Effect of Different Nanosized NiO Addition on Ag-Sheathed (Bi1.6Pb0.4)Sr2Ca2Cu3O10 Superconductor Tapes

(Bi1.6Pb0.4)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, Jc 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 (Bi1.6Pb0.4)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 Jc 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 Jc (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 Jc in the bulk and tape form. Moreover, NiO with size closer to the coherence length, ξ was more effective in enhancing Jc.