Thermoelectric efficiency of graded SicGe1–c alloys

Abstract

We consider SicGe1–c graded systems of length L = 3 mm and L = 100 nm, under the action of an electric field E, and crossed by an electrical current i, the two sides of which are kept at two different temperatures Th and Tc. The dependence on composition and temperature of the thermal conductivity is analyzed. We evaluate the thermal conductivity in correspondence of the constant temperatures T = 300 K, T = 400 K, and T = 500 K and investigate the thermoelectric efficiency of the system as a function of the stoichiometric variable c and of the effective temperature gradient Th−TcL. For each temperature, we calculate the values of c in the interval [0, 1] which realize the optimal efficiency of the thermoelectric energy conversion. The corresponding values of the thermal conductivity are determined as well. For L = 3 mm, we find that the best efficiency of thermoelectric energy conversion is achieved at T = 500 K, c = 0.325568, and λ = 7.3444 Wm−1 K−1. For L = 100 nm, we obtain the best efficiency at T = 500 K, c = 0.613937, and λ = 0.1510 Wm−1 K−1.