Phase analysis and volume properties of the (LiF–NaF–KF)eut–K2ZrF6 system

Abstract

The influence of the addition of K2ZrF6 to the eutectic system of LiF–NaF–KF on temperatures of primary crystallization and volume properties was investigated in the entire composition range. Thermal analysis and Archimedean method were used for the determination of the phase equilibrium and density. Molar volume and excess molar volume were calculated on the basis of the experimental density data. Temperatures of primary crystallization do not change considerably in a wide concentration range $$ x_{{\rm{K_{2} ZrF_{6} }}} = 0.20 - 0.70 $$ and concentration dependences of densities and molar volumes show monotonous behavior for selected temperatures (t = 850, 900, 950 °C). “Compressibility parameters” of K2ZrF6 and (LiF–NaF–KF)eut were calculated in order to discuss the volume contraction or expansion in the investigated system at selected temperatures (t = 850, 900, 950 °C). On the basis of the negative values of the calculated compressibility parameters volume contractions can be considered for both components.