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 B SCCO/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 dens ity (J(c)) is a limiting factor. A requirement for a J(c) of 10(5) A/c m(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 w ere removed from rolled tapes. The thin superconducting layer region n ext to the silver sheath was shown to be the actual current carrying r egion in the tape. These results confirm the presence of a high critic al current density region adjacent to the silver in silver-sheathed ta pes, and provide a basis for further improvements in J(c). Regions of silver were also found to be present in the superconducting core.