Electrical conductivity of systems based on Na3AlF6-SiO2 melt

The electrical conductivity of molten binary and ternary mixtures based on the NaF-AlF₃-SiO₂ system was investigated by means of a tube-cell (composed of pyrolytic boron nitride) with stationary electrodes. An impedance/gain-phase analyser (National Instruments; a high-performance modular chassis controlled by Labview? software) was used for the cell impedance measurement. The conductivity was found to vary linearly with temperature in all the mixtures investigated. The concentration dependence of electrical conductivity (isotherms) thus obtained was divided into two parts. The first represents the concentration region of up to 10 mole % of SiO₂, the second the region with a higher concentration of SiO₂ (from 10 mole % to 40 mole %). While the conductivity decreased considerably with the concentration of SiO₂ in the second part, it increased surprisingly in the low concentration range. From these results, the influence of electrolyte composition and temperature on the electrical conductivity was examined.