Phase diagram of the system Bi1.6Pb0.4Sr2CuO6-CaCuO2 above 825°C

Abstract The phase diagram of the lead-substituted Bi 2 O 3 -SrO-CaO-CuO system has been investigated, in the temperature range 825°C–1100°C, and in static air, along the line Bi 1.6 Pb 0.4 Sr 2 Ca n−1 Cu n O 2n + 4 + x . For n~3, the ration SR Ca has been systematically varied. The diagram involves nine distinct solid phases and two liquid ones. The transformation and melting lines of the superconducting n = 1, 2, 3 phases are located below 900°C. Below the solidus(~855°C), the sequence of stable {n} phases is {1}, {1} + {2}, {2}, {2} + {3}, and {3}. The {3} phase (110K) exists, as dominant phase, between ~835°C and ~875°C, for 3 ~900°C), mainly contains the transformation and melting lines of CuO, (Ca, Sr) 2 CuO 3 , and (Ca, Sr) 14 Cu 24 O y . The presence of Pb shifts the transformation lines of the superconducting phases downwards by 10–15°C. The practical implications of this diagram are discussed.