US 4,973,575 AGranted

Preferential orientation of metal oxide superconducting materials by mechanical means

AssigneeArch Development Corporation

InventorDonald W. Capone

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Abstract

A superconductor comprised of a polycrystalline metal oxide such as YBa.sub.2 Cu.sub.3 O.sub.7-X (where 0<.times.<0.5) is capable of accommodating very large current densities. By aligning the two-dimensional Cu--O layers which carry the current in the superconducting state in the a- and b-directions, i.e., within the basal plane, a high degree of crystalline axes alignment is provided between adjacent grains permitting the metal oxide material to accommodate high current densities. The orthorhombic crystalline particles have a tendency to lie down on one of the longer sides, i.e., on the a- or b-direction. Aligning the crystals in this orientation is accomplished by mechanical working of the material such as by extrusion, tape casting or slip casting, provided a single crystal powder is used as a starting material, to provide a highly oriented, e.g., approximately 90% of the crystal particles have a common orientation, superconducting matrix capable of supporting large current densities.

Claims8

Dependent claims

A method of forming a superconducting metal oxide with improved current carrying capacity wherein said superconducting metal oxide has a polycrystalline structure and is anisotropically superconducting having one or more longer crystal axes along which said metal oxide is superconducting, said method comprising the steps of:

reducing the superconducting metal oxide of flake-like particles of single crystals by pressing the superconducting metal oxide into a compact form, heating the compacted superconducting metal oxide to a temperature on the order of its melting point for an extended period sufficient to induce large grain growth in the superconducting metal oxide, and reducing the superconducting metal oxide to a flake-like, powder form, wherein the metal oxide powder is comprised of particles of single crystals;
mixing said particles of single crystals with a liquid to form a loose matrix of said particles;
mechanically orienting said metal oxide single crystal particles along a preferential direction such that said one or more longer axes of each of said metal oxide crystals are in general alignment;
and
removing the liquid from the aligned metal oxide single crystal particles and sintering said metal oxide single crystal particles.

2 more elements

Dependencies are inferred from the claim text.