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

The influence of long length scale structural inhomogeneities on the e lectrical resistivity of polycrystalline YBa2Cu3O7-delta samples is an alyzed on the grounds of an empirical picture proposed by our group so me time ago. For that, the electrical resistivity, rho(T), has been me asured in different polycrystalline YBa2Cu3O7-delta samples, all singl e phase to 4% and with delta less than or similar to 0.15, and the res ults compared with rho(ab)(T), the intrinsic resistivity in the ab pla ne of single crystals with the same nominal composition. Our analysis fully confirms our earlier proposal that the structural inhomogeneitie s at scales much larger than the superconducting correlation length st rongly affects the paraconductivity amplitude, but its reduced tempera ture behaviour is not affected.