Phase diagram and ternary bromides of the CsBr–LaBr3 binary system

•CALPHAD method was used to derive thermodynamic parameters of the system.•Heat capacities of Cs3LaBr6 and Cs2LaBr5 were fitted to literature data.•Phase diagram of CsBr–LaBr3 was calculated.

The phase diagram of the CsBr–LaBr3 binary system was investigated by Calphad approach. The Gibbs energy functions of the ternary bromides Cs3LaBr6 and Cs2LaBr5 were evaluated using an independent polynomial to fit the experimental heat capacities. For the CsLa2Br7 ternary bromide, Neumann–Kopp rule was used. A two sub-lattice ionic solution model (Cs+)P: (Br−,LaBr6−3,LaBr3)Q was adopted to describe the liquid phase. The thermodynamic parameters for each phase in the considered system were optimized by using available experimental data from literature, which were used to calculate the phase diagram and thermodynamic properties of the CsBr–LaBr3 system.