Effect of Different Nanosized NiO Addition on Ag-Sheathed (Bi_1.6Pb_0.4)Sr₂Ca₂Cu₃O₁₀ Superconductor Tapes

Abstract

(Bi_1.6Pb_0.4)Sr₂Ca₂Cu₃O₁₀–(NiO) _x superconductor with x=0, 0.01, 0.02, 0.03, 0.04, and 0.05 wt.% was prepared using the coprecipitation technique. The average size of NiO used was 8 nm and 16 nm. The highest value of the transport critical current density, J _c in the bulk form was observed in the x=0.01 wt.% samples for both sizes. Based on this result, Ag sheathed superconductor tapes with starting composition (Bi_1.6Pb_0.4)Sr₂Ca₂Cu₃O₁₀–(NiO)_0.01 (with NiO particle size 8 and 16 nm) were fabricated using the powder-in-tube method. The effect of these nanoparticles addition on the microstructure, phase formation, and transport critical current density were studied. The J _c of the tape at 77 K in zero fields with NiO (8 nm) addition (4500 A/cm²) was slightly higher than that of NiO (16 nm) added tape (4120 A/cm²). The nonadded tape showed a lower J _c (1080 A/cm² at 77 K). These results indicated that magnetic nanoparticles such as NiO could act as an effective flux pinning centers leading to the enhancement of J _c in the bulk and tape form. Moreover, NiO with size closer to the coherence length, ξ was more effective in enhancing J _c.