|Title:||The fabrication and characterization of BiFeO₃nanotubes|
|Subject:||Hong Kong Polytechnic University -- Dissertations|
|Department:||Department of Applied Physics|
|Pages:||75 leaves : ill. ; 31 cm.|
|Abstract:||Bismuth ferrite (BiFeO₃) nanotubes were fabricated using the sol-gel nano-channel alumina (NCA) template method. The resulting nanotubes were about 60 μm in length and 200 nm in diameter. Different fabrication parameters were applied systematically to different BiFeO₃samples in order to assess the influence of the most effective parameters on the crystallization of the nanotubes. Extended crystallization, accompanied by reduction in second-phases within the nanotubes was the main goal of the studies. The parameters used in the fabrication of the nanotubes, included: different annealing temperatures, different annealing temperatures times, template thickness, precursor solution concentration and composition. The characterization of the structure, microstructure and local composition of the nanotubes were carried out using transmission electron microscopy (TEM) and X-ray energy dispersive microanalysis (EDS). Scanning electron microscopy (SEM) was used extensively to study the morphology of the resulting nanotubes. Investigations showed that the majority of the individual nanotubes were multi-phase, non-stoichiometric polycrystalline structure and primarily composed of numerous nano-particles imbedded within each nanotube. It was established that the major parameters that influenced the crystallization of the nanotubes or the nano-particles embedded within the nanotubes, were the annealing time, as well as the concentration of the precursor solution. In addition, the crystallization of the nanotubes was markedly dependent on the annealing temperature applied to the nanotubes. Higher solution concentration was the secondary factor that influenced the crystallization of the nanotubes. The Piezo-Force Microscopy (PFM) technique was used to measure the properties of the nanotubes with very limited success. Using PFM, major difficulties were encountered in measuring the electrical properties of the nanotubes accurately. The difficulty was attributed mainly to excessively small tube size, as well as the inability to adhere proper electrical contacts to a nanotube. Isolating an individual and complete nanotube from the template proved extremely difficult.|
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