The TbBr3–LiBr binary system: Experimental thermodynamic investigation and assessment of phase diagram

DSC was used to study the phase equilibrium in the TbBr3–LiBr binary system. The results obtained provided a basis for constructing the phase diagram of this system. It exhibits two compounds: Li5TbBr8, which decomposes in the solid state at 611 K, and Li3TbBr6, which melts congruently at 785 K with the related enthalpy 59.1 kJ·mol−1. The binary LiBr–TbBr3 system was then optimized using the available experimental information on phase diagram and thermodynamic properties. A two-sub-lattice ionic solution model (Li+)P:(Br−, TbBr6−3, TbBr3)Q was adopted to describe the liquid phase. The present assessment of the binary LiBr–TbBr3 system was in good agreement with the corresponding experimental data and confirmed their consistency.

► DSC measurements for the (LiBr + TbBr3) system.
► congruently Li3TbBr6 and incongruently melting Li5TbBr8 compounds.
► Thermodynamic description of the liquid phase in the (LiBr + TbBr3) system.
► Assessment with a two-sublattice ionic solution model.