Synthesis And Characterization Of Rare-Earth Ions Doped Core-Shell Phosphors By The Hydrothermal Synthesis

In this article, monodisperse polystyrene (PS) microspheres templates were produced by dispersion polymerization, and then we improved the surface character of the template by the simple sulfonation with concentrated sulfuric acid. Core-shell structured luminescent materials, including rare earth doped SrCO3 and GdPO4 were synthesized by hydro-thermal method using monodisperse PS as cores. The luminescence of rare earth ions (Tb³⁺,Ce³⁺) and energy transfer properties fromCe³⁺→Tb³⁺,Gd³⁺→Tb³⁺were studied in core-shell structured luminescent materials.Core-shell structured PS@SrCO₃:Tb³⁺ phosphor powders were obtained by coating mondisperse PS particles with SrCO₃:Tb³⁺ phosphor layer through hydro-thermal method. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence (PL) as well as lifetimes was utilized to characterize the resulting phosphors. The results of FESEM and TEM indicated that the core-shell structured phosphor particles were smooth and uniform, maintained the morphology of monodisperse PS. The thickness of the shells could be easily controlled by changing the number of deposition cycles. Under the excitation of ultraviolet (272 nm) and electron beams, the Tb³⁺ ion mainly shows its characteristic green(544 nm, 5D4-7F5) emissions in the core-shell particles. The kinetic properties for the luminescence of Tb³⁺ in PS@SrCO₃:Tb³⁺ particles were investigated by PL decay. The PL decay curves of the luminescence of Tb³⁺ (5D4-7F5) in PS@SrCO3:Tb³⁺ particles can be well fitted by a single exponential function. The photoluminescence intensity of PS@SrCO₃:Tb³⁺ core-shell phosphors can be tuned by several experimental factors, such as Tb³⁺ on its doping concentration in PS@SrCO₃:Tb³⁺and the number of coatings. Spherical PS Particles have been coated with GdPO₄:Tb³⁺(Ce³⁺) phosphors layers by a hydro-thermal process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence (PL) as well as lifetimes was utilized to characterize the resulting phosphors. The doped Tb³⁺,Ce³⁺shows a strong photoluminescence (PL) due to an efficient energy transfer from Ce³⁺ to Tb³⁺. The decay curves for emission 5D4-7F5 (542nm) of Tb³⁺ can be well fitted into a single exponential function. Thus the average lifetimes of PS/GdPO₄:Tb³⁺ and PS/GdPO4:Tb³⁺(Ce³⁺) emission can be determined to be 3.07 ms and 2.73 ms, respectively.