Microstructure driven magnetodielectric behavior in ex-situ combustion derived BaTiO3-ferrite multiferroic composites

The present work investigates the magnetodielectric behavior of ex-situ combustion derived 7BaTiO(3)@3ferrite and 3ferrite@7BaTiO(3) multiferroic composites. Three different ferrites, such as CoFe2O4, ZnFe2O4, and Co0.5Zn0.5Fe2O4, have been selected for the preparation of multiferroic composites. Distinct microstructural features were observed in 7BaTiO(3)@3ferrite and 3ferrite@7BaTiO(3) composites. X-ray diffraction study confirmed the presence of hexagonal and tetragonal BaTiO3 in 3ferrite@7BaTiO(3) composites. Plate-like and spherical BaTiO3 grains were observed in these composites. However, only spherical or polyhedral BaTiO3 grains were found in 7BaTiO(3)@3ferrite composites, as confirmed from EDS mapping. Also, plate-like BaFe12O19 and polyhedral ferrite grains were detected in all composites. The presence of BaFe12O19 and its effect on magnetic and dielectric behavior of composites was also analyzed in this work. Maxwell-Wagner polarization phenomenon due to charge depletion at the BaTiO3-ferrite interface was found to be prominent in 7BaTiO(3)@3ferrite composites because of the maximum connectivity of ferrite phases. The main factors for the magnetocapacitance response in the present systems are due to the combined effects of interface-dominated magnetoresistance, magnetostriction of ferrites and microstructure of composites. The variation in magnetocapacitance response of these multiferroic composites may be suitable for potential applications in the field of sensors and devices.