The enhanced dielectric permittivity (ε') while retaining a low loss tangent (tanδ) in silver nanoparticle-(In1/2Nb1/2)0.1Ti0.9O2/poly(vinylidene fluoride) (Ag-INTO/PVDF) composites with different volume fractions of a filler (fAg-INTO) was investigated. The hybrid particles were fabricated by coating Ag nanoparticles onto the surface of INTO particles, as confirmed by X-ray diffraction. The ε' of the Ag-INTO/PVDF composites could be significantly enhanced to ~86 at 1 kHz with a low tanδ of ~0.044. The enhanced ε' value was approximately >8-fold higher than that of the pure PVDF polymer for the composite with fAg-INTO = 0.5. Furthermore, ε' was nearly independent of frequency in the range of 102-106 Hz. Therefore, filling Ag-INTO hybrid particles into a PVDF matrix is an effective way to increase ε' while retaining a low tanδ of polymer composites. The effective medium percolation theory model can be used to fit the experimental ε' values with various fAg-INTO values. The greatly increased ε' primarily originated from interfacial polarization at the conducting Ag nanoparticle-PVDF and Ag-INTO interfaces, and it was partially contributed by the high ε' of INTO particles. A low tanδ was obtained because the formation of the conducting network in the polymer was inhibited by preventing the direct contact of Ag nanoparticles.
Keywords: TiO2; colossal permittivity; hybrid particle; polymeric composite; polyvinylidene fluoride (PVDF); silver nanoparticles.