Current may flow free and cheap

Ceramic materials that carry electricity at low temperatures with no resistance are showing up in prototype cables, transformers, and other devices. In place of copper-based equipment, superconducting devices offer potentially large energy savings, but at premium prices. Now, an advance in wire making offers promise of lower-cost superconducting wires.

These remarkable ceramic materials are known as high-temperature superconductors because they operate resistancefree at temperatures in the range of 77 kelvins or more, rather than the 20 kelvins or less that conventional superconductors require.

Currently, wire makers blend silver with a compound containing bismuth, strontium, calcium, copper, and oxygen (BSCCO). Researchers are rushing to develop wires from a different compound, one of yttrium, barium, copper, and oxygen (YBCO). YBCO wire promises to cost much less than BSCCO and perform better, but no one has come up with methods for making YBCO wire in practical lengths (SN: 11/18/00, p. 330).

Now, researchers at Los Alamos (N.M.) National Laboratory report they’ve overcome a major impediment to manufacturing long wires. They’ve shortened the lengthy processing time for the method they’re developing to fabricate YBCO wire.

The method requires depositing multiple layers of materials on a metal backing. By replacing a 100-nanometer-thick layer of cubic zirconia with a magnesium oxide layer only one-tenth as thick, the Los Alamos team has made the processing step 100 times faster. “That was the slow step; everything else is very fast,” says team leader Dean E. Peterson.

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