The Solution?

Carbon nanotubes (also called buckytubes) are derivatives of Buckminster fullerene (C₆₀), and were discovered in 1991 by Sumio Iijima [4], working for the NEC Corporation in Japan. He produced a spark between two graphite rods and in the debris formed he found perfect tubes, made of pure carbon.

Nanotubes are an excellent replacement for copper and silicon in computer chips. One individual nanotube is approximately 1 nm in diameter and can be on average 10 µm long (although theoretically they can be any length) [1]. Nanotubes can be made to conduct freely like metal wires or can be made semi-conductors like silicon [2].

They are formed of hexagons of carbon atoms, covalently bonded:

Nanotubes can be thought of as originating from graphite, which consists of large sheets of carbon hexagons.

In sheets of graphite (graphene ‘layers'), there are strong covalent bonds between each carbon atom and the next in each hexagon. Covalent bonds consist of a pair of shared electrons between each atom, holding the atoms together. There are also very weak forces of attraction between each graphene layer (Van der Walls forces), caused by the one unbonded electron in each carbon atom [9].

[9]

This one unbonded electron is important because it allows the carbon to conduct electricity (there is a current if the electron moves).

If one individual graphene layer is thought of a being ‘rolled up' into a cylinder, then this is a carbon nanotube. There may also be hemispherical ends, similar to half a ‘bucky-ball' [2]:

[10]

As carbon nanotubes have a similar structure to graphite, they also conduct electricity, as electrons can move along in the centre of the tube.

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