Enhancement of dielectric and electrical properties in BFN/Ni/PVDF three-phase composites

To develop dielectric materials with high dielectric constant and low dielectric loss, a novel three-phase composite was prepared by embedding the nano-sized Ba(Fe0.5Nb0.5)O3 (BFN) crystallites and Ni crystallites into poly(vinylidene fluoride) (PVDF) matrix. The structure, dielectric and electrical properties of the composites were investigated. The superiority of this method is that, when compared with the two-phase Ni/PVDF composites, three-phase composites not only show significantly increased dielectric constants but also have lower dielectric loss. Our results show that a high dielectric constant of 475 and a relatively low loss of 0.61 were achieved at 100 Hz with 25 vol.% Ni and 50 vol.% BFN, respectively. The enhancement of dielectric constant of polymer based composites can be interpreted by the mini-capacitor principle and the interfacial polarization. The relatively low dielectric loss could be attributed to the isolation effect of BFN fillers. These composites with high dielectric constant and low dielectric loss are found to be potentially useful for embedded capacitor applications.