Improvement in dielectric properties of poly(vinylidene fluoride) by incorporation of Au–BiFeO3 hybrid nanoparticles

Abstract

Poly(vinylidene fluoride) (PVDF)-based nanocomposites were fabricated using a hybrid combination of Au nanoparticles (AuNPs) and BiFeO3 (BFO) NPs as a filler. AuNPs with sizes of 10–20 nm were deposited onto the surface of the BFO NPs via a modified Turkevich's method to obtain Au–BFO hybrid NPs. α-, β-, and γ-PVDF phases were detected in all the polymer nanocomposites. The fraction of the electroactive (i.e. polar) β-phase of the PVDF polymer increased after the incorporation of the hybrid NPs. The AuNPs and BFO NPs were homogeneously dispersed in the PVDF matrix. PVDF filled with the Au–BFO hybrid NPs showed a significantly increased dielectric permittivity—which was 5 times that of pure PVDF polymer—whereas the conductivity and corresponding loss tangent of all the nanocomposites remained lower than 0.05 at room temperature and 1 kHz. The enhanced permittivity was primarily a result of the strong interfacial polarisation and partly a result of the high permittivity of the BFO NPs and the formation of the β-PVDF phase. The suppressed loss tangent was attributed to the discrete growth of AuNPs on the surface of the BFO NPs, which inhibited the formation of the conduction pathway in the PVDF matrix.