LOW-FREQUENCY AC ELECTRICAL-RESISTIVITY OF GRANULAR Y1BA2CU3O7-DELTA COMPOUNDS

The behaviour (amplitude and phase) of the AC electrical resistivity, rho-(nu) of five bulk polycrystalline Y1Ba2Cu3O7-delta single phase (to within 4%) samples with delta less-than-or-equal-to 0.1 and T(cI) > 90 K, but with very different granular structure, was studied quantitatively up to 120 kHz. The measurements were performed in the temperature range of room temperature down to below the superconducting transition, and at low effective current densities (up to 25 A/cm2) and applied magnetic fields (up to 30 mT). In all cases, within a resistivity resolution of 1-mu-OMEGA-cm, no frequency-dependent effects were observed. Appreciable localization effects, including hopping conductivity, must therefore be excluded in the ab-plane of Y1Ba2Cu3O7-delta materials, for the low energy range analysed.