Luminescence Characterization of Mg Doped Y2O2S:Ti Long Afterglow Phosphor

Abstract Y 1.94- x Mg x O 2 S:0.06Ti (0≤ x ≤0.10) phosphors with long afterglow were synthesized by solid state reaction route. The photoluminescence spectra, decay curves, thermoluminescent spectra and chromaticity coordinate curves were investigated. The results show that the luminescence intensity of Y 1.94- x Mg x O 2 S:0.06Ti (0≤ x ≤0.10) phosphors decrease gradually with increasing Mg 2+ ion content, and the shape of luminescence spectra and chromaticity coordinate change as well. Furthermore, two thermoluminescent peaks in single Ti-doped Y 2 O 2 S sample are found at 91.8 and 221.5 °C, respectively. Nevertheless, significant different spectra were found for the Mg, Ti co-doped Y 2 O 2 S samples that three thermoluminescence peaks appear at 52.3, 141.7 and 226.8 °C, respectively. These results indicate that the co-doped Mg ion changes the inherent trap depth of single Ti-doped Y 2 O 2 S: Ti phosphor, and induces simultaneously a new trap level in the Y 1.94- x Mg x O 2 S:0.06Ti phosphor. Based on the analysis of thermoluminescent spectra, photoluminescent spectra, decay curve and crystal structure defect, it was proposed that the varied structure defect and introduced new trap level by the doped Mg 2+ ions should be responsible for reducing luminescence intensity and varying color in the Y 1.94- x Mg x O 2 S:0.06Ti phosphor.