Influence of silver cladding on the formation and alignment of the (Bi2−xPbx)Sr2Ca2Cu3O10+δ phase

Abstract
Cross‐section transmission electron microscopy was used to investigate the interaction of silver with (Bi,Pb)‐Sr‐Ca‐Cu‐O phases during the formation of (Bi2−xPbx)Sr2Ca2Cu3O10+δ (Bi‐2223) in a silver‐sheathed wire containing a powder composed of (Bi,Pb)2Sr2CaCu2O8+δ (Bi‐2212) plus second phases. Observations of the interfacial regions of samples quenched at different stages of conversion revealed that (1) Bi‐2212 is initially in direct contact with silver, with the (001) planes parallel to the interface; (2) an amorphous layer between Bi‐2212 and silver appears during the induction period that precedes the conversion reaction; and (3) Bi‐2223 is detected at the silver/powder interface hundreds of minutes before it begins to appear in regions of the powder away from the interface. The implications of these results are presented and discussed.