C. Chiteme | Searcharxiv

arXiv2000

Higher Order Effects in the Dielectric Constant of Percolative Metal-Insulator Systems above the Critical Point

The dielectric constant of a conductor-insulator mixture shows a pronounced maximum above the critical volume concentration. Further experimental evidence is presented as well as a theoretical consideration based on a phenomenological equation. Explicit expressions are given for the position of the maximum in terms of scaling parameters and the (complex) conductances of the conductor and insulator. In order to fit some of the data, a volume fraction dependent expression for the conductivity of the more highly conductive component is introduced.

cond-mat↗

arXiv1998

Analytic Scaling Functions Applicable to Dispersion Measurements

Scaling functions, $F_+(ω/ω_c^+)$ and $F_-(ω/ω_c^-)$ for $ϕ>ϕ_c$ and $ϕ<ϕ_c$, respectively, are derived from an equation for the complex conductivity of binary conductor-insulator composites. It is shown that the real and imaginary parts of $F_{\pm}$ display most properties required for the percolation scaling functions. One difference is that, for $ω/ω_c<1$, $\Re F_-(ω/ω_c)$ has an $ω$-dependence of $(1+t)/t $ and not $ω^2$ as previously predicted, but never conclusively observed. Experimental results on a Graphite-Boron Nitride system are given which are in reasonable agreement with the $ω^{(1+t)/t}$ behaviour for $\Re F_-$. Anomalies in the real dielectric constant just above $ϕ_c$ are also discussed.

cond-mat↗