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Scientists Make Big Breakthroughs : New Superconductors May Aid Medicine, Computers

January 19, 1987|From Reuters

NEW YORK — Scientists in Europe, Japan and the United States have made breakthroughs in superconductivity that could lead to major advances in medicine, computers, communications and a range of other fields.

The scientists say the successes mark a new phase in the quest for materials that become superconducting, or lose all resistance to electricity, at temperatures high enough to make their use safe and economical.

The advantages of superconductivity have been known for many years. The problem for scientists seeking to harness it is that it happens only when materials become very cold, near absolute zero, the total absence of heat which is equal to minus 460 degrees Fahrenheit.

Bell Laboratories, the research and development wing of American Telephone & Telegraph Co., disclosed recently that it had developed a material that becomes fully superconducting at the relatively warm temperature of 36 degrees Kelvin, minus 395 degrees Fahrenheit.

Previously, scientists were unable to get superconductivity to work above 23 degrees Kelvin (minus 418 degrees Fahrenheit).

Meanwhile, the University of Houston has reportedly found a compound of lanthanum, barium, copper and oxygen that under high pressure, loses its resistance to electricity at 40.2 degrees Kelvin.

These results come just nine months after researchers at an International Business Machines lab in Zurich, Switzerland, produced a lanthanum-barium-copper oxide that became superconducting at 30 degrees Kelvin. IBM's method was later improved by scientists at the University of Tokyo.

"This is a great leap," said Robert Dynes, director of the chemical physics research lab at Bell Labs in Murray Hill, N.J. "It took 50 years to get to 23 degrees Kelvin, but in less than a year we've gotten to 36."

Moreover, the University of Houston team, led by Paul C. W. Chu, believes it can eventually achieve superconductivity at temperatures of 77 degrees Kelvin.

By raising the temperature at which superconductivity occurs, scientists hope to learn more about the fundamental principles of the materials they use as conductors.

At the same time, they are searching for ways to reduce a conductor's resistance to electricity, which becomes greater as its temperature increases.

Higher temperatures will also broaden the range of coolants that can be used to obtain superconducting materials.

"When 23 degrees Kelvin was the limit for superconducting materials, only a few types of coolants, primarily liquid helium, could be used," said Thomas Nolle, president of CIMI Corp., a high-technology consulting firm. "But in the 40-degree range, more manageable coolants such as liquid hydrogen become practical."

Thus, superconducting materials are currently limited to applications where liquid helium can be used safely and economically, such as for specialized magnetics used in laboratory experiments, nuclear particle accelerators and medical imaging.

Future uses, however, will extend to semiconductors for super-fast computers and to transmission of electric power, which would become radically more efficient in a superconducting environment because the loss of power from resistance in the wire would be eliminated.

Superconducting materials are useful in medical imaging equipment, but their applications have been limited because of the low temperatures necessary.

As use at higher temperatures becomes possible, scientists hope they will more easily be able to take pictures of the brain and other organs.

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