The phase diagrams of the binary system LiF-K2NbF7 and the ternary system LiF-KF -KiNbF7 were determined using thermal analysis. Subsequent coupled analysis of the thermodynamic and phase diagram data was performed to obtain thermodynamically consistent phase diagrams. The system LiF-K2NbF7 is a simple eutectic one with a calculated the eutectic point 72 mole % K2NbF7 and 670°C. The probable inaccuracy in the calculated phase diagram is 5.4°C.
In the binary system KF-K2NbF7 the intermediate compound KsNbFg is formed. The K3NbFg-LiF join divides the ternary system into two simple eutectic ones. The calculated coordinates of the two ternary eutectic points are:
e1: 22.3 mole % LiF, 9.4 mole % KF; 68.3 mole % K2NbF7; t = 649°C e2: 45.5 mole % LiF, 51.7 mole % KF; 2.8 mole % K2NbF7; t = 486°C The probable inaccuracy in the calculated ternary phase diagram is 4.7°C.