Effect of nano-sized PbO on the transport critical current density of (Bi1.6Pb0.4Sr2Ca2Cu3O10)/Ag tapes

The effect of nano-sized PbO (10–30 nm) addition on the transport critical current density, J_c of (Bi_1.6Pb_0.4)Sr₂Ca₂Cu₃O₁₀ (PbO)_x (x=0–0.15 wt%) was investigated. J_c of PbO added pellet samples showed the maximal value at x=0.05 wt%. Using this result, Ag-sheathed (Bi_1.6Pb_0.4)Sr₂Ca₂Cu₃O₁₀ (PbO)_x/Ag tapes (x=0 and 0.05 wt %) were fabricated by the powder-in-tube (PIT) method. The tapes were sintered for 50 h and 100 h at 845 °C. The temperature dependence of J_c for the non-added and PbO added tapes in applied field was investigated. J_c of the non-added tapes was 4510 A/cm² at 40 K and 949 A/cm² at 77 K. J_c of (Bi_1.6Pb_0.4)Sr₂Ca₂Cu₃O₁₀ (PbO)_0.05/Ag tape sintered for 100 h was 26,800 A/cm² at 40 K and 10,700 A/cm² at 40 K, which was higher than the tapes sintered for 50 h (8590 A/cm² at 40 K and 1880 A/cm² at 77 K). Nano-sized PbO added tapes sintered for 100 h showed a higher J_c (more than 10 times) under magnetic field (0–0.75 T) compared with the non-added tape. A combined effect of enhanced flux pinning and improved microstructure led to the significant increase in J_c of the nano-sized PbO added tapes.