Synthesis and characterization of an oxidized wustite stabilized by a trace of calcium

Article abstract of DOI:10.1016/0025-5408(95)00071-2

By thermal decomposition of CaFe₅O₇ at 1125°C in a sealed silica tube during about ten days, we obtained the oxide Fe_0.832Ca_0.028O₁ referred to as 'Fe₆O₇'. Like wustite, 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 wustite, 'Fe₆O₇' is antiferromagnetic (T_N = 207 K), but the room temperature Mossbauer spectrum is different. It seems that this phase is stabilized by traces of calcium and that there is no tetrahedral interstitial iron (III).