Preparation and investigation of structure, magnetic, and dielectric properties of (1 − x)Bi₂Fe₄O₉–xMgFe₂O₄ bicomponent ceramics

Crystal structure, morphology, magnetic, and dielectric properties of (1 − x)Bi₂Fe₄O₉–xMgFe₂O₄ bicomponent ceramics are investigated in detail. The material has been synthesized via sol–gel method. Analysis of X-ray diffraction data of the bicomponent ceramics shows the coexistence of orthorhombic Bi₂Fe₄O₉ and spinel MgFe₂O₄ phases with no third phase. Microstructural and surface morphology displays the homogeneous grain distribution with different grain sizes of Bi₂Fe₄O₉ and MgFe₂O₄. The magnetic measurement shows decreasing coercivity and increasing values of remnant and saturation magnetization with the increase in MgFe₂O₄. Temperature-dependent dielectric properties and electrical modulus are conducted in the temperature range of 27–527 °C with the frequency ranging from 1 to 30 kHz. Two abnormal peaks are, respectively, observed at low and high temperature ranges. The variation of electric properties is closely related to the composition of MgFe₂O₄. The results of dielectric and electrical modulus indicate the appearance of dielectric relaxation in (1 − x)Bi₂Fe₄O₉–xMgFe₂O₄. Combined with the study of activation energy, the dielectric relaxation is mainly induced by different electric responses of various charge carriers intrinsically dominating in a thermally activated process with the incorporation of MgFe₂O₄. The combination of Bi₂Fe₄O₉ and MgFe₂O₄ enhances the coexistence of magnetic and electric properties in the present composites. It is quite promising from application point of view.