Enhancement of magnetic properties in Mn–Zn substituted M-type Sr-hexaferrites

We report the magnetic properties of Mn–Zn substituted M-type Sr-hexaferrites (SrM), SrFe_12−2xMn_xZn_xO₁₉, and compare them with those of non-substituted SrM and La–Zn substituted SrM. The highest saturation magnetization (M_S) of 75.6 emu/g was obtained at a Mn–Zn substitution of x=0.1 (SrFe_11.8Mn_0.1Zn_0.1O₁₉), which is higher than those of the non-substituted SrM and La–Zn substituted SrM by 2.6% and 1.7%, respectively. The enhanced M_S can be attributed to the selective substitution of Zn²⁺ and Mn⁴⁺ into the down-spin site of Fe³⁺ (4f₁ or 4f₂). Sintered anisotropic magnets fabricated with the optimal Mn−Zn doping level of x=0.1 exhibited a remanent magnetic induction (B_r) over 4300 G and maximum energy product (BH)_max of ~4.6 MGOe (36.6 kJ/m³). - Highlights: • The magnetic properties of Mn–Zn SrM were compared with those of non-substituted SrM and La–Zn SrM. • The highest M_S of 75.6 emu/g was obtained at the Mn–Zn substitution x=0.1 (SrFe_11.8Mn_0.1Zn_0.1O₁₉). • Sintered anisotropic Mn–Zn SrM magnets showed values of B_r over 4300 G and (BH)_max of ~4.6 MGOe (36.6 kJ/m³)