Study On Preparation,Microanalysis And Application Of Metal Oxides Semiconductor Materials

In this thesis, some relevant problems of diluted magnetic semiconductor (DMS) ZnO and nano-TiO2 photocatalyst material were mainly studied by the surface micro-analysis methods. The aim is twofold. The former is to find the relationship between the preparation conditions and material composition, microstructure, morphology, performance and application. The latter is to investigate the effect the carrier and magnetic field on the photocatalytic properties nano-TiO2. Moreover, the cationic polyacrylamide/TiO2 composite flocculant were also prepared, which displays some practical application prospect. The whole paper consists of the following six chapters.Chapterâ… . In this chapter, the photocatalytic properties and diluted magnetic specialities of functional metal-oxide semiconductor materials are summarized. Meanwhile, the relevant preparation methods, the current research progress and micro-area analysis techniques were introduced.Chapterâ…¡. In this chapter we studied doped elements on zinc oxide-based diluted magnetic semiconductor crystal growth for the preparation and microanalysis. Mainly, different transition metal(TM) doped ZnO-based diluted magnetic semiconductor (ZnO-DMS) crystals were synthesized by hydrothermal method. Then the morphology and the relative content and distribution uniformity of the surface and inner TM element of synthesizing crystals were investigated by the scanning electron microscope (SEM) and x-ray energy dispersive spectrometry(XREDS), respectively. The studies show that the effect of different doped-TMed on the growth, size and morphology of ZnO crystal. In addition, it is found that the exposed face also changed with crystal morphology. Furthermore, the X-ray micro-analysis confirmed that the doped-ions distributed homogeneously in crystal surface and crystal inner, relatively. These result showed that the ions of Co and Mn were easier doping than Fe and Ni. Meanwhile, the morphologic effect of In and TM codoping ZnO crystals on polarity growth was also studied and as result, the mechanism and the relevant factors affected the crystal growth were discussed by hydrothermal theory.Chapterâ…¢. The preparation, microstructure and properties of nano-titanium dioxide (TiO2) are presented. This chapter included two parts. In the first section, uniform anatase nano-TiO2 thin films were prepared by using sol-gel method on the ordinary glass. The microstructure and transmission rate of thin film were investigated by scanning probe microscope(SPM). The study showed that the prepared thin films were with uniformly convex anatase nano-TiO2. On the basis of analysis, the relationship between the photocatalytic properties and microstructure were discussed. In the second section, the main comparison of microstructure and photocatalytic properties of nano-TiO2 powders prepared by three different liquid wet chemical methods(i.e.,sol-gel, liquid deposition and Hydrothermal) are made. The relation between the microstructure and the photocatalytic property has been studied. Correspondingly, the reasons of different photocatalytic activity have been discussed from the crystal surface crystallinity, lattice defects, as well as the distribution of surface hydroxyl on TiO2 surface.Chapterâ…£. The investigations are focused on the microanalysis of fly ash for loading nano-TiO2 layer and its application. At first, Fly ash was separated by water and magnetism methods, and then their phase composition, microstructure and x-ray microanalysis were studied by XRD, SEM and EDS. The microstructure properties of fly ash have been understood, which provided useful information for the development and utilization of fly ash. In terms of this, the surface of fly ash particle was loaded nano-TiO2 film by sol-gel method, and then the relationship between the photocatalytic degradation performance and carrier effect are discussed.Chapterâ…¤. The effect of nano-TiO2 photocatalytic capability under magnetic field condition is performed in order to improve nano-TiO2 photocatalytic properties. In this chapter, the effect of different magnetic field strength and values of the pH on nano-TiO2 photocatalytic degradation performance was studied. The results showed that the magnetic field had the significant effects on its photocatalysis property. Meanwhile, the mechanism was also discussed.Chapterâ…¥. The nano-TiO2 particles are applied to composite flocculant material. In this chapter, the nano-TiO2 is treated with appropriate surfactant, and then the new cationic polyacrylamide P(DMC-AM)/TiO2 composite flocculant was synthesized. The results show that, P(DMC-AM)/TiO2 composite flocculant have the best decoloring performance and important practical application. In detail, the decolorization rate of can reach in 95% at 1.5h.