INFLUENCE OF SILVER CLADDING ON THE FORMATION AND ALIGNMENT OF THE (BI2-XPBX)SR2CA2CU3O10+DELTA PHASE

Cross-section transmission electron microscopy was used to investigate the interaction of silver with (Bi,Pb)-Sr-Ca-Cu-O phases during the f ormation of (Bi2-xPbx)Sr2Ca2Cu3O10+delta (Bi-2223) in a silver-sheathe d wire containing a powder composed of (Bi,Pb)2Sr2CaCu2O8+delta (Bi-22 12) plus second phases. Observations of the interfacial regions of sam ples quenched at different stages of conversion revealed that (1) Bi-2 212 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 conversio n reaction; and (3) Bi-2223 is detected at the silver/powder interface hundreds of minutes before it begins to appear in regions of the powd er away from the interface. The implications of these results are pres ented and discussed.