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Abstract:
We suggest a modification of the well-known Maxwell-Garnett
equation for the, mobility (effective diffusion coefficient) in
two-phase media (a matrix with inclusions) which permits the
description of a wide range of experimental situations. The
novel approach correctly treats the partial trapping of a
diffusing particle by an inclusion as well as consequences of
an energy barrier for the particle penetration into an
inclusion. Computer simulations show that the presented mean-
field theory reproduces surprisingly well results for square
inclusions without concentration limitation. For inclusions
with other shapes (e.g. spherical) the theory works well up to
concentrations at which mobile particles become trapped in
'pockets' between inclusions. (C) 2002 Elsevier Science Ltd.
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