Magnetic and transport properties of superconducting (YBa2Cu3O7-δ)1-xAgx ceramics

The introduction of silver in the intergranular space of YBa2Cu3O7 ceramics improves their normal state electrical and mechanical properties. The authors report a study of such composites of which the grain size was found to increase with the annealing temperature, and goes through a maximum around 20% wt. silver for a constant annealing temperature (1000°C). Moreover, a maximum in the filling factor of YBa2Cu3O7 is found from AC susceptibility measurements for X≃15% wt. of silver, which also corresponds to the maximum of the current density. The intergranular silver is found to improve the diamagnetic shielding in very low field. The irreversible fields, Hcs, as determined by magnetoresistance are only decreased by ~10% for a composite containing ~15% weight of silver