POTENTIOMETRIC STUDIES OF SOME OXYANIONS IN MOLTEN FLUORIDES

The dissociation of several oxyanions: WO42-, SiO32-, TaO3-, TiO32-, and MoO42- in molten FLINAK has been studied potentiometrically with a stabilized zirconia electrode. The interaction of these melts with O2- has similarly been studied. All of these ions appear to be stable in FLINAK, but SiO32- and TaO32- take up IO2- to form higher oxides, probably SiO44- and TaO43-, respectively. The behavior of the Pt electrode in these melts is quite complex. Its potential varies with ln[O2-], the slope being RT/F or larger. It is therefore not suitable as either reference or O2- indicator electrode.