Thermoelectric oxides

The best thermoelectric efficiency has been so far achieved using antimony-, bismuth-, tellurium- and lead-based intermetallic compounds such as Bi2Te3, PbTe, and CoSb3, which can express a figure of merit above 1. However, these materials present a high cost, high toxicity, and a relatively low melting point, which limits their use in high-temperature applications.

On the contrary, despite their low thermoelectric efficiency, oxides such as layered cobaltites, titanates, or transition metal oxides can be a valid alternative for high-temperature applications. They present also low toxicity, low cost, and elevated chemical resistance.

In the effort to increase the figure of merit of thermoelectric oxides nanostructuring can be a successful strategy, as it reduces the phonon thermal contribution, as grain boundaries can scatter phonons very efficiently.

We successfully applied this approach to layered cobaltites using the High-pressure Field Assisted Sintering (FAST) as a tool to obtain a high level of densification with minimal grain growth. 

Related publications:

A.Soffientini, I.G.Tredici, S.Boldrini, A.Famengo, G.Spinolo, U.Anselmi-Tamburini, “Synthesis and characterization of bulk nanostructured thermoelectric Ca3Co4O9“, in press