Preparation And Characterization Of Aligned Carbon Nanotubes By Chemical Vapour Deposition

Because of their unique mechanical and electronic properties, Aligned carbon nanotubes (ACNTs) are considered to have important and universal applications, such as in nanocomposite materials and nanoelectronic devices. The studies on preparation, properties and applications of ACNTs have been developed rapidly. The method used often have complex process and some limitations, so it needs to explore a more common and efficient preparation method.In this thesis, the ACNTs were prepared by chemical vapour deposition (CVD) method. The Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) were used to study the effects of temperature, the catalytic precursor concentrations and spraying time on the morphology and structure of the product obtained from the CVD reaction.The experimental results presented that the temperature had the important effect on the morphology of the product. If the reaction temperature is 840℃, the well-aligned CNTs can be formed, having less carbon particles and their hight is about 30μm. If the reaction temperature is 860℃, the product is mainly of carbon particals having less carbon nanotubes. If the reaction temperature is 820℃, the CNTs in the product do not align very well, i.e., they grow in a snaky way. When the concentration of the catalyst precursor was 5wt%, the well-aligned CNTs were formed. If the concentration was 7.0%, aligned CNTs were formed. If the concentration was 3.0%, the product is mainly of particles. The experimental results also presented that the longer spraying time is the much the quantity of the product is, but having little effect on the morphology of the product. TEM measurements reveals that the outer diameters of the nanotubes vary over the range of 10-30nm, the inner diameter is ca. several nm. One thick nanotube is filled with transitional metal catalyst.