Thermodynamic Optimization And Calculation Of Phase Diagrams Related To The Rare Earth Halides With The Alkali Halides Or Alkaline Halides

By using CALPHAD (Computer Coupling of Thermochemistry and Phase Diagram) technique the optimization and calculation of the binary systems related to the rare earth halide were carried out. According to the characters of stronger interactivities of the rare earth halide systems, the new modified quasichemical model in the pair-approximation for short-range ordering developed by A. D. Pelton et al was used as basic theory to optimize and calculate this kind of phase diagrams by rational analysis. Based on some databases and literature data, several programs were made separately to optimize and calculate the binary systems of rare earth trichlorides and alkali chlorides. For the first time the model was applied into the molten salts systems, and through optimization and calculation, we get the thermodynamic properties and optical self-consistent phase diagrams of those binary systems such as EuCl₃-MCl (M= Na, K, Rb, Cs), GdCl₃-MCl (M= Na, K, Rb, Cs), DyCl₃-CaCl₂and DyCl₃-KCl, EuCl₃-CaCl₂.According to the theory of self-consistence between thermodynamic parameters or functions, some thermodynamic models were chosen and constructed, all data from measured phase equilibria and experimental integral properties scattered in literature were put together to check their consistency and to optimize and calculate these systems. Finally the thermodynamic description of the studied systems was obtained, which is reasonable, reliable and self-consistent. Through the analysis and comparison between the calculated and experimental phase diagrams, some experimental phase diagrams were improved. We compared the experimental data of binary...