ABSTRACT
The studies on the dependence of diffusion of iron, cobalt and chromium in magnetite on the oxygen pressure showed that at low oxygen pressures the transport of ions occurs through interstitial iron ions, while at higher oxygen pressures it occurs through iron vacancies. Studies on diffusion have shown that interstitial iron ions and iron vacancies are present in magnetite. Concentrations of both types of ionic defects were correlated with the expressions describing the equilibrium constants. The formation of interstitial cations is also associated with the release of oxygen atoms that leave electrons, causing an increase in their concentration. Therefore, there occurs a perturbation of the equilibrium between the electronic defects. The “loose” structure of magnetite and the existence of a high number of octahedral and tetrahedral voids favours the formation, at high temperatures, of quasi-free ionic defects; these are iron vacancies, but also interstitial iron ions, with the concentration depending on the oxygen pressure.
