Formation of Bi, Pb-2223 and Microstructural Evolution in Pb-Ca-Cu Deposited Bi-2212(001) Single Crystal by Heat Treatment

In order to study the mechanism of phase transformation from Bi-2212 to Bi-2223, we fabricated Pb-Ca-Cu deposited Bi-2212 (001) single crystals as precursors of the Bi,Pb-2223 phase. These single crystals were heated in a sintered Bi-Pb-Sr-Ca-Cu-O pellet, and microstructure was observed by analytical electron microscopy. As a result of the microstructural observation around the Bi,Pb- 2223 phase, two formation paths of Bi,Pb-2223 were recognized. One is the formation from a liquid phase which is formed by Bi- 2212 and melting of the secondary phases such as (Ca,Sr)2PbO4 and CuO. The other is the growth of Bi,Pb-2223 into Bi-2212 phase by diffusion of Pb, Ca and Cu atoms along the directions of Bi-2212.