Interfacial Polarity Modulation of KTa_0.5Nb_0.5O₃ Nanoparticles and Its Effect on Dielectric Loss and Breakdown Strength of Poly(vinylidene fluoride) Nanocomposites with High Permittivity

The effects of the morphology, interface, and dielectric constant of inorganic fillers on the dielectric properties of nanocomposites were systemically studied in this paper. It is found that two kinds of KTa 0.5 Nb 0.5 O 3 (KTN) nanoparticles, synthesized via solid-state reaction and hydrothermal method respectively, can bring different influences on the structure and electrical performance of the KTN/PVDF composites. This is caused by the OH groups on the surface of the H-KTN nanoparticles which were generated through the hydrothermal method. Theoretical models, including the Maxwell–Garnett model, logarithmic model, Jayasundere–Smith model, effective medium theory model, and Weibull distribution method, are employed to explain the dielectric behavior of the composite. Through the comparison between the experimental data and theoretical models, it is concluded that the geometric shape of fillers plays a more crucial role than the dielectric constant of fillers in enhancing the dielectric constant of KTN/PVDF composite films. Consequently, it is an effective way to fabricate the composites with excellent dielectric properties by modulating the geometric shape of inorganic fillers.