BiFeO₃-CoFe₂O₄ Based Multiferroic Composites With Magnetically Driven Polarization

Multiferroic composites are getting the spotlight in scientific community because of their versatility in various room temperature applications including the spintronics devices,actuators,sensors,and other multifunctional memory devices.Multiferroic materials with magnetoelectric coupling have attracted researchers and scientists as these materials can provide higher freedom to facilitate the functioning of multifunctional devices.Magnetoelectric coupling in some special materials among the multiferroics family can provide an extra degree of freedom for the functioning of future multifunctional devices.The three-phase multiferroic composites consisting of rhombohedral Bi Fe O₃,spinel cubic Co Fe₂O₄,and tetragonal Pb(Zr_0.52Ti_0.48)O₃ of the form（1-x）（0.3Co Fe₂O₄-0.7Bi Fe O₃）-x Pb(Zr_0.52Ti_0.48)O₃（x=0,0.1,0.2,and 0.3）were synthesized following a three-step route.The X-ray diffraction analysis confirmed the respective crystalline phases of the Bi Fe O₃,Co Fe₂O₄,and Pb(Zr_0.52Ti_0.48)O₃.The Surface microstructures of the composites were analyzed by the scanning electron microscope（SEM）and elemental stoichiometric contents were confirmed by the energy dispersive X-ray（EDX）analysis.Reversible polarization with the application of an applied magnetic field was observed in the form of ME response for all the samples.The electric and magnetic properties（Dielectric,ferroelectric,and ferromagnetic properties）were significantly enhanced in the 0.3Co Fe₂O₄-0.7Bi Fe O₃ system with the addition of piezoelectric Pb(Zr_0.52Ti_0.48)O₃ without suppressing their magnetoelectric coupling coefficient（ME）,proving the potential of these multiferroic composites for the fabrication of modern devices with multifunctional applications.Multiferroic,3-phase,（1-x）[0.7Bi Fe O₃-0.3Co Fe₂O₄]-x Pb Ti O₃ composites（x=0,0.1,0.2,0.3,0.4,and 0.5）with magnetically tunned robust magnetoelectric（ME）coupling were prepared by Sol-gel method combined with solid state reaction method.The crystalline phases of rhombohedral Bi Fe O₃,spinel cubic Co Fe₂O₄,and tetragonal Pb Ti O₃ were confirmed by X-ray diffraction analysis.A scanning electron microscope was used to analyze the surface microstructures and an energy dispersive spectroscopy provided the stoichiometric elemental confirmation.Significantly improved dielectric,magnetic,ferroelectric and lower ac-leakage behavior were observed.The optimum best dielectric properties,saturation polarization,saturation magnetization,and ME couplings were observed for the 10%PTO in the composite series.These results show that a critical amount of PTO can effectively improve the magnetoelectric coupling performance.Multiferroic 4-phase polymer-ceramic composites in the form of（1-x）[0.9（0.3Co Fe₂O₄-0.7Bi Fe O₃）-0.1Pb(Zr_0.52,Ti_0.48)O₃]-x PVDF（BFO-CFOPZT/PVDF）have been synthesized by a sol–gel and hot-pressed combined low temperature process.The impact of the PDVF addition with different volume on the microstructure,ferroelectric,dielectric,magnetic,and magnetoelectric features are investigated.XRD analysis shows the presence of 4 distinct phases of CFO,BFO,PZT,and PVDF.The dielectric loss and remanent polarization were found decrease proportionally with the addition of PVDF.In the meantime,the magnetoelectric coupling retain similar large values irrelevant with the addition of PVDF.It is then concluded that the introduction of PVDF polymer matrix can overcome the flaws such as dielectric loss of BFO-CFO-PZT composite while retain its exceptional multiferroic properties.