Correlation of radial inhomogeneties and critical current at 77 K in LFZ Bi-2212 textured thin rods

Abstract

The fabrication of thin Bi-2212 rods by laser floating zone techniques gives high critical currents, Ic, but strong radial inhomogeneities in microstructure and physical properties. By changing the precursor stoichiometry or the processing parameters, we have succeeded in improving the homogeneity and the Ic values. Towards the centre of the rods, the superconducting material tends to have lower Tc values associated to higher Bi content in the Bi-2212 superconducting grains. At 77 K, this gradient of Bi originates strong variations of critical current density across the rod.