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

Abstract

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 (<100nm) with different volume fractions (fBT=0–0.4) were investigated. The dielectric permittivity (ε′) of BT/PVDF prepared by a liquid-phase assisted dispersion (LAD) method was nearly independent of frequency in the range of 102–106Hz. In contrast, the strong frequency dependence of ε′ 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. ε′ values at 103Hz of the BT/PVDF nanocomposites with fBT=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 ∼10–30μm. 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.