| Abstract
| - This paper focuses on the growth mechanism of the multiwalled carbon nanotubes exhibiting helical andzigzag growth morphologies. Our data support a kinetically controlled growth model in which the creationrates of the pentagon and heptagon carbon rings determine the geometrical shapes of the nanotubes. Thecarbon nanotube is believed to be grown from a carbon cluster that is nucleated from a pentagon carbon ringfollowed by a spiral shell growth. The pairing of pentagonal−heptagonal (P−H) carbon rings is essential informing the helical and zigzag structures. If there is no twist in the P−H orientation along the body of thecarbon nanotube, a planar-spiral structure would be formed. If the P−H pairs twist their orientations alongthe growth direction of the nanotube, a helical structure would be formed. The periodicity and the coilingdiameter of the helix are determined by the angle of the twist and the distance between the adjacent P−Hpairs. If the P−H pairs are densely accumulated at a local region and the interpair distance is small, a nodeis formed, thus, the zigzag growth morphology.
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