Thermoelectric properties of a composite medium

Abstract

We study the thermoelectric properties of a composite medium. Various approximations are developed for calculating the matrix Q̂e of the bulk effective transport coefficients of the medium, including exact upper and lower bounds for Q̂e under various conditions. Results are especially detailed for two-component composites, where a field decoupling transformation is used to reduce the thermoelectric problem to two uncoupled quasi-conductivity problems. Exact bounds are then obtained for the absolute thermopower αe and the thermoelectric figure of merit Ze in two-component composites. We prove that Ze of the composite can never exceed the largest value of Z in any component. Some of these results are extended to certain classes of multicomponent composites.