Ceramic superconductors disappoint

28/06/2010

Predictions revisited

Why ceramic superconductors are disappointing

Helping to explain one of the biggest let-downs of 20th Century technology is a report from a US-European team centred at the University of Florida. It was released yesterday online by Nature Physics. Any scientifically minded person over 35 may remember the huge excitement about ceramic superconductors in 1987. For example, Time magazine called them “a discovery that could change the world” and continued:

That discovery, most scientists believe, could lead to incredible savings in energy; trains that speed across the countryside at hundreds of miles per hour on a cushion of magnetism; practical electric cars; powerful, yet smaller computers and particle accelerators; safer reactors operating on nuclear fusion rather than fission and a host of other rewards still undreamed of. There might even be benefits for the Strategic Defense Initiative, which could draw on efficient, superconductor power sources for its space-based weapons.

Most scientists believe.” Now where have we heard that before?

Writing in Scientific Europe (1990), Ian Corbett of the UK’s Rutherford Appleton Lab summarized the ceramics story, but much more cautiously.

Sensational events are rare in materials science, but superconducting ceramics attracted media attention of a kind normally reserved for football cup finals. In a heady year that followed their discovery in 1986, even respected newspapers implied that our lives were going to be revolutionized overnight, and that an instant fortune awaited anyone who was quick off the mark in exploiting the new superconductors commercially. Such exaggerated expectations were soon damped down by the reality of the technical problems still be overcome.

The scientific breakthrough was real enough. The phenomenon of superconductivity, in which a material loses all resistance to the flow of an electric current, was previously known only in certain metals and alloys, and at temperatures below -250 oC, close to absolute zero. A wholly new class of superconductors opens the way to higher operating temperatures and presumably to wider applications in the electrical and electronic ind ustries.

Georg Bednorz (left) and Alex Muller. Image AIP

In the autumn of 1987 one of the fastest Nobel Prizes ever was awarded to Georg Bednorz and Alex Muller of IBM’s Research Laboratories at Ruschlikon near Zurich – just a year after the first publication, in Zeitschrift für Physik, of their observation of apparent superconductivity in a ceramic material, lanthanum-barium-copper oxide, and at a somewhat higher temperature than any previously authenticated in other materials.

The promise of new applications remains, but unless another unexpected discovery changes the prospects, the road ahead appears at the time of writing to be long and stony.

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