In- Situ Observation of the Continuous Phase Transition in Determining the High Thermoelectric Performance of Polycrystalline Sn0.98Se

Matthew Dargusch; Xiao-Lei Shi; Xuan Quy Tran; Tianli Feng; Flora Somidin; Xin Tan; Weidi Liu; Kevin Jack; Jeffrey Venezuela; Hiroshi Maeno; Takaaki Toriyama; Syo Matsumura; Sokrates T Pantelides; Zhi-Gang Chen

doi:10.1021/acs.jpclett.9b02818

In- Situ Observation of the Continuous Phase Transition in Determining the High Thermoelectric Performance of Polycrystalline Sn_0.98Se

J Phys Chem Lett. 2019 Nov 7;10(21):6512-6517. doi: 10.1021/acs.jpclett.9b02818. Epub 2019 Oct 14.

Authors

Matthew Dargusch¹, Xiao-Lei Shi¹, Xuan Quy Tran², Tianli Feng^{3

4}, Flora Somidin¹, Xin Tan¹, Weidi Liu¹, Kevin Jack⁵, Jeffrey Venezuela¹, Hiroshi Maeno², Takaaki Toriyama², Syo Matsumura^{2

6}, Sokrates T Pantelides^{3

4}, Zhi-Gang Chen^{1

7}

Affiliations

¹ School of Mechanical and Mining Engineering , The University of Queensland , Brisbane , Queensland 4072 , Australia.
² Department of Applied Quantum Physics and Nuclear Engineering , Kyushu University , Fukuoka 819-0395 , Japan.
³ Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science , Vanderbilt University , Nashville , Tennessee 37235 , United States.
⁴ Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States.
⁵ Center for Microscopy and Microanalysis , The University of Queensland , St Lucia , QLD 4072 , Australia.
⁶ The Ultramicroscopy Research Centre , Kyushu University , Fukuoka 819-0395 , Japan.
⁷ Centre for Future Materials , University of Southern Queensland , Springfield Central , QLD 4300 , Australia.

PMID: 31597419
DOI: 10.1021/acs.jpclett.9b02818

Abstract

We report a comprehensive in-situ phase-change study on polycrystalline Sn_0.98Se via high-temperature X-ray diffraction and in-situ high-voltage transmission electron microscopy from room temperature to 843 K. The results clearly demonstrate a continuous phase transition from Pnma to Cmcm starting from 573 to 843 K, rather than a sudden transition at 800 K. We also find that the thermal-conductivity rise at high temperature after the phase transition, as commonly seen in pristine SnSe, does not occur in Sn_0.98Se, leading to a high thermoelectric figure of merit. Density functional theory calculations reveal the origin to be the suppression of bipolar thermal conduction in the Cmcm phase of Sn_0.98Se due to the enlarged bandgap. This work fills the gap of in-situ characterization on polycrystalline Sn_0.98Se and provides new insights into the outstanding thermoelectric performance of polycrystalline Sn_0.98Se.