This year scientists at Brookhaven National Laboratory have discovered two ways of improving the conductivity of "high temperature" superconductors (HTCs). They have found that both increasing the substrate roughness and adding calcium to boundaries between the grains of superconductors can significantly increase the current carrying capacity.
A superconductor is a material that conducts electricity with no resistance. These discoveries are important steps in creating superconductor-based electric and power-delivery devices, such as power transmission lines, motors, and generators. “High-temperature” superconductors are conductors that superconduct at temperatures much “warmer” than conventional superconductors (although still very cold) — for example, -300°F rather than -440°F. This difference, while not huge, is enough to make HTCs more viable for practical applications than materials that must be kept much colder.
The superconducting material they studied is a "cuprate," dubbed YBCO consisting of the elements yttrium, barium, copper and oxygen. YBCO films are deposited onto a ‘normal’ metal surface (the “substrate”), forming components known as coated conductors. They found that nanoscale corrugated surfaces on the substrate produces a 30 percent increase in the current carried by the YBCO films. They had previously thought that surface roughness degraded the performance of HTSCs.
HTSCs are made of many tiny crystalline grains. The boundaries between grains act like barriers to electrical flow. Previously scientists had discovered that adding calcium to the boundries between the grains improved the conductivity, seemingly because the calcium changed the electric-charge structure at the boundaries. In the latest discovery it was found that the chemical structure was changed by adding the calcium and that is what leads to improved conductivity. The importance of this discovery is that it means that similarly sized elements could be equally or more effective than calcium.
This technology is increasingly important as the energy loss in electrical transmission lines is already very significant. If we are to become more dependent on electrical generation methods that are geographically restricted; such as solar, wind, ocean power and geothermal; this technology becomes even more important. Commercial use of this technology is far away, but I believe some early, small scale experiments with transmission lines have been conducted.
"Helping out a High Temperature Superconductor" , Physics.com, 9/14/05
"Pushing the Boundaries of High-Temperature Superconductors" , Physics.com 5/26/05