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Conductivity and Noise Measurements in 3D Percolative Cellular Structures

Published online by Cambridge University Press:  10 February 2011

C. Chiteme  and
D. S. McLachlan
C. Chiteme
Affiliation:
Physics Department, University of the Witwatersrand, Johannesburg, SA.
D. S. McLachlan
Affiliation:
Physics Department, University of the Witwatersrand, Johannesburg, SA.
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Abstract

Conductivity results and 1/f noise (Sav) measurements from some systems with a cellular structure (composites in which small conductor particles embed on the surface of larger and regular insulator particles) are given. The usual DC percolation parameters (φc,t & s) were obtained from fitting the results to the Percolation equations. φc values for the systems have been found to lie in the range 0.01 – 0.07, while both non-universal and close to universal values have been measured for the exponents s and t. In addition, 1/f or flicker noise results on the systems give an additional exponent ω from the relationship Sav/Vdc2 = KRω. For the systems measured so far, the exponent ω is observed to take different values ω1 close to and ω2 further away from the conductor-insulator transition, but on the conducting side (ω > ωc). The very different values (s, t & ω), obtained for the various conducting powders, in the same macroscopic structure, indicates that the way the powders distribute themselves on the insulating particles is a major factor in determining the exponents.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 500: Symposium EE – Electrically Based Microstructural Characterization II , 1997 , 357
Copyright
Copyright © Materials Research Society 1998

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