Luminescent properties of blue green Sr3Al2O5Cl2:Pr3+ and orange red Sr3Al2O5Cl2:Eu2+, Pr3+ afterglow phosphors

Abstract

The Sr3Al2O5Cl2:Eu2+, Pr3+ phosphor has been synthesized via high temperature solid state reaction. The X-ray powder diffraction confirms that the obtained samples are pure orthorhombic Sr3Al2O5Cl2 phases, with a space group of D24-P212121. Blue green emission is observed when the sample is doped with Pr3+ ions and an orange red emission with Eu2+ ions doping. Both of the samples show obvious afterglow emission. The intensity and lifetime of such afterglow can be substantially enhanced in the case of Pr3+-Eu2+ co-doped, whose afterglow can last for approximately 300 min in the dark and the intensity is five times higher than the sample single doped with Eu2+. According to the thermoluminescence glow curves, the trap depth of these double-doped samples is about 0.95 eV, which is suitable for the generation of afterglow luminescence. And Pr3+ ions help to enhance the traps concentrations and modify the trap depth, which contributes to prolong the afterglow duration and increase the afterglow intensity of the phosphors. Finally, a feasible explanation of this afterglow generation is also discussed in this work.