Buckeyballs get their first major physical.

Buckeyballs get their first major physical

For eight hours last week, a hotel ballroom in Boston percolated with excitement as materials researchers from around the world shared their hot-off-the-bench discoveries about fullerenes -- beautifully symmetric molecules they've been finding in soot.

This new class of materials joins diamond, with its tetrahedral arrangement of atoms, and graphite, whose structure resembles layers of chicken wire, to become the third known form of carbon. At last week's meeting of the Materials Research Society, the fullerene-of-honor was a 60-carbon ([C.sub.60]) molecule known as a buckeyball or Buckminsterfullerene (SN: 1/28/89, p.56). Its extremely stable, soccerball-shaped configuration, echoing Buckminster Fuller's geodesic domes, has 12 pentagonal and 20 hexagonal sides.

Like zoologists studying a newly discovered animal, materials scientists are probing how these new carbon species behave as individual molecules, as crystalline films and in the presence of other chemical species. By poking and prodding their specimens with lasers and electrodes, researchers are learning about the bonds linking a fullerene's atoms and the amount of energy needed to pull electrons away from them. With scanning tunneling microscopes, some investigators have even sneaked tantalizing peeks at what appear to be individual spheres of different sizes -- presumably [C.sub.60] and [C.sub.70] fullerenes. Others have tried studding the [C.sub.60] buckeyballs with hydrogen atoms or trapping metal ions inside them.

Most of the work described last week was inspired by a report in the Sept. 27 NATURE (SN: 10/13/90, p.238). In that paper, a team led by Donald R. Huffman of the University of Arizona in Tucson and Wolfgang Kratschmer of the Max Planck Institute in Heidelberg, Germany, showed that making molecular soccerballs takes little more than a vacuum chamber, one or two heated graphite rods, and a brush to help collect the fullerene-ridden soot that deposits on chamber surfaces.

Although much of the new research has focused on buckeyballs, scientists at the Boston meeting also shared observations of more oddly shaped [C.sub.70] and [C.sub.84] fullerenes. And gargantuan fullerenes with 240, 540 or more carbon atoms may be in the offing, notes Harold W. Kroto of the University of Sussex in Brighton, England.

In 1988, Kroto and his colleagues suggested that scientists might create huge all-carbon structures, including some that spiral around a core to ultimately resemble a nautilus shell. "I don't have any doubt that people will make these objects," Kroto reiterated last week. "It's early days yet."

Conference participants agree that it's too early to predict the eventual uses of fullerenes. Like graphite, the new materials might serve as lubricants; like diamond, they might provide superhard coatings. Although Defense Department researchers say their early tests indicate [C.sub.60] may not measure up as a rocket fuel, other scientists report signs that [C.sub.60] has the electrical properties of a semiconductor.

"I'm staggered by the wealth of talent that so quickly has been brought to bear on this topic," Huffman told SCIENCE NEWS. Already, he says, fullerene research has demonstrated that new phenomena await discovery, that important science doesn't have to cost much, and that science is fun.