Single Walled Nanotube's (SWNT):

Carbon nanotubes are unique nanostructures with remarkable electronic and mechanical properties. A carbon nanotube is an extremely small, thin, and hallow cylinder structure formed by rolling seamlessly a single layer of graphite (pictured below). As other properties have been discovered, particularly strength, interest has grown in potential applications for example, in nanometre-sized electronics or to strengthen polymer materials. There are two species of carbon nanotubes. (Look at the image below to see the different shapes of a nanotube.) One is a single wall nanotube (SWNT), which consist of one single shell, and the other is a multi -wall nanotube, which may have 7-20 concentric grapheme cylinders.

The image above should give you a better mental image of what a carbon nanotube looks like as well as the different shapes of a nanotube.

Growing Nanotubes:

Ordered nanotubes are prepared by the pulse laser vaporization (PLV) of a carbon target in a furnace at 1200°C. A cobalt-nickel catalyst helps the growth of the nanotubes because the catalyst prevents the ends from being capped during synthesis, and about 70-90% of the carbon target can be converted to single-wall nanotubes. By using two laser pulses 50 nanometers apart, growth conditions can be maintained, which provides more uniform vaporization. Finally, flowing argon gas sweeps the nanotubes from the furnace to a water cooled copper collector.

Techniques:

The most common techniques used today for the production of single walled nanotubes (SWNT) are listed below.

1. Carbon Arc-Discharge (AD) 2. Chemical Vapor Deposition (CVD) 3. Laser Pyrolysis (LP) 4. Pulse Laser Vaporization (PLV) - (This techniques has been discussed up above.)

Each of the techniques mentioned above will be thoroughly examined in each of the upcoming pages. If you would like to read about a particular technique please choose the one that interests you from the list above or use the navigation bar.