Transport critical current density of (Bi1.6Pb0.4)Sr2Ca2Cu3O10/Ag superconductor tapes with addition of nanosized CoFe2O4

Abstract

The effect of nanosized CoFe2O4 (60 nm) addition on the transport critical current density, Jc, of (Bi1.6Pb0.4)Sr2Ca2Cu3O10(CoFe2O4)x (x = 0–0.05 wt%) superconductor prepared by the co-precipitation method was investigated. The optimal Jc (measured using the four-point probe method) was observed in the x = 0.01 wt% pellets. Using this optimal wt%, Ag-sheathed (Bi1.6Pb0.4)Sr2Ca2Cu3O10(CoFe2O4)0.01 superconductor tapes were fabricated using the powder-in-tube method. The tapes were sintered for 50 and 100 h at 845 °C. The phase and microstructure of the samples were determined using the powder X-ray diffraction method and scanning electron microscopy, respectively. The temperature dependence of Jc for the tapes in various applied magnetic fields was also measured. Jc of (Bi1.6Pb0.4)Sr2Ca2Cu3O10(CoFe2O4)0.01/Ag tapes sintered for 100 h was 22,420 A/cm2 at 30 K. The non-added tapes sintered for 100 h showed a much lower Jc (8280 A/cm2 at 30 K). This study showed that addition of CoFe2O4 nanoparticles enhanced the transport critical current density in the (Bi1.6Pb0.4)Sr2Ca2Cu3O10 superconductor tapes. This result is consistent with the previous calculations on frozen flux superconductor in a nanomagnet–superconductor hybrid system.