Dielectric response and percolation behavior of Ni–P(VDF–TrFE) nanocomposites

Abstract

Conductor-dielectric 0-3 nanocomposites using spherical nickel nanoparticles as filler and poly(vinylidene fluoride-trifluoroethylene) 70/30 mol.% as matrix are prepared using a newly developed process that combines a solution cast and a hotpressing method with a unique configuration and creates a uniform microstructure in the composites. The uniform microstructure results in a high percolation threshold ' c (> 55 vol.%). The dielectric properties of the nanocomposites at different frequencies over a temperature range from À70 C to 135 C are studied. The results indicate that the composites exhibit a lower electrical conductivity than the polymer matrix. It is found that the nanocomposites can exhibit an ultra-high dielectric constant, more than 1500 with a loss of about 1.0 at 1 kHz, when the Ni content (53 vol.%) is close to percolation threshold. For the nanocomposites with 50 vol.% Ni particles, a dielectric constant more than 600 with a loss less than 0.2 is achieved. It is concluded that the loss including high loss is dominated by polarization process rather than the electrical conductivity. It is also found that the appearance of Ni particles has a strong influence on the crystallization process in the polymer matrix so that the polymer is converted from a typical ferroelectric to a relaxor ferroelectric. It is also demonstrated that the widely used relationship between the dielectric constant and the composition of the composites may not be valid.

Recent progress on nanostructured conducting polymers and composites: synthesis, application and future aspects

“…More importantly, the dielectric loss of 1 is lower than the loss reported in most of conductor-dielectric composites using metallic particles and 1D conductive fillers. The loss observed in the composites at low temperatures is mainly determined by this relaxation process rather than the conductivity [273].…”

Recent Advances on Conducting Polymers Based Nanogenerators for Energy Harvesting

“…Recently, PVDF/PANI nanofibers for energy harvesting were investigated [63,71,72]. The use of conductive fillers such as metal, CNT, graphene, and PANI aids in the formation of an electrically conductive network [73][74][75][76][77][78][79], which improves the piezoelectric conversion efficiency. However, CNT and graphene are very easy to substantial aggregation within the PVDF nanofibers.…”

Frequency-dependent scaling behavior of polyvinylidene fluoride/metal composites

“…[21][22][23] Similarly, the other type of PD is the polymer/metal composites (PMC), where the composites undergo an insulator to metal transition (IMT) at a critical concentration of the conductor called the percolation threshold (f c ). [24][25][26][27][28][29][30][31][32] In particular, as the filler concentration approaches f c from below, the effective a.c. electrical conductivity ( eff ) and the dielectric constant (" eff ) of the composite increase dramatically which undergoes as a second order phase transition. 31 The fundamental physics around the IMT of these PD in the vicinity of f c is very interesting both from theoretical and experimental point of view.…”