INFLUENCE OF THE POLYCRYSTALLINITY ON THE PARACONDUCTIVITY IN COPPER-OXIDE SUPERCONDUCTORS

The influence of long length scale structural inhomogeneities on the electrical resistivity of polycrystalline YBa2Cu3O7-delta samples is analyzed on the grounds of an empirical picture proposed by our group some time ago. For that, the electrical resistivity, rho(T), has been measured in different polycrystalline YBa2Cu3O7-delta samples, all single phase to 4% and with delta less than or similar to 0.15, and the results compared with rho(ab)(T), the intrinsic resistivity in the ab plane of single crystals with the same nominal composition. Our analysis fully confirms our earlier proposal that the structural inhomogeneities at scales much larger than the superconducting correlation length strongly affects the paraconductivity amplitude, but its reduced temperature behaviour is not affected.