Luminescent properties of a novel afterglow phosphor Sr3Al2O5Cl2:Eu2+, Ce3+

Abstract A series of Eu 2+ and Ce 3+ doped/co-doped Sr 3 Al 2 O 5 Cl 2 afterglow phosphors that presented various bright colors were successfully synthesized via high temperature solid state reaction. The structure and luminescence properties of the obtained samples were characterized by X-ray powder diffraction (XRD), photoluminescence (PL) spectra and decay curves as well as the thermoluminescence (TL) glow curves. The XRD results showed that all the phase could be indexed to the orthorhombic structure with the space group P2 1 2 1 2 1 . After being exposed to a 254 nm or 365 nm mercury lamp, blue/yellow-orange afterglow emissions with broad bands peaking around 620 nm/435 nm, which were ascribed to the characteristic 4f 6 5d–4f 7 /5d 1 –4f 1 transitions of Eu 2+ /Ce 3+ , could be observed in phosphors of Sr 3 Al 2 O 5 Cl 2 :Eu 2+ /Sr 3 Al 2 O 5 Cl 2 :Ce 3+ , respectively. Because of the overlap spectral range between the Sr 3 Al 2 O 5 Cl 2 :Eu 2+ and Sr 3 Al 2 O 5 Cl 2 :Ce 3+ phosphors, the energy transfer (ET) from Ce 3+ to Eu 2+ occurred. The related ET process was discussed in detail. Moreover, the incorporation of Ce 3+ could significantly prolong the afterglow duration of Sr 3 Al 2 O 5 Cl 2 :Eu 2+ phosphor, which was due to the increase of trap concentration. Consequently, 6 h of the afterglow duration could be observed in Sr 3 Al 2 O 5 Cl 2 :1.0%Eu 2+ , 0.5%Ce 3+ sample, exhibiting much longer than that of Sr 3 Al 2 O 5 Cl 2 : 1.0%Eu 2+ (3 h). From the afterglow decay curves and the fitting results, the optimal concentration of Ce 3+ for the enhanced afterglow property was experimentally determined to be 0.5%.