Studies On Doping And Luminescence Properties Of Silicate Phosphors

White light-emitting diode （WLED） is a new-style solid-state lighting source,currently，in the market which is mainly prepared by phosphor-converting method. In thetechnology of phosphor-converting, phosphor is allimportant for the luminous efficiency,working life and other properties of WLED. As phosphors used in WLED, due to theadvantage such as the wider excitation spectra and excellent color rendering, silicate withrare earth doping is receiving more and more attention. In the dissertation, a greenphosphor Li₂Sr_1-xBa_xSiO₄:0.01Eu²⁺,0.0075Ce³⁺and the other red phosphor Li₂SrSiO₄:Eu³⁺were prepared by high temperature solid state reaction, using fluorescencespectrophotometer, X-ray Diffractometer （XRD） and scanning electron microscope（SEM）to test their crystal structure、fluorescence and micro morphology properties.The green phosphor Li₂Sr_1-xBa_xSiO₄:0.01Eu²⁺,0.0075Ce³⁺was prepared under areductive atmosphere. The phosphors were synthesized: on the basis of the crystalstructure and spectral analysis, and the possible preparation technology which may affectthe luminescence property were investigated in details, including the sinter point, soakingtime, excitation and emitting wavelength and doped ions with its concentration，weobtained the optimum calcination conditions:850℃and2h. The optimum additiveamount of Eu²⁺is0.01mol, and Ce³⁺is0.0075mol, Ba²⁺is0.8mol. With the increase ofBa²⁺ions, emission spectrum have blue shift phenomenon to appear. XRD analysis showsthat the phosphor Li₂Sr_1-xBa_xSiO₄: Eu, Ce belongs to the hexagonal system. The phosphoris intensive green-yellow light which has a broad emission spectrum. The emittionspectrum ranges from500nm to525nm and the peak appears at513nm. The excitationspectrum ranges from300nm to450nm and the peak appears at385nm, seated nearultraviolet area.The red phosphor Li₂SrSiO₄: Eu³⁺was also prepared by high temperature solid statereaction, which belongs to the hexagonal system. On the basis of the crystal structure and spectral analysis, we obtained the optimum calcination conditions:850℃and2.5h. Theemittion spectrum of Li₂SrSiO₄: Eu³⁺exist bimodal phenomena, and the peak appears at592nm and618nm. The excitation spectrum peak of the phosphor appears at396nm,which is suitable to be phosphors used in WLED which is excited by InGaN chips（350⁴10nm）.