Correlation between the normal state resistivity and the critical current density of Ag sheathed Bi(2223) tapes

Abstract The normal state resistivities of Ag/Bi(2223) tapes with critical current densities between 7 and 34 kA/cm 2 at 77 K were measured after chemical etching of the silver sheath surrounding the superconducting filament. A strong correlation between the critical current density and the normal state resistivity was observed, their product J c × ρ being constant, regardless of the sample quality. This observation is in quantitative agreement with the railway-switch and the parallel pipe model which have been proposed for the explanation of the current transport mechanism in Bi(2223) tapes. Moreover, an extrapolated critical current density value exceeding 1.3 × 10 5 A/cm 2 at 77 K has been deduced for a hypothetical Bi(2223) tape in which all grains are connected by railway switches.