Physicochemical analysis and structure of melts of the system LiF-NaF-K2NbF7

摘要

The complex physicochemical analysis of the system LiF-NaF-K2NbF7, based on the phase diagram, density, surface tension, and viscosity measurements, as well as on the X-ray diffraction and IR spectroscopic analyses, was performed. The results proved that the investigated system forms a simple eutectic phase diagram with the coordinates of the ternary eutectic point 16 mol% LiF, 31 mol% NaF, 53 mol% K2NbF7, and t(e) = 585 degreesC. The probable inaccuracy of temperature of primary crystallization in the calculated ternary phase diagram is 4.3 degreesC. From the molar volume, surface tension, and viscosity excesses, as well as from the X-ray diffraction and IR spectroscopic measurements of the quenched melts, it follows that the formation of the [NbF8](3-) anions in the liquid phase was confirmed by all of the studied physicochemical parameters and is the general feature of this system. (C) 2004 Elsevier B.V. All rights reserved.