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Research On The Preparation And Characterization Of Aligned Carbon Nanotubes And Their Composite Film

Posted on:2005-08-23Degree:DoctorType:Dissertation
Country:ChinaCandidate:J M XuFull Text:PDF
GTID:1101360125961054Subject:Materials Physics and Chemistry
Abstract/Summary:PDF Full Text Request
The energy band structure of carbon nanotubes calculated by 1-D tight-binding model indicates that carbon nanotubes can behave either as a metal or semiconductor depending on their diameter and helicity. Electrons are bound into the one dimensional in the carbon nanotubes, that is, electrons can transport in the axial and not in the radial, it is a typical quantum confinement effect. So defect-free carbon nanotubes can be considered as ballistic conductor and their conductivity is only lower than superconductors. So, the use of its charge conductivity is the one of most goals for carbon nanotube researches. Synthesis of carbon nanotube composites with organic is one of effective ways to overcome the obstacles of the intrinsic low charge mobility of organic marterials. When a functional organic material produces charge carriers under the light, the local recombination of charge carriers is usually rather serious, which will lower the effectiveness of the devices greatly. When the carbon nanotubes-organic composite is obtained, the carbon nanotubes can efficiently draw the charges from the organic own to their high transport ability, so that to improve the capability of photo-electricity conversion. Up to now researches have been focused on the mixture of organic and carbon nanotubes and the results show that the charge transport and photo-electricity conversion ability has been improved. Most of organic materials used in these mixtures composite are polymers. Polyatomic organic, especial organic dyes, is hard to be used in this way because of their low solubility. But they are useful for organic devices because of their low price and high performance. So organic and carbon nanotubes separated double-layer device is our goal to make them as a composite. In this thesis, the aligned carbon nanotubes and common carbon nanotubes film were prepared; the composite of carbon nanotube films with organic dyes using vacuum vapor deposition were obtained and their performances were primarily studied; a high efficient way to produce carbon nanotubes was also presented.In this thesis, AAO (aluminum anodic oxide) template was prepared under acontrollable way, to control the diameter and depth of nanopore columns on AAO film. Catalyst was electro-deposited into the bottom of the pores. Carbon nanotubes can be produced from these catalysts along the pores using CVD method. So, carbon nanotubes were normal to the substrate own to the confinement of these pores. The effect of quantity of deposited cobalt on growth of the aligned carbon nanotubes was studied. The effect of shape of cobalt in the pores on the carbon nanotubes was also examined. When the condition of electro-deposition was changed, the distribution of cobalt in the bottom is changed to be several separate grains but only one. The carbon nanotubes from these catalysts were a very bamboo-shaped, with a narrow distribution of the diameter, but much smaller than that of pores.When the carbon nanotubes grew out of the pores, their alignment was lost gradually without the confinement of pores. Sonication treatment was adopted to cut the carbon nanotubes out of the template. The results showed that the top of carbon nanotubes would be shortened gradually and the aligned carbon nanotubes could be got again. Another way was used to obtain smooth surface of aligned carbon nanotubes, in which the bottom near to substrate aluminum was converted to the surface as a working face.Aligned carbon nanotubes on silicon or silicon oxide is obtained. Catalyst was deposited using radio frequency magnetic sputtering technique and grew carbon nanotubes using CVD method. The catalyst on the top and middle of carbon nanotubes was observed carefully, it is believed that the catalyst will become quasi-liquid state and the carbon nanotubes have strong capillarity phenomena in the growth. The wall of carbon nanotubes was found not to have the same orientation to their axial, and lots of linear fault in their inner wall is observed. According to these observations, a growth mechanism was p...
Keywords/Search Tags:MWNTs, Aligned MWNTs, AAO template, Composite film, CuPc
PDF Full Text Request
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