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 intergrain 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 less 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 order to increase the precision and eliminate possible spurious heating. Also, rho(ct) for each sample has been extracted from the normal-state resistivity. It is found experimentally that for all single phase granular samples of the same composition, but having different granulosity, the corresponding critical current scaled as rho(ct)J(c) fit into the same curve as a function of the reduced temperature. This result opens a way to estimate J(c) in granular samples simply from normal state resistivity measurements.