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Superconductive barriers surpassed.

Superconductive Barriers Surpassed

True breakthroughs are rare in science.But if recent work on superconducting materials at the University of Houston and the University of Alabama in Huntsville is confirmed, it may very well join that exclusive "breakthrough' club.

The research team, led by Houston'sPaul C. W. Chu, has made a material that becomes superconducting at 98|K, or -283|F. This breaks the group's record of 52.5|K, set with another material just two months ago (SN: 1/10/87, p.23). Since superconductivity, or the loss of all electrical resistance, was discovered at temperatures around absolute zero in 1911, scientists have hoped to increase the temperature at which the phenomenon occurs so that it could be more readily used in practice.

The recent discovery is technologicallyimportant because it will enable scientists to use liquid nitrogen to get to superconducting temperatures. At 77|K, liquid nitrogen is 10 times less expensive and 20 times more effective as a coolant than is the currently used coolant liquid helium, according to the National Science Foundation, which announced the find on Feb. 16.

With the new material, says Chu, a widerange of previously conceived applications becomes practical--including no-loss electric power lines, magnetically levitated trains, and very large magnets for medical magnetic resonance imaging. (Two weeks ago, a prototype "Maglev' train in Japan established a world record when it reached 400 miles per hour, according to the Feb. 12 NATURE.) At the moment, the material is too brittle to be made into wires, but Chu expects this problem to be overcome. If this is done soon, he says, the new material "will also surely have a great impact on the construction of the [recently approved] Superconducting Super Collider' particle accelerator (see p. 119).

Chu's group had set its 52.5|K record bypressurizing a lanthanum copper oxide compound. In their most recent work, the researchers were able to mimic the effects of pressure by manipulating the chemical makeup and structure of the material. Chu says he cannot yet reveal the composition or structure of the new material, which is not lanthanum copper oxide, because a patent is pending. More information will become public, he says, when his group's papers are published in the March 2 PHYSICAL REVIEW LETTERS.

But even these papers may soon beoutdated. Chu says his group has had a very preliminary indication that superconductivity may occur at 240|K. That number, says one scientist in the field, "just leaves me speechless.'
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Author:Weisburd, Stefi
Publication:Science News
Date:Feb 21, 1987
Words:412
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