NOVEL POLYMER-SOLUTION SYNTHESIS OF THE 110-K SUPERCONDUCTING PHASE IN THE BISMUTH SYSTEM

A simplified and highly efficient route to the 110 K (Bi1-xPbx)2Sr2Ca2Cu3O10+delta superconductor has been developed, based on the use of polyethylenimine aqueous solutions containing the corresponding metal acetates. Characterization of the starting solutions by UV-vis spectroscopy has contributed to the optimization of the synthetic procedure, whereas IR spectroscopy and TGA results, combined with XRD patterns, provide valuable information on intermediates. Ac magnetic susceptibility studies are consistent with XRD results, indicating the presence of the (Bi1-xPbx)2Sr2CaCu2O8+delta' 80 K superconducting phase before final sintering. Improved sintering conditions result in a nearly single-phase 110 K superconductor. In contrast to other solution methods, the use of polyethylenimine as active matrix agent gives rise to homogeneously sized but relatively large (ca. 20 mum) particles.