Study On Properties Of Y（P, W） O₄: Eu Red Phosphors For White LED

White LED with the low color temperature and high color rendering index is the trend of development of white LED lighting in this days. The methods currently to made the white LED is using the blue LED chips and yellow phosphor mixed to produce white light. However, due to lack of a red component in its emission, therefore, the luminous efficiency and color rendering index of white LED is not high. Adding red phosphor can significantly improve the efficiency of white LED light and color rendering index. Currently commercial red phosphors for white LED are mainly silicates and nitride/nitrogen oxide system. But the white LED use silicate red phosphor can not show the high color rendering index because of its orange light emitting. The preparation of nitride red phosphor is complex, often require high temperature and high pressure, it also has strict requirements about the raw material and with a high price. All of this have affected its promotion and application. Therefore, Development the red phosphors which can be efficiently excited by blue chip is the key technology for white LED. Tungstate and phosphate is a good matrix material, we use high-temperature solid reaction to prepared series Y（P, W） O₄: Eu red phosphors and study the effects of different matrix composition, different activator concentration, Gd replaced as well as the influence of different flux added to the material structure and luminescence properties.The products were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, particle size distribution, stimulate analysis and emission spectra.Experimental results show that: the Y（P, W） O₄: Eu samples prepared by high solid reaction has a good luminescent performance in the blue light-emitting excitation, its emission is a narrow-band emission peaking at around 615 nm, it also have high brightness and good color purity. By adjusting the P/W ratio, it is possible to improve the emission luminance of the sample. When Eu³⁺ concentration was 0.15, the sample has the maximum luminous intensity.With the continued increase of Eu³⁺ concentration, there are a significant concentration quenching phenomenon.The phase composition and the light emitting brightness of the（YxGd1-x）(P_0.5W_0.5) O₄: 0.15 Eu sample have changing with Y³⁺/Gd³⁺ changes and different. When Y³⁺/Gd³⁺=7:3, the sample have the maximum luminous intensity, the strongest emission peak at 611.5nm, corresponding to the 5D0â†'7F2 electric dipole transition of Eu³⁺. Different flux added to the sample has a different effect on the degree of crystallization of samples. Adding the flux of NH₄NO₃ at a concentration of 3%（mass fraction）, the emission spectrum of the sample reached the highest peak intensity and brightness up, the sample also have moderate phosphor particle size and uniform particle size distribution. Too much flux will affect the luminous flux properties of the material.