Thermodynamic properties of some lanthanide chlorides

Article abstract of DOI:10.1007/BF02138598

The heat capacities of the lanthanide chlorides NdCl₂, SmCl₂, EuCl₂, DyCl₂, TmCl₂, YbCl₂, DyCl₃, YbCl₃ and LuCl₃ were measured at 10-320 K with an adiabatic microcalorimeter. Standard thermodynamic properties were calculated from the experimental results. The heat capacities of these chlorides are composed of the lattice heat capacity and an additional contribution caused by the thermal population of the low-lying Stark electronic levels (Schottky anomaly). The Schottky heat capacity was estimated as the difference between the experimental C_p values for the isostructural paramagnetic and diamagnetic chlorides. Experimental Schottky contributions were found to be in good agreement with those calculated for SmCl₂, TmCl₂ and YbCl₃ via a general model of the main-term Stark splitting of the respective ions in the orthorhombic and monoclinic crystal fields.