YBACUO AND YBACUO AG SUPERCONDUCTING THICK-FILMS - PROCESSING, PROPERTIES AND DEGRADATION/

YBaCuO and YBaCuO/Ag thick films (similar to 20 mu m) were deposited o nto Al2O3, spinel and ZrO2-based substrates. The films were characteri zed by X-ray diffraction (XRD), reflected light optical microscopy (RL OM), scanning electron microscopy (SEM-EDX) and d.c. resistivity measu rements (77-300 K). The effect of the calcining cycle on the microstru cture, adherence and electrical properties was determined. Superconduc ting films with T(R = 0) greater than or equal to 85 K were only obtai ned in the ZrO2-based substrates. Silver addition promoted liquid appe arance at lower temperatures and improved the electrical properties of the film. Environmental, as well as thermal cycling degradation, were studied by de resistivity measurements. Water and CO2 attacks lead to a significant increase on the room temperature resistivity of the fil m; conversely, thermal cycling between 77 and 290 K did not affect the electrical properties. The effect of the substrate roughness was also investigated.