Synthese et caracterisation dʹune wustite tres oxydee stabilisee par des traces de calcium

By thermal decomposition of CaFe5O7 at 1125 °C in a sealed silica tube during about ten days, we obtained the oxide Fe0.832Ca0.028O1 referred to as “Fe6O7”. Like wüstite, it is iron deficient, very rich in iron (III) cations (Fe2+Fe3+ = 1.97), has the rock-salt structure (a = 429.4 pm), but the x-ray diffraction pattern does not show satellite reflections around the Bragg peaks. Like wüstite, “Fe6O7” is antiferromagnetic (TN = 207 K), but the room temperature Mössbauer spectrum is different. It seems that this phase is stabilized by traces of calcium and that there is no tetrahedral interstitial iron (III).