Nanotube growth

Key Words—Carbon nanotubes, vapor-grown carbon fibers, high-resolution transmission electron microscope, graphite structure, nanotube growth mechanism, toroidal network. 

Determination of the structure of nanotubes is crucial for two reasons (1) to aid understanding the nanotube growth mechanism and (2) to anticipate whether intercalation can occur. Of the two models, only the paper roll structure can be intercalated. 

Electron irradiation (100 keV) of the sample, heated to 800°C, yields MWCNTs (20-100 nm in length) attached to the surface. Such nanotube growth does not take place if natural graphite, carbon nanoparticles or PTFE are subjected to electron irradiation. The result implies that the material may be a unique precursor for CNTs and may constitute a new preparation method. 

Lin M et al. (2006). Direct observation of single-walled carbon nanotube growth at the atomistic scale. Nano. Lett. 6(3) 449 452. 

Recently, carbon nanotubes, an important class of one-dimensional nanostructures, have been fabricated within the pores of anodic alumina via CVD (Davydov et al, 1999 Li et al, 1999 Iwasaki et al., 1999 Suh et al, 1999). A small amount of metal (e.g., Co) is first electrochemically deposited on the bottom of the pores as a catalyst for the carbon nanotube growth, and the template is heated to 700 to 800°C in a flowing gas mixture of N2 and acetylene or ethylene. The hydrocarbon molecules are then pyrolyzed to... 

Iwasaki, T., Motoi, T., and Den, T., Mutiwalled carbon nanotubes growth in anodic alumina nanoholes. Appl. Phys Lett 75,2044 (1999). 

As authors supposed from the generally accepted concepts of mechanisms of carbon nanotube growth, the dispersed nickel sputtered must catalyze the growth of these nanotubes. The source for carbon should be carbon from the hydrocarbon that transforms into the vaporous state in the arc zone. It has been supposed to prepare single-wall nanotubes on the nickel particles 1-10 nm in size and the layer of nanotubes up to 1 pm thick on the larger nickel particles. 

B) Yudasaka, M. Kikuchi. R. Ohki, Y. Yoshimura, S. Nitrogen-containing carbon nanotube growth from Ni-phthalocyanine by chemical vapor deposition Carbon 1997, 35, 195. 

Pinheiro et al. (2002) C, Co-alumina Phase growth Phase distinction between CNT and whiskers + + + Carbon nanotube growth... 

Dikonimos Makris, T., Giorgi, R., Lisi, N., Pilloni, L., Salemitano, E., Sarto, F. and Alvisi, M. (2004), Carbon nanotubes growth by HFCVD Effect of the process parameters and catalyst preparation. Diam. Relat. Mater., 13(2) 305-310. 

The formation of either of two morphologically different types of graphite crystallites depends on the diameter of the Co particles. The graphite crust that forms over the coarse cobalt particles causes a rapid cat alyst deactivation due to hindered mass exchange between the catalyst sur face and gas phase. At the same time, fine cobalt particles behave as centers of nanotube growth at higher temperatures (see Figure 5.4). 

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