PHASE-EQUILIBRIA OF THE BISMUTH OXIDE CALCIUM-OXIDE COPPER-OXIDE SYSTEM IN OXYGEN AT 1 ATM

Phase equilibria in the bismuth oxide-calcium oxide-copper oxide syste m have been determined at 1 atm pressure in oxygen over the temperatur e range of 750 degrees-1000 degrees C. The phases found to be stable a t 750 degrees C are Bi2CuO4, CuO, Ca2CuO3, CaO, Bi2Ca2O5, Bi6Ca4O13, B i14Ca5O26, a rhombohedral Bi-Ca oxide solid solution (Rh-ss), and a fa ce-centered cubic Bi-Ca oxide solid solution (Fcc(ss)) that includes B i2O3. At 800 degrees C, the stable phases are Bi2CuO4, CuO, Ca2CuO3, C aO, Bi2Ca2O5, Bi6Ca4O13, a hexagonal Bi-Ca oxide solid solution (delta (ss)), Rh-ss, Fcc(ss), and liquid. The phases found to be stable at 85 0 degrees C are CuO, Ca2CuO3, CaO, Bi2Ca2O5, Bi6Ca4O13, Fcc(ss), and l iquid. The phases found to be stable at 900 degrees C are CuO, Ca2CuO3 , CaO, Bi2Ca2O5, a body-centered cubic Bi-Ca oxide solid solution (Bcc (ss)), and liquid. The stable phases at 950 degrees C are CuO, Ca2CuO3 , CaO, and liquid. At 1000 degrees C, the stable phases are CuO, Ca3Cu 7O10, Ca2CuO3, CaO, and liquid.