Dielectric properties of Ni-BaTiO3-PVDF composites with different Ni morphology

In this article, Ni particles with different morphologies including spherical Ni and fibrous Ni particles had been synthesized by co-precipitation and e polyol methods, respectively.. As such, a three-phase percolative composites containing Ni as the conductive phase with different morphologies, BaTiO₃ as the ceramic phase embedded into poly(vinylidene fluoride) (PVDF) matrix was prepared through a hot-molding technique by pressing these materials at about 190 °C under a pressure of 3 Mpa for 15 min. The effect of filler Ni morphology and content on the dielectric response of Ni-BaTiO₃-PVDF composites had been investigated in detail by the characterization of Agilent E4991 for high frequency from 1 MHz to 1 GHz. The fibrous Ni-BaTiO₃-PVDF composite material processes a lower percolation threshold at about 15% than 28% of the spherical system. And at the same time, other dielectric properties such as dielectric constant k enhanced through the spherical Ni conductive filler substituted by the fibrous Ni particles. This work could provide a new process to achieve a material system with low percolation threshold which is beneficial to obtain both high dielectric constant and good mechanical performance polymer high k composites.