| Summary: | 碩士 === 國立高雄應用科技大學 === 電子工程系 === 100 === Nowadays, field emission displays (FEDs) have attracted much attention in the technologies of flat panel displays. The luminous efficiency of phosphor determines the performance of FED. Therefore, development of a high efficient low-voltage phosphor has become an important issue for FEDs. Among the materials of phosphors, LaPO4 has two major advantages, which are high insolubility and stability against high temperatures. It has been widely used in the field of plasma display panel (PDP), mercury-free lamp and visible lasers, but it has not been application on FEDs. Coprecipitation method can produce a high yield for phosphor preparation with no expensive equipment. That is the reason why this theme attempts to use this method to synthesize reddish-orange LaPO4:Eu3+ phosphor, which can reduce the costs of FED.
There are three subjects in this thesis: (1) the preparation parameters of doping concentration, sintering temperature, and sintering time were optimized in order to achieve high efficiency of La1-xPO4:xEu phosphor; (2) the influence of raw materials on the characteristic of phosphor was investigated and discussed; (3) surfactant SDS and dispersant (NaPO3)6 were added and the coprecipitation method was used to modify the surface property of particles in order to improve the luminescence properties of the phosphor, in addition, high conductivity of carbon nanotubes (CNTs) was used to enhance the cathodoluminescence (CL) intensity of LaPO4:Eu3+ phosphor.
LaPO4:Eu3+ phosphor is synthesized by coprecipitation method in this theme, which shows reddish-orange emission at wavelength of 594 nm (5D0→7F1) under the excitation at wavelength of 396 nm. The maximum luminescence intensity of LaPO4:Eu3+ phosphor was prepared with the conditions of Eu3+ concentration 7 mol%, sintering temperature 1200°C, and sintering time 2 hours, in which the strongest radiation peak is at 594 nm. In addition, the properties of phosphor prepared with different raw materials were measured and discussed. It shows that the best purity of reddish-orange emission was obtained when (NH4)2HPO4 was used. Furthermore, surface modification was executed, which can effectively enhance the luminescence properties of phosphors. Comparison with the commercial reddish-orange phosphor, the luminescence properties of the as-prepared phosphors is better than that of the commercial phosphor. Moreover, this research confirms that adding CNT does enhance the cathodoluminescence (CL ) intensity of phosphor.
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