THE HIGH-FIELD MAGNETIC DEPENDENCE OF CRITICAL CURRENT-DENSITY AT 4.2 K FOR AG-SHEATHED BI2SR2CACU2OY SUPERCONDUCTING TAPE

Critical current density (Jc) at 4.2 K and its dependence on applied magnetic field was measured for Ag-sheathed Bi2Sr2CaCu2Oy superconducting tape. The specimen showed a strong grain alignment which could be attained by adjusting the conditions of heat treatment. The degree of crystal orientation (F) was evaluated to be up to 95% by XRD for this specimen. In the case of magnetic field applied in a direction parallel to the tape, the Jc initially decreased with the magnetic field from 1.2×105 A/cm2 at 1 T to 5×104 A/cm2 at 10T and then remained almost constant up to 23 T. As the F value decreased from 95%, Jc also decreased. The pinning force (Fp) of the 95%-F-value tape was estimated to be about 1×1010 N/m3 at 23 T. This value is larger than those of conventional low-Tc superconductors. © 1990 The Japan Society of Applied Physics.