Magnetocapacitance Response in Ex Situ Combustion Derived BaTiO3–Ferrite Magnetodielectric Composite

This research focuses on the field- and frequency-dependent magnetocapacitance (MC) response in ex situ combustion derived homogeneous microstructure of magnetodielectric (MD) composite having plate-like and polyhedral barium titanate as well as plate-like ferrite phases. Barium hexaferrite has also emerged in the composite due to the diffusion of Ba ions into cobalt ferrite. The composite shows an effective permittivity of 320 at 1 MHz. The saturation magnetization ( $\text{M}s$ ), coercivity ( $\text{H}c$ ), and remanence magnetization ( $\text{M}r$ ) of the composite are found ~3 emu/g, ~510 Oe, and ~0.86 emu/g, respectively. A maximum slope of magnetization of ~0.002 emu g−lOe−l is observed in the composite at ~0.87 kOe, which is in correlation with the maximum MC of approximately −2.9% at 0.87 kOe. Magnetic field-dependent MC of approximately −4% at low frequency is due to the contribution from the Maxwell–Wagner polarization and magnetoresistance. The MC of approximately −1.23% is found at 1 MHz under 2.68 kOe, and it is due to the contribution from the strain-mediated coupling. Nearly, the constant dielectric losses of ~0.46, ~0.10, and ~0.03 are observed at 1, 100, and 1 MHz, respectively, under the applied magnetic field. Cole–Cole plot also confirms the existence of low magnetoresistance in the composite. The combined contribution of Maxwell–Wagner polarization and magnetoresistance influences the MC response in the MD composite.