Critical Current Density and Flux Pinning Mechanism in Flat-Rolled Sr-122/Ag Tapes

We fabricate Ag sheathed Sr-122 superconducting tapes via a scalable rolling process. The critical current density and its homogeneity are studied by electrical and magnetic measurements. At 4.2 K and 10 T, the transport critical current density J
_c
achieves 3.3×10
⁴
A/cm
²
. The magneto-optical images of the superconducting core indicate a global supercurrent throughout the sample. A scaling analysis reveals a universal behavior of normalized pinning force as a function of reduced field, suggesting that grain boundary is the prevailing pinning source. Combined with the scanning electron microscope images of the superconducting core, we conclude that the pores and the relatively low c -axis texture are the main factors that limit the critical current density.