| White LED has attracted a great deal of attention especially for general lighting, due to its low power consumption, long life, environment friendly and reliability. Phosphor is one of the key materials for white LED, and its fluorescence spectra can determine the luminance, Color Rendering Index (CRI), colour temperature and luminous efficacy.In this dissertation, Ca2MgSi2O7:Eu2+, R3+(R=Ce3+, Y3+, Pr3+, Gd3+) and Sr4Si3O8Cl4: Eu2+ phosphors were synthesized by the high-temperature solid state reaction method. The crystallization phase structure and the lumenscent properties of the samples were characterized by X-ray diffraction and spectrometer.Alkaline earth silicate Ca2MgSi2O7:Eu2+ phosphors were prepared under a reducing atmosphere by solid-state reaction using CaCl2 as flux medium and starting materials. Phosphors prepared with different CaCO3 amount, at different temperatures and time were obtained. The effect of these factors on the phase structure was studied by X-ray diffraction (XRD). The synthetic conditions were optimized at the molar ratio of starting materials CaCO3, Mg(OH)2, SiO2, CaCl2 equal to 1.5:1:2:2.4, sintering temperature 900℃and soaking time 3 h. The fluorescence spectra of the as-prepared phosphor powders were measured. The results indicated that the Ca2MgSi2O7:Eu2+ phosphor can be effectively excited by the light in the wavelength range of 360nm～480nm and emission spectrum shows a broad green emission band centered at 529nm, leading to a bright green emission. The Ca2MgSi2O7:Eu2+ phosphors were also synthesized at 1200℃for 4 h in a reducing atmosphere using H3BO3as flux medium and CaCO3, Mg(OH)2, SiO2 as starting materials. Comparing the high temperature method with low temperature methods, we found that their exitaiton spectrum profiles were different, and the emission intensity of Ca2MgSi2O7:xEu2+(x=0.01,0.02,0.03, 0.04,0.07) phosphor prepared at 900℃was higher than those prepared at 1200℃. The doping of Ce3+ or Y3+ can enhance the fluorescent intensity of Ca2MgSi207:Eu2+ phosphors. These results showed that co-doping with Ce3+ can enhance the fluorescent intensity due to the energy transfer process from Ce3+ to Eu2+ in Ca2MgSi2O7:Eu2+, Ce3+ phosphors, and that co-doping with the Y3+ can increase the fluorescent intensity because of the charge defects resulting from the co-doping Y3+ ion in Ca2MgSi2O7:Eu2+, Y3+ phosphors.Sr4Si3O8Cl4:Eu2+ phosphors were also synthesized by the solid-reaction at high temperature. The emission intensity reaches a maximum at 0.08 of Eu2+ concentration. The effects of Zn2+ on the crystallization behavior and photoluminescence (PL) properties of Sr4Si3O8Cl4:0.08Eu2+ phosphor were studied. Results suggested that no new phase was introduced by co-doping with a small amount of Zn2+ ions, but when co-doped with excessive amount of Zn2+ ions, Sr2ZnSi2O7 appearsed. It was found that the co-doping of a small amount of Zn2+ could remarkably improve the PL intensity of Sr4Si3O8Cl4:0.08Eu2+ When x=0.05, the intensity of Sr4Si3O8Cl4:0.08Eu2+,xZn2+ was increased up to 2.3 times that of pure Sr4Si3O8Cl4:0.08Eu2+, which could be attributed to the flux effect of Zn2+ ions, and the reduction of energy transfer between Eu2+ by Zn2+ doping. Sr4Si3O8Cl4:Eu3+ phosphor can be effectively excited by the 266nm,405nm,464nm light, and its emission spectrum mainly center at 615nm. Doping of Bi3+ can enhance the fluorescence intensity of :Eu3+ phosphors because of the energy transfer between Bi3+ and Eu3+.
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