Enhanced dielectric and ferroelectric properties of cobalt ferrite (CoFe2O4) fiber embedded polyvinylidene fluoride (PVDF) multiferroic composite films

Abstract

One-dimensional, ferromagnetic cobalt ferrite fibers were synthesized through electrospinning technique and were used as the fillers in poly(vinylidene fluoride) (PVDF) matrix to fabricate flexible, free-standing homogeneous PVDF/CoFe2O4 films. The structural properties of the composite films were analyzed through x-ray diffraction (XRD) whereas the functional groups were identified using FTIR studies, and a maximum enhancement of 76% of electroactive β-phase was observed with the incorporation of CoFe2O4 fibers. Morphological studies confirmed the formation of spherulites of diameter ranging from 5.2 to 15 μm. The roughness parameters of the PVDF/CoFe2O4 composite films were analyzed by atomic force microscopy (AFM). The variation in the dielectric constant and loss, and ferroelectric characteristics of the composite films at room temperature were investigated with respect to the fiber concentration. The enhanced dielectric constant of 29 with a tangent loss 0.21 was observed for 20 wt% filler loading at 100 Hz. The ferromagnetic nature of the composite films was analyzed with vibrating sample magnetometer (VSM), and the maximum saturation magnetization of 10.7 emu cm−3 was obtained for 20 wt% of the composite film. Further, the ferroelectric nature of the films was examined by the domain switching behavior using DC-EFM.