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|Title: ||Fabrication and characterization of 1D oxide nanostructures|
|Authors: ||Jin, Kewang|
|Issue Date: ||2005 |
|Abstract: ||One-dimensional nanostructures such as nanowires (NWs) and nanotubes (NTs) have attracted extensive interest in view of their interesting electronic and optical properties for applications in nanoelectronic and nanophotonic devices. In this study, a systematic fabrication and investigation of the formation of 1D oxide nanostructures (TiO2 and SiO2 nanostructures) was carried out.
Transmission electron microscopy (TEM) observation showed that TiO2 nanostructures synthesized via a simple hydrothermal chemical process were very sensitive to the growth temperature, i.e., lower-temperature growth (100℃-180°C) produces nanotubes, while higher-temperature growth (185°C-220℃) results in nanowires. High-resolution TEM study showed that TiO2 nanostructures formed from nanosheets combined with further one-dimensional growth. Unlike the multi-walled carbon nanotubes, TiO2 nanotube walls were not seamless. The formation mechanism of these nanostructures were proposed and discussed. The optical properties of TiO2 nanomaterials were also investigated. Random laser action was first observed in TiO2 NWs although it needs to be further verified.
Highly-ordered SiO2 NW arrays were fabricated inside the pores of porous anodic aluminum oxide (AAO) templates using a simple sol-gel method at different aging conditions. High-resolution TEM investigation showed that the structure of silica NWs was very sensitive to the template structure and the aging environment. For the samples aged with the presence of water, all the nanochannels in the silica NWs were found to be circular around the NW axes. However, for those samples aged without water, most silica NWs have a tube-like structure due to the confinement effect of the AAO pore walls. Those tube-like silica NWs formed in large AAO pores generally consist of a core (hexagonally arranged nanochannels parallel to the NW axis) wrapped by shells. The formation mechanism for these novel structures of mesoporous silica NWs were proposed and discussed.|
|Description: ||Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005|
xii, 78 leaves : ill. ; 30 cm
HKUST Call Number: Thesis PHYS 2005 Jin
|Appears in Collections:||PHYS Master Theses |
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