| White light emitting diode(LED) is recognized as the fourth-generation light source because of its energy saving, long life, fast response, small volume, planar packaging and many other advantages. The main scheme to implement white LED is phosphor converting at present, however, the red phosphor is inefficient and unstable, which limit the high CRI white LED development, therefore, the study of red phosphor which has high efficiency and fit for the near ultraviolet chip become very important. This thesis mainly researched the red phosphor fitting near UV chips, and Sr2MgWO6:Eu, Sr2CaMO6:Eu, Sr3WO6:Eu three systems red phosphors were synthesized via a simple sol-gel method.(1) Firstly, the fluorescent performance of Sr2CaMO6:Eu was investigated through experiments. The relationship between the concentration of activator and luminescence performance was explored. The influence of the introduction of Sm3+ ions and charge compensation on the luminescence performance were also studied. The result reveals that Sr2-2xMgWO6:2x Eu performs best when x equal to 0.1, Sm3+ ions can work as efficient sensitizer in Sr2MgWO6: Eu system, the introduction of Sm3+ ions not only can broaden the excitation spectrum of the near UV region, but also can significantly increase the emission intensity without the characteristic emission spectrum from Sm3+ ions, and The use of Li+ ions do the charge compensation can get the best effect, the emission intensity is about seven times than do not do charge compensation, and the color purity is up to 98.4%, the color coordinates is(0.66, 0.33), whitch is very close to the NTSC standard value(0.67, 0.33). In addition, the Sr2MgWO6:Eu system red phosphor can be get higher emission intensity under 465 nm light, indicating that this system phosphor also suite to apply in blue chips.(2) Secondly, the fluorescent proterty of Sr2CaMO6:Eu was studied through experiments. Its excitation spectrum excellently matched with near UV chip, the charge transfer band cover the near UV region field and its peak value stands at ~400nm. The experimental result shows that the fluorescent properties of Sr2-2xCaMoO6:2x Eu performs best when the centration of activator is x = 0.04, and the use of Li+, Na+, K+ can improve fluorescent properties, however, Li+, Na+ contribute more on improving the purity of phosphors, and the use of W and Mo as doping rescource can obviously increase the fluorescence properties and electric dipole transition 5D0-7F2 of emission intensity, when W/Mo = 1:1, the overall fluorescence property can get best performance, what is more, the introduction of W in Sr2CaMoO6:Eu system can improve the regularity of the morphology of phosphor.(3) Finally, the fluorescent performance of Sr3WO6:Eu was investigated through experiments. The material has high intensity in near UV region and its emission efficiency and color purity are also very high. The Sr3WO6:Eu is a kind of high-quality red phosphor using in near UV chip. The experimental result reveals that the the overall effect of Sr3-xWO6: x Eu is the best when x is equal to 0.3, and Sm3+ ions can not behave as well sensitizer in this system, and K+ ions is a high-quality charge compensation agent, K+ can performe as well charge compensation, Also the use of K+ can improve the fluorescent performance and the preparation of samples have high color purity, the color coordinates is(0.655, 0.655). |
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