Investigation on synthesis of Bi-based thin films on flat sputter-deposited Ag film by melting process

We report on the fabrication of ribbon-like thin films on flat sputter-deposited Ag films whose surface smoothness remained within the order of tens of nm. It was found that the addition of Pb to the starting material improves the wettability of molten phase and facilitates the growth of Bi-2212 ribbon-like thin films on a flat Ag substrate, and that the increase of Ca and Cu in starting material suppresses the intergrowth of the Bi-2201 phase in ribbon-like thin films. By using (Bi,Pb)-2246 powders, with nominal composition of Bi1.6Pb0.4Sr1.6Ca3.2Cu4.8Oy, as the starting material, the superconducting Bi-2212 ribbon-like thin films with an onset Tc at 74 K on a very flat Ag substrate were successfully synthesized. Additionally, the growth mechanism of ribbon-like thin films on flat Ag substrate was investigated by in situ high temperature microscope observation