Development of BiFeO₃/MnFe₂O₄ ferrite nanocomposites with enhanced magnetic and electrical properties

Herein we report the development of novel multiferroic nanocomposites for their enhanced magnetic and electrical properties by employing a simple cost-effective chemical process at low temperatures. Novel perovskite-mixed spinel nanocomposites of (1 - x)BiFeO₃/xMnFe₂O₄ where x = 0.1-0.5 have been prepared by a sol-gel auto-combustion technique. The calcination temperature was optimized and the phase formation of BiFeO₃/MnFe₂O₄ nanocomposites was confirmed from the X-ray diffraction patterns for the samples calcined at 500 °C for 2 h. The grain sizes have been found to vary from 60 to 90 nm. The vibrational modes of the prepared nanocomposites were studied using Raman spectroscopy and FESEM and EDX were used to carry out the microstructural and composition analysis respectively. The magnetic properties seemed to have a strong dependence on the concentration of the spinel ferrite in the composite system. Saturation magnetization and coercivity exhibit an increase with increase in the MnFe₂O₄ content. The electrical properties from solid state impedance analysis confirm the non-Debye characteristics and the maximum activation energy is 0.931 eV for the 0.5BiFeO₃/0.5MnFe₂O₄ nanocomposite. Dispersion in the dielectric constant and dielectric loss in the low frequency range has also been determined, which decreases with increase in temperature at lower ac frequencies.