Dependence of critical current density on microstructures in superconducting Bi(Pb)-Sr-Ca-Cu-O wires

摘要: The dependence of the critical current density Jc on microstructures in superconducting Ag-sheathed Bi(Pb)-SrCa-Cu-O wires has been investigated. A mixture oxide powders with a composition Bi1.84Pb0.34Sr1.9Ca2.0Cu3.1Ox was calcined and resulting powder placed silver tubes. tubes were processed by drawing rolling to give 0.3 nm thick tapes. tapes annealed at 825-843 degrees C for 300 h intermediate pressing. Different annealing temperatures gave three types sample different microstructures. samples depended kind foreign phases, such as Cu-free (Bi,Pb)-(Sr,Ca)-O phase or 2201 phase, well orientation a-b plane. weak link structure an S-N-S junction regardless conditions. flux pinning force Fp followed power law (1-(T/Tc)2)m; exponent m much larger than that metal superconductors phases.