One-step solvothermal synthesis, a worm-shaped morphology and luminescence properties of green-emitting Y2O2S:Tb3+ nanophosphors

Abstract

The worm-shaped Y2O2S:Tb3+ nanophosphors have been successfully prepared via one-step solvothermal synthesis, using ethanediamine as the main solvent and sublimed sulfur powder as the source of sulfur without adding additional structure-directing reagents. XRD, FT-IR, FESEM, PL and CIE chromaticity diagram were used to characterize the obtained products. XRD results demonstrate that all diffraction peaks of the sample can be well indexed to pure hexagonal phase of Y2O2S with optimal condition, i.e. the molar ration of S/Y3+m=10, solvothermal temperature T=220°C and synthetic time t=24h. When t varies from 2h to 24h, the morphology of Y2O2S transforms from cauliflower-like structure to worm-shaped nanoparticles with the length of ∼80nm. The formation mechanism depending on t has also been proposed. Upon 250nm ultraviolet (UV) light excitation, the worm-shaped Y2O2S:Tb3+ nanophosphors exhibit green emissions, corresponding to the 5D4→7FJ (J=6, 5, 4, 3) transitions of Tb3+ions. The quenching concentration is 7% and its corresponding lifetime is 1216μs. The CIE chromaticity coordinates show the tuneable emission shifting from yellow green to yellowish green with increasing concentration of Tb3+ions from 1% to 7%. Those results suggest that the worm-shaped Y2O2S:Tb3+ nanophosphors may have potential applications in X-ray intensifying screens, fluorescence and biomedical fields.