A model for the critical current in (Bi,Pb)2Sr2Ca2Cu3Ox silver-sheathed tapes: The role of small-angle c-axis grain boundaries and of the texture

摘要: Detailed analyses of the microstructure silver-sheathed (Bi, Pb)2Sr2Ca2Cu3Ox tapes by scanning electron microscopy and X-ray diffraction, as well measurements critical current density electrical resistivity isolated superconductor cores, have been performed on a series short samples with filament thicknesses approx. 40–50 μm jc (77 K, B=0) ≈ 15 000 A/cm2. The experimental data cannot be satisfactorily explained within framework “brick wall” model for transport in highly textured polycrystalline high-temperature superconductors. We therefore propose new Bi/Pb(2223) tapes, based frequent small-angle c-axis grain boundaries that serve conducting connections between neighbouring grains, without necessity supercurrent to flow perpendicularly CuO planes. provides semi-quantitative description field dependence its anisotropy, correlates them characteristics microstructural features tapes.