Superconducting properties and microstructures of Bi-2223 AgCu alloy sheathed tapes doped with Ti, Zr or Hf

Abstract

AgCu doped with Ti, Zr or Hf have been used as sheath material for Bi-2223 superconducting tapes prepared by the powder-in-tube technique. Critical current density, J c, was obtained to be 9.2 × 10 4 A/cm 2at 4.2 K, 14 T and 3.4 × 10 4 A/cm 2 at 77 K, 0 T, which is 2–3 times larger than that of non-doped samples. A small amount of doping such as Ti, Zr or Hf of 0.03–0.1 at.% into Ag-10 at.% Cu alloy sheath enhanced growth of large plate-like grains, especially at interfaces between the AgCu alloy sheath and oxide core. Furthermore, Bi-2223 phase alignment was significantly improved. These microstructural modifications are believed to be responsible for the improved high-J c property.