Preparation of nano-scale magnetite Fe3O4 and its effects on the bulk bi-2223 superconductors

Nano-scale magnetite (Fe3O4) powders were prepared from metallic iron and distilled water by wet milling technique. Magnetite powders so obtained were added to Bi1.6Pb0.4Sr2Ca2Oy superconductor by 0.00 0.05, 0.10 and 0.30 wt (x), with solid state reaction method. The structural and superconducting properties were studied by x-ray diffraction, transmission electron microscopy, magnetization and magnetic susceptibility measurements. Single-phase magnetite samples with average particle size about 25 nm were obtained with the wet milling technique. Nanoscale magnetite additions up to 0.10 wt % enhance the critical current density (J(c)) of the superconductor preserving the fraction of the high T, phase Bi-2223. Magnetite additions above 0.10 wt % decrease the critical parameters (T-c, J(c)) and the fraction of the high T-c phase.