Résumé
The interest in renewable energies to sustain economic growth and environmental concerns has increased dramatically these last decades. Among renewable energies, thermoelectric materials, which allows to convert heat into electricity, without moving part, can participate to this effort. Their thermoelectric performances are characterized by their dimensionless figure of merit ZT = α 2 σT/λ, with α the Seebeck coefficient, σ the electrical conductivity and λ the thermal conductivity. It is about 1 for the best conventional thermoelectric materials such as Bi 2 Te 3 or PbTe. In this work we investigate thermoelectric silicides, which could be competitive with such alloys, and more particularly on SrSi 2 alloys. This cubic semiconducting alloy has a narrow band gap and a power factor (α 2 σ) comparable to Bi 2 Te 3 at 300K however its performances are limited by the phonon contribution to the thermal conductivity (about 5 Wm -1 K -1 at 300K). To optimize its properties, a solution would be to reduce its phonon contribution to the thermal conductivity using a multi-scale approach and to optimize the charge carrier concentration to enhance the power factor. Such approach permits to scatter a broad phonon energy range and to tune the electron structure. In this work, we will present the nanostructuring of SrSi 2 through different approach such as ball milling and melt spinning followed by spark plasma sintering. A careful analysis of the impact of the microstructure on the thermoelectric performances between 300 and 600K will be presented.