Lanthanide Halides With Alkali Metal Halide Mixture Phase Diagram Of The System Thermodynamic Study

This work shows the approaches and progress to achieve the phase data and thermodynamic data, as well as analyzed the thermodynamic properties, and phase diagrams of the MBr-TbBr3 (M=Cs, Rb), MBr-CeBr3 (M=Na, Li, K, Rb, Cs) and the CsBr-LaBr3 systems using the CALPHAD method. In optimization of these systems, according to their thermodynamic properties and the ionic groups existing in the liquid phase realistically, we choose the models of the liquid complex formation phase and the middle phase MxLnyBrz (M= alkali metal, Ln= lanthanide) compound. The mixing enthalpies of liquid phase, the heat capacity, the transferring enthalpies of the middle phase, and the data of phase diagrams are used in the calculation. At last, we obtain the optimizing phase diagrams and the Gibbs energy of middle phases. Comparison of calculated phase diagram and thermodynamic values with corresponding experimental data demonstrated that the present calculations, based on the optimized parameters, reproduce experimental data very well. Meanwhile, the thermal properties of lanthanide metal halides, and the relation concerning their mixtures with alkali metal halides related to the atomic diameter of lanthanide, as well as the atomic number of the alkali metal have been discussed in this work.