Posted by: Bystander PJ4 APR 2012
Superconductivity is the sudden complete loss of electrical resistivity in some metallic conductors when they are cooled below a critical temperature. The phenomenon was discovered over a century ago, but useful applications only began to emerge after 50 years, and even today scientists have a limited understanding of how it works.
As recently as 2008, physicists discovered a new class of superconductors based on iron, and a team of researchers in Japan focused their attention on iron telluride. This material only becomes superconductive if some of its tellurium atoms are replaced by sulphur, and even then it does not superconduct until it has gone through a final processing stage such as heating it in water.
Nobody knows how this process is able to convert an ordinary material into a superconductor. But last year the Japanese researchers announced their finding that a greater fraction of the material is converted into a superconductor if it is soaked not in water but in an alcoholic beverage, which could be beer, wine or spirit.
Having found that red wine was by far the most effective agent, the Japanese researchers refined their work and have now tested a range of vins rouges derived from single grape varieties. They discovered that beaujolais, made from the Gamay grape, performs better than any other.
Beaujolais is lower in tannins than most red wines but has greater acidity. And it turns out that its high content of tartaric acid plays an important role in the conversion process.
When the team repeated their experiments using an aqueous solution of tartaric acid, they found that the solution performed better than water but was still not as effective as beaujolais.
So tartaric acid may be part of the answer, but one or more other components of beaujolais must also somehow help to encourage the iron telluride’s transition to a superconducting state. The research continues.