Effects of Mn–Zr substitution on the magnetic properties of Ba-ferrites fabricated by sol–gel auto-combustion

Polycrystalline samples of BaMn x Zr x Fe 11.5−2 × O 18.25 having different doping contents of Mn–Zr were fabricated and their magnetic properties investigated accordingly. The results show that the average crystalline size of this specimen is about 150 nm. As the doping content, x , of Mn–Zr increases from 0.1 to 1, the coercive force, Hc , continuously decreases from 368 kA/m to 120 kA/m, while the saturation magnetization, Ms , initially increases, and then subsequently decreased. The maximum Ms obtained in BaMn x Zr x Fe 11.5−2 × O 18.25 with x = 0.3 is 63.03 Am 2 /kg. Moreover, residual magnetization, Mr , increases initially and then consistently decreased as the doping content, x , increases. The maximum Mr obtained when x is 0.2 is 30.85 Am 2 /kg. This study suggests that the magnetic properties of Barium ferrites can be adjusted to suit various application requirements by doping with different Mn and Zr contents at Fe sites. Highlights Mn–Zr doped Barium ferrites were fabricated by a method of sol–gel auto-combustion with self-propagating at high temperature. The substitution of Mn–Zr at Fe sites occurred and the pure Barium hexaferrite phase was formed in the samples. Magnetic properties of Barium ferrites can be successfully adjusted by varying the doping contents of Mn and Zr to meet different application requirements.