Experimental Study On Nanometer Zinc Oxide Prepared By Sol-gel

Nano ZnO, the particle size between 1 and 100 nm, is a kind of widely used and high added value inorganic function material. Because of its special properties, it is widely used in gas sensors, image recording material, conductive material, piezoelectric materials, piezoelectricity resistance, magnetic materials, UV radiation shielding materials, efficient catalysts, photo catalyst etc.Based on the reference of numerous literatures domestic and abroad, the basic principle and application of nano ZnO powder prepared by sol-gel are emphasized in the paper. Firstly, through to the comparative research of the systems with CH3(CH2)16COOH, C6H8O7?2H2O, and (COOH)2?2H2O as the three different complexing agents, the sol-gel method should be used to produce the ZnO with the Zn(Ac)2?2H2O as the precursor, (COOH)2?2H2O as the complexing agent, PEG-400 and (NH4)3C6H5O7 as the modifier, C2H5OH as the solvent. The experimental schemes are optimized by the orthogonal methods and the influencing factors to the experiment are discussed. At the same time, the surface modification process is optimized according to the settling rate. At last, the ZnO powder was characterized by TGA, AFM, XRD and UV-Vis light absorption spectrum.The appropriate conditions for preparing nano ZnO can be concluded from the experiment and listed as follows: the reaction temperature is 80℃, the reaction period is 2h, the mole ratio of (COOH)2?2H2O to Zn(Ac)2?2H2O is 3:1, the concentration of Zn(Ac)2?2H2O solution is 0.6mol/l, the pH is 6, Zn(Ac)2?2H2O solution is slowly distributed to (COOH)2?2H2O solution, calcinations time is 3h, calcinations temperature is 600℃. The proper surface modification condition for nano ZnO is that, the mass ratio of (NH4)3C6H5O7 to Zn(Ac)2?2H2O is 0.05:1, the surface modification time is 1.5h, the stirring speed is 1800 r/m with the (NH4)3C6H5O7 as the surface modifier.Through to the TGA analysis of the precursor and xerogel, it is proved that the final product is ZnO and the calcination temperature should be higher than 440℃. According to the results of the UV-Vis light absorbing capability of the nano ZnO ethanol solution, it is found that ultraviolet can be absorbed effectively, the transmittance can not be absorbed easily in the visible light wave band. Also, the UV-shielding capacity of nano ZnO modified by surface modifiers is better than the one which is not. At the same time, when the concentration of nano ZnO ethanol solution is in the proper range, the higher the concentration is, the better its UV-shielding capacity, but its transmittance will decrease relevantly.According to the XRD (X-ray Diffraction) results, it is concluded that the product is hexagonal wurtzite structure ZnO with fine crystallization and high purity, the particle average size is 34nm. The AFM(Atomic Force Microscopy) examination to the surface and the particle size of ZnO shows that the specimen particle size is bigger than the results concluded from the XRD analysis, which is caused by the reunion because of the poor dispersion of the ZnO ethanol solution.