Metallic Ag Addition Effects on Y1Ba2Cu3O7-x Superconducting Thick Films

Metallic Ag addition effects on Y1Ba2Cu3O7-x (YBCO) thick film were investigated from the viewpoints of both superconducting properties and microstructure. With the addition of Ag2O (the starting material), the current density at 77 K (Jc), as well as the zero-resistivity temperature (Tc,off), was improved, resulting in Jc=1300 A/cm2 and Tc,off=93 K. The YBCO superconducting phase partly decomposed to yield Y2Ba1Cu1O5, Ba1Cu1O2 and CuO as a result of the addition of metallic Ag, which varied from Ag2O. Ba1Cu1O2, with a melting point around 900°C, promoted liquid phase sintering for YBCO. Although the YBCO superconducting phase decreased by 40 vol% as a result of these decompositions, Jc and Tc,off improved, compared with those in undoped YBCO thick film, because the YBCO was grown into a large plate and densified, and its c-direction was oriented perpendicular to the substrate.