| Summary: | 博士 === 國立清華大學 === 材料科學工程學系 === 92 === In this work, carbon nanotubes were synthesized by a microwave plasma enhanced chemical vapor deposition system, and the extended research for the carbon nanotubes were investigated, which can be divided into two categories: “filling nanowires inside the carbon nanotubes templates” and “nitrogen doping effects of the carbon nanotubes.”
In the field of the template function for the carbon annotubes, we had successfully synthesized two kinds of materials, including Pd metal nanowires and Pd-Si alloy nanowires. Based on the selected area diffraction patterns of the transmission electron microscopy, the characteristic long period structures of the multiple-twins are revealed. The period of the twinning interfaces is about 12 times the inter-planar spacing of the (311) planes and this phenomenon is seldom reported in the academic researches. Furthermore, the carbon nanotubes template can be taken off and the defects can be effectively eliminated by the long-time etching (15 minutes) of the oxygen plasma. After this oxygen plasma treatment, the mold-free and well-crystallized Pd nanowires are obtained. As to the Pd-Si nanowires filled inside the carbon nanotubes, it is found that the concentration distribution appears gradient tendency along the axial direction of the nanowires, but not uniform through the whole nanowires. The results are quite different from the concentration distribution of the nanowires synthesized by the vapor-liquid-solid mechanism.
In the field of the doping effects on the carbon nanotubes, the results show that nanostructures, binding configurations and field emission behaviors of the carbon nanotubes are apparently changed when nitrogen atoms substitute carbon atoms.
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