Sample - substrate interactions during melting of Bi-2212 on Ag

Abstract

During melt-processing of Bi 2.2 Sr 2.05 Ca 0.95 Cu 2 O x (Bi-2212) thick films and bulk components, a liquid phase is formed which dissolves silver from the silver substrate. The dissolved silver precipitates during cooling as soon as the Bi-2212 phase is reformed. The amount of silver taken up from the substrate during the whole heat treatment is 3 wt% if the maximum processing temperature T max does not exceed 910 • C and 4 wt% if T max > 910 • C if the starting Bi-2212 powder contained no silver. If 2.7 wt% silver were added to the raw Bi-2212 powder the final silver amount of fully processed samples is 3.5 wt% if T max < 910 • C, but still 4 wt% if T max > 910 • C. Excessive grain boundary corrosion of the silver substrate can be avoided by adding 2.7 wt% silver to the raw Bi-2212 powder prior to processing.