Surface tension of the system LiF-KF-K2NbF7

The surface tension of the molten system LiF-KF-K2NbF7 has been determined using the maximum bubble pressure method. The error in the surface tension measurement was estimated to be +/- 1.5 %. On the basis of the obtained dat a the composition dependence of the surface tension and of the surface tens ion excess of the investigated system was calculated and the possible chemi cal interaction of components Tvas elucidated. The results are discussed in terms of the anionic composition. From the obtained surface tension data the surface adsorption of K2NbF7 in the systems LIF-K2NbF7 and KF-K2NbF7 was calculated. The results indicated the presence of the surface-active [NbF7](2-) and [NbF8](3-) anions in the melt.