The higher the current density the greater the amount of electric current that can be transmitted through the wire. Standard household wires typically carry less than 1000 amperes per square centimeter. Superconductors have virtually no resistance to electric current, offering the possibility of new electric power equipment with improved energy efficiency, smaller size, and lower operating costs than today's devices. These systems could help reduce the U.S. requirements for new power plants, since electricity demand is expected to double by the year 2030. Substrates provide the underlying foundation for the superconducting wire.
Grains are homogeneous regions within a material in which the atoms are well aligned.
The ORNL team, comprising researchers from the Solid State, Metals and Ceramics, and Chemical and Analytical Sciences divisions, developed substrates for the wire that are chemically compatible with high-temperature superconductors and exhibit sharp biaxial texture. Texture refers to the alignment of the atomic planes within the wire. No further surface treatments, such as polishing, are used. Next, a buffer layer technology, developed specifically for these textured metals, was used to provide a chemical barrier between the nickel and the superconductor while maintaining the texture. For this, a thin layer of palladium is deposited using electron beam evaporation or sputtering.