Influence of graphene oxide and reduced graphene oxide on dielectric properties of PZT/PVDF composite films

Abstract

Attributed to its high piezoelectric coefficient, Lead Zirconate Titanate (PZT) is a fascinating material for sensing applications. However, being a brittle material, PZT is prone to fracture during flexible load-bearing applications. Polyvinylidene fluoride (PVDF), a semi-crystalline polymer exhibits five distinct polymorphs named as α, β, γ, and e. Among them β-polymorph possesses good dielectric, piezoelectric and pyroelectric behavior. When Graphene Oxide (GO) and reduced Graphene Oxide (RGO) are added to α-PVDF it facilitates the nucleation of β form. This research aims at examining the effect of addition of GO and RGO, as a filler, on the dielectric behavior of flexible PZT/PVDF composite. GO used in this research was prepared using modified Hummers method and subsequently reduced through thermal reduction to form RGO. The formation of GO and RGO was confirmed using XRD and FTIR. PZT/PVDF/GO and PZT/PVDF/RGO composites were made by solution casting technique with 25 vol% PZT and 0.2 wt% GO/RGO. Dielectric constant was calculated at various frequencies ranging from 100 Hz to 5 MHz for the composite films with LCR meter. It was noted that the dielectric constant decreases with increasing frequency for all the films. The highest value of the dielectric constant observed in this work was 93.41 and 90.09 at 100 Hz for PZT/PVDF/RGO and PZT/PVDF/GO composite films, respectively. The increase in the dielectric constant for GO and RGO containing films is ascribed to the formation of polar β-polymorph PVDF.