Effect of Ca-Cu-O Particle Size on the Phase Evolution Process of Bi-2223 High-Temperature Superconductors

The spray pyrolysis technology produces Bi-2223 precursor powders in large quantities with high stability. In our study, we have combined this method with the two-powder process to enhance the current-carrying performance of Bi-2223 tapes. Aiming at understanding the effect of Ca-Cu-O particle size on the phase evolution mechanism of Bi-2223 high-temperature superconducting tapes. Our findings indicate that with the bigger Ca-Cu-O particle, the Bi-2223 formation temperature increases, but the formation rate decreases. The Bi-2223 tape fabricated with the precursor powders containing larger Ca-Cu-O particles, with an average size of ∼2.00 ± 0.05 um, exhibits better current-carrying performance. It shows an increase of ∼30% compared to the critical current
I
_c
of that with smaller particles. This enhancement is attributed to the slower reaction of the Ca-Cu-O particles with larger size, leading to complete formation and no decomposition even when subjected to 830 °C for 50 hours.