The effect of concentration of Dy3+ ions on luminescence properties of Y2O2S:Dy3+, Mg2+, Ti4+ phosphors

Y2O2S:Dy3+, Mg2+, Ti4+ white-light long-lasting phosphors were synthesized by the sol–gel method. The effect of Dy3+ doping concentration on the luminescence properties was investigated. The samples were characterized by X-ray diffraction, photoluminescence spectroscopy and thermally stimulated spectrometry. The samples doped with different concentrations of Dy3+ ions were composed of the pure Y2O2S phase. Under 359 nm UV excitation, the phosphor presented white luminescence due to mixing of the dominating emissions centered at 488 nm (blue) and 579 nm (yellow), corresponding to 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions of Dy3+, respectively. When Dy3+ concentration was 1 mol%, the CIE chromaticity diagram was (0.375,0.374), and the decay time could last for over 65 min (≥1 mcd/m2).