This work provided an alternative route to balance the significantly increased dielectric permittivity (ε') and effectively retained tanδ using an effective two-step concept. Ag-deposited nano-sized BaTiO3 (Ag-nBT) hybrid particle was used as the first filler to increase the ε' of the poly(vinylidene-fluoride) (PVDF) polymer via the strong interfacial polarization and a high permittivity of nBT and suppress the increased loss tangent (tanδ) owing to the discrete growth of Ag nanoparticles on the surface of nBT, preventing a continuous percolating path. The ε' and tanδ values at 103 Hz of the Ag-nBT/PVDF composite with fAg-nBT~0.29 were 61.7 and 0.036. The sub-micron-sized BaTiO3 (μBT) particle was selected as the blocking particles to doubly reduce the tanδ with simultaneously enhanced ε' due to the presence of the tetragonal BT phase. The μBT blocking particles can effectively further inhibit the formation of conducting network and hence further reducing tanδ. By incorporation of μBT clocking particles with fμBT = 0.2, the ε' value of the Ag-nBT/PVDF-μBT composite (fAg-nBT = 0.30) can significantly increase to 161.4, while the tanδ was reduced to 0.026. Furthermore, the tanδ was lower than 0.09 in the temperature range of -60-150 °C due to the blocking effect of μBT particles.
Keywords: barium titanate; dielectric polymer composites; hybrid nanoparticles; poly(vinylidene fluoride); silver nanoparticle.