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POTENTIAL FOR NEW SUPERCONDUCTING MATERIALS ADVANCES
30 May 2001 - University of Wisconsin-Madison
| Commercial potential is growing for magnesium-diboride, a recently discovered high-temperature superconducting metal, with new evidence that alloying enables the metal to carry very high electric current at a high magnetic field. |
Scientists in the Applied Superconductivity Center in the College of Engineering at the University of Wisconsin-Madison added oxygen during a processing step for making magnesium-diboride thin films. The resulting alloy can carry 100,000 amps of current per square centimeter in very strong magnetic fields (10 tesla) and withstand twice as high a magnetic field as the current commercially used superconducting material, niobium-titanium. Results of the study, conducted in collaboration with chemist Robert Cava's research group at the Princeton Materials Institute, are detailed in the Thursday, May 31, issue of the journal Nature. Previous attempts to improve superconducting properties by alloying magnesium diboride as a bulk material have not been successful, says Chang-Beom Eom, professor of materials science and engineering and lead author of the paper. Thin films, however, are comprised of layers just a few atoms thick. "We discovered this material can be alloyed in thin film by a different element. At the same time, that can improve substantially one of the very important properties: the critical field," Eom says. Superconductors must maintain high current densities, yet withstand a high magnetic field, to function in commercial applications such as electrical power transmission lines, motors and superconducting magnets. Superconducting materials can conduct electricity with almost no loss of energy. Earlier this year, Japanese scientists discovered that magnesium diboride superconducts up to 39 degrees Kelvin (minus 390 degrees Fahrenheit), almost twice the temperature of any other metallic superconductor. Just a short while later, UW-Madison researchers David Larbalestier, Eric Hellstrom, Susan Babcock and Eom overcame another challenge when they found evidence that the material can transport high electrical currents because its grain boundaries do not obstruct current flow. In addition to solidifying the material's commercial potential, this latest discovery will lay the scientific groundwork for alloying magnesium diboride in bulk, says Eom. "This alloying can be done in the thin-film form with a different root and that can be adapted to bulk processing in many different ways," he says.
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About: University of Wisconsin-Madison
In achievement and prestige, the University of Wisconsin-Madison has long been recognized as one of America’s great universities. A public, land-grant institution, UW-Madison offers a complete spectrum of liberal arts studies, professional programs and student activities. Many of its programs are hailed as world leaders in instruction, research and public service.The university traces its roots to a clause in the Wisconsin Constitution, which decreed that the state should have a prominent public university. In 1848, Nelson Dewey, Wisconsin’s first governor, signed the act that formally created the university, and its first class, with 17 students, met in a Madison school building on February 5, 1849. From those humble beginnings, the university has grown into a large, diverse community, with about 40,000 students enrolled each year. These students represent every state in the nation, as well as countries from around the globe, making for a truly international population. UW-Madison is the oldest and largest campus in the University of Wisconsin System, a statewide network of 13 comprehensive universities, 13 freshman-sophomore transfer colleges and an extension service. One of two doctorate-granting universities in the system, UW-Madison’s specific mission is to provide "a learning environment in which faculty, staff and students can discover, examine critically, preserve and transmit the knowledge, wisdom and values that will help insure the survival of this and future generations and improve the quality of life for all." The university achieves these ends through innovative programs of research, teaching and public service. Throughout its history, UW-Madison has sought to bring the power of learning into the daily lives of its students through innovations such as residential learning communities and service-learning opportunities. Students also participate freely in research, which has led to life-improving inventions from more fuel-efficient engines to cutting-edge genetic therapies. Students, faculty and staff are motivated by a tradition known as the "Wisconsin Idea," described by UW President Charles Van Hise in 1904 as the compelling need to carry "the beneficent influence of the university ... to every home in the state." The Wisconsin Idea permeates the university’s work and helps forge close working relationships among university faculty and students and the state’s industries and government. |
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