Abstract Submitted to the    NANOTUBE'04 Conference:

Carbon nanotubes were synthesized by decomposition of methane on Co/MgO catalyst in a temperature range from 900 to 1000 C. The samples were purified by a hydrochloric acid treatment. The structure of small bundles of these nanotubes was investigated by selected area electron diffraction and analyzed with the kinematical theory of diffraction. Most of the bundles studied were made of nanotubes presenting unique or double helicities [1]. The diffraction pattern of some bundles with unique or double helicities is undoubtedly produced by double-walled carbon nanotubes [2], which are known to be syntesized under the experimental conditions used here [3]. It is then concluded that the majority, if not all, of the double-wall nanotubes in a given such bundle have the same helicities. The synthesis of a bundle composed of identical double-wall nanotubes most likely results from a cooperative mechanism taking place on a catalyst particle.

Work performed within the Belgian IAP program P5/01 "Quantum size effects in reduced dimensionality systems".

[1] J.F. Colomer, L. Henrard, Ph. Lambin, and G. Van Tendeloo, Phys. Rev. B 64 (2001) 125425.
[2] J.F. Colomer, L. Henrard, G. Van Tendeloo, A. Lucas, and Ph. Lambin, J. Mater. Chem. 14 (2004) 603.
[3] E. Flahaut, A. Peigney, Ch. Laurent, and A. Rousset, J. Mater. Chem. 10 (2000) 249.