TRANSPORT AND MAGNETIC-PROPERTIES OF YBCO AG COMPOSITES/

The transport and magnetic properties of pure Y-Ba-Cu-0 and Y-Ba-Cu-O/ Ag composites prepared by the co-precipitation method have been studie d. The normal state resistivity decreases with addition of silver. The magnetic properties reveal that addition of silver to the YBCO sample degrades the superconducting properties. However, the increase in tra nsport critical current density both at 77 and 4.2 K suggests the pres ence of proximity junctions (SNS) at the intergranular regions. The ma gnetic critical current density is reduced and the magnetization hyste resis loops measured at both 77 and 4.2 K shrink with addition of silv er, indicating changes in the inter- and intragranular properties. The flux creep rate increases and the activation energy calculated from t he relaxation data (5.5 T) at 4.2 K decreases with increasing silver c oncentration, showing a reduction in the number of pinning centres.