Abstract
A high temperature quartz conductance cell with tungsten electrodes was designed and built. Using it, electrical conductivities of three alkali metal tetrachloroaluminates, namely LiAlCl4, NaAlCl4 and KAlCl4, were measured at temperatures up to 800 K. The conductivity values decreased in the order NaAlCl4>LiAlCl4>KAlCl4 and the activation energy for conduction followed the order LiAlCl4≅NaAlCl4<KAlCl4. The conductivity behaviour indicated that alkali metal cations are the predominant charge carrying species in these melts and the conductivity is related to their size dependent mobilities. The anomalous conductivity behaviour of molten LiAlCl4 in the group was attributed to the small size of the highly polarising Li+ cation and some unique structural aspects of the melt. The melting points of LiAlCl4, NaAlCl4 and KAlCl4 were determined to be 421 ± 1, 426 ± 1 and 534 ± 1 K respectively by the conductivity method. It was demonstrated that the conductance cell developed can be used for electrical conductivity measurements of non-volatile molten salts at temperatures up to ∼ 1200 K.
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