The effect of starting material composition on the growth of Bi-based ribbon-like thin films

The effect of Pb addition and Ca, Cu enrichment in starting material on the formation of Bi-2212 ribbon-like thin films on a flat Ag substrate was studied. It was found that the addition of Pb to the starting material improves the wettability of the molten phase to Ag substrate and facilitates the growth of ribbon-like thin films, and that the increase of amount of Ca and Cu in starting material suppresses the intergrowth of Bi-2201 phase in Bi-2212 ribbon-like thin films. Using (Bi, Pb)-2246 powders, with nominal composition of Bi_1.6Pb_0.4Sr_1.6Ca_3.2Cu_4.8O_y, as starting material, the superconducting Bi-2212 ribbon-like thin films with an onset T_c at 74 K were successfully synthesized on a flat Ag substrate.