Abstract
Bi-Pb-Sr-Ca-Cu-O superconducting films were prepared on poly- or single crystal MgO substrate by sol-gel method. For the starting solution, we used acetates-solutes propionic(C2H5COOH) or butyric acid(C3H7COOH) with or without the addition of aqueous ammonia. The films were prepared by repeating the process of coating and decomposition(at 700°Cfor30 min) 3-10 times and by fin ally sintering at 855°C for 12h. The increase of CH2 number of solvent and the addition of NH3⋅H2O increase the values of pH and viscosity of the solution. These increases make a film twice thickerthan the film obtained from propionic acid solution. For the film sample prepared using butyric acid solution with 6 vol% of NH3⋅H2O, the percentage of high-Tc phase was determined by XRD(002) lines to be 40%, which was higher by 7% than that of the film prepared using propionic acid solution. The highest value of Tco(77K) was obtained for the film using butyric acid-NH3⋅20 system.
