Scientists at Germany's University of Augsburg have dramatically increased the electrical capacity of a promising superconducting material. Its most recent configuration transmits up to six times more current than its earlier counterparts. While the material is currently in the form of a 0.5-in.2 wafer, researchers hope to construct sections long enough to function as power cables.
In the past, the construction of nonresisting, superconducting wires has been both expensive and time-consuming. These devices are generally built as metal-and-ceramic tapes. Gaps in the crystalline structure of such devices have limited their electric capacity. The material being studied by the university's research team, led by Jochen Mannhart, is such a superconducting wire. Yet the scientists have bridged gaps in the crystalline structure to enhance electric capacity.
The team began with yttrium barium copper oxide (YBCO), which becomes a superconductor when chilled to −320°C using liquid nitrogen. Then, the team grew layers of YBCO doped with small amounts of calcium. The calcium-doped layers were placed between layers of pure YBCO. Next, the calcium migrated within the structure and bridged the gaps between the crystals. This alteration in the structure of the YBCO lets it transmit several hundred thousand amperes through each half-inch square.
While the experiment has resulted in three to six times the current capacity in the YBCO material, researchers believe that ten times the normal electric capacity is possible through further manipulation of the crystalline structure. Also, a similar approach may conceivably increase the transmission capabilities of other superconducting materials.
High-performance superconductors could reduce power interruptions in power grids. Engine and transformer design may also benefit from such superconductors. Experts believe that true commercial viability of such applications is at least five years away.
For details about this experiment, go to www.physik.uni-augsburg.de.