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Synthesis, characterization and properties of nano-sized transition metal oxides

Posted on:2006-09-05Degree:Ph.DType:Thesis
University:Columbia UniversityCandidate:Yin, MingFull Text:PDF
GTID:2451390008454649Subject:Engineering
Abstract/Summary:
Chapter 1. A General introduction to the emerging field of nanomaterials is presented highlighting the category of transition metal oxides. The wide variety of structures, properties, and phenomena of transition metal oxides are stressed. Nano-sized transition metal oxides are presented as systems for fundamental and application research. Examples of individual transition metal oxides are provided. Important developments in the synthesis and characterization of nano-sized transition metal oxides that have contributed to this work are reviewed. A novel synthesis (TDMA) is developed and successfully applied to the synthesis of transition metal oxide nanocrystals.; Chapter 2. The synthesis of monodisperse cubic wuestite FexO nanocrystals is presented. The influence of reaction temperature and the molar ratio of surfactant to iron precursor was investigated, in order to further understand the ability to control particle size and monodispersity. In contrast to bulk material, it is also found that the nano-sized ligand-capped wuestite FexO particles were stable at room temperature. The procedure enable the collection of highly monodisperse nanocrystals of variable and uniform diameters as a function of time. Sharp Hancock analysis indicates that the reaction proceeds by a diffusion limited mechanism.; Routes to control the size of gamma-Fe2O3 nanocrystals are also presented. gamma-Fe2O3 nanocrystals from 6 nm to 12 nm in diameter with uniform size, shape, consistent crystal structure were prepared.; Chapter 3. A simple reaction to prepare monodisperse MnO nanocrystals is presented. MnO nanocrystals was prepared by thermal decomposition of manganese acetate in the presence of oleic acid at high temperature and by following annealing. Particles with different sizes and shapes were obtained by controlling annealing time. The morphology of MnO nanocrystals was studied based on their crystal structure and surface energy. SQUID measurement shows ferromagnetic magnetism at low temperature.; Chapter 4. Nanosized Copper (I) oxide particles have been prepared by a thereto decomposition of Cu (I) acetate in the presence of oleic acid at high temperature. Nanoparticles from 3.6 net to 10.7 nm could be synthesized by increasing the stoichiometric ratio of surfactant to copper precursor.; Chapter 5. Nano-sized ZnO rods are prepared from a simple acetate precursor. The resulting ZnO nanorods are highly crystalline, uniform and with a narrow size distribution, which facilitates the understanding of the optical properties of nanosized ZnO. (Abstract shortened by UMI.)...
Keywords/Search Tags:Transition metal oxides, Synthesis, Presented, Nanocrystals
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