A Study On The Ultrasonic Preparation Of Nanocrystalline Zinc Oxide And Titania

The preparation and application of nanomaterials have attracted much attention for both fundamental and technological reasons in recent years. Many methods have been developed to prepare nano-materials, among which sonochemical method has been proved to be a simple and efficient technical for preparing nanomaterials with excellent performance.This thesis includes the following five chapters:In the first chapter, the discovery, definition, a series of especial properties and leading preparation methods of nanomaterials are summarized briefly. According to the basic theories of sonochemical preparation of nanomaterials, the preparation methods and application of sonochemisty are introduced.In the second chapter, the primary analysis methods of nanomaterials, such as X-ray Diffraction (XRD), Transmission Electron Microscope (TEM), Photoacoustic Spectroscopy (PAS) and Photoluminescence (PL) are introduced. The background, basic principle, development, application of the PAS techcique is mainly reviewed.In the third chapter, the mechanism of the sol-gel process and the influence of the ultrasonic irradiation are mainly studied. The nanocrystalline Ho-doped TiO2particles with good dispersibility and stability are prepared. We analyzed the composition and structure of the TiO2samples with heat treatment at different temperatures by XRD. Moreover, sizes and micromechanism of samples are represented by TEM. At last, the Ho-doped influence to the TiO2lattice and its phase transition during the heat treatment are studied.In the fourth chapter, ZnO nanorods have been prepared in an ionic liquid,1-buty1-3-meyhylimidazolium tetrafluoroborate, via ultrasonic irradiation. The method is simple, fast.For comparison, ZnO nanomatials have been prepared in triethylene glycol. A possible mechanism is proposed to explain the formation of ZnO nanostructures, and a reaction model is also established. The influence of the ionic liquid to the growth of ZnO is mainly discussed. Additionally, the Eu-doped ZnO has been prepared via ultrasonic irradiation with ionic liquid as solvent and DEA as alkaline reactant. From PL spectra of ZnO, we analyzed its emission mechanism. Finally, the growth mechanism of ZnO under the combined effect of the ionic liquid and diethanolamine is discussed.In the last chapter, the work is summarized.