The Reseach Of Mixed Doped Of W-type Barium Ferrites For Self-biased Gyromagnetic Material

he barium ferrite of hexagonal crystal system is the first choice for the research of microwave high frequency ferrite because of its high magnetic crystal anisotropic field.High saturation magnetization,strong magnetocrystalline anisotropy field?self biasing?,and so on.These excellent gyromagnetic feature is more suitable for circulator and isolator,in order to improve the reliability of the device,and realize the miniaturization and integration.W-type barium ferrite has a strong uniaxial magnetic crystal anisotropy,high saturation magnetization,coercivity and Curie temperature.So the main research content of this paper is:single-phase W barium ferrite materials production,grain orientation,the basic relations of material structure and properties,the basic law of ion instead of changing the characteristics of the material,in order to improve the material hysteresis loop rectangle ratio and reduce the loss.The first part of this paper is the research of the technology of preparing single phase of Ba W materials,the experiment selected the oxide method.First fixed sintering temperature,change steps and parameters of powder preparation experiment,in order to optimize powder preparation process;Secondly,the preparation process of powder is unchanged and the sintering temperature is changed.In this case,we analyze the performance of different samples.Results showed that increasing presintering temperature to 1200?-2 h can promote the growth of the early stage of the grain,and improve the final material grain size.The dry pressure forming before pre-firing has a slight effect on the micro morphology of the final sintered samples,which can improve the rotational magnetic energy and increase the rectangular ratio of the hysteresis loop.Choosing the sintering temperature between 1100?and 1150?,can get the sample of magnetic optimality.The second part of this paper is that we conducted ion substitution of W type barium ferrite to change its performance.Co²⁺partially replaces Zn²⁺ion in Zn₂W,and the chemical formula is Ba(Zn_1-xCO_x)₂Fe₁₆O₂₇?x=0.20,0.30,0.40?.The results show that with the increase of Co²⁺ion content,the coercive force has a tendency to decrease.With the increase of the doping amount of Co²⁺,the saturation magnetization intensity increased,but the residual magnetism of the sample was not high.The rectangular ratio?M_r/M_s?of the hysteresis loop is also lower,with a maximum of 48.87%.This is because the doping of Co²⁺can weaken the characteristic of BaW type ferrite's crystallographic c-axis texture,which makes the magnetic crystal of the materials tend to the c-plane.Zn²⁺and Ti⁴⁺partially replace the Fe³⁺ions in Zn₂W,and the chemical formula is BaZn₂?ZnTi?_xFe_16-2xO₂₇?x=0,0.5,1.0,1.5?.In order to improve the self-biased performance of the material,the wet pressure magnetic field was used to replace the granulation process in the experiment ofZn²⁺and Ti⁴⁺partially replace the Fe³⁺ions in Zn₂W.The results show that with the increase of Zn²⁺ion and Ti⁴⁺ion doping,the average diameter of the grain decreased,but this did not affect the shape of the hysteresis loop of W type barium ferrite.The coercive force decreased slightly with the increase of doping.The magnetic crystal anisotropy of the material which is Ha is about10kOe,with the increase of the doping amount x,there is a slight decrease in the magnetic crystal anisotropy field.The saturation magnetization intensity decreased significantly with the increase of x,the saturation magnetization decreased from 3385G to 2903G.The rectangular ratio of the hysteresis loop is greatly improved,which is up to 87%?the sintering temperature is 1140?,x=1.0?.VSM tests respectively along the axial direction and difficult magnetization magnetization axis,the hysteresis loop of rectangular than differ by about 60%,which proves the crystallographic c-axis texture,and wet compression process steps can effectively promote rotary magnetic field orientation magnetic hysteresis loop of the rectangular of the materials,and optimize its self-biased performance.All of this can enable W type Ba ferrite to meet the application requirements of microwave millimeter-wave non-reciprocal devices?self-biased circulator,etc.?.