Preparation and Magnetic Properties of Nd–Co-Substituted M-Type Strontium Ferrite by Microwave-Assisted Synthesis Method

Abstract

M-strontium hexaferrites (Sr1−xNdxFeyCo1−y O19) with the substitution of Co2+ and Nd3+ were prepared by the microwave-assisted solid-phase reaction process. M-strontium hexaferrite with magnetoplumbite structure can be formed at 950 °C for 90 min by applying microwave-assisted calcination. For Co2+-substituted M-strontium ferrites, the saturation magnetization (σs) and remanent magnetization (σr) tend to decrease with the increasing calcination temperature, accompanying by the improvement of coercivity for the enhancement of morphology anisotropy. For Nd–Co-co-substituted strontium ferrites, the appearance of α-Fe2O3 phase and the conversion of Fe3+(5 μB) into Fe2+ (4 μB) decrease the net magnetic moment, resulting in the dilution of the σs and σr. The coercivity of Nd–Co-co-substituted strontium ferrite increases slightly for the improvement of magnetocrystalline anisotropy, which could be attributed to the enhancement of anisotropy field for the substitution of Fe3+ ions by Co2+ ions and the formation of grains with plate-like shape.