Characterization of percolation behavior in conductor–dielectric 0-3 composites

Abstract

The equation " eff / ð c À Þ Às which shows the relationship between effective dielectric constant (" eff ) and the filler concentration ('), is widely used to determine the percolation behavior and obtain parameters, such as percolation threshold ' c and the power constant s in conductor-dielectric composites (CDCs). Six different systems of CDCs were used to check the expression by fitting experimental results. It is found that the equation can fit the experimental results at any frequency. However, it is found that the fitting constants do not reflect the real percolation behavior of the composites. It is found that the dielectric constant is strongly dependent on the frequency, which is mainly due to the fact that the frequency dependence of the dielectric constant for the composites close to ' c is almost independent of the matrix.

Frequency-dependent scaling behavior of polyvinylidene fluoride/metal composites

“…The values of s and s 0 are found to decrease with the increase of frequency, while the observation of increase of critical exponents with the increase of frequency have been reported in some other reported dielectric conductor composites. 30 The decrease of 's' and 's 0 ' with increase of frequency is attributed to the method of preparation, particle size, adhesiveness of polymer/filler and the rate of decrease of " eff with frequency (due to the absence of different extent of contribution of various types polarizations present in the PMC).…”

“…[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.…”

“…Generally, it has been seen that the scaling/ percolation behavior of these systems is reported at dc/low frequencies 29 and interestingly, in some literatures the frequency-dependent percolation and scaling behavior has been reported. 30 In this paper, I would like to investigate the frequency-dependent percolation and scaling behavior (i.e., how the percolation parameters, such as; percolation threshold, critical exponents and dielectric properties are dependent on the frequency of the applied ac signal) of a general class of PMC based on PVDF matrix and metal/alloy particles of different size, prepared through cold/hot pressing process conditions.…”

Physical aspects of 0-3 dielectric composites

“…(3). 81 Therefore, a new relationship/equation is needed to describe the composition dependence of the " eff for the CDCs. In the development of a new relationship, the critical phenomenon, Eq.…”

Microstructure and dielectric response of BaSrTiO3/P(VDF-CTFE) nanocomposites

“…To achieve high dielectric constant, composites with two different types of filler are used. One is to use ferroelectric ceramics which generally have very high dielectric constant, and the other is to use conductor which can increase dielectric constant of composites according to percolative behavior [9][10][11][12][13][14][15][16].…”