The new Eu 3+ doped lanthanum oxysulfide phosphors,which have the orange-red long afterg low emission,were synthesized by solid-state reaction method.The synthesized phosphors were characterized by X-ray diffraction.The excitation and emission spectra,afterglow spectra and afterglow decay curves were examined.XRD confirm ed the phosphor as pure phase La 2 O 2 S.The phosphors showed typical transitions 5 D J (J=0,1) → 7 F J (J=0,1,2,3,4)of Eu 3+ .The photoluminescence spectra and afterglow spectra presented the regular alteration with various Eu 3+ concentration,due to cross relaxation between energy levels of Eu 3+ .In addition,we studied the effects of activator concentration and dopants species on the afterglow property.The data showed afterglow result was the bes t with2%Eu 3+ and doped with Mg 2+ and Zr 4+ .A prominent phosphorescence can be seen in this phosphor after illuminated with UV light.
The new Er3+, Ho3+ and Tm3+ doped gadolinium oxysulfide phosphors with the long afterglow emission were synthesized by solid-state reaction method. The synthesized phosphors were characterized by X-ray diffraction. The excitation and photoluminescence spectra, afterglow spectra and afterglow decay curve were examined by fluorescence spectroscopy. The afterglow spectra of Gd2O2S∶Er3+, Mg, Ti showed typical transitions of Er3+ at 528 (2H11/2 → 4I15/2),548 (4S3/2 → 4I15/2) and 669 nm (4F9/2 → 4I15/2). In the afterglow spectra of Gd2O2S∶ Ho3+, Mg, Ti, typical transitions of Ho3+ at 546 nm (5S2 → 5I8), 651 and 661 nm (5F5 → 5I8) were observed. In Gd2O2S∶Tm3+, Mg, Ti, the afterglow emission at 800 nm (1G4 → 3H5) of Tm3+ was seen. The mechnism and model of afterglow energy transfer were proposed.
