Abstract
Since oxide high-Tc superconductors were discovered in 1986, there were reports of Y-Ba-Cu-O superconductor with Tc in the 90-K class, followed by a 110-K class Bi-Sr-Ca-Cu-O superconductor and a 125-K class Tl-Ba-Ca-Cu-O superconductor. There have been many efforts towards developing superconducting wires using these oxide superconductors. Many processing technologies including solid reaction process, liquid process and film process have been investigated. To make the application of oxide superconducting wires practical, they should be long (-1, 000m), carry a high critical current density, of at least 10, 000A/cm2 at the minimum value under a relevant magnetic field, and not be strain-sensitive so that they can withstand the winding process, which is inevitable in practical applications. At present, a 1, 080m-long wire has been achieved using bismuth-based compounds with silver-sheathing processing technology. Critical current density of oxide superconducting wires has been improved through the understanding of how microstructures are related to Jc and can be controlled. In addition, multifilamentary wires proved to have good strain-resistant properties. Prototypes for practical applications have been fabricated using oxide superconducting wires. Among these applications, two categories proved to be promising. The first one is large current conductor application, such as current leads for magnets, bus bars and power transmission cables. The second one is magnet applications. Since oxide superconductors have a wide critical surface, we expect that these magnets can be used under a variety of cooling conditions with different coolants.
