SCALING OF CRITICAL CURRENTS VERSUS TEMPERATURE IN GRANULAR Y1BA2CU3O7-DELTA SUPERCONDUCTORS AT ZERO APPLIED MAGNETIC-FIELD

Simultaneous measurement of critical currents at zero applied magnetic field, J(c), as a function of the temperature, and of the average int ergrain resistivity, rho(ct), have been performed for six single phase (to better than 5%) polycrystalline Y1Ba2Cu3O7-delta (YBCO) samples, with distinct granularity characteristics, i.e., having 20 muOMEGAcm l ess than or similar to rho(ct) less than or similar to 110 muOMEGAcm. J(c) has been measured by using a low-frequency induction method in or der to increase the precision and eliminate possible spurious heating. Also, rho(ct) for each sample has been extracted from the normal-stat e resistivity. It is found experimentally that for all single phase gr anular samples of the same composition, but having different granulosi ty, the corresponding critical current scaled as rho(ct)J(c) fit into the same curve as a function of the reduced temperature. This result o pens a way to estimate J(c) in granular samples simply from normal sta te resistivity measurements.