Y < Sub > 2 < / Sub > The Sio < Sub > 5 < / Sub > : Pr < Sup > 3 + < / Sup > Transformation On The Fluorescent Material Preparation And Its Performance Study

The upconversion photoluminescence materials are a kind of materials which can radiate short-wave after absorbing long-wave radiation. Upconversion materials have been widely applied in physics, chemistry and biology. In this study, sol-gel method and co-precipitation method were employed to prepare the upconversion fluorescent material and complexes. The effect factors on upconversion photoluminescence material structure and photo-degradation performances of complexes on organic pollutants were also investigated.Firstly, with the matrix material of Yttrium silicates and doping elements of trivalent praseodymium, sol-gel method and co-precipitation method were employed to prepare the upconversion fluorescent material. The effect factors of sol-gel, including water content, doping quantity of praseodymium, and calcinations temperature, on the crystal and luminous effect of upconversion material were studied. Along with the increase of the moisture content in colloid, the luminous intensity was increase; research also showed that when upconversion phosphors with1%praseodymium element and under the excitation wavelength of425nm, radiating conversion fluorescence from300nm-400nm and with the strongest fluorescence intensity, and in this case the fluorescence intensity is about5500000cps; the transition temperature of phosphor crystal type is between900℃and950℃. Furthermore, the effect factors by using co-precipitation method, including silicon contents and calcinations temperature on upconversion phosphors were also investigated. The results showed that the yttrium silicate matrix was prepared with a Y:Si ratio of2:1; the temperature of phosphor crystal type transition is between800℃and900℃.At the same time, the study found that the sol-gel method made the samples fluorescence intensity is eight times as high as coprecipitation method,Secondly, titanium dioxide and conversion phosphor powder composite photocatalyst was prepared by sol-gel method. The connections of calcinations temperature, water content and pH conditions with photocatalyst surface area were discussed in this paper. The results indicated that when the doping amount was less than5%and the temperature was between400℃and700℃, a good anatase structure could be obtained. While the pH of solution is2.5Sample heat treatment temperature of400℃and V(tetrabutyl titanate):V(water)=1:3with maximum specific surface areas of photocatalyst, and the specific surface area and pore volume of the composite materialsare227m2.g-1and0.46cm.g-1respectively.Finally, photocatalyst was employed to depredate methyl orange. The effects of the initial solution concentration, solution pH, catalyst amount, doping amount and some other factors were analysed in details. The results stated clearly that when the initial solution concentration was5mg/L, the doping amount was4%and catalyst amount was3mg/L with the highest degradation rate of methyl orange, and in this case the degradation rate of methyl orange could reach97.2%.