Thermoelectric properties of a composite medium

We study the thermoelectric properties of a composite medium. Various approximations are developed for calculating the matrix Q̂_e of the bulk effective transport coefficients of the medium, including exact upper and lower bounds for Q̂_e 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 α_e and the thermoelectric figure of merit Z _e in two-component composites. We prove that Z_e 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.