MINIMUM CRITICAL-CURRENT DENSITY OF 10(5)-A/CM(2) AT 77-K IN THE THIN-LAYER OF BI(1.8)PB(0.4)SR(2.0)CA(2.2)CU(3.0)O(Y) SUPERCONDUCTOR NEAR THE AG IN AG-SHEATHED TAPES

We report for the first time a minimum critical current density in a BSCCO/Ag polycrystalline sample of 1.1X10(5) A/cm(2) at 77 K in a self-field. For practical applications of(Bi, Pb)(2)Sr2Ca2Cu3Oy (BSCCO-2223) high-temperature superconducting material, the critical current density (J(c)) is a limiting factor. A requirement for a J(c) of 10(5) A/cm(2) in long length wires and tapes, at 77 K and high magnetic field, has been established. The transport J(c) were measured on samples that retained a 10 mu m thickness of the superconducting core after they were removed from rolled tapes. The thin superconducting layer region next to the silver sheath was shown to be the actual current carrying region in the tape. These results confirm the presence of a high critical current density region adjacent to the silver in silver-sheathed tapes, and provide a basis for further improvements in J(c). Regions of silver were also found to be present in the superconducting core.