Solution-based Preparation Of Low-melting Point Metal And Their Sulphide Nanomaterials

Both solution-based"Top-down"and"Bottom-up"approaches have been successfully used to synthesize low-melting point metal from metal powders or acetates, and the synthesis mechanism are also discussed. The morphology and size of the product could be controlled by tuning the experiment parameters, and flower-like indium nanoparticles and monodispersed sulfide hollow spheres are prepared.The thesis mainly includes three parts:1. In poly-glycol, monodisperse spherical colloids of Cd, Pb, Bi were synthesized from "Top-down" or "Bottom-up" approach using PVP as the stabilizer, and the diameter of the spheres could be controlled by simply modified the magnetic stirring rates for the "Top-down" approach or the concentration of metal acetate for the "Bottom-up" approach. The samples were investigated by TEM, SEM, XRD and TG/DTA. Results indicate that the as-synthesized products have the same structure as their bulk metal.2. Uniform CdS, PbS hollow sphericals have been successfully synthesized by using Cd, Pb monodisperse colloidal spheres and thioacetamide (TAA) as precursor through a hydrothermal process. We could obtain different morphology and structure samples by easily adjusting the reaction time or temperature. The as-prepared products were characterized by means of TEM, SEM, XRD and PL. The possible mechanisms for the growth of these hollow nanostructures under hydrothermal reaction are tentatively proposed.3. In the mixed polyol system, BiIn alloy nanocrystals have been prepared by a solution dispersion method using PVP as surfactants. The morphology of the nanocrystals could be controlled by adjusting the concentration of PVP in the system. And the morphology and structure of the sample were studied by TEM, XRD and TG/DTA, respectively. Meanwhile, the tribological properties of the as-prepared nanocrystals as lubricating additives in oil were discussed. Results showed that BiIn alloy nanocrystals are good lubricating additive. In mixed polyol, the ultrasonic-assisted process has been used to prepare flower-like indium nanocrystals. We also use TEM, XRD, TG/DTA and four-ball machine to study their morphology, structure and tribological properties. TEM and XRD studies indicate that the flower-like samples are built from nanorods and nanopeatals, and have the same crystal structure of bulk indium. Because of the large surface area of such a structure, these indium nanocrystals would be more stabile in solvent which allowed them more comfortable using as oil additives. The tribological test indicated that these indium nanostructures show good friction reduction and antiwear properties.