Phase evolution of lead oxide compounds corresponding with oxygen release and absorption processes of BSCCO powders during heat treatment

摘要

The phase evolution of lead oxide compounds in (Bi,Pb)_2Sr_2Ca_2Cu_3O_x (BSCCO) precursor powder during heat treatment was studied. The BSCCO powder oxygen release and absorption processes occurring during heat treatment were investigated by using an oxygen analyser. The experimental results show that the oxygen release and absorption processes are related to evolution of the lead oxide compounds in the BSCCO powder. Oxygen absorption may result from the segregation of Pb from the (Bi,Pb)-2212 phase as well as the formation of the Pb_3Sr_(2.5)Bi_(0.5)Ca_2CuO_y (3321) and Ca_2PbO_4 phases. Oxygen release could be related to decomposition of the 3321 and Ca_2PbO_4 phases as well as incorporation of Pb into the (Bi,Pb)-2212 phase. The formation and decomposition of the 3321 and Ca_2PbO_4 phases, which depend on temperature and oxygen partial pressure, have also been identified.