Stability and Thermoelectric Properties of Transition Metal Silicides from First Principles Calculations

"We report an ab-initio study of the stability and electronic properties of transition metal silicides in order to study their potential for high temperature thermoelectric applications. We focus on the family M5Si3 (M = Ta, W) which is stable up to about 2000 °C. We first investigate the structural stability of the two compounds and then determine the thermopower of the equilibrium structure using the electronic density of states and Mott’s law. We find that W5Si3 has a relatively large thermopower but probably not sufficient enough for thermoelectric applications.IntroductionIn the search of new sustainable energies, thermogeneration of electricity is one of the promising ways, notably because it is able to produce electricity from different kinds of heat wastes and to its portability. However, despite recent progress in the field, the state-of-the art materials have specificities making their mass-production difficult or even impossible: toxicity (thallium, chalcogen or/and pnictogen based alloys), weak abundance (tellurium based alloys) or cost (germanium or rare-earth based alloys). For all these reasons, finding thermoelectric materials without these drawbacks is vital if we wish to use high temperature thermoelectricity for generating electricity in the near future. Due to their abundance, low cost and low toxicity, transition metal silicides are candidate materials of primary interest and the slightest advance in this field would immediately find an application for the thermogeneration of electricity."