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 system have been determined at 1 atm pressure in oxygen over the temperature range of 750°–1000°C. The phases found to be stable at 750°C are Bi 2 CuO 4 , CuO, Ca 2 CuO 3 , CaO, Bi 2 Ca 2 O 5 , Bi 6 Ca 4 O 13 , Bi 14 Ca 5 O 26 , a rhombohedral Bi‐Ca oxide solid solution (Rh ss ), and a face‐centered cubic Bi‐Ca oxide solid solution (Fcc ss ) that includes Bi 2 O 3 . At 800°C, the stable phases are Bi 2 CuO 4 , CuO, Ca 2 CuO 3 , CaO, Bi 2 Ca 2 O 5 , Bi 6 Ca 4 O 13 , a hexagonal Bi‐Ca oxide solid solution (δ ss ), Rh ss , Fcc ss , and liquid. The phases found to be stable at 850°C are CuO, Ca 2 CuO 3 , CaO, Bi 2 Ca 2 O 5 , Bi 6 Ca 4 O 13 , Fcc ss , and liquid. The phases found to be stable at 900°C are CuO, Ca 2 CuO 3 , CaO, Bi 2 Ca 2 O 5 , a body‐centered cubic Bi‐Ca oxide solid solution (Bccss), and liquid. The stable phases at 950°C are CuO, Ca 2 CuO 3 , CaO, and liquid. At 1000°C, the stable phases are CuO, Ca 3 Cu 7 O 10 , Ca 2 CuO 3 , CaO, and liquid.