PERCOLATION IN YBA2CU3O7-DELTA CUO MIXTURES

The critical exponents of the electrical conductivity a for several te mperatures above T-c and of the critical current density J(c) at 77 K, are investigated in composites formed between the superconductor YBa2 Cu3O7-delta and the insulator CuO. Their experimental calculated value s agree with their theoretical counterpart obtained from the continuum percolation model (''Swiss-cheese'' model). A slight improvement of s uperconducting properties of YBa2Cu3O7-delta is observed also at a low CuO concentration (5%).