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10 April 2014 11:44 am ,
Vol. 344 ,
Balkan endemic kidney disease surfaced in the 1950s and for decades defied attempts to finger the cause. It occurred...
The Pyrenean ibex, an impressive mountain goat that lived in the central Pyrenees in Spain, went extinct in 2000. But a...
Tight budgets are forcing NASA to consider turning off one or more planetary science projects that have completed their...
Ebola is not a stranger to West Africa—an outbreak in the 1990s killed chimpanzees and sickened one researcher. But the...
In an as-yet-unpublished report, an international panel of geoscientists has concluded that a pair of deadly...
Tropical disease experts tried and failed before to eradicate yaws, a rare disfiguring disease of poor countries. Now,...
Since 2002, researchers have reported that agricultural communities in the hot and humid Pacific Coast of Central...
- 10 April 2014 11:44 am , Vol. 344 , #6180
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Superconducting Buckyballs Switch Allegiances
27 April 2000 6:30 pm
Buckyballs, those versatile, soccer-ball-shaped spheres of carbon, have a newly discovered ability. Under the right circumstances, they can transmit electricity without any resistance. What's more, the buckyballs can start and stop this superconducting with an electronic command--a trick that might let them one day serve as rapid electrical switches.
The spherical carbon molecules, also called fullerenes, were discovered in 1985. Lattices of 60, 70, or more carbon atoms form geodesic-dome shaped structures that have a range of unusual electronic properties and can encapsulate other molecules. Researchers already knew that crystals made of buckyballs could superconduct--but only if fortified with a few atoms of certain metals per sphere. The metal atoms donate electrons and allow the buckyballs to transmit an electric current much like metals do; at temperatures approaching absolute zero, the mix superconducts.
Now researchers have come up with a technique that induces buckyballs to switch in and out of superconductivity. Physicist Bertram Batlogg of Lucent Technologies in Murray Hill, New Jersey, and colleagues connected a tiny crystal slab of pure buckyballs a few millimeters long to two electrodes and passed a current through it. They found they could control the current by applying a voltage to a third electrode, separated from the buckyball solid by an insulating layer of aluminum oxide. If they cooled the contraption to within 11 degrees of absolute zero and applied 200 volts to the third electrode, called the gate, the buckyballs superconducted.
Apparently, the gate electrode temporarily injects electrons from the bulk of the buckyball solid into a thin layer of buckyballs adjacent to the aluminum oxide. The souped-up buckyballs act like a superconductor, says physicist George Sawatzky of Groningen University in the Netherlands. Team member Robert Haddon of the University of Kentucky, Lexington, speculates that such a switch might speed up electronic devices, if someone could figure out how to make the process work at higher temperatures.