A REACTION COUPLE STUDY OF REACTIONS AMONGST BI2SR2CACU2OX, CA2PBO4, AND CUO TO FORM (BI, PB)(2)SR2CA2CU3OX

Reaction couples in which Bi(2)Sr(2)CaCu(2)Ox (2212) was in contact with a mixture of Ca2PbO4 and CuO were made to study phase evolution during the formation of (Bi, Pb)(2)Sr2Ca2Cu3Ox [(Bi, Pb)-2223]. During heat treatment in 7.5% O-2/Ar, two reaction layers formed at the interface; (Bi, Pb)-2223 formed on the 2212 side and (Sr, Ca)(2)CuO3 formed on the other side. Ca2PbO4 decomposed in the presence of 2212. Ca2PbO4 has multiple roles in the formation of(Bi, Pb)-2223 that are both positive and negative. The Ca and Pb released from Ca2PbO4 react with 2212 and CuO to form (Bi, Pb)-2223, which is positive. The Ca can also react with CuO to form (Sr, Ca)(2)CuO3. This is a negative role, since forming (Sr, Ca)(2)CuO3 adds an extra step in the reaction path to form (Bi, Pb)-2223. These results show that the mixture of 2212, Ca2PbO4, and CuO is not well suited for forming (Bi, Pb)-2223, since the formation of (Sr, Ca)(2)CuO3 from this mixture is unavoidable.