Enhanced dielectric properties of PVDF-based three-phase composite films through introducing the semiconductive ZnO and ferroelectric NKBT filler

The three-phase composites have emerged as a research focus in advanced electronic manufacturing due to their high permittivity, low loss, flexibility, and unique integration capabilities. In this study, ZnO-Na0.25K0.25Bi0.5TiO3/PVDF three-phase composites with varying filler contents were prepared through the solution-casting method. The incorporation of ZnO particles increased the content of the β-phase in PVDF, directly enhancing permittivity (ε′). The ε′ of the composites increased with increasing the content of the filler, and it achieved 164 with low tanδ of 0.12 at the volume ratio of 0.5. Moreover, the film exhibited the large breakdown strength of 359.5 kV/mm and excellent flexible properties. The enhancement of ε′ could be attributed to the interfaces of ZnO-PVDF and NKBT-PVDF, which created space charge accumulation that strengthened interfacial polarization. The dielectric response of ZnO-NKBT/PVDF composites was governed by the effective medium percolation theory (EMPT) model, with the ε′ dependence on filler content closely aligning with its theoretical predictions. This study provided a basis for the design of three-phase composites with high permittivity and low loss via interface regulation and model optimization.