosphors were prepared by a solid-state reaction at high temperature. The persistent phosphors were investigated by XRD, photoluminescence, persistent luminescence and thermoluminescence glow curves. Radiative/nonradiative energy transfer from Eu2+ to Pr3+/Tb3+ were observed due to the overlap between the Eu2+ emission and Pr3+/Tb3+ absorption spectra. The relevant transitions of Pr3+ and Tb3+ are respectively spin allowed and forbidden, so that the energy transfer occurs in different manners. After irradiated by ultraviolet light, all these codoped phosphors show a broad-band persistent luminescence located at similar to 435 nm at room temperature. Codoping with Tb3+ considerably enhances the afterglow intensity while Pr3+ codoped sample only shows weak afterglow. These properties can also be confirmed by their thermoluminescence glow curves. The emissions for both photoluminescence and persistent luminescence are due to the 5d -> 4f transition of Eu2+. The influence of auxiliary codopants is discussed in terms of ionization energy and ionic radius. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.