Synthesis Of Nanosize Magnetic Powder Materials And Application In Microwave Absorbing

In this thesis, the several methods to prepare nano-magnetoplumbite compoundoxide-BaCo₂Fe₁₆O₂₇ -were studied and the advantages and disadvantages ofdifferent methods were compared. By measuring and analyzing at the process ofexperiments, the conclusion can be drawn that citrate sol-gel method was the suitabletechnique. Therefore, the different factors that affected the citrate sol-gel synthesiswere investigated and the appropriate conditions of citrate sol-gel synthesis wereconfirmed after a series of experiments.After the citrate sol-gel synthesis method was confirmed as the optimal route, Zn²⁺was used in substituent element experiments. As a result, Zn-Co magnetoplumbiteferrites were made. On the basic of the method, the spine ferrite MnFe₂O₄ andNiFe₂O₄ were synthesized by self-propagating combustion technology, The elementsin the compound oxides were replaced by Zn²⁺ and La³⁺. The nanometer magneticcompound oxides were characterized by XRD,TEM,IR,TG-DTA,VSM. The magneticproperties of samples were studied in detail. Physical parameters such as specificsaturation magnetization intensity and coercive force were discussed with the changefor the constitution of samples and synthesized temperature.The applied experiments of the nanometer magnetic powder were made in themicrowave absorbing and the electromagnetic parameters (ε′′,ε′, μ′′and μ′) weredetermined. The magnetic powders were mixed with epoxy and low molecularpolyamide resin by certain proportion. They were pressed as microwave absorbingmaterials in order to measure reflectivity of microwave. And the microwave absorbingmechanism of ferrite were explained.The nano-spinel and magnetoplumbite magnetic materials were of broadapplications in many fields, and the investigations of synthesis and properties aboutabove ferrite oxides were of universal significance.