Fabrication and properties of high-T/sub c/ superconducting wires

The discovery of high-temperature superconductivity in perovskite-related oxides has generated an enormous amount of research activity and development effort toward applications. Commercially useful bulk superconductors typically require stabilization using a normal metal cladding for reasons of electrical, thermal, and mechanical protection, and in general need to be fabricated into fine fibers and wound into a solenoid configuration. The YBa/sub 2/Cu/sub 3/O/sub 7-//sub delta/ type compound is a ceramic material which is mechanically hard and brittle, and is difficult to fabricate into fine wires. However, this difficulty has been overcome by several fabrication methods such as powder-in-tube method (metal-clad composite), powder-coating method (metal-core composite), and molten oxide processing method. The effect of various processing steps on the structure and superconducting properties such as transition temperature and critical current density will be discussed. Some experiments to raise the high field critical current through chemistry and microstructural control will also be described.