Thermodynamic modeling of the CaO–CaF2–Al2O3 system aided by first-principles calculations

Abstract The CaO–CaF 2 , Al 2 O 3 –CaF 2 , and CaO–CaF 2 –Al 2 O 3 systems are modeled using the CALculation of PHAse Diagram (CALPHAD) approach. The liquid phase is described by a two-sublattice ionic model (Al +3 , Ca +2 ) p (F − , O −2 , AlO 3/2 ) q . The compounds Al 2 O 3 , CaF 2 , and CaO are treated as stoichiometric phases. The Gibbs energy of formation of (CaO) 11 (Al 2 O 3 ) 7 (CaF 2 ) is predicted by means of first-principles calculations. Phase diagrams of the CaO–CaF 2 and Al 2 O 3 –CaF 2 quasibinaries as well as the isothermal and vertical sections and the liquid surface projection of the CaO–CaF 2 –Al 2 O 3 system are calculated, showing favorable accord with available experiments in the literature.