Thermodynamic and physicochemical properties of EuCl2 and EuCl2-NaCl melts

Lanthanide and actinide halides and their mixtures with alkali metal halides are important for electrolytic production of rare-earth metals but also in the processing of nuclear wastes and recycling of spent nuclear fuel. However, reference data are still missing both for the pure salts and the mixtures. Several thermodynamic, physicochemical and structural properties, investigations have been or are being conducted with a variety of experimental methods. Other more theoretical approaches include molecular dynamics calculations and new modeling aspects. The present work deals with the EuCl2 and EuCl2-NaCl melts. Temperatures and enthalpies of phase transitions, heat capacity and density were determined for EuCl2 while enthalpy of mixing and phase diagram investigations were conducted for the EuCl2-NaCl mixtures. These data were tested for thermodynamic consistency by assessing the phase diagram. The agreement obtained between experimental and calculated phase diagrams is discussed in terms of the relevance of the models used in the numerical procedure.