The cell parameter and M-O bond lengths are also comparatively bigger. The presence of Ni also stabilises the monoxide phase, which might form during the oxidation. Similarly, ZnCo2O4 also introduces Zn 2+ only dopants, substituting all Co 2+ , and stabilizing the monoxide phase; however, ZnCo2O4 is a normal spinel. The cell parameter of ZnCo2O4 is more similar to the one of Co3O4, highlighting a trend of the dependence of the cell sizes on the normal vs inverse distribution. CoFe2O4 is different from the rest of the samples as it is a ferrite. FeCo2O4 is not stable at room temperature: it disproportionates into two cubic spinels, a Corich normal spinel like Co3O4, and an inverse one like Fe3O4. On the other hand, CoFe2O4, which is also inverse, is stable over a very broad range of temperatures. In terms of our study, iron has a stronger preference for the Fe 3+ oxidation state, and Co should be almost exclusively present as Co 2+ . CoFe2O4's diffraction pattern is strongly shifted towards lower angles and the cell parameter is comparatively much higher than the cobaltites.