Scaling of AC electrical conductivity of

powders under compression

M. Creyssels1, E. Falcon1,2 and B. Castaing1

1 Laboratoire de Physique, Ecole Normale Supérieure de Lyon, CNRS, 69 007 Lyon, France
2 MSC, Université Paris Diderot - Paris 7, CNRS, 75 013 Paris, France


Phys. Rev. B 77, 075135 (2008)


We measured, at low applied voltage, the AC electrical resistance and capacitance of a metallic powder sample under uniaxial compression. Whatever the applied stress, the frequency dependent resistance curves can be displayed on a master curve by an appropriated rescaling. The same property is also observed for the capacitance. A one-dimensional model shows that the strong frequency dependence of the macroscopic resistance and capacitance is a consequence of the broad contact resistance distribution between grains. No microscopic model of conduction nor any parameter related to the unknown disorder need to be assumed. Relevance to other systems like random conductor-insulator mixtures or metal-cluster compounds is discussed.

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