Ternary Reciprocal System Li⁺, K⁺ || Br^–, ${\text{WO}}_{4}^{{2 - }}$

Abstract—

We have studied the ternary reciprocal system Li⁺, K⁺ || Br^–, ${\text{WO}}_{4}^{{2 - }}$. A likely phase compatibility diagram of the system has been chosen using thermodynamic calculations of the enthalpy and Gibbs energy of exchange reactions and confirmed by differential thermal analysis data for the stable joins KBr–Li₂WO₄ and KBr–Li₂WO₄∙K₂WO₄. The stable joins have been shown to be pseudobinary systems, and their T–x phase diagrams have been mapped out. We have constructed a phase tree of the system, which has a linear structure and includes three stable triangles (LiBr–KBr–Li₂WO₄, KBr–Li₂WO₄–Li₂WO₄∙K₂WO₄, and KBr–Li₂WO₄∙K₂WO₄–K₂WO₄) connected to each other by two stable joins. To find ternary eutectic mixtures in the stable triangles, T–x phase diagrams for a number of sections have been constructed. We have measured the specific enthalpy of fusion of the pseudobinary and ternary eutectics. The ternary mixture with the lowest melting point in the Li⁺, K⁺ || Br^–, ${\text{WO}}_{4}^{{2 - }}$ system, 328°C, has the highest specific enthalpy of fusion: 200 kJ/kg.