Multiferroic properties of multilayered BaTiO3–CoFe2O4 composites via tape casting method

Abstract

Multiferroic magnetoelectric (ME) BaTiO3–CoFe2O4 (BTO–CFO) ceramic composites with different thicknesses were fabricated via tape casting technique. The interfacial morphology of the composite demonstrates the presence of plate-like grains with a thickness of ~400 nm. This could be associated with the residual stresses originated from lattice mismatch and different thermal expansion coefficients between BTO and CFO layers. The dielectric constant, piezoelectric constant, and ferroelectric properties of the multilayered composite are degraded in the presence of CFO layers in comparison with those of BTO bulk. Furthermore, the dielectric constant and polarization of the composite decrease with increasing frequency. The leakage current density and magnetic remanence ratio of the composite reach up to the order of 10−6 A/cm2 and 40 %, respectively. The direct and converse ME coefficients were measured to be 8.1 μV/cm Oe and 1.1 × 10−3 G/V, respectively. Based on the converse ME effect, an electrically controlled ME inductor was designed using the composite as its core. The inductance and tunability of the inductor increase with increase of applied dc electric field.