Thermodynamic Properties Determination in LiF-CaF ₂ Using Electrochemistry in High Temperature Fused Salts: Application to CeF ₃

Abstract

Combining thermodynamic database and electrochemical measurements, CeF 3 thermodynamics properties were determined between 1113 K and 1233 K in LiF-CaF 2 solution. First, standard potentials of CeF 3 /Ce were calculated in different reference states: liquid and solid, and infinite dilution. Then activity coefficients of CeF 3 were estimated in the different reference states and for different composition scales: molarity, molality and molar fraction. Finally, constants which interconnected the infinite dilution reference state and the solid and liquid reference states were evaluated.Standard potential determination.-Theoretical thermodynamic values were extracted from FactSage and HSC 6.1 database, where the composition scale is the molar fraction.Liquid reference state.-HSC 6.1 software allows the standard Gibbs enthalpy G 0,L of the reaction presented below to be determined, where the solute is considered as pure compound in a liquid state.CeF 3 (l) = Ce + 1.5F 2 (g)