Significantly Enhanced Dielectric Properties of Ag-Deposited (InNb)TiO/PVDF Polymer Composites.

The enhanced dielectric permittivity (ε') while retaining a low loss tangent (tanδ) in silver nanoparticle-(InNb)TiO/poly(vinylidene fluoride) (Ag-INTO/PVDF) composites with different volume fractions of a filler () 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 = 0.5. Furthermore, ε' was nearly independent of frequency in the range of 10-10 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 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.