Thermodynamic investigation of the RbBr– [formula omitted] system

Abstract

The thermodynamic properties and phase diagram of the RbBr–TbBr 3 system were analyzed by means of the CALPHAD method in this work. Thermodynamic models were defined in order to describe the Gibbs energies of the individual phases, and the model parameters were optimized from the experimental thermodynamic and phase diagram data. The phase diagram, the heat capacity of Rb 3TbBr 6 and the enthalpy of mixing of RbBr–TbBr 3 liquid were calculated. The structural transitions for the Rb 3TbBr 6 and RbTb 2Br 7 compounds were also considered. Good agreement between the present calculations and the experimental data was obtained. The Gibbs energies of formation of Rb 3TbBr 6 and RbTb 2Br 7 from the pure components were predicted. A further check on the reliability of the thermodynamic modeling was provided by means of the calculated entropy of mixing of RbBr–TbBr 3 liquid.