快猫短视频

A PREVIOUSLY ignored 鈥渙ff-the-shelf鈥� chemical has been found to superconduct
at higher temperatures than previously thought possible for a simple metallic
compound. The discovery opens up the possibility of making cheap superconducting
wires and devices that operate at accessible temperatures.

Because superconductors offer no resistance to the flow of electric current,
they would be ideal for power transmission cables and high-speed circuits. The
trouble is that they only lose resistance below a certain critical
temperature鈥攂elow 23 Kelvin for metals or simple metallic compounds.

In 1986, researchers in Switzerland discovered a whole new class of ceramic
copper oxide superconductors with much higher critical temperatures, sometimes
over 100 Kelvin. However, these materials are expensive and difficult to make
and use.

But now Jun Akimitsu and his colleagues at Aoyama Gakuin University in Tokyo
have found that magnesium diboride (MgB₂) will superconduct at 39
Kelvin. Akimitsu believes this to be 鈥渢he highest yet determined for a
non-copper-oxide bulk superconductor鈥�, he reports in this week鈥檚 Nature
(vol 410, p 63).

鈥淚t鈥檚 terribly exciting,鈥� says physicist Lesley Cohen of Imperial College,
London. She says one big attraction of MgB₂ is that it is easy to work
with at room temperature.

The race is now on to understand how MgB₂ superconducts, and push it
to higher temperatures. 鈥淭his holds tremendous promise for even higher
temperatures in conventional materials,鈥� says Robert Cava of Princeton
University. Paul Canfield and colleagues at Iowa State University are reported
to have already made MgB₂ superconducting wires.