Thermodynamic description of phase equilibria in the Cu2O-CeO2-Ce2O3-La2O3 system

Thermodynamic modeling of liquidus lines for binary oxide phase diagrams and liquidus surfaces for ternary oxide phase diagrams that make up the Cu2O-CeO2-Ce2O3-La2O3 system was performed using the theories of ideal ionic solutions and subregular ionic solutions. Solidus line, limiting the existence of a solid solution in the CeO2-La2O3 system, was calculated using the theory of regular ionic solutions. The values of parameters of the used theories and the temperature dependence of the equilibrium constants of transition from solid to liquid, used to calculate the phase diagrams of the investigation systems, were determined during this work. Most of the systems (Cu2O-CeO2, Cu2O-Ce2O3, Cu2O-La2O3, CeO2-Ce2O3, Ce2O3-La2O3, Cu2O-CeO2-Ce2O3, Cu2O-Ce2O3-La2O3) are eutectic type diagrams with one eutectic point for each diagram. For the above systems including Cu2O as a component, it was concluded that these systems are characterized by sufficiently low eutectic equilibrium temperatures. The CeO2-La2O3 system is characterized by the presence of a solid solution and a point on the liquidus line, having a zero crystallization interval. Phase diagrams Cu2O-CeO2-La2O3 and CeO2-La2O3-Ce2O3 are characterized by a vast area of the equilibrium of oxide melt with the solid solution |CeO2, La2O3|ss.