Magnetic, dielectric, magnetoelectric, and microstructural studies demonstrating improved magnetoelectric sensitivity in three-phase BaTiO₃–CoFe₂O₄–poly(vinylidene-fluoride) composite

A three-phase BaTiO₃–CoFe₂O₄–poly(vinylidene-fluoride) (BT-CF-PVDF) particulate composite showing a maximum magnetoelectric voltage coefficient α_E33∼26 mV/cm Oe, at a small applied magnetic field H_DC=263 Oe, has been demonstrated in this work. Large magnetoelectric response in this composite (particulate BT-CF embedded in PVDF matrix) is possibly a result of the effective mechanical interaction between CF and BT through the PVDF matrix. Processing temperatures for composite preparation are low, ensuring no chemical reaction or interdiffusion between the atoms of piezoelectric and magnetostrictive phases, leading to large value of magnetoelectric voltage coefficient. Detailed measurements of dielectric, magnetic, and static magnetoelectric data are reported. Peak in the dielectric spectrum is shown to correlate with the buildup of magnetization in the composite. Although the M-H loop gives M_s, M_r, and H_c (=37.2 emu/g, 16.4 emu/g, and 830 Oe, respectively) in accordance with the expected values (wt % of CF in the composite is 52.5%), the overall magnetic behavior of the composite is identified as “spin glass.”