Experimental study of the three-dimensional ac conductivity and dielectric constant of a conductor-insulator composite near the percolation threshold

Critical behaviors of the conductivity and dielectric constant of Ti3SiC2∕Al2O3 hybrids

“…2͑a͒ just below the percolation threshold, the critical exponent y is found to be y = 0.081± 0.005. Our experimental values of x = 0.92± 0.06 and y = 0.081± 0.005 are close to the values x = 0.86± 0.06 and y = 0.12± 0.04 from conductor-insulator composites reported by Song et al 11 In summary, the dc conductivity of the Ti 3 SiC 2 /Al 2 O 3 hybrids follows the percolation theory, and the ac conductivity and dielectric constant also follow the power-law behavior. The dielectric constant is enhanced greatly with the Ti 3 SiC 2 addition near the percolation threshold and reaches 10 4 above the percolation threshold.…”

“…Recently, there have been growing interests in the electric conductivity and dielectric properties in insulator-conductor hybrids, in which percolation and some critical behaviors are much attractive. [9][10][11][12][13] It is known that near the percolation threshold, the singular behaviors of the dc conductivity and dielectric constant versus conducting phase content follow the power law, [9][10][11][12] as shown below,…”

“…Summing up Figs. 2͑a͒ and 4, near the percolation threshold, the ac conductivity and dielectric constant obey the power law: 9,11 ͑f,…”

“…The critical exponents t and s depend primarily on the dimensionality of the percolating systems but not on the details of the geometric structures or the interactions: t = 1.1-1.3 and s = 1.1-1.3 for dimensionality d =2, t = 1.6-2.0 and s = 0.7-1.0 for d = 3, and t = 3 and s =0 ͑exactly͒ for d =6. 10,11 V and V c are the volume fraction and critical volume fraction ͑i.e., percolation threshold͒ of the conducting component, respectively. The percolation threshold V c depends not only on the microstructure and character of each component itself, but also on their dispersion status.…”

Fabrication and electrical conducting behavior of carbon nanofiber reinforced high-density polyethylene/ polystyrene nanocomposites with low percolation threshold

“…The capacitive effect between clusters on the conductivity is controlling only at high frequencies. As a result, the conductivity increases with frequency at high-frequency regime [13]. To investigate the nature of charge transfer in the ternary composites, conductivity, σ, is tested as a function of temperature for HDPE/PS/1.1 vol% CNF composite.…”