Intergranular Coupling, Critical Current Density, and Phase Formation Enhancement of Polycrystalline Bi1.6Pb0.4Sr2Ca2Cu3O10−y Superconductors by α-Al2O3 Nanoparticle Addition

In this work, the effect of alumina (α-Al2O3) nanoparticle addition on the phase formation and superconducting properties of Bi1.6Pb0.4Sr2Ca2Cu3O10−y ((Bi,Pb)-2223) system has been investigated. Six samples with different alumina nanoparticle contents (0.0, 0.1, 0.2, 0.3, 0.5, and 1 wt % of the sample’s total mass) were prepared by conventional solid-state reaction. X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods have been used to study phase formation and microstructure of the prepared samples, respectively. Also, electrical resistivity and critical current density of the prepared samples were measured by four-probe technique. AC susceptibility of the samples has been measured by an LCR meter. XRD results showed that addition of small amounts of the alumina nanoparticles improves (Bi,Pb)-2223 phase formation significantly. Temperature dependency of AC susceptibility measurements revealed that addition of α-Al2O3 nanoparticles improves the intergranular coupling. The I-V measurements show that critical current density of samples increased from about 36 A/cm 2 for the alumina nanoparticle-free sample to about 107 A/cm 2 for the sample with 0.5 wt % α-Al2O3 nanoparticles.