The Research Of Control For Coercive Force And Preparation Process Of Chemical Co-precipitation Of Hexagonal Ferrite

As a hexagonal magnetic material, M-type barium ferrite has been widely used in the area of soft magnetic materials and hard magnetic materials, because of its excellent cost-effective, high magnetic permeability and moderate coercive force. The preparation process and performance regulation of M-type barium ferrite has become the research focus.This paper had studied the Ba M prepared by chemical co-precipitation,and further explored the influences from some factors, such as, the value of reaction liquid PH, the way of dropping, the types of precipitating agent, stirring time, sintering temperature and other processing parameters during the preparation of the samples. Finally, the appropriate preparation program had been obtained for preparing small?nanometer level?particles, high purity, uniformly dispersed Ba M ferrites. The coercive force?Hc? of the preparing samples were 5057 Oe. And the doping affects of Ba M were investigated for enhancing applications.On the one hand, the Zn²⁺?Co²⁺?Nb5+doping singlely were studied in this paper. The Hc can be obvious decreased by Co²⁺ doping, with the minimum values of 1988.3Oe.The Ba Zn_0.6Nb_0.4CoxFe_11-xO₁₉ had high saturation magnetization?Ms? with the value of 60.208 emu/g and the lowest Hc with the value of 579.54 Oe, when sintering at 1000 degree.On the other hand, the works for enhancing the Hc of Ba M by doping elements, such as Al³⁺ and Mn²⁺, were also researched in this paper. Through the experiments, we found that Al³⁺ can refine particles and prevent the growth of pariticles effectively, so its effects on increasing the Hc is more significant. At this point, the effects of doping Mn²⁺ enhanced the Hc with smaller changes. Finally, the complex doped samples Ba Mn_0.8AlxFe_11.2-xO₁₉ can achieve the further improvement of the Hc with the maximum value of 8015.9Oe.