Luminescent properties of red long-lasting phosphor Y2O2S:Eu3+, M2+ (MÂ =Â Mg, Ca, Sr, Ba), Ti4+ nanotubes via hydrothermal method

Red long-lasting phosphor Y2O2S:Eu3+, M2+ (M = Mg, Ca, Sr, Ba), Ti4+ nanotubes were synthesized by hydrothermal method. The Y2O2S:Eu3+, M2+ (M = Mg, Ca, Sr, Ba), Ti4+ phosphors were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL), and thermoluminescence spectra (TL). The samples doped with different divalent alkaline-earth metal ions were calcined at 750 °C for 6 h in CS2 atmosphere, they were composed of pure Y2O2S phase. SEM observation showed that the sulfuretted phosphors inherited the tube-like shape from the precursors. Under 325 nm UV excitation, the result indicated that the strongest red-emission lines at 627 nm, which corresponded to the transition from 5D0 to 7F2 level of Eu3+ ion. The afterglow property of phosphors doped with different divalent alkaline-earth metal ions decreased according to the order of Mg2+, Sr2+, Ca2+, Ba2+. For the sample doped with Mg2+, the trap depth was 1.32 eV and the decay time could last for over 1065 s (⩾1 mcd/m2) after 365 nm UV radiation for 10 min.