Thermodynamic assessment of LaBr3 unary and LiBr-LaBr3 binary system

Experimental data for the system LiBr-LaBr3 was subjected to a critical thermodynamic assessment using the CALPHAD approach. To reach a self-consistent thermodynamic description for the constituent phases in the system, it appeared to be necessary to reassess the experimental heat capacity data of the stoichiometric compound LaBr3. A two-sublattice ionic solution model for the liquid, denoted as (Li+)P: (Br−,LaBr6−3,LaBr3)Q, was employed to represent the phase diagram and heat of mixing data. Our assessment resulted in a Gibbs energy formation covering the temperature range between 300 and 1100 K. To give our assessment of LiBr-LaBr3 a wider application to higher-order alkali-bormide-LaBr3 systems, additional assessments of the binaries NaBr-LaBr3 and KBr-LaBr3 were carried out. By modelling the liquid phase with the two-sublattice ionic solution model, a thermodynamic description, compatible in the three binary systems, was obtained for these systems covering the temperature range between 300 and 1100 K.