Preparation Of Supferfine CeO₂ By Wet Solid Phase Mechanochemical Method

Because of the various functional characteristics about the typical rare earth oxide CeO₂. such as electronical pottery, glass of polishing, anti-radialization,illuminant material and so on. Recently, the preparation and the performance investigation is crying for solve.In this thesis, the performance of rare earth oxides and preparation by precursor, solid state reaction in low temperature and mechanochemcial have been realized. To overcome the existing troubles and limitations of preparing rare earth oxides, the solid state reaction in low temperature is combined with precursor and mechanochemcial method. The granularity, appearance and phase have been analyzed by DSC, XRD and SEM. The mechanism of wet solid phase mechanochemical method has been discussed and the technical parameters of the wet solid phase mechanochemical method compared.During the experimental investigation, the precursor of Cerium oxide were selected and prepared by wet solid phase mechanochemical method, in which the chemical reaction of H₂C₂O₄·H₂O and CeCl₃·7 H₂O happened. According to the analysis of DSC, the precursor was decomposed in 400℃for 2 hours, then a lot of high quality superfine particles of ceria has been obtained. Compared to the handwork grinding during reaction of wet solid phase, the mechanochemical method will enlarge the function of cutting power. As a result, the pervasion speed and the reaction velocity were increased, the dynamic and thermodynamic conditions of multiphase chemical reaction in the low temperature solid-state reaction were improved, then the low temperature solid-state reaction was facilitated. So, the smaller precursor and product were obtained. When decomposed into ceria particles, the precursor burst apart from～510nm to～300nm because of the gas come into being and expand.Grinding time, inverse proportion of ball and material, ratio of filling, decomposing time directly influence the granularity, shape and appearance of ceria particles. According to the experimentation results, the appropriate process parameters have been optimized. The optimal process are: wet solid phase mechanochemical method, using the dispersant NaCl, inverse proportion15∶1 of ball and material, 2.5h of grinding time, 40% ratio of filling, calcining in 400℃for 2 hours. Then, the uniform ceria particles, which have a better decentralization, a near spherical shape, and a granularity of about 300nm, have been prepared.Because of a lower decomposition temperature of precursor, i.e. decomposing in 400℃into rare earth oxides, the producing cost will be reduced. In the meant time, avoiding using solvent, wet solid phase mechanochemical method can reduce raw materials and subsidiary products. And environment pollution can be decreased or avoided. So, wet solid phase mechanochemical method is simple, easy, and economic, environment-friend, with which nanometer rare earth oxides can be prepared, and has a bright industrialization foreground.