Synthesis and characterization of composite MgFe_2O_4-BaTiO_3 multiferroic system

摘要

Multiferroic ceramics with the general formula (x)MgFe_2O_4-(1-x)BaTiO_3 (x=0.4, 0.5, and 0.6) were synthesized by solid-state sintering process. From the x-ray diffraction analysis, it was observed that almost no chemical reaction occurs between the ferrite and the ferroelectric materials used to form the diphase composite systems. No impure phase was observed in all the sintered composite systems. Leakage current density, ferroelectric properties and dielectric properties were found to improve with the addition of the ferroelectric phase. For the composite with the least amount of ferrite, the values of remnant polarization (2P_r) before and after dc magnetic poling at 7 kOe for 1 h were found to be 1.35 and 2.12 μC/cm~2, respectively. This showed marked improvement as high as 57% and confirmed the coupling of the electrical dipoles with the magnetic field applied. All the studied composite systems proved to be multiferroic in nature. The highest magnetoelectric coupling coefficient of 50.2mV/cm Oe was measured at dc magnetic field of 10 kOe along with ac frequency of 50 Hz at room temperature for the 0.6MgFe_2O_4-0.4BaTiO_3 composite system. Magnetoelectric effect at resonance frequency increases by a factor of 80 compared to the other frequencies for such composite systems.