Functionalized graphene-BaTiO3/ferroelectric polymer nanodielectric composites with high permittivity, low dielectric loss, and low percolation threshold

The fabrication and dielectric properties of a novel multi-component high-k composite system consisting of poly(vinylidene fluoride), surface-functionalized graphene nanosheets and BT nanoparticles (fRGO-BT/PVDF) were investigated. The fRGO nanosheets were prepared through the pi-pi stacking of polyaniline and GO following in situ hydrazine reduction. The fRGO-BT/PVDF nanocomposites were fabricated by a solution casting and hot-pressing approach. SEM results confirm that fRGO and BT are well dispersed within the PVDF matrix. The dielectric properties of the binary fRGO/PVDF nanocomposites exhibit a typical percolation transition with the percolation threshold of 1.49 vol%. This type of nanocomposite, co-filled with conductive graphene nanosheets and high-k ceramics, shows a high k(r) (65) and a relatively low dielectric loss (tan delta = 0.35) at a high frequency of 1 MHz. Meanwhile, the dielectric properties of the fRGO-BT/PVDF nanocomposites show temperature independent behavior over a wide temperature range. These flexible, high-k fRGO-BT/PVDF nanocomposites are potential flexible dielectric materials for use in high-frequency capacitors and electronic devices.