The term "superconductivity" is generally used in connection with materials exhibiting no resistance to the flow of electric current when cooled below a certain critical temperature (T.sub.c). T.sub.c provides a conveniently identified and generally accepted reference point for marking the onset of superconductivity and providing temperature rank using superconductivity in differing materials. Most superconducting materials have a T.sub.c of 125.degree. K.
The primary drawback to the highest of such T.sub.c materials is that they contain elements that are toxic or difficult to handle, which involves not only additional manufacturing costs but environmental concerns as well. An ideal superconducting material would not pose such processing problems and would have a T.sub.c approximately equal to higher than those currently in use. Additionally, an ideal superconductor would be capable of being easily processed into useful form such as wires and cables, a formidable technological challenge for the current classes of ceramic materials which have the drawback of being too brittle to easily work with and form into the necessary shapes for industrial use.
Copper oxide superconductors are inherently brittle, making their processing into wires, discs, or other useful forms difficult. Currently, a preferred technology for the fabrication of wires of these materials involves making a composite of the superconducting compound and a metal phase which functions as a support, a source of tensile strength and protection against conductivity lapses during temperature transitions. Silver is one such metal phase; however, it is prohibitively expensive for large scale applications and often lacks structural integrity after processing the material. Other metal phases often do not protect against oxygen loss from the superconducting phase or migrate into the superconducting phase.