Development of a novel fabrication technique for high-quality Bi-2223 bulks with high superconducting performance

The superior intergranular connectivity and strong flux pinning are indispensable for achieving high current capacity in Bi-2223 high-temperature superconductors (HTS). In contrast to the traditional one-step sintering method, a newly developed pressing extension texture enhancement (PETE) method was employed to synthesize high-quality Bi-2223 bulks with larger superconducting phase content of 98.5 % and stronger textural structure of 97.8 %. The improved superconducting quality is beneficial for optimizing carrier concentration, and high critical temperature (Tc- 109.4 K) has been obtained. High-resolution transmission electron microscopy (HRTEM) images further reveal the inhibition of amorphous phase and secondary phase particles at grain boundaries, along with enhanced inter-grain connections during the PETE process. The higher inter-grain Jc in 2nd Bi-2223 (Jc,inter-77.3 A/cm2 at 97 K) compared with 1st Bi-2223 (Jc,inter-3.68 A/cm2 at 95 K) was found. Moreover, an enhancement in intra-granular pinning force density (Fp) and a transition in the flux pinning mechanism were observed at different temperatures. And the larger intra-grain Jc (Jc, intra -107 A/cm2 at 4.2 K,0 T) in 2nd Bi-2223 was obtained. Our work provides a novel technique for preparing high-performance Bi-2223 superconducting bulks, establishing a solid foundation for in-depth study on Bi-2223 superconductors.