Modeling of the Thermodynamics of the Pseudobinary RbCl-GdCl3 System

Abstract

The Gibbs energies of formation of the pseudobinary compounds Rb3GdCl6(s) and RbGd2Cl7(s) from the constituent metal halides, determined by Knudsen effusion mass spectrometry, were compared with the thermodynamic properties of the solid and liquid phases of the RbCl-GdCl3 system, obtained by different methods. The compatibility of the results obtained in this work for pseudobinary compounds with literature data was assessed by an optimization procedure using the CALPHAD method. The liquid phase in the RbCl-GdCl3 system was described by the associate model. The phase diagram, thermodynamic functions of mixing of the system studied, and the Gibbs energies of formation of the pseudobinary compounds: Rb2GdCl5(s), Rb3GdCl6(s), and RbGd2Cl7(s) resulted from this optimization procedure.