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Solution-synthesis And Property Studies On Bismuth Nanomaterials

Posted on:2010-12-19Degree:MasterType:Thesis
Country:ChinaCandidate:D C MaFull Text:PDF
GTID:2131330338482391Subject:Inorganic Chemistry
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Nanomaterials have unique physical, chemical and mechanical properties that are neither those of bulk materials nor those of molecular compounds. They have been exploited for their extensive potential applications in optics, electronics, magnetic, catalyst,sensing, biomedicine, etc. Bismuth provides a very attractive model system for studying physical phenomena owing to the light effective masses, long mean free path and high carrier mobility. Bismuth nanostructures have been the focus of extensive studies worldwide due to their unique applications in mesoscopic physics and fabrication of nanoscale devices.In this dissertation, the synthesis of bismuth nanorods,nanospheres and nanotubes has been explored. A newly rational low-temperature solution-synthetic route has been presented for the synthesis of metallic bismuth nanotubes. The solution-synthetic process of bismuth nanoparticles has been studied systematically to examine the processing parameters that control the morphology and purity. An aqueous chemical reduction method has been proposed to prepare nanocrystals of bismuth using hydrazine hydrate as reductive agent in alkaline medium. The effect of reaction temperature, solvent, concentration of reductive and surfactants on the formation of bismuth have been described in detail using XRD,TEM and SEM. In addition, it is observed that bismuth nanoparticles melted upon beam irradiation and gathered together. The dissertation offered a simple but very effective methodology to synthesize smaller Bi nanoparticles using TEM, varying TEM electron beam irradiation intensity produces controllable sizes of Bi nanoparticle.A synthesis approach for shape control of Bi nanostructures has been developed. Here,The dissertation demonstrated a work for selective preparation of bismuth nanospheres and nanorods reduced by hydrazine hydrate in the presence of controlling agent, Bismuth nanotubes could be also obtained by changing some reaction parameters. The size and dispersibility of Bi nanoparticles by changing the synthetic conditions such as the molar ratio of citric acid to Bi(NO3)3, Bi nanospheres with average diameter of 100nm, Bi nanorods with length of 50nm or 200nm,and Bi nanotubes with length of 100-200nm have been successfully synthesized. The dissertation also proposed the possible growth mechanism of the bismuth nanoparticles by studying the influences of different experimental conditions.The paper have demonstrated a solution-phase approach to the large-scale synthesis of Bi nanoparticles by reducing Bi(NO3)3 with hydrazine hydrate in the presence of controlling agent molecules. The controlling agent molecules in the reaction system have been found to play a key role in kinetically controlling the growth of bismuth, capping molecules serves as ligand that makes initial Bi nanoparticles grow anisotropically into nanospheres,nanorods or nanotubes.In this article, showed a relatively simple solution-synthetic approach for controlling the synthesis of bismuth nanocrystals. In contrast to organic and other methods, this approach is environment friendly and limitation of energy consume. In short, we tried to use mild method to prepare some nanomaterials which was synthesized complicatedly by conventional methods.
Keywords/Search Tags:Solution-phase synthesis, Characterization, Bismuth, Bismuth nanopheres, Bismuth nanorods, Bismuth nanotubes
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