Developments to Watch
LAYERED TAPE MAKES SUPERCONDUCTORS MORE SUPER
Coming up with methods to make high-temperature superconductors into wires that conduct high levels of electricity is one of the most vexing hurdles to developing practical uses for the valuable ceramic materials. Extruding the powdered superconductors through a silver tube is one of the most promising methods. But in this technique, the crystals are aligned randomly, which impedes the flow of electricity.
Now, researchers at Lawrence Berkeley Laboratory have made layered tapes that can carry 10 times as much current as the drawn wires. The Berkeley team starts with a foundation of nickel alloy. It then deposits a layer of zirconia on top. As the zirconia crystals grow, they are bombarded with an ion beam to make them optimally aligned. Then the superconducting material is deposited on top of the zirconia crystals. The superconducting crystals automatically align themselves with the zirconia crystals. The tapes made this way can conduct 600,000 amps per square centimeter, sufficient for uses such as superconducting magnets. But the technique needs to be refined to produce large quantities of the tape at lower cost.EDITED BY EMILY T. SMITH