| There is a research interest in high quality monodisperse magnetic nanoparticles and nanocomposites in recent years driven by their broad technological ramifications. A new approach is proposed in this thesis to synthesize transition metal-containing core-shell nanoparticles including Pt Fe2O3, CoPt3 Fe2O3, and SmCo5 Fe2O3. The core-shell nanoparticles can be converted into high magneto-crystalline compounds through a reduction and alloy formation process at enhanced temperature. By controlling the synthetic condition, the magnetic property of the products can be tuned. Through this approach, magnetic FePt and CoFePt nanoparticles were synthesized and FePt-containing nanocomposites were also obtained. These nanomaterials are important to the practical applications in ultrahigh density data storage and magnetic nano device. At last, the oxidation-resistant property of SmCo5 Fe 2O3 core-shell nanoparticles was also studied.; Magnetic nanoparticles of metal oxide, such as iron oxide, are particularly useful in various magnetic and biological applications. By changing the surfactant, reaction time and seed, monodisperse gamma-Fe2O3 nanoparticles were synthesized with diameters range from 3 nm to 25 nm. The shape evolution of those particles was also studied.; Shape and size also play important roles in the catalytic properties of platinum nanoparticles. In this thesis, a systemic study of the synthesis and electrocatalytic property of Pt and Pt alloy nanostructures was presented. Effect of surfactants, reaction temperature and heterogeneous species on shape and compositions control of the final products was studied. The effect of size and shapes of platinum-containing cubic, spherical, porous nanoparticles on the electrocatalytic property was investigated using direct methanol oxidation as the model reaction. |
