Preparation And Magnetoelectric Properties Of Fe Doped BaTiO₃ Textured Ceramics

Multiferroic materials have become a research hotspot because of the coexistence of two or more basic ferrites.Among them,magnetoelectric multiferroic materials are favored by the majority of researchers because of their potential application value in logic devices and information memory devices.Therefore,it is of great significance to prepare ferroelectric and magnetic multiferroic materials.BaTiO₃ is a typical ferroelectric material.Doping transition metal ions can introduce magnetism into BaTiO₃.But at present,the main problem is that it is difficult to ensure that the ferroelectric properties do not decline while introducing magnetism.In order to solve the above problems,in this paper,BaTiO₃ template with high orientation in[00l]direction was prepared by doping Fe3⁺to introduce magnetism and using the Templated Grain Growth（TGG）method to prepare Ba Ti_1-xFe_xO₃ textured ceramics.The excellent ferroelectric properties were ensured by adjusting the structure.The effect of molten salt temperature on the phase and morphology of the template was studied.The results show that the optimal molten salt temperature for the first step preparation of Bi₄Ti₃O₁₂ template by TGG method is 1100 ^oC,and the template size is concentrated in 5～10μm.Average thickness0.2μm.The ratio of length to diameter is more than 20,which is suitable for tape casting.The molten salt temperature of Ba Bi₄Ti₄O₁₅ template prepared in the second step is 1060 ^oC,and the template size is concentrated in 5～10μm.Average thickness 0.4μm.The ratio of length to diameter is between 12 and 25.In the third step,the optimal molten salt temperature for preparing BaTiO₃ template is 930^oC,and the template size is concentrated in 8～10μm.Average thickness is 0.6μm.The ratio of length to diameter is between 13 and 16,which meets the requirements of tape casting.The relationship between orientation degree and magnetoelectric properties of textured ceramics was studied by changing Fe doping level and sintering temperature.The results show that when the Fe doping level is 3%and8%,the ceramics are tetragonal phase and hexagonal phase coexisting,which makes it difficult for the ceramics to texture,and the existence of hexagonal paraelectric phase can not guarantee the excellent ferroelectric properties.Therefore,we adjust the Fe doping level to 0.5%,1%and 1.5%,at this time,the ceramic phase is tetragonal ferroelectric phase,and the orientation degree is more than 80%.When the Fe doping level is 0.5%,1%and 1.5%,the textured ceramics with 80%,89%and 93%orientation degree are obtained.With the increase of orientation,the relative permittivity decreases from 1294 to 1041 at 1 MHz.With the increase of doping level,c/a decreases from 1.011 to 1.007.When the sintering temperature increases from 1100 ^oC to 1500 ^oC,the degree of orientation increases from 14%to 96%.The relative permittivity decreases from 1994 to 1118 at 1K Hz with the increase of orientation from 56%to 96%at 1200 ^oC～1500 ^oC.With the increase of Fe doping level,the orientation degree and the saturation polarization Pmax of textured ceramics are enhanced,and the maximum polarization is 27.9μC/cm² at 30 k V/cm When the doping level is 1.5%,the coercive field E_C is 2.01 k V/cm.Taking the textured ceramics with doping level of 1%as an example,with the increase of orientation degree,the ferroelectric properties are improved,and the saturation polarization value P_max of the ceramics is enhanced,and the maximum saturation polarization value is P_max=39.9μC/cm²The maximum P_r is 15.9μC/cm²。Magnetism has successfully introduced by Fe doping The dielectric,ferroelectric and magnetic properties of textured ceramics are anisotropic.