Structural defects and oxidation‐reduction equilibrium in Mn, Zn ferrites

摘要

AbstractEquilibrium equations between ions, defects, and the oxygen partial pressure are given, taking into account the site preference of the different cations. It is shown that oxidation of one Mn2+ion is possible if previously two Fe2+ions have been oxidized, in other word, if ΔFe3+/ΔMn3+= 2 (with ΔFe3+and ΔMn3+being the deviation from stoichiometry). In general, this ratio is in relation with the percentage of Mn ions in tetrahedral sites (A‐sites). The above particular value of the ratio ΔFe3+/ΔMn3+leads to a Mn2+content in the A‐sites equal to about 75 of the total Mn content. The proposed model for oxidation‐reduction equilibria fits the experimental data obtained by therm