Synthesis And Luminescent Properties Of CeO₂: Eu～(3+) And SrCeO₃: Eu～(3+) Powder Phosphors

CeO₂:Eu³⁺ phosphor powders with various Eu³⁺ concentrations have been synthesized by the solid state reaction method. X-ray diffraction (XRD) analysis showed the formation of pure solid solution Ce_1-xEu_xO₂ up to 10at.% concentration of Eu³⁺. The Photoluminescence (PL) measurements indicated the dependence of PL emission intensity on the Eu³⁺ concentrations. The CeO-2:Eu³⁺ phosphor powders showed the strongest photoluminescence for 1 at.% concentration of Eu³⁺ and then abruptly decreased indicating the concentration quenching.SrCeO₃:Eu³⁺ phosphor powders have been synthesized by the sol-gel method and solid state reaction method. TG-DTA and XRD were employed to analyze the synthesis process and the crystalline structure of SrCeO₃:Eu³⁺ powders. SrCeO₃:Eu³⁺ phosphor powders with almost pure perovskite phase were obtained at sintering temperature of 1250°C. The detailed analysis demonstrated that Eu³⁺ ions mainly occupy the Ce⁴⁺ sites in SrCeO₃ lattice.The Photoluminescence (PL) measurements indicated the dependence of PL emission intensity on the Eu³⁺ concentrations. The excitation spectra of SrCeO₃:Eu³⁺ consist of a series of excitation bands. Among these bands, the ones at ²39nm and ²58nm originate from ultraviolet absorption of the host; the bands at ²73nm and ²98nm are Eu³⁺-O^2- charge transition band (CTB), and the bands at ²85nm and ³10nm are Ce⁴⁺-O^2- CTB. The emission spectra of SrCeO₃:Eu³⁺ showed Do-⁷F₁ and ⁵D₀-⁷F₂ transitions of Eu³⁺ are the strongest emissions for the samples with Eu³⁺ concentration of 15at.% and no concentration quenching was observed. The sample with 5at.% Eu³⁺ exhibited the strongest emission band centered at 422nm. The emission intensities of SrCeO₃:Eu³⁺ powders showed obvious dependence on the excitation wavelength. The sensitive excitation wavelengths for the emissions at 422nm, 370-470nm and 4f transitions of Eu³⁺ are 236nm, 241nm and 290nm, respectively.