Microstructure and properties of lanthanide series M-type hexaferrites

Abstract

A series of M-type hexagonal ferrites with the composition Ba1−xLaxFe11.6Co0.2Ti0.2O19 (x = 0.00, 0.10, 0.15, 0.20, 0.25, 0.30) were prepared by the ceramic process during the whole process of pre-sintering and sintering. The phase composition, micro-morphology, and magnetic properties of the particles were investigated by XRD, SEM, and VSM. With the increase of La content, the single magnetoplumbite phase structure transformed into multiphase structure. Meanwhile, the small amount of α-Fe2O3 phase existed in M-type phase. It was found that powders were crystallized into M-type hexaferrites phase at 1250 °C. The micrographs of the magnetic powders were observed by a field emission scanning electron microscopy (SEM). With different La contents, the micro-morphology of the particles exhibited the uniform plane hexagonal structures of M-type ferrites. The magnetic properties were investigated by Vibrating sample magnetometer (VSM). The saturation magnetization (Ms) increases and then decreases with the increasing of La content. The saturation magnetization (Ms) has the maximum value at x = 0.20 (Ms = 61.85 emu/g). The value of coercivity (Hc) is up to 3428 Oe when the amount of doping is 0.30, and the value of coercivity (Hc) increases with the increasing of La content.