Carbon nanotubes graphitic/substitutional

Because of the speeial atomie arrangement of the earbon atoms in a carbon nanotube, substitutional impurities are inhibited by the small size of the carbon atoms. Furthermore, the serew axis disloeation, the most eommon defeet found in bulk graphite, is inhibited by the monolayer strueture of the Cfj() nanotube. For these reasons, we expeet relatively few substitutional or struetural impurities in single-wall earbon nanotubes. Multi-wall carbon nanotubes frequently show bamboo-like defects associated with the termination of inner shells, and pentagon-heptagon (5 - 7) defects are also found frequently [7]. 

The BC4N nanotubes can be formed in different ways. They could arise from the substitution of the BN layer in graphitic layers as proposed hy earlier reports of BCN nanotubes.4 Kawaguchi2 described a BCN structure in terms of an infinite array of six-mernbered rings of carbon with ordered... 

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