Evidence for enhancement of critical current by intergrain Ag in YBaCuO-Ag ceramics

We report the evidence for enhancement of critical current density Jc by ∼50%, which occurs when ∼10 wt. % Ag is added to Y1Ba2Cu3O7−δ ceramics. The maximal Jc (∼700 A/cm2 at T=77 K) appears simultaneously with maximum YBaCuO compactness in the samples. The silver fills the intergranular space (holes) without Cu substitution, and the critical temperature Tc is not reduced from the bulk value (∼91 K). Normal-state resistivity of Ag-YBaCuO samples is decreased by an order of magnitude, and samples exhibit improved contact resistance and resistance to water. While the critical density is improved by adding ∼10 wt. % Ag, it decreases at higher Ag concentrations.