Thermal analysis of pseudo-binary system: LiCl-KCl eutectic and lanthanide trichloride

The phase diagrams of the pseudo-binary systems of LiCl-KCl eutectic and lanthanide trichloride (LnCl3: Ln=La, Ce, Pr, Nd, Sm, and Gd) were determined for compositions less than 25 mol% LnCl3 by means of thermal analysis, visual observation, electromotive force measurement and powder X-ray diffraction. The existence of K2LnCl5 compounds was confirmed in all the systems, but K3LnCl6 was observed only in the systems containing Sm and Gd. In the region up to 17 mol% LnCl3, the eutectic temperature and composition were observed to be close to those of the LiCl-KCl eutectic system (625±1 K, LiCl-41 at.% KCl). For compositions greater than 17 mol% LnCl3, on the other hand, the eutectic points were 701±1, 691±1, 681±1, 656±1, 635±1 and 649±1 K for La, Ce, Pr, Nd, Sm, and Gd, respectively. The liquidus surface of the LiCl-KCl-LaCl3 system was also determined at compositions up to 40 mol% LnCl3. (orig.)