"Bucky Balls"

By: Jesse Savell

This research paper is concerned with the discovery and possible uses of a new form of carbon that was discovered about fifteen years ago. This new carbon molecule is in the shape of a soccer ball and contains sixty, or sometimes seventy carbon atoms. It was named Buckminster Fullerene or "Bucky Balls" after the great Engineering genius, Buckminster Fuller.

Quite a few events in the scientific community preceded this historical discovery. In 1966 A. Deadalus considered the possibility that there might be another form of carbon in existence as a theoretical "cage" containing sixty atoms. Four years later it was proposed that this "C-60", if it existed, would be a perfectly stable molecule. This intrigued scientists; however, everyone knew that there were only two forms of carbon. Since no one had ever actually seen this "C-60" molecule it was never pursued in depth. However, Harry Kroto at the University of Sussex in England had his own ideas about C-60. Kroto believed that stardust was made up of carbon in a form that was not known. Kroto had no hard evidence of this, other than the fact that he knew carbon was emitted from dying stars and that whatever did make up stardust had never before been analyzed on earth. In 1985 Kroto traveled to Rice University in Houston, Texas. At Rice University, Kroto and Rick Smalley used a laser to vaporize carbon atoms, and a magnetic field to force the vaporized atoms into a mass spectrometer. Here they could measure the number of clusters and the number of atoms per cluster. Surprisingly, there was a peak on the printout at 60 and 70 atoms per cluster. This showed that C-60 did exist in a stable form. However, Kroto and Smalley didn’t know about the earlier idea of carbon cages, so the complete answer didn’t fall into place at that time. They knew that the molecule had sixty atoms, but still had no idea how this molecule formed.

At about the same time, Donald Huffman of the University of Arizona and Wolfgang Kratschmer of Max Planck Institute for Nuclear Physics were trying to create C-60 another way. Huffman and Kratschmer pushed an electrical current through two sticks of graphite in a bell jar in a vacuum, which produced a cloud of carbon atoms until the vacuum was removed. Shortly after this, they produced an absorption spectrum with peaks at 60 and at 70. This was surprising because Huffman and Kratschmer had no idea that there was another stable form of carbon!

All branches of Science are involved with carbon and its properties. Since nobody had ever defined the properties of C-60, these scientists wanted to be sure that what they had discovered was a concrete finding. In diamonds, carbon forms four bonds ending with hydrogen. In graphite carbon forms three bonds ending with hydrogen. However, Huffman and Kratschmer knew that there was no hydrogen in the bell jar. So why did this molecule stop at sixty atoms? Did it form a cage? They tried to wrap a graphite model into a ball shape, but the bond angles wouldn’t allow all sides to join. Kroto and Smalley examined the geodesic domes built by Buckminster Fuller and realized that the structure must contain pentagons in order to curve. Smalley cut out pieces of paper and formed a C-60 molecule – and the Bucky Ball was born! Now they had a solid theory that could explain the phenomenon. Computer simulation was used to examine this "Bucky Ball" and how it would react to certain stimuli. The computer-simulated absorption spectrum produced a double hump with peaks at 60 and 70 atoms. When Huffman heard this, he remembered his own absorption spectrum and reproduced the experiment. Yet, neither team could create C-60 outside of a vacuum. Both teams tried to extract C-60 from the soot that remained in the testing machines, and finally the soot was dissolved in a Benzene solution, which left a red liquid containing C-60 molecules. Huffman evaporated the red liquid and viewed it under a microscope. At last, in 1990, the existence of C-60 in a stable tangible form was finally proven.

The possibilities for the use of C-60 are infinite. Some improvements in nano-engineering have already been made. The scanning-force microscope uses fine tips called nanoprobes to detect and nudge molecules. Until now these tips were up to 2000 nanometers thick. However, using fullerenes as tips, it is possible to create nanoprobes that are 5 - 20 nanometers thick, thus allowing more accurate atomic manipulation. Furthermore, fullerene flexibility and strength causes them to be much more durable. Metal atoms can also be enclosed inside fullerenes, and by the process of zapping away carbon atoms with a laser, the fullerene is able to confine the metal atom. Scientists are still hoping that these metallofullerite molecules will have useful electrochemical properties. C-60 also has very unique superconducting capabilities. When alkali metal atoms are added to fullerenes, they take on different electrical properties than they would otherwise have. When three alkali atoms per each octahedral pattern are added, the resulting salt can take on superconducting properties. However, when more than three alkali atoms are added to the lattice, the C-60 salts will develop more resistance as the electronic bands fill up. The highest of these has six alkali atoms added, and is a very strong insulator.

Another possible use of fullerenes is as a light blocker. When light hits a fullerene, it changes the nature of the molecule by increasing the amount of light that the fullerene can absorb. As the light increases, more of the C-60 molecules pass into the absorption state. The molecules will let light through up to a certain point, and then more or less clamp it off. This technology is expected to be used in sunglasses, especially for pilots, and as protection against blinding light such as in welding and the military field. "Hairy Balls", which are Bucky Balls with twelve or more ethylene diamines bonded to them, can be dissolved in water. This makes it more useful for medical applications, such as the hopes that they will eventually be able to block the protease enzymes of HIV, making it inactive. "Hairy Balls" can also be used as a lubricant. Since Hairy Balls can be put into solution, their spherical shape causes them to act somewhat like molecular sized ball bearings. Oil companies are very interested in the use of these Hairy Balls as a possible oil or fuel additive, or as an alternative to fossil fuel lubricants.

However, there is still one factor that has held back the research for other possible uses. Though prices have dropped over the past few years, C-60 still costs somewhere between $25 - $200 per gram. This translates to about $11,000 - $91,000 per pound.