Anisotropy and thermopower in Ti3SiC2 -: art. no. 121104

The Seebeck coefficient of the Ti3SiC2 compound has recently been measured and found to be constant and negligible over a wide range of temperature. Materials with essentially zero thermopower allow us to measure the absolute thermopower of another material and could therefore be considered as reference material in thermoelectric measurements. In this paper we analyze the origin of this unusual behavior. The thermopower is calculated from ab initio electronic structure in the framework of Boltzmann transport theory. Under the Mott approximation for the relaxation time, we found the thermopower negative along the z axis and positive in the basal plane. The very small value which is experimentally observed can be ascribed to a compensation between the nonequivalent crystallographic axes.