Technology And Application Research Of Hydrothermal Synthesis Hexaferrite

M-type hexaferrite is widely used in traditional industries such as magnetic cores,magnetic recording,microwave and millimeter-wave circuits for the abundant raw material reserve,high curie temperature,high saturation magnetization,good chemical stability and other good properties.With the development of information technology,microwave and millimeter-wave devices starts to develop in the direction of high performance and low cost.Hexaferrite has the advantages of low microwave loss,low cost,and high application potential in the direction of low-cost microwave devices.Hence,the research on the optimization of hexagonal ferrite performance is very important.In this paper,M-type hexagonal strontium ferrite(SrM)was synthesized by the hydrothermal method.The effects of the concentration of overall reactants and sodium hydroxide in the initial formula on the phase composition,microstructure and magnetic properties were systematically investigated.Additionally,the empirical formula for the synthesis of single-phase SrM is summarized.Based on empirical formula,the effects of the molar ratio of strontium ion to iron ion(RF/S),Al3+ ion substitution on the phase composition and magnetic properties of the sample were systematically studied,Finally,the design and simulation of the microstrip circulator was carried out used the self-developed materials.First,the stoichiometric proportion of high-purity SrM was studied by hydrothermal method.This part mainly include the effects of the concentration of overall reactants and sodium hydroxide in the initial mixed solution.The result showed that the concentration of sodium hydroxide in the initial mixed solution is a key factor in the synthesis of single-phase SrM.Based on the above research results,we summarizes the stoichiometric proportion for the synthesis of single-phase SrM,and corrects the empirical formula by changing the concentration of iron ions in the initial formula Verified.Based on this empirical formula,the effect of changing the RF/S in the initial formulation on the product phase,morphology and magnetic properties was studied.Secondly,based on the stoichiometric proportion of SrM,SrM powder with Al3+ ion substitution was synthesized,and the effect of Al3+ ion substitution on the sample microstructure and magnetic properties was studied.According to the magnetic properties of the self-developed SrM material,a K-band microstirp circulator with an operating frequency of 19-27GHz was designed using 3D electromagnetic simulation software HFSS.The reflection loss and the isolation loss of the toroidal were less than-18dB,and the insertion loss was greater than-3dB.