Multiferroic properties in poly(vinylidene-fluoride)-based magnetostrictive/piezoelectric laminate composites

Multiferroic materials (MFM) have drawn considerable attention for developing smart multifunctional devices. Herein, poly(vinylidene-fluoride)-based (PVDF) MFM composite films of Ba0.85Ca0.15Zr0.1Ti0.9O3-PVDF/CoFe2O4-PVDF/Ba0.85Ca0.15Zr0.1Ti0.9O3-PVDF with sandwich-laminated structure are developed and investigated for its dielectric, magnetic, ferroelectric and magnetodielectric (MD) properties. An improved polar beta-phase is formed with the particles of CoFe2O4 and Ba0.85Ca0.15Zr0.1Ti0.9O3 embedded in PVDF matrix. Both magnetic (M-H) and ferroelectric polarization (P-E) hysteresis loops indicate the multiferroic nature at room temperature, i.e., the coexistence of ferroelectric and ferromagnetic ordering in composite films. An enhanced ferroelectricity is obtained for the maximum polarization (P-max similar to 1.57 mu C/cm(2) at 750 kV/cm) and the higher dielectric constant (epsilon(r)similar to 16.84) as well as a lower dielectric loss tan delta < 0.04, compared to the pristine PVDF matrix (P-max similar to 0.88 mu C/cm(2), epsilon(r)similar to 10.26). A recyclable energy density of W-rec similar to 0.84 J/cm(3) at 750 kV/cm is observed, together with a high efficiency (eta similar to 87.82 %). The ferromagnetic behavior is confirmed by the M-H hysteresis loop, which exhibits significant magnetic properties, i.e., saturation magnetization (M-S similar to 0.58 emu/g) and coercivity (H-C similar to 1.72 kOe). Additionally, a robust magnetodielectric effect with a large negative coefficient (similar to 8.23 %) is achieved at a low magnetic field H similar to 3 kOe. The laminate composite film exhibits room temperature multiferroic with a large MD response, making it a promising candidate for utilization in intelligent multifunctional devices.