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Frequency and Temperature Scaling in the Conductivity and Its Structural Consequences
Author(s) -
Brom H. B.,
Reedijk J. A.,
Martens H. C. F.,
Adriaanse L. J.,
de Jongh L. J.,
Michels M. A. J.,
Michels M. A. J.
Publication year - 1998
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/(sici)1521-3951(199801)205:1<103::aid-pssb103>3.0.co;2-r
Subject(s) - conductivity , percolation (cognitive psychology) , materials science , scaling , carbon black , doping , polythiophene , thermal conduction , cluster (spacecraft) , polymer , percolation threshold , diffusion , condensed matter physics , function (biology) , thermodynamics , electrical resistivity and conductivity , conductive polymer , chemistry , composite material , physics , mathematics , quantum mechanics , geometry , computer science , biology , natural rubber , evolutionary biology , programming language , neuroscience
We have studied the temperature ( T ) and frequency (ω/2π) dependence of the complex conductivity σ(ω, T ) of several systems where hopping conduction is dominant: conducting carbon‐black/polymer composites as a function of carbon‐black (CB) concentration, aggregates of molecular cluster compounds as a function of the size and of the distance between the metal cores and polymers as a function of degree of doping. For all compounds the conductivity as a function of ω and T can be scaled onto single curves. Using an extension of the anomalous diffusion model the specific details of these curves for the CB composites are shown to be characteristic of the underlying fractal structure. The main features of the scaled dependence of σ(ω, T ) of the randomly packed cluster compounds are well described by effective medium theories, except at low frequencies where percolation effects become important. Similar features are seen in polythiophene derivatives at doping levels above the percolation threshold.