Investigations of PbO-modified Bi-Sr-Ca-Cu-O superconductors by Auger electron spectroscopy

High-temperature superconducting ceramic with the nominal composition Bi2Pb0.5Sr2Ca2.5Cu3.5Ox was prepared by firing at different temperatures and investigated by high-resolution Auger electron spectroscopy (AES). The ceramic material was inhomogeneous with a higher concentration of calcium at the grain boundaries. Generally, the differences in concentration of calcium are less pronounced for ceramics fired at higher temperatures. In PbO-modified Bi-Sr-Ca-Cu-O superconducting material lead was observed mainly at the grain boundaries. Depth profiling through the grain boundaries of Bi-Sr-Ca-Cu-O material fired at higher temperatures reversed the concentration variation of bismuth and oxygen.