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

Abstract

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 β–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 (Pmax∼1.57 μC/cm2 at 750 kV/cm) and the higher dielectric constant (εr∼16.84) as well as a lower dielectric loss tanδ < 0.04, compared to the pristine PVDF matrix (Pmax∼0.88 μC/cm2, εr∼10.26). A recyclable energy density of Wrec∼0.84 J/cm3 at 750 kV/cm is observed, together with a high efficiency (η∼87.82 %). The ferromagnetic behavior is confirmed by the M-H hysteresis loop, which exhibits significant magnetic properties, i.e., saturation magnetization (MS∼0.58 emu/g) and coercivity (HC∼1.72 kOe). Additionally, a robust magnetodielectric effect with a large negative coefficient (∼8.23 %) is achieved at a low magnetic field H∼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.