Calculation of the static permittivity of suspensions from the stored energy

It is shown that the static permittivity of suspensions of charged particles in electrolyte solution can be deduced from the field-induced change of the Gibbs free energy stored outside the double layer. This energy is related to the changes of the electrolyte concentration around the particle and is obtained solving a purely static problem, The method is first verified deducing well-known results corresponding to suspensions of spherical particles, It is then used to calculate the static permittivity of suspensions of spheroidal particles, leading to a new result that cannot be analytically obtained using the classical approach. (C) 1997 Academic Press.