Iron-Doped Hausmannite – (Mn1−x Fe x )3±δO4

The chapter discusses the diagrams of defect concentrations for the spinel (Mn_1−x Fe _x )_3±δO₄ with the iron content x _Fe = 0.1–0.4 mol at 1473 K based on the deviation from the stoichiometry. Iron ions in the spinel (Mn_1−x Fe _x )_3±δO₄ practically do not affect the point defects structure. In the range of higher oxygen pressures, cation vacancies [V^‴ _Mn ] dominate. In the range of low oxygen pressures, intenrstitial cations [Mn ^3• _i] dominate; their concentration at the same oxygen pressure decreases when the iron content increases. The ratio of the coefficients of diffusion (mobility) of iron ions via interstitial cations to the coefficient of diffusion via vacancies (D ^o _I(Fe)/D ^o _V(Fe) = b _D) was also determined with the use of the concentration of ionic defects and the values of coefficients of self-diffusion of iron ions ⁵⁹Fe. It was found that at the iron content x _Fe = 0.2–0.4 mol in the spinel (Mn_1−x Fe _x )_3±δO₄, the mobility via interstitial cations is higher than the mobility via cation vacancies and it increases to the value of b _D ≈ 2.5 12 at the iron content of x _Fe = 0.4 mol.