Composition-dependent structural, electrical, magnetic and magnetoelectric properties of (1 − x)BaTiO3−xCoFe2O4 particulate composites

Multiferroic composite with the general formula (1 − x)BaTiO3−xCoFe2O4 (x = 0.05, 0.15, 0.25, 0.35 and 0.45) has been synthesized by a standard solid-state reaction route. Powder X-ray diffraction analysis confirms the existence of ferrite (spinel CoFe2O4) and ferroelectric (tetragonal BaTiO3) biphase without any impurity phases in the sintered composites. Microstructure of the composite displays two different grain sizes and shapes studied from SEM analysis. The composites show both ferroelectric and ferromagnetic ordering: the saturation magnetization (Ms) and retentivity (Mr) of the composite are improved with the increase in ferrite phase, while leakage current, ferroelectric and dielectric properties of the composites show a drop. Existence of coupling between ferroelectric and ferromagnetic ordering measured through magnetodielectric (MD) and magnetoelectric (ME) studies reveal an increase in % MD and ME coefficients with an increase in ferrite content. An enhanced ME coupling coefficient of 17 mV cm−1 Oe−1 has been realized at a dc magnetic field of 5 kOe with a ac frequency of 50 Hz in (1 − x)BaTiO3−xCoFe2O4 (x = 0.45) composite.