The effect of intermediate layer densification on the critical current of a Bi-2223 superconducting joint

The effect of intermediate layer densification on the critical current (I (c)) of Bi-2223 superconducting joints was quantitatively studied. First, we evaluated the phase purity, density, and intergrain critical current density (J (c)) of Bi-2223 thick film samples simulating the intermediate layer. The samples were uniaxially pressed to increase the film density. After two heat treatments of the pressed film, an increase in J (c) was achieved. Second, we fabricated superconducting joints by synthesizing an intermediate layer between two Bi-2223 tapes. Applying a uniform uniaxial pressure on the joint resulted in the formation of a homogeneous structure. This process enables the reproducible fabrication of superconducting joints with high n values. The I (c) of the superconducting joint was increased by intermediate pressing (IP) and two heat treatments. However, pressing at high pressures can mechanically damage filaments in the Bi-2223 tapes, leading to a decrease in I (c). Sample characterization showed that the optimum IP pressure range to produce high I (c) was 1.5-2 x 10(8) Pa. We confirmed that pressing densified the intermediate layer of the superconducting joints. Our experimental results and analyses reveal that densification of the intermediate layer increases the I (c) of Bi-2223 superconducting joints.

Automated summary

This study quantitatively investigated the effect of intermediate layer densification on the critical current (Ic) of Bi-2223 superconducting joints. The results showed that pressing the film samples to increase density can enhance the intergrain critical current density (Jc). Additionally, synthesizing an intermediate layer between two Bi-2223 tapes with uniform uniaxial pressure resulted in reproducible superconducting joints with high Ic.