Thermodynamic properties of the pseudo-binary CsCl–LnCl3 (Ln=Ce,Pr,Nd) systems

The Gibbs energies of formation of the pseudo-binary compounds Cs3LnCl6(s) and CsLn2Cl7(s), Ln=Ce,Pr,Nd, from the constituent metal halides, determined by Knudsen effusion mass spectrometry have been compared with the thermodynamic properties of the solid and liquid phases of the pseudo-binary CsCl–LnCl3 systems, obtained by different methods. The enthalpy of mixing of the liquid CsCl–PrCl3 system has been predicted from data for the CsCl–CeCl3 and CsCl–NdCl3 systems. The compatibility of results obtained in this work for the pseudo-binary compounds with literature data has been assessed using the optimization program BINGSS of H.L. Lukas. The liquid phases in the CsCl–LnCl3 systems have been described using the associate solution model. The phase diagrams, the thermodynamic functions of mixing of the systems studied, and the entropies of formation of Cs2LnCl5(s) resulted from the optimization procedure.