Phase diagram and thermodynamic properties of the GdBr3-CsBr binary system

Phase diagram of the GdBr3-Csfir binary system was established by Differential Scanning Calorimetry (DSC) method. This system exhibits three stoichiometric compounds, namely Cs3GdBr6, Cs3Gd2Br9 and CsGd2Br7; and three eutectics located at GdBr3 molar fraction x = 0.11 (T = 847 K), x = 0.52 (T = 798 K) and x = 0.72 (T = 859 K), respectively. Cs3GdBr6 undergoes a solid-solid phase transition at 701 K and melts congruently at 1077 K. Cs3Gd2Br9 melts incongruently at 841 K and finally CsGd2Br7 undergoes a solid-solid phase transition at 788 K and melts congruently at 880 K. Experimentally determined phase diagram was optimized by CALPHAD method and thermodynamic properties of compounds existing in the system were estimated. Phase transition of pure GdBr(3)were determined at 533 K and Delta H-tr = 0.41 kJ mol(-1).