Compositional and microstructural analysis of high I/sub c/ and J/sub c/ Bi-2212 conductors

Compositional analysis of the Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub y/ (Bi-2212) and secondary phases in high-current Bi-2212 conductors was performed. The composition of the Bi-2212 phase in dip-coated Bi-2212 tapes tended toward the Sr-rich end of the Bi-2212 solid solution. The strontium and calcium contents of the Bi-2212 phase in round wire tended to lie closer to the starting composition of the powder. In all cases, there was an excess of bismuth and a deficiency of the alkaline earths with respect to the ideal 2212 stoichiometry. Microstructural analysis by transmission electron microscopy has shown the presence of Bi-2201 intergrowths within Bi-2212 grains and amorphous layers within the colonies of Bi-2212.