Effects of processing methods on dielectric properties of BaTiO3/poly(vinylidene fluoride) nanocomposites

Effects of different liquid phase processes on microstructure and dielectric properties of BaTiO3/poly(vinylidene fluoride) (BT/PVDF) nanocomposites fabricated by using spherical BT nanoparticles (<100 nm) with different volume fractions (f(BT) = 0-0.4) were investigated. The dielectric permittivity (epsilon') of BT/PVDF prepared by a liquid-phase assisted dispersion (LAD) method was nearly independent of frequency in the range of 10(2)-10(6) Hz. In contrast, the strong frequency dependence of epsilon' in a low-frequency range was observed in the nanocomposites that were prepared by a solution processing (SP) method, especially for high-loading BT nanoparticles. epsilon' values at 10(3) Hz of the BT/PVDF nanocomposites with f(BT) = 0.4 prepared by these two methods were found to be 61.9 and 623.3, respectively, while the loss tangent values were 0.218 and 0.887, respectively. Uniformly dispersed BT/PVDF nanocomposites were obtained by a LAD method. For a SP method, a strong agglomeration of BT nanoparticles resulted in the formation of large spherical clusters with sizes of similar to 10-30 mu m. The different dielectric responses were described based on the strong dipole polarization in the large clusters of agglomerated BT nanoparticles and the interfacial polarization at the large interface area of PVDF thin layer between BT clusters. (C) 2015 Elsevier B.V. All rights reserved.