Thermodynamic Investigation of the CaF2–ThF4 and the LiF–CaF2–ThF4 Systems

• Published in: Journal of chemical and engineering data 2015-11, Vol.60 (11), p.3166-3174
• Main Authors: Capelli, E, Beneš, O, Raison, P. E, Beilmann, M, Künzel, C, Konings, R. J. M
• Format: Article
• Language: English
• ISSN: 0021-9568; 1520-5134
• DOI: 10.1021/acs.jced.5b00347

In this study we present the thermodynamic description of the binary CaF2–ThF4 system and the ternary LiF–CaF2–ThF4 system. In order to describe the general shape of the phase diagram, the phase equilibria of several intermediate compositions of the CaF2–ThF4 system have been measured for the first time in the present work using the DSC technique. These results have been combined with X-ray diffraction studies for the identification of the phases in equilibrium and for the determination of the structure of the CaThF6 compound. Considering all of the novel experimental data, the CaF2–ThF4 system has been assessed for the first time using the Calphad approach. Moreover, the ternary LiF–CaF2–ThF4 phase diagram has been calculated and optimized using the experimental data obtained in this study for the ternary mixtures. The model developed reproduces very well all the measurements performed and correctly predicts the lowest eutectic temperature and composition.