Jc characteristics of textured Bi-based oxide tapes

Critical current densities J_c have been measured by both the resistive and the magnetic methods at various temperatures and magnetic fields for grain-oriented Bi₂Sr₂Ca₁ Cu₂O_x/Ag composite tapes which were prepared by the combined process of doctor blade casting and crystal growth from the partially molten state. At 77 K, J_c of the tapes was greater than 10⁴ A/cm² in zero magnetic field. However, J_c at 77 K is very sensitive to an applied magnetic field due to the large flux creep. This sensitivity of J_c to the magnetic field is significantly reduced at lower temperatures such that J_c´s of a practical level (~10⁵ A/cm² ) are obtained at fields above 25 T at 4.2 K. The textured tape has an anisotropy in J_c with respect to magnetic field direction. This anisotropy increases with increasing temperature. However, the anisotropy factor at 4.2 K is small (~1.5) and should not limit practical application