Low-frequency dielectric phenomena in BaTiO3/polymer nanocomposites

BaTiO₃ (BT) with various diameters were synthesized by alkoxide route and then loaded into different polymers (poly (vinylidene fluoride) (PVDF) and polyimide (PI)) at 50 vol. % to fabricate BT/PVDF and BT/PI nanocomposite films. The effects of nanoparticles and polymer matrixes on dielectric properties were studied in a wide range of frequency from 10^-2 Hz to 10⁶ Hz. A significant low-frequency dielectric permittivity increase was observed. Interfacial polarization and crystal phase effect are considered to analyze the significant increase at low frequency. A significant discrepancy between BT/PVDF and BT/PI composites in dielectric behaviors was discussed. Herein, nanoparticles influenced more on dielectric behavior in the BT/PVDF than in BT/PI composites. It resulted from the strong polarization interaction between ferroelectric BT phase and ferroelectric PVDF phase. Therefore, the roles of nanoparticles (size and crystal phases) and properties of polymers (chemistry and chain structure) are considered to explain the difference in dielectric behaviors.