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In most uses, however, the cost of liquid helium outweighs the benefits of superconducting technology. For that reason, scientists have long searched for a compound that would become a superconductor at less extreme temperatures -- particularly above 77 K (-320 degrees F), the point at which nitrogen gas liquefies. Reason: nitrogen is a common gas and costs no more than a tenth as much in liquid form as helium. In fact, says Iowa State University Physicist Douglas Finnemore, liquid nitrogen, priced as low as a nickel a liter, is a "heck of a lot cheaper than beer."
The much sought-after goal proved to be elusive. In the early 1970s scientists found an alloy of niobium and germanium that lost all resistance at 23 K. Then, last April, a group at the IBM Zurich Research Laboratory in Switzerland announced development of a compound of barium, lanthanum, copper and oxygen that appeared to begin the transition to superconductivity at 35 K.
In October the Zurichers confirmed their result, which other researchers duplicated and then tried to beat. A slow-moving branch of physics became a horse race as laboratories around the world attempted to push temperatures higher. Last week's announcement does not end the competition. Says Paul Fleury, director of AT&T Bell Laboratories' Physical Research Laboratory: "It took physicists 75 years to raise superconductivity temperatures by 19 degrees. We have more than doubled that in the last 75 days. We're now dealing with new science, and we don't know what the upper limits are."
Chu foresees a balmy 120 K within a few months, and does not rule out superconductors that could operate at 300 K (room temperature). University of Illinois Physicist John Bardeen, who shared the Nobel Prize in 1972 for his part in explaining the quantum-mechanical basis of superconductivity, agrees that there is no theoretical reason precluding higher temperature superconductors. But, he says, "finding materials with the right combination of properties is tricky." Admits Chu: "There was a bit of serendipity involved."
Chu will describe the new material and details of how it was developed in an upcoming issue of Physical Review Letters, but the University of Houston has already applied for a patent on both product and process. If it is granted, Chu stands to share in the profits, which could be large. "It's phenomenal -- we're excited," says Robert Jake of American Magnetics, a manufacturer of superconducting magnets. "But it will take several years of research and development to make it feasible for commercial application." When such applications come, says Chu, they will make clear the significance of his discovery: "I think it could almost be like the discovery of electricity."
FOOTNOTE: *It is resistance that converts electric energy into heat, as in the coils of an electric heater.