Simple expressions for the dielectric response of suspensions in an electrolyte

We have compared various theories for the dielectric response of suspensions of solid spheres in an electrolyte, due to electrochemical double-layer effects. We find that all theories have close to the same frequency dependence, which can be described by simple approximate formulae. The asymptotic behavior is the same: at high frequencies, epsilon' varies as omega(-1.5) and epsilon '' as omega(-1.0). At low frequencies, Delta epsilon' varies as omega(0.5) and epsilon '' as omega(0.5). The theories predict somewhat different magnitudes of the dielectric response, The approximation starts to break down when the double layer is of the order of the Debye length. (C) 1996 academic Press, Inc.