Effect of Different Nanosized MgO on the Transport Critical Current Density of Bi1.6Pb0.4Sr2Ca2Cu3O10 Superconductor

Magnesium oxide powders with average particle size 20 and 40 nm were added into Bi1.6Pb0.4Sr2Ca2Cu3O10 (Bi,Pb-2223) with nominal composition Bi1.6Pb0.4Sr2Ca2Cu3O10(MgO) (x) (x=0-0.15 wt.%). The transport critical current density (J (c)) and transition temperature were determined using the four-probe method. The structure and microstructure were examined by X-ray diffraction method and scanning electron microscopy, respectively. The transition temperature and J (c) increased with nanosized MgO addition. The 20 nm MgO added samples showed a higher J (c) compared with the 40 nm MgO added samples. J (c) was higher as size of MgO was closer to the coherence length of the superconductor. These results showed that the size variation of flux pinning center at the nanoscale is important in enhancing J (c).