Effect of La–Zn Substitution on the Structure and Magnetic Properties of Low Temperature Co-Fired M-Type Barium Ferrite

Ba(LaZn)xFe12−2xO19 (0≤x≤0.5) powders with Bi2O3 as an additive was synthesized by a sintered route at 900 °C or 950 °C. The structure and magnetic properties of La–Zn substituted M-type barium ferrites were also investigated. When 0≤x≤0.5, only one crystal phase existed in the sample, and the morphology of the grains were shown to be gradually irregular. The little amount of La3+ ions and Zn2+ ions changed the equilibrium of Fe2+ and Fe3+ at the 2a site, which increased the Fe3+–O–Fe2+ superexchange interaction strength, and the saturation magnetization (Ms) of the samples was also improved. Meanwhile, the substitution of La3+ and Zn2+ ions and the grains’ size bought great effects on the magnetocrystalline anisotropy field. As a result, with sintering at 950 °C for 6 h, the max Ms value of the samples with x=0.1 was 67.26 emu/g, and the minimum coercivity (Hc) value was 1718.89 Oe with x=0.3, respectively.