Structure and method of manufacture for minimizing filament coupling

Abstract

A multifilamentary superconducting composite article comprising multiple substantially electrically decoupled domains, each including one or more fine, preferably twisted filaments of a desired superconducting oxide material. In a preferred embodiment, the article comprises a matrix, which substantially comprises a noble metal, a conductive jacketing layer surrounding the matrix, a plurality of discrete filament decoupling layers, each comprising an insulating material, disposed within the matrix to separate the matrix into a plurality of substantially electrically decoupled domains; a plurality of filaments, each comprising a desired superconducting oxide, which are disposed within and essentially encapsulated by the matrix and chemically isolated thereby from the decoupling layers, each of the electrically decoupled domains containing at least one filament. It provides multifilamentary articles that exhibit high DC performance characteristics and AC performance markedly superior to any currently available for these materials. The article may be manufactured by first, forming a composite intermediate comprising multiple domains, each including one or more fine, preferably twisted filaments of a superconducting oxide or its precursors and then thermomechanically processing the intermediate at conditions sufficient to produce at least one of the effects of texturing, crack healing and, if a precursor to the desired superconducting oxide remains, phase transformation in the filament material under conditions which support the electrical separation of the domains. Preferably, the forming step includes the step of providing filament decoupling layers comprising insulating materials or their predecessors to provide the desired domain separation and most preferably, the insulating material is formed in situ from its predecessor during the thermomechanical processing step. Oxide-forming predecessors are preferred, especially oxide forming materials selected from the group consisting of the transition metals, the alkaline earths, titanium, zirconium, niobium, molybdenum, aluminum, and their alloys. In a preferred embodiment, the desired superconducting oxide material is a member of the bismuth or yttrium families of oxide superconductors.