Thermodynamic investigation of the KBr–TbBr 3 system

Abstract

Experimental data for the system KBr–TbBr 3 were subjected to a critical thermodynamic assessment using the CALPHAD approach. The thermodynamic parameters of the KBr and TbBr 3 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 K 3TbBr 6 were reassessed. A two-sublattice ionic solution model for the liquid, denoted as (K +) P :(Br −,TbBr 6 −3,TbBr 3) Q , was employed to represent phase diagram and enthalpy of mixing data. To make our investigation on K 3TbBr 6 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.