Preparation and magnetoelectric properties of M-type hexagonal ferrite by solid state reaction and sol-gel

In order to investigate the magnetoelectric coupling performance of BaFe_10.2Sc_1.8O₁₉ samples at room temperature, BaFe_10.2Sc_1.8O₁₉ samples were prepared by solid phase method and sol-gel method. The phase structure was determined by X-ray diffraction, the prepared samples are all single-phase polycrystals with a space group of P63/mmc. The surface morphology was observed by field emission scanning electron microscopy, the samples prepared by solid phase method show that there is not uniform in composition and a "scandium-rich phase". The morphology analysis of the sample prepared by sol-gel method shows that the grains of BaFe_10.2Sc_1.8O₁₉ exhibit uniform distribution with hexagonal platelet-shaped structure, and the grain size is about 3-5 μm. The magnetic results of the samples prepared by the sol-gel method and the solid state reaction show that the solid state reaction sample undergoes phase transition at about 250 K, and the hysteresis line does not exhibit magnetoelectric coupling behavior at room temperature; Temperature and magnetic field dependence of magnetization for the sample prepared by sol-gel method show that BaFe_10.2Sc_1.8O₁₉ exhibits ferrimagnetic to conical spin structures phase transition near 330 K. Magnetic field dependence of magnetocapacitance is similar to the behavior in magnetization, which indicate that the systems exist ferroelectric polarization induced by the conical spin structures. It can be understood by the inverse Dzyaloshinskii-Moriya model.