Thermodynamic evaluation and optimization of (LiF + ReF₃) (Re = La, Nd, Gd, Yb, Y, Lu) binary systems

All available phase equilibria and thermodynamic data for (LiF + ReF₃) (Re = La, Nd, Gd, Yb, Y, Lu) binary systems were carefully evaluated to obtain the optimized model parameters for all solid and liquid phases. A detailed review of the thermodynamic properties of all the pure and intermediate compounds in these binary systems provides a solid foundation for thermodynamic optimization. The enthalpies of mixing predicted at 1360 K for (50 mol% LiF + 50 mol% GdF₃) and (50 mol% LiF + 50 mol% LuF₃), using an empirical method, further enriched the experimental database. A modified quasichemical model in the pair approximation was used to model the molten salt phase of the (LiF + ReF₃) (Re = La, Nd, Gd, Yb, Y, Lu) binary systems. All thermodynamic data available for the six binary systems were reproduced within the experimental error limits.