Al-substituted M-type hexaferrite is a high anisotropy ferromagnetic material. In this paper, we report the synthesis and characterization of BaAl4Fe8O19 powders from two microemulsion systems of po1yoxyethylene octylphenol ether/1, 2-propylene glycol or ethanol/cyclohexane/water and cetrimonium bromide/1, 2-propylene glycol/cyclohexane/water. Two microemulsion systems were found to give wide stable regions. The synthesized powders were characterized with X-ray diffraction, scanning electron microscopy and a vibrating sample magnetometer. The experimental results indicated that the surfactant, co-surfactant, and oil/water ratio remarkably affected the particle size, size distribution, anisotropy and magnetic properties of the powders. The powder prepared with the microemulsion of po1yoxyethylene octylphenol ether/1, 2-propylene glycol/cyclohexane/water exhibited the best particle characters, that is, a uniform thin particle morphology, a large shape anisotropy, a small particle size, a large coercivity of 8734.16 Oe, and a saturation magnetization of 20.821 emu/g.

Keywords: BaAl4Fe8O19, Microemulsion method, Anisotropy, Magnetic property