Production Of Fullerenes
For reasons that are not yet fully understood, C60 seems to be the inevitable result of condensing carbon slowly at high temperatures. At high temperatures when carbon is vaporized, most of the atoms initially coalesce into clusters of 2-15 atoms. Small clusters from chains, but clusters containing at least 10 atoms commonly form monocyclic rings. Although these rings are favored at low temperatures, at very high temperatures they break open to form linear chains of up to 25 carbon atoms. These carbon chains may then link together at high temperatures to form graphite sheets, which somehow manage to form the geodesic fullerenes. One theory has it that the carbon sheets, when heated sufficiently, close in on themselves to form fullerenes.
Scientists later demonstrated that fullerenes can be conveniently generated by setting up an electric arc between two graphite electrodes. In their method, the tips of the electrodes are screwed toward each other as fast as the graphite is evaporated to maintain a constant gap. The process has been found to work best in a helium atmosphere in which other gases such as hydrogen and water vapor have been eliminated.
Fullerenes have been reported to occur naturally in certain coals, as well as in structures produced by lightening known as fulgurites, and in the soot of many flames.