Fe(IV) disproportionation in AFeO3 (A = Ca, Sr)perovskite lattices studied by ll9Sn diamagnetic probe Mössbauer spectroscopy

Fe(IV) is an interesting unusual oxidation state of iron stabilized under oxygen pressure. In a perovskite lattice such an oxidation state disporportionates into Fe(III) and Fe(V). The study of this phenomenon is important for a better knowledge of instable valencies. Using 119 Sn(IV) as diamagnetic prohe in the perovskite lattice of AFeO 3 (A=Ca,Sr) the disproportionation 2Fe(IV)?Fe(III) + Fe(V) is discussed versus local steric and electrostatic interactions.