Microstructural and magnetic properties of Ti²⁺-Mn⁴⁺ substituted barium hexaferrite

In this paper we report the microstructure and magnetic properties of Ti²⁺-Mn⁴⁺ substituted barium hexaferrites with formula of BaFe_12-2xTi_xMn_xO₁₉ (x=0.2, 0.4, 0.6 and 0.8) which prepared by solid state reaction process. The ions were obtained from TiO and MnO₂ precursors and mechanically alloyed with BaCO₃ and Fe₂O₃ precursors. X-ray diffraction patterns for sintered samples confirmed that the materials are consisted with single phase BHF. Cell volume and crystallite size was found increase with increasing x. The crystallite size for all samples is below 70 nm, but the morphology shown that the grains is around 200-400 nm, which concluded that each grain are polycrystalline. The saturation magnetization increases up to x =0.4 and decrease for higher x, while the coercivity remain decreases monotonically for all x. The results can be interpreted as the site preferential occupation of Ti²⁺ and Mn⁴⁺ ions at low level substitution.