Theory of thermoelectric effects in metals and alloys

The electron-diffusion Seebeck coefficient of metals and dilute alloys is investigated in a simple model in which free electrons are scattered by phonons or by substitutional impurities bound in the lattice. Second-order corrections to the $T$ matrix for electron scattering involving intermediate virtual phonon states are found to be of small magnitude but to have a very strong energy dependence. They thus make a large contribution to the thermoelectric coefficients while leaving the conductivities essentially unaltered. The pronounced temperature dependence of these second-order contributions allows an interpretation of experimental results that relies less on the phonomenon of phonon drag then has previously been the case.