Imagine walking into a hardware store to look for wire and the clerk asks if you'd like "regular or superconducting." This ultimate promise of superconductivity-a practical material with no resistance at room temperature-may never be fulfilled, but researchers are hoping to develop a superconductor that will revolutionize our everyday world.

There are two main issues in superconductivity that must be dealt with in order to develop practical technology. First, the material must be abundant and easily manufactured. The so-called "low-temperature superconductors" are primarily niobium compounds- not an abundant substance. The ceramic, high- temperature superconductors are complex mixtures of yttrium, barium, carbon, and oxygen and are difficult to make into wire. Second, the material must exhibit superconductivity at a high enough temperature to limit the cost of cooling the material to its transition temperature. The low-temperature niobium compounds require large amounts of costly liquid helium to maintain superconductivity, but the high-temperature ceramics only require less expensive liquid nitrogen.

Magnesium diboride wires as they appear after removal from the tantalum tube and part of a U.S. dime for scale. Photo courtesy of Paul Canfield and the U.S. Department of Energy's Ames Laboratory.

In January 2001 a team of Japanese physicists provided an adrenaline shot to superconductor research by announcing that they had observed superconductivity in an abundant magnesium-boron compound, MgB2. While the transition temperature, 40K, of the magnesium diboride is still lower than that of high- temperature ceramic compounds, it is much higher than ever observed in an intermetallic compound and requires only half as much liquid helium. Researchers have already begun to develop techniques for creating magnesium diboride wires, and have shown that the crystal structure of the compound allows it to carry far more electrical current than ceramic superconductors.

Given the fast progress already made with developing this new superconductor, researchers are optimistic that they will be able to tweak the chemical structure to raise the transition temperature to within the reach of liquid nitrogen. But even if this proves impossible, magnesium diboride already promises to surpass the niobium compounds as the low-temperature superconductor of choice.