March 07, 2006

Other tech: Superconductor advance

A new study makes more reliable superconductors with higher critical current density Maximizing oxygen in the Grain Boundary(GB) helps maximize critical current density (Jc), or the maximum current that a superconductor can carry. The superconducting material used in this study was a ceramic compound consisting of millions of microscopic crystals (grains). The WUSTL/Argonne team specifically developed a technique to determine whether a desired maximum number of possible sites are filled with oxygen in the GB, which surrounds every crystalline grain. The GB is a region of misfit between the grains and usually is only a few atoms wide. It is very difficult to determine how much oxygen is really present in the GB. The researchers have developed a method which allows one to estimate this, called pressure-induced oxygen relaxation.

Hopefully this kind of work would lead to higher critical temperatures. In one atmosphere of pressure, the YBCO superconducts at 93 K (or –180 C). YBCOs can superconduct at temperatures as high as 110 K (–163 C) at highest pressure (about 100,000 atmospheres). Maybe adjusting oxygenation and other factors will lead to superconductors with higher Tc that did not need have the high pressures maintained.

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