Scaling behaviour of the thermopower in a two-component composite near a percolation threshold

An exact relation between the bulk effective Seebeck coefficient alpha e of a composite conductor and the bulk effective electrical and thermal conductivities sigma e and gamma e is used to study the scaling behaviour of alpha e near percolation. The behaviour turns out to be quite rich, as a result of its dependence on three dimensionless small parameters, namely, the electrical and thermal conductivity ratios of the two components sigma I / sigma M , gamma I / gamma M , and the distance away from the percolation threshold Delta p identical to p M -p c . The behaviour of the thermoelectric figure of merit Z e in the different parts of the critical region is also discussed.