Preparation And Fluorescence Properties Of The Green Borophosphate Phosphor

Plasma display panels (PDP) can be made in large sizes and are expected to be the best candidates for wall-mount display. Phosphors are the key materials of PDP which have been extensively applied owing to their outstanding combination of brightness, color gamut, and lifetime. Green phosphor based on borophosphates as matrix and rare earth doping shows a superior performance and has been widely studied for the higher brightness, the bigger X values of the color coordinate, the lower thermal quenching. In this paper, the RE(BO3, PO4)(RE=La, Y) green phosphor systems based on RE(BO3, PO4)(RE=La, Y) matrix, sensitized by Ce³⁺ and activated by Tb³⁺ were prepared by solid state method and sol-gel method, respectively. In order to improve the fluorescence intensity of the PDP phosphor, the green phosphor was modified by SiO2 through surface coating method. The properties and structure of the powder were analyzed by X-ray diffraction, scanning electron microscopy and energy dispersive spectrometer. The fluorescence properties of RE(BO3, PO4)(RE=La, Y) were studied by excitation spectra and emission spectra. Moreover, the influences of sintering temperature on the fluorescence properties were investigated, and experimental results indicate that the proper sintering temperature(1050℃) was determined.The results revealed that the borophosphate phosphor prepared by sol-gel method had small particle size, regular shape and higher fluorescence intensity. The crystalline structure, morphology and luminescence were influenced by the sintering temperature and time. The optimal fluorescence intensity of borophosphate phosphor sintered at 1050℃for two hours was obtained. The fluorescence intensity can be adjusted by the ratio of B, P and Ce, Tb. (La_0.6Ce_0.2Tb_0.2)2O₃·0.8P₂O₅·0.2B₂O₃ and (Y_0.5Ce_0.3Tb_0.2)2O3·0.8P₂O₅·0.3B2O3 was determined to be the most appropriate structure. In order to improve the fluorescence intensity of the phosphor, the phosphor was coated with SiO2. It found that the crystalline structure of the phosphor was not changed after being coated with SiO2. It became much smaller and more homogeneous; however, the fluorescence intensity was also reduced.