Thermodynamic assessment of the SrBr2-MBr (M: alkali metal) binary systems

Abstract

The phase diagrams of the SrBr2-MBr (M: alkali metal) binary systems based on phase equilibria and thermochemical data were evaluated and optimized using the CALPHAD method. The substitutional solution model was used to describe the Gibbs energies of all liquid phases. All intermediate compounds were handled to be stoichiometric of which the Gibbs energies comply with the Neumann-Kopp rule. Self-consistent datasets with all model parameters were developed, and thermodynamic properties of liquid phase (mixing enthalpy and activity) were also calculated for the whole range of compositions. Meanwhile, the empirical method based on ionic parameter function was successfully used to validate the mixing enthalpies calculated. Results manifest that the calculated results were in excellent agreement with the experimental values reported in the present work. By means of thermodynamic calculation, this database of strontium bromide system was used to predict the SrBr2-based multicomponent system with low melting points, which will design and prepare composite materials for low temperature thermal energy storage (TES).