Insight into Interfacial Polarization for Enhancing Piezoelectricity in Ferroelectric Nanocomposites.

The interfacial effect is widely used to optimize the properties of ferroelectric nanocomposites, however, there is still a lack of direct evidence to understand its underlying mechanisms limited by the nano size and complex structures. Here, taking piezoelectricity, for example, the mechanism of interfacial polarization in barium titanate/poly(vinylidene fluoride-ran-trifluoroethylene) (BTO/P(VDF-TrFE)) nanocomposite is revealed at multiple scales by combining Kelvin probe force microscope (KPFM) with theoretical stimulation. The results prove that the mismatch of permittivity between matrix and filler leads to the accumulation of charges, which in turn induces local polarization in the interfacial region, and thus can promote piezoelectricity independently. Furthermore, the strategy of interfacial polarization to enhance piezoelectricity is extended and validated in other two similar nanocomposites. This work uncovers the mechanism of interfacial polarization and paves newfangled insights to boost performances in ferroelectric nanocomposites.