Ionic conduction and molecular structure of molten FeCl3

Abstract

Former experiments on molten FeCl3 have shown that, as for AlCl3, melting is accompanied by a transition from sixfold to essentially fourfold coordination. However, in contrast to AlCl3, the FeCl3 melt near freezing has an appreciable ionic conductivity. We propose a model for the structure of FeCl3 melt as consisting of closely packed Fe2Cl6 bitetrahedral molecules in equilibrium with (Fe2Cl5)(+) ana (Fe2Cl7)(-) ionised species.