Study Of Silicate Phosphor For NUV-white Light Emitting Diodes

White LED is a promising light source in 21^st century with large market and great potential of lighting applications. The white LED achieved by stimulating trichromatic phosphors using near ultraviolet light(380-410nm) InGaN die has attracted great attentions recently, and become one of main solutions for the next generation white LED lighting. But currently there are few phosphors suitable for efficient near UV light excitation. In this thesis, we synthesized two types of silicate phosphors Sr₃MgSi₂O₈:Bi³⁺,Eu²⁺ and Ca₈Mg(SiO₄)4Cl₂:Ce³⁺,Eu²⁺,Mn²⁺, which can be excited efficiently under near UV light.The Sr₃MgSi₂O₈:Br³⁺,Eu²⁺ blue phosphors were synthesized by high temperature solid-state reaction method. XRD, particle size analyzer, fluorescence spectrophotometer were employed to characterize the synthesis process, which can impact on phase composition, structure, as well as light-emitting properties. The synthesis temperature, concentration of activator Eu²⁺ ion, particle sizes of the phosphor were determined through our experiments. It was found that the blue phosphor Sr₃MgSi₂O₈:Bi³⁺,Eu²⁺ has good luminous properties, and the luminous intensity of phosphor Sr₃MgSi₂O₈:0.02Bi³⁺,0.04Eu²⁺ is 34.6 percent higher than that of phosphor Sr₃MgSi₂O₈:0.04Eu²⁺, indicating that Bi²⁺ can greatly enhance the luminous performance of the phosphor Sr₃MgSi₂O₈:0.04Eu²⁺, or that Bi³⁺ ion cansensitize Eu²⁺ ion greatly. The energy transfer mechanism is likely to be multipolar resonant energy transfer between Bi³⁺ and Eu²⁺.The Ca₈Mg(SiO₄)4Cl₂:Ce³⁺,Eu²⁺,Mn²⁺ green phosphor were also prepared by solid state reaction technique. XRD and fluorescence spectrophotometer were utilized to investigate the influence of Ce³⁺ and Eu²⁺ concentration and CaCl₂ amount on the light-emitting properties of Ca₈Mg(SiO₄)₄Cl₂ phosphors. The energy transfer between Eu²⁺ and Mn²⁺, and energy transfer between Ce³⁺ and Eu²⁺ were discussed. Three-doped Ca₈Mg(SiO₄)₄Cl₂:Ce³⁺,Eu²⁺,Mn²⁺ green phosphors were prepared, and results showed that the luminous intensity of the three-doped phosphors was much higher than those of CMSC:Eu²⁺,Mn²⁺ phosphors and CMSC:Eu²⁺ phosphors.