| Nanomaterials has become a very important research object and has profound impacted on the development of future economy and society. In general, nano-particles are defined as tiny solid particles with size between 1nm and 100 nm. As the parcitle size approaches nanometer scale, their physical and chemical properties become quite different with brilliant application potentials.There are many methods that can be utilized to synthesis nanometarials. Generally, gas, liquid, and solid phase reactions are the three most important methods. Every method has its advantages and disadvantages. Liquid-phase synthesis is widely used to preparing nanomaterials in solvents. It contains co-precipitation, solution reduction, metal organic salt hydrolyzation, micro-emulsion, hydrothermal or solvothermal and so on. These liquid synthesis methods usually requires rigorous conditions like high temperature and high pressure and may also need expensive metalorganic salt, surfactant and so on. Some of those conditions are too rigorous and may not be easy to repeat. Another barrier for liquid synthesis is low product rate and high cost. The addition of surfactant also could have negative effect on the properties of the final product. As a result, it limits the usage and industrialization of these methods. Recently our research group demonstrated a novel method, which uses anhydrous mixed hydroxides as solvent. The reactants are inexpensive metal inorganic salts or oxides. A series of complex oxide nanomaterials with single crystal structures have been synthesized by using this method at atmosphere environment at 200℃.In this thesis, some sulphides and nickel nanostructures are synthesized by using the mixed hydroxide method. The aspects of their microstructures and some physical properties are characterized and discussed.Firstly, the CdS nanowires are obtained by using the mixed hydroxide method. XRD results and electron diffraction (ED) patterns indicate that the nanowires are single crystals with hexagonal structure. TEM results reveals that the width of CdS nanowires are typically 300-5000 nm and the length can reach several hundreds micrometers. The reaction process was studied and the mechanisms governing the growth of CdS nanowires was discussed. The infrared and fluorescence aspects of the nanowires were characterized and discussed. The electric properties of CdS nanowires were also studied and the electrical resistivity was calculated. Our results indicate that CdS nanowires have high conductance and has potential to be used as components in light battery.Secondly, the CdSe nanowires was also synthesized by using the mixed hydroxide method. XRD and ED analysis indicate that the nanowires are hexagonal CdSe single crystal. TEM results reveal that the width of CdSe nanowires is 200-500 nm and the length can reach several tens of micrometers. The reaction mechanism is also discussed and a growth mechanism is proposed.Thirdly, ZnS nanoparticles was synthesized by using this method. XRD results indicate that the products are hexagonal phase ZnS. The size of nanoparticles ranges from several tens of nanometers to 200 nanometers. The experimental results indicate that the reaction time is more important factor than reaction temperature in the determination of the final shape of the products. The fluorescence measurement indicates that there is a small blue shift of the emission band position relative to that of the bulk ZnS. The reaction mechanism was proposed.Fourthly, we synthesized Ni nanoparticles by using the mixed hydroxide method. XRD results indicate that most of the nanostructures are cubic nickel with size ranged from several tens of nanometers to 500 nanometers. It is demonstrated that the 190℃ is the best reaction temperature. The reaction process is also discussed.In summary, a systematic investigation has been conducted on the preparation, characterization, and growth mechanism of CdS, CdSe, ZnS, and Ni nanoparticles. Some important and novel experimental results have been obtained. |
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