Fabrication And Electromagnetic Properties Of Textured Bi₅Ti₃FeO₁₅ Based Ceramics

In recent years,multiferroic materials have wide application properties such as spin electric devices,sensor and memory because its has ferromagnetism,ferroelectricity and other two or more of the orders.Bi₅Ti₃FeO₁₅（BTFO）is a bismuth layer of multiferroic material with good performance of multiferroic property,but there are also problems such as anisotropic structure and properties,low relative density,weak ferromagnetic properties.Thus,in this work,the molten salt method and plasma activated sintering have been suggested to prepare textured BTFO ceramics.The preparation process of textured BTFO ceramics was studied in detail.For further enhance the ferromagnetism of the BTFO ceramics,the textured Bi₅Ti₃FeO₁₅-CoFe₂O₄ ceramics（BTFO-CFO）were prepared by microwave hydrothermal synthesis followed by plasma activated sintering.Firstly,the BTFO powders were synthesized by solid state reaction and molten salt method,respectively.The results show that the BTFO powder is successfully synthesized.Compared with the solid state reaction,the molten salt method can significantly reduce the synthesis temperature,and the synthesized BTFO powder has a more obvious lamellar morphology.Then,the BTFO ceramics were prepared by plasma activated sintering.The effect of sintering temperature and powder morphology on ceramics microstructure was studied.The results show that the BTFO ceramics with single phase and high density（≥96%）have been successfully prepared at 800^oC¹00^oC.The BTFO powders after compaction by plasma activated sintering has high degree of texture with[001]preferred orientation of grains,the texture factor are 0.38（solid state reaction）and0.82（molten salt method）.An important characteristic of BTFO is its remarkable anisotropy properties due to its anisotropic structure,which has implications for its possible applications.Thus,the dielectric,ferroelectric and ferromagnetic properties of textured BTFO ceramics were studied in detail.The results show that the BTFO ceramics have high texture factor,it can improve the dielectric and ferroelectric properties of BTFO.The properties of textured BTFO ceramics have obvious anisotropy.The anisotropic grain boundary structure has obvious regulation effect on the conductivity and dielectric relaxation of the textured BTFO ceramic.Finally,in order to enhance the ferromagnetism of the BTFO ceramics,the textured Bi₅Ti₃FeO₁₅-CoFe₂O₄ ceramics（BTFO-CFO）were prepared by microwave hydrothermal synthesis followed by plasma activated sintering.The ferroelectric and ferromagnetic properties of textured BTFO-CFO ceramics were studied.The results show that the BTFO-CFO ceramics exhibit a high degree of texture along the c-axis crystallographic orientation（≥0.82）.The magnetization of the composites slightly increases with increasing concentration of CFO.The ferroelectric and ferromagnetic properties were obvious enhanced.