Thermodynamic assessment of the bismuth-calcium-oxygen oxide system

Abstract

The experimental data on the oxide part of the Bi-Ca-O system have been reviewed, and an optimized thermodynamic description is presented. There are six known stable ternary oxide phases, two of which show considerable solid-solution ranges. At least two phases - δ-Bi2O3 and the rhombohedral β-phase - are good oxygen-ion conductors. Because all oxide phases are found on the Bi2O3-CaO line, the Bi2O3-CaO system can be treated as a true binary system. Most experimental data are in reasonable agreement with each other; however, there are fairly large uncertainties on the extension of the solid-solution phases and on the thermodynamic properties.