Multifilamentary oxide superconducting wires

An oxide superconducting stranded wire, which is formed by twining a plurality of multifilamentary oxide superconducting wires, and is flatly shaped, wherein said multifilamentary oxide superconducting wires are prepared by a powder-in-tube method, and comprise:

• a plurality of filaments, consisting essentially of an oxide superconductor, extending along the longitudinal direction of said wire in the form of ribbons;
• and
• a matrix, consisting essentially of a stabilizer, covering said plurality of filaments,
• said plurality of filaments being prepared by said powder-in-tube method,
• the aspect ratio of each said ribbon-shaped filament being within the range of 4 to 40,
• the thickness of each said filament being within the range of 5 to 50 .mu.m,
• said wire having a substantially circular sectional shape of an at least hexagonal polygonal sectional shape being substantially rotation-symmetrical,
• the longitudinal direction of said plurality of filaments in the section of said wire being substantially perpendicular to the radial direction in said section of said wire, and
• said wire exhibiting a critical current density of at least 2000 A/cm.sup.2 at a temperature of 77 K with no application of a magnetic field.

A flat oxide superconducting stranded wire, which is formed by winding a multifilamentary oxide superconducting wire on a core of a stranded wire being formed by twining a plurality of said multifilamentary oxide superconducting wires and being flatly shaped, wherein said multifilamentary oxide superconducting wires forming said core are prepared by a powder-in-tube method, and comprise:

• a plurality of filaments, consisting essentially of an oxide superconductor, extending along the longitudinal direction of said wire in the form of ribbons;
• and
• a matrix, consisting essentially of a stabilizer, covering said plurality of filaments,
• said plurality of filaments being prepared by said powder-in-tube method,
• the aspect ratio of each said ribbon-shaped filament being within the range of 4 to 40,
• the thickness of each said filament being within the range of 5 to 50 .mu.m,
• said wire having a substantially circular sectional shape or an at least hexagonal polygonal sectional shape being substantially rotation-symmetrical,
• the longitudinal direction of said plurality of filaments in the section of said wire being substantially perpendicular to the radial direction in said section of said wire, and
• said wire exhibiting a critical current density of at least 2000 A/cm.sup.2 at a temperature of 77 K with no application of a magnetic field.

A superconducting conductor, which is formed by spirally winding a plurality of stranded wires each being formed by twining a plurality of multifilamentary oxide superconducting wires and being flatly shaped, on a cylindrical or spiral core in one or more layers, wherein said multifilamentary oxide superconducting wires are prepared by a powder-in-tube method, and comprise:

• a plurality of filaments, consisting essentially of an oxide superconductor, extending along the longitudinal direction of said wire in the form of ribbons;
• and
• a matrix, consisting essentially of a stabilizer, covering said plurality of filaments,
• said plurality of filaments being prepared by said powder-in-tube method,
• the aspect ratio of each said ribbon-shaped filament being within the range of 4 to 40,
• the thickness of each said ribbon-shaped filament being within the range of 5 to 50 .mu.m,
• said wire having a substantially circular sectional shape or an at least hexagonal polygonal sectional shape being substantially rotation-symmetrical,
• the longitudinal direction of said plurality of filaments in the section of said wire being substantially perpendicular to the radial direction in said section of said wire, and
• said wire exhibiting a critical current density of at least 2000 A/cm.sup.2 at a temperature of 77 K. with no application of a magnetic field.