Ultralow thermal conductivity is of great interest in a variety of fields, including thermoelectric energy conversion. We report, for the first time, experimental evidence that Ga-doping in SnTe may lower the lattice thermal conduction slightly below the theoretical amorphous minimum at high temperature. Such an effect is justified by the spontaneous formation of nanoprecipitates we characterized as GaTe. Remarkably, the introduction of Ga (2-10%) in SnTe also improves the electronic transport properties by activating several hole pockets in the multivalley valence band. Experimental results are supported by density functional theory calculations. The thermoelectric figure of merit, ZT, reaches ∼1 at 873 K in Sn0.96Ga0.07Te, which corresponds to an ∼80% improvement with respect to pure SnTe.
Bibliographical noteFunding Information:
R.A.R.A.O. and D.W. thank Solvay Special Chemicals for financial support. This work was partially supported by Midcareer Researcher Program (Grant 2011-0028729) and the Nanomaterial Technology Development Program (Grant 2011-0030147) through the National Research Foundation of Korea (NRF) grant funded by the Ministry of Education, Science and Technology (MEST). Computations were performed at the Institut des Sciences Chimiques de Rennes and at the High Performance Computing Center, Michigan State University.
© 2016 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Materials Chemistry