Phase complex modeling and experimental identification of the compositions of low-melting electrolyte mixtures in the stable triangle LiF-NaF-KCl of the quaternary reciprocal system Li+ ,Na+ ,K+ ||F− ,Cl−

Abstract

Alkali metal halides are used as heat-storing materials, electrolytes for chemical power sources and solvents for inorganic substances. Using three-dimensional vector graphics software, a 3D model of the phase equilibrium states of the quasi-ternary system LiF-NaF-KCl, which is a stable triangle of the four-component reciprocal system Li+ ,Na+ ,K+ ||F-,Cl, was constructed. Based on the 3D model, the polythermal and isothermal sections and the polytherm of crystallization of the phases were constructed for the first time. The stable nature of the LiF-NaF-KCl triangle is confirmed by thermodynamic calculations for several temperatures of interaction of mixtures of the substances being a part of the unstable LiCl-NaF-KF triangle. The crystallization polytherm allows us to select mixture compositions in the temperature range from 590 to 650 and from 590 to 700°C for practical use as molten electrolytes for mid-temperature chemical current sources.

Keywords

• fusibility electrolyte
• alkali metal halides
• 3d model
• phase complex
• quasi-ternary system
• polythermal section
• isothermal section
• phase crystallization polytherm