Thermodynamic investigation of the (LiF + NaF + CaF2 + LaF3) system

Highlights: → Thermodynamic description of the liquid phases in the (LiF + NaF + CaF2 + LaF3) system. → DSC measurements for the systems (LiF + CaF2 + LaF3), (NaF + CaF2 + LaF3), and (LiF + NaF + CaF2 + LaF3). → Improved encapsulation technique for fluoride salts show better agreement to theory. → Similar extrapolation with quasi-chemical model and classical polynomial model. - Abstract: In this work a thermodynamic assessment of the (LiF + NaF + CaF2 + LaF3) system is reported. For the thermodynamic modeling of the liquid phase, the classical polynomial model, and the modified quasi-chemical model were used in parallel and compared. The extrapolation to higher order systems was done according to the Toop mathematical formalism. Furthermore, differential-scanning calorimetry data of the ternary (LiF + CaF2 + LaF3), (NaF + CaF2 + LaF3), and the quaternary (LiF + NaF + CaF2 + LaF3) mixtures are presented. Good agreement between the experimental data and the thermodynamic assessment was obtained.