Influences of Pb content on the critical current of Bi-2223 multi-filamentary tapes

• Optimized Pb content was obtained for PIT process of Bi-2223 tapes.
• Influences of Pb content on carrier concentrations was investigated.
• Relationship between Pb content, microstructure and critical current was discussed.

Multifilament Bi-2223/Ag tapes with different Pb contents in precursor powders were fabricated by powder in tube (PIT) method. The influence of Pb contents on the phase formation, microstructure and critical current density of Bi-2223/Ag tapes were systematically investigated. X-ray photoelectron spectroscopy (XPS) demonstrated that the content and oxidation states change of Pb ions can influence the carrier concentration of superconducting phase. Scanning electron microscopy (SEM) revealed that the variation of Pb content can lead to the difference in microstructure due to the change of thermodynamic properties. The results showed that with the Pb content of x=0.35 in the nominal composition of Bi2−xPbxSr2Ca2Cu3Oy, proper content of liquid phase can be formed during the sintering process, thus maximum critical current (Ic) was obtained. The correlation between the transport property, carrier concentration and Pb content was discussed.