Contrasting effect of tetrahedral and octahedral complexing of trivalent cations on binary molten salt solution transport properties

The viscosities and electrical conductances of solutions in two superficially similar binary molten salt systems, FeCl₃ + α-picolinium chloride and CrCl₃ + α-picolinium chloride, have been measured and shown to have strikingly different characteristics. In the first case the fluidity and the conductivity increase as FeCl₃ is added to the organic salt, while with CrCl₃ additions rapid decreases in these properties occur. The differences are attributed to the different coordination numbers assumed by the trivalent cations in the two cases. Both systems exhibit considerable regions of glass formations, and correlations of the transport behavior with glass transition temperatures may be made.