of the electric current at the interface. The thickness of this The relationship is derived, within the scope of irreversible therlayer has the order of the so-called Debye length.
modynamics, to predict the dc conductivity of a disperse system
The concentration polarization gives rise to concentration of the ''conductor-in-conductor'' type. The results enable one to distributions of the carriers in the bulk of each constituent describe the dc conductivity of the system with the help of the phase. Therefore the concentration polarization needs much preliminary known expression for the ac conductivity as a function more time to be established, provided that the dimensions of the specific conductivities of the constituent phases. The derived of the corresponding phases are much larger than the Debye relationship is used to study the systems with various types of length.
morphology. It is discussed how the difference between the ac and
The conductivity of the systems under consideration is dc conductivities depends on the system morphology and transport characteristics of both the connected and the disconnected constit-often studied in the ac regime characterized by a moderate uent phases. Some ways of using the results are suggested. ᭧ 1996 applied frequency. This frequency is sufficiently high to de-Academic Press, Inc.
press the concentration polarization. At the same time, the Key Words: ac conductivity; dc conductivity; transference numfrequency is chosen to be much lower than the characteristic ber; average over a volume; electric current. value of the Maxwell-Vagner polarization. Thus, the Maxwell-Vagner polarization has time to be fully developed under the experimental conditions. The concentration polar-1 To whom correspondence should be addressed.
are written for each homogeneous constituent phase, 414