SCALING OF THE VOLUME PINNING FORCE IN SUPERCONDUCTING WIRES AND TAPES BASED ON BI2SR2CACU2OX

Silver-sheathed Bi2Sr2CaCu2Ox wires and tapes were fabricated by the powder-in-tube method. The wires show critical current densities of about 18 000 A/cm2 in zero magnetic field and 5300 A/cm2 in a field of 23 T at 4.2 K, respectively. A detailed study of the critical current density as a function of the temperature and the magnetic field resulted in a scaling behavior of the derived volume pinning force FV, which approximately obeys the formula F V≊H*h0.75(1-h)2.75. Here H* represents the irreversible field and h=H/H* is the scaling field. Further, the critical current densities of our textured tapes were measured. In zero magnetic field they reach critical current densities of about 43 000 A/cm2. In a magnetic field applied perpendicularly to the current direction the critical current density shows an anisotropic behavior with respect to the direction of the magnetic field. For a magnetic field of 23 T applied parallel to the tape plane the tapes reached critical current densities of about 15 000 A/cm2 at 4.2 K. In the unfavorable direction, the magnetic field is applied perpendicularly to the tape plane, the current density was reduced to 10 000 A/cm2. The volume pinning force in the tapes was investigated versus the magnetic field at 4.2 K and a power-law behavior FV≊Hp with p=0.75 for H parallel and p=0.55 for H perpendicular to the tape plane was found. © 1994 American Institute of Physics.