In a surprising discovery, scientists reported Wednesday that a new form of carbon shaped like a soccer ball appears to be a good superconductor.
The carbon, called buckminsterfullerene or "buckyballs" after geodesic dome inventor Buckminster Fuller, captured the attention of the scientific community in September, when the fascinating material was first produced in quantities large enough to study.Researchers speculated that buckyballs - large molecules each consisting of 60 carbon atoms arranged in a spherical, geodesic pattern - would have practical applications as lubricants or as containers for carrying other tiny particles.
However, it was not forecast that buckyballs would turn out to have value as superconductors. Superconductors are materials that allow electricity to flow with virtually no energy lost to resistance and wasted as heat.
Superconductivity research has helped fuel speculation about a futuristic world of resistance-free electrical movement in which commuters could ride to work on "flying" trains and computers could make calculations at the speed of light.
Now, reporting in the British journal Nature, Arthur Hebard and his colleagues from AT&T Bell Laboratories in Murray Hill, N.J., said they found when gaps in buckyball material were filled with potassium atoms, the material became a superconductor.
"I never heard of anyone predicting buckyballs would do this. It really is completely astonishing to everybody," said Robert Whetten, a professor of physical chemistry at University of California-Los Angeles.
"Who knows where this will lead. The material is simple, easy to prepare, lightweight and both carbon and potassium are cheap," said Whetten, who has been able to reproduce the AT&T results in his laboratory.
The principle of superconductivity has been studied for most of this century. But recent years have seen giant leaps, especially in the higher temperatures at which new materials exhibit the property.
Buckyball material showed evidence of superconductivity below 18 degrees Kelvin or minus 427 degrees Fahrenheit - the highest temperature yet observed for a molecular supercondutor.
However, that temperature is still considerably below the record for so-called ceramic superconductors, which differ from molecular superconductors because the atoms are more tightly bound together. Ceramic superconductors tend to be more difficult to make and handle than buckyball material, Whetten said.
A ceramic mixture of copper, calcium and thallium oxides created by Allen Herman of the University of Arkansas in 1988 is the current record holder. That material that loses resistance at 125 degrees Kelvin or minus 234 degrees Fahrenheit, and can be cooled with liquid nitrogen rather than more costly liquid helium.
Hebard would not speculate on any practical applications of buckyball superconductors. "This is extremely exciting from a scientific point of view - we have a new class of superconducting compounds to work with. We don't know where it is going to go, but we have a . . . new building block: buckyballs," the AT&T researcher said.
Whetten said it should be possible to push up buckyball's superconducting temperature threshold, perhaps by increasing pressure on the material. However, the commercial value of superconducting buckyballs also hinges on how readily the material can be fashioned into wire and other practical materials, he said.