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Ultralow Lattice Thermal Conductivity and Enhanced Thermoelectric Performance in SnTe:Ga Materials

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journal contribution
posted on 12.12.2016, 00:00 by Rabih Al Rahal Al Orabi, Junphil Hwang, Chan-Chieh Lin, Régis Gautier, Bruno Fontaine, Woochul Kim, Jong-Soo Rhyee, Daehyun Wee, Marco Fornari
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.