Reactions of Formation and Stability of Iron (II) and (III) Oxides in LiCl ‐ KCl Eutectic Melt at 470°C

The study of the different oxides of iron (II) and iron (III) was carried out potentiometrically in LiCl-KCl eutectic at 470/sup 0/C by means of an yttria-stabilized zirconia electrode indicator of the oxide ion activity and an iron electrode indicator of the ferrous ion activity. These measurements were complemented by the determination of cyclic voltammograms and by x-ray diffraction and infrared spectrophotometrY analysis of certain compounds formed. The main results obtained are the following: strong oxidizing power (oxidation of Cl-/sup 1/ ions into Cl/sub 2/) and high oxoacidity (great stability of ferric oxide) of Fe/sup 3/ ions; possible redissolution of Fe/sub 2/O/sup 3/ in the oxide ion rich media by the formation of ferrate (III) ion; FeO/sub 2/-*Fe/sup 2 +/ ions react with O/sup 2/- ions to to form ferrous oxide, which is probably stabilized in the form of a solid solution FeO-LiFeO/sub 2/ of composition Fe/sub 1-y/Li/sub y/O. Magnetic oxide, Fe/sub 3/O/sub 4/, is stable and can be obtained by the action of oxide ions on a mixture of iron (II) and iron (III). This work is pertinent to the construction of rechargeable and high performance batteries. 34 refs.