| In order to investigate the influence of cold-working degree and thermomechanical treatment cycle on the critical current density(Jc), magnetic field dependence of Jc and microstructure of Ag sheathed Bi-Pb-Sr-Ca-Cu-O ceramic superconducting tapes, various types of specimens were prepared by powder-in-tube method. By means of XRD and EPMA, major 2223 phase, minor 2212phase and impurity phases such as Ca₂PbO₄, CuO and (Sr, Ca)₃Cu_5O_x were confirmed to exist in oxide layer. It was made clear that the critical current density strongly depends on the degree of cold-working and the number of TMT cycle. This is attributed to the refining of microstructure such as densification and preferred orientation of c plane in 2223 superconducting phase. Magnetic field dependence of critical current density could be improved for BPSCCO tapes prepared with the higher degree of cold-working. |
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