Thermodynamic modeling of the GdF3-MF (M: Li, K, Rb, Cs) systems

The phase equilibria and thermochemical data for the GdF3-MF (M: Li, K, Rb, Cs) binary systems were critically evaluated and optimized based upon the CALPHAD approach. Two kinds of models like associated and substitutional solution were used to describe the liquid phase where cations were apt to form short range order (SRO) and random mixing, respectively. All the intermediate compounds were treated as stoichiometric of which Gibbs energies comply with the Neumann-Kopp rule. Model parameters optimization for respective phases was conducted by the least squares minimization procedure with required input data available from experimental measurements and empirical predictions (ionic parameter function). Satisfactory agreements between all calculated results and experimental & predicted data were achieved which demonstrates that thermodynamic databases for the GdF3-MF (M: Li, K, Rb, Cs) binary systems were ultimately derived in the present work allowing safe extrapolation into multicomponent system for guiding relative industrial applications.