Low-Temperature Superconductivity Is Warming Up
Magnesium diboride defies the once conventional wisdom about what makes a good superconductor. It becomes superconducting near the relatively warm temperature of 40 kelvins--which promises a variety of applications
By Paul C. Canfield and Sergey L. Bud'ko
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Imagine walking around in your backyard and suddenly discovering a vein of gold in a corner you thought you knew well. Or imagine how Jed Clampett of the Beverly Hillbillies felt when oil started bubbling up through the ground. A similar sensation of incredulous excitement swept over the solid-state physics community in the early weeks of 2001, when researchers announced that magnesium diboride (MgB2) superconducts--conducts electricity without resistance--at temperatures approaching 40 kelvins.
This simple compound had been studied in the 1950s and had been on the shelves in some laboratories for various mundane purposes for decades, with no one suspecting its enormously valuable hidden talent. Although 40 K (or ¿233 degrees Celsius) may sound rather low, it was nearly double the record for compounds made of metals (about 23 K for niobium-based alloys, which are widely used in research and industry). A transition temperature that high can be achieved by technologies that cost much less than those needed to bring about superconductivity in the niobium alloys. Possible applications include superconducting magnets and power lines.
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