Thermodynamic investigation of the KBr-TbBr3 system

Experimental data for the system KBr-TbBr3 were subjected to a critical thermodynamic assessment using the CALPHAD approach. The thermodynamic parameters of the KBr and TbBr3 compounds were taken from the SGTE recommended database and the authors' previous assessment, respectively. To reach a self-consistent thermodynamic description for the constituent phases in the system, the experimental heat capacity data for the intermediate compound K3TbBr6 were reassessed. A two-sublattice ionic solution model for the liquid, denoted as (K+)P:(Br−,TbBr6−3,TbBr3)Q, was employed to represent phase diagram and enthalpy of mixing data. To make our investigation on K3TbBr6 more accurate, a new and complementary experimental DSC determination regarding the compound was carried out. Our thermodynamic description, compatible with ones for other lanthanide-alkali halide systems, resulted in a good agreement between the calculated and experimental data.