Carbon nanotubes are hollow cylindrical tubes. The length of carbon nanotubes may vary from several micrometers to millimeters and the diameter will vary from 1 to 20 nm. The ends are closed with caps containing pentagonal rings. A tube may contain one cylindrical wall of graphite or a number of concentric cylindrical walls. Under the transmission electron microscope, these cylindrical walls appear as planes. Single wall nanotubes appear with two planes whereas the multiwall nanotubes appear with more than two planes and are seen as a series of parallel lines as shown in Fig. 13.6.
Figure 13.6 Carbon nanotubes
The single-walled carbon nanotubes are of three different types. They are: (i) arm chair, ...