EFFECTS OF LITHIUM DOPING ON THE FORMATION AND MICROSTRUCTURE OF BULK BI-SR-CA-CU-O

The effects of Li doping on Bi2Sr2CaCu2Ox Pellets has been studied by considering Li substitution for Sr and Cu and Li additions to stoichiometric Bi2Sr2CaCu2Ox. As the Li substitution reduces the melting temperature by as much as 160-degrees-C, melting studies were performed to determine the sintering conditions for melt-quenching. While a variety of stoichiometries all exhibited S-N transitions above 80 K, the transition of Bi2Sr2Ca(Cu0.55Li0.45)2Ox was significantly narrower than other cation combinations. However, Li did not increase T(c) relative to Bi2Sr2CaCu2Ox [1-4]. Microstructural analysis by SEM and SIMS indicated that the Bi, Sr, Ca and Cu are all distributed uniformly throughout the pellet, while the Li distribution is quite inhomogeneous. Furthermore, SIMS depth profiling into the Ag/BSCCOLi interface showed that although the Bi:Sr:Ca:Cu ratio remains relatively constant, the Bi:Li ratio increases by over 100%, indicating that the Li penetrates the Ag interface to a greater extent than the other cations and that Li doping may effect the behaviour at the BSCCO/Ag interface.