Carbon Nanotubes

Of course, carbon, in the form of a crystal, is what makes-up diamonds – often called the strongest material know to man. In a diamond, every carbon atom is bonded to four other carbon atoms. This, essentially, creates a large, three-dimensional block of carbon, held entirely together by covalent bonds, making it exceptionally strong.

Carbon nanotubes, on the other hand, can perhaps best be visualized as a hexagonal, honeycomb-shaped array of carbon atoms. Each of these atoms is bonded to just three other carbon atoms, but only in two dimensions. However, if this two-dimensional structure could be wrapped into a hallow tube, like a flat piece of paper rolled into a cylinder, this would be the basic three-dimensional structure of a carbon nanotube.

Interestingly, the chemical bonds linking these carbon atoms together are different than those in diamonds – they occupy a different orbital. In fact, the bonds holding nanotubes together are actually stronger than those in diamond, effectively making the nanotube a stronger material than diamond.

Still, exceptional strength is only one of the many unique properties that carbon nanotubes offer.

The physical shape of nanotubes significantly influences their theoretical ability to carry an electric current. If the carbon atoms were simply kept in their two-dimensional array, electrons would be able to move in all directions. But once this array is wrapped into a tubular shape, quantum confinement will only allow electrons to move down the length of the tube and not around it.

Because of this, some types of nanotubes – depending on their diameter – can theoretically carry charges some 1,000 times greater than common conductive materials, such as copper or silver.

So, if a number of technical hurdles can be overcome, carbon nanotubes could end up being the foundation for the integrated electric circuits of the future. They would make-up vastly smaller microchips than those in production today and, potentially, they would function several times more efficiently.

Yet, much about nanotubes remains unknown; researchers around the world are scrambling to quantify their properties and to find practical uses for them before anyone else.



The microscopic image of carbon nanotubes was provided courtesy of Professor of Mechanical Engineering Paul Rice at the University of Colorado-Boulder. ncf.colorado.edu


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