| As one of the most important rear-earth compounds, ceria has wide application in many fields, such as catalyze, sensor, photoelectricity and so on. In this work, ceria nanomaterials were synthesized by microemulsion method, microemulsion mediated hydrothermal process and solvothermal respectively. By systematically adjusting the reaction parameters, the different size and dimension of the product ceria nanomaterials could be successfully controlled. The morphology, structure, composition and optical property of the precursors and the final products have been characterized by thermo-gravimetry /differential scanning calorimeter(TG/DSC), X-ray powder diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), high resolution transmission electron microscopy(HRTEM) and ultraviolet -visible spectrum(UV-Vis) respectively.(1) In the Triton X-100+n-hexanol/ cyclohexane/water solution system of W/O microemulsion, the influences on the homogeneous region in W/O microemulsion were studied by utilizing the pseudo-triangle phase diagram. Slice-shaped cerium oxalate as the precursor was obtained from the microemulsion process by using ammonium oxalate as precipitant and Ce(NO3)3 as cerium source. Ceria nanomaterials with corresponding appearance of the precursors were obtained by calcining the precursors.(2) Ceria nanoslices and nanorods were prepared by calcining precursors with the same morphologies synthesized by microemulsion-hydrothermal method. The effects of reaction temperature, reaction time, stiring time, solvent types and surfactants on the size and dimension of nanomaterials were discussed. Nano-ceria was obtained under optimum preparation conditions. The result showed the precursors were slice-shaped when the reaction temperature was 100℃and reaction time was 1h, and the precursors were of nanorod when the reaction temperature was 160℃and reaction time was 6h. The nanoslices and nanorods of ceria were composed of ceria nanoparticles with diameters of 3-5nm.(3) Nano-spheres of cerium oxide were synthesized by template-free solvothermal method in glycol solvent with Ce(NO3)3 as raw material. The result showed reaction conditions had obviously effects on the appearance of nano-spheres of cerium oxide. The spinous microspheres of CeO2 were Synthesized under suitable reaction conditions: the reaction temperature was 140℃, the reaction time was 18h, the concentration of Ce(NO3)3 was 0.5 mol·L-1, the volume of the glycol was 30ml and the volume of water was 1ml.(4) Nano CeO2 synthesized in this work can selectively absorb UV light. It has been proved by the study that the ultraviolet-visible spectrum of nano CeO2 has the relationship with the size of the ceria nanoparticles. The blue shift of the absorption peaks and the descent of the edge of the absorption peaks are observed.
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