Thermodynamic description for the NaF-KF-RbF-ZnF2 system

Abstract

Thermodynamic evaluations and optimizations of the NaF-ZnF2, KF-ZnF2, RbF-ZnF2, NaF-RbF and KF-RbF systems were determined by use of the CAlculation of PHAse Diagrams (CALPHAD) approach in this work. The subregular solution model was applied to model liquid phase, while the stoichiometric compound model was used to describe the intermediate phases. All the model parameters were evaluated on the basis of the required thermochemical and phase equilibrium data from experimental measurements in literature and theoretical predictions from first-principles method. A set of self-consistent and reliable thermodynamic database for the NaF-KF-RbF-ZnF2 quaternary system was finally derived by merging the model parameters of relevant binary systems (model parameters of NaF-KF were adopted from the literature) based upon the Muggianu extrapolation model. The invariant reactions of ternary systems from NaF-KF-RbF-ZnF2 were obtained according to the database. This work will provide beneficial instructions in the relevant multi-components molten salt design in industrial fields.