Page 103 - Carbon Nanotubes

Graphitizable coiled carbon nanotubes 93
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Fig. 8. Planar representation of the (9n,0)-(5n,5n) knees, having a 36" bend angle produced by a
heptagon-pentagon pair on the equatorial plane. The arrows show the dotted line of bonds where the
knee N, or Nn,c is connected to the corresponding straight tubules: (a) knee N, for n= 1; (b) stretched
knee for n= 1 and c=38; (c) general knees N, and N,,c.

sections and by the distribution of bond shifts. The heptagon-pentagon pairs in a concerted manner at
diameter and pitch of observed coiled tubules vary the catalyst surface ~ is first explained from the
greatlyC7-121. macroscopic and then from the chemical bond points
of view.
3. A POSSIBLE MECHANISM FOR THE GROWTH 3.1 kfQCrOSCOpiC point of view
OF NANOTUBES ON A CATALYST PARTICLE
Some insight can be gained from the observation
The formation of a helix or torus - the regularity of tubule growth on the catalyst surface by the
of which could be controlled by the production of decomposition of acetylene (Fig. 11). At the beginning