Substitution effect of manganese for iron in “114” YBaFe4O7 ferrite: structure, magnetism and oxygen hyperstoichiometry

Abstract

The study of the ferrites YBaFe_4−xMn_xO₇ shows that the substitution of Mn²⁺ for Fe²⁺ in YBaFe₄O₇ stabilizes the hexagonal symmetry at the expense of the cubic one for 1 ≤ x ≤ 2. Using combined measurements of a.c. and d.c. magnetization, we establish that Mn substitution for Fe in YBaFe₄O₇ leading to a cationic disorder induces a spin glass behaviour. An important characteristic of these Mn substituted ferrites deals with their ability to absorb and desorb reversibly oxygen, leading to the oxides YBaFe_4−xMn_xO_7+δ, with the highest δ values 2–2.25 that have been observed to date in this “114” family. These oxidized “Mn ferrites” keep the hexagonal symmetry and the spin glass characteristic temperature, T_sg, is varying with the oxygen content δ.