Influence of Pb Doping on Phase Stability and Superconducting Properties of Bi₂₋ₓPbₓSr₂Ca₂Cu₃O₁₀ Ceramics

This work explores the impact of lead (Pb) doping on the structural and superconducting properties of Bi2-xPbxSr2Ca2Cu2Oy ceramics with x = 0.0, 0.1, 0.2, and 0.3. Samples were prepared using a solid-state reaction route: high-purity powders were mixed, calcined at 820 °C for 12 hours, pressed into pellets, and sintered at 840 °C for 72 hours with intermittent grinding and repressing. X-ray diffraction (XRD) showed that increasing Pb content stabilised the Bi-2223 phase and suppressed Bi-2212 impurities. Four-probe resistivity measurements between 120 K and 80 K determined Tc, onset and Tc, zero at 100 K conditions, revealing an increase in Tc, onset from 108.0 K (x = 0.0) to 111.0 K (x = 0.3) and in Tc, zero from 105.5 K to 108.2 K. Critical current density (Jc) measured at 100 K rose from 1.0 × 10⁴ A/cm² to 1.7 × 10⁴ A/cm² across the same doping range. The enhancements in Tc and Jc are attributed to improved oxygen stoichiometry and stronger intergranular connectivity induced by Pb doping. The best performance was observed at x = 0.3, suggesting that Bi2-xPbxSr2Ca2Cu2Oy is a promising candidate for superconducting applications near 100 K.