Issue 48, 2017

Thermoelectric properties and thermal stability of layered chalcogenides, TlScQ2, Q = Se, Te

Abstract

A few thallium based layered chalcogenides of α-NaFeO2 structure-type are known for their excellent thermoelectric properties and interesting topological insulator nature. TlScQ2 belongs to this structural category. In the present work, we have studied the electronic structure, electrical and thermal transport properties and thermal stability of the title compounds within the temperature range 2–600 K. Density functional theory (DFT) predicts a metallic nature for TlScTe2 and a semiconducting nature for TlScSe2. DFT calculations also show significant lowering of energies of frontier bands upon inclusion of spin–orbit coupling contribution in the calculation. The electronic structure also shows the simultaneous occurrence of holes and electron pockets for the telluride. Experiments reveal that the telluride shows a semi-metallic behaviour whereas the selenide is a semiconductor. The thermoelectric properties for both the materials were also investigated. Both these materials possess very low thermal conductivity which is an attractive feature for thermoelectrics. However, they lack thermal stability and decompose upon warming above room temperature, as evidenced from high temperature powder X-ray diffraction and thermal analysis.

Graphical abstract: Thermoelectric properties and thermal stability of layered chalcogenides, TlScQ2, Q = Se, Te

Supplementary files

Article information

Article type
Paper
Submitted
14 Sep 2017
Accepted
15 Nov 2017
First published
15 Nov 2017

Dalton Trans., 2017,46, 17053-17060

Thermoelectric properties and thermal stability of layered chalcogenides, TlScQ2, Q = Se, Te

V. S. Aswathy, C. R. Sankar, M. R. Varma, A. Assoud, M. Bieringer and H. Kleinke, Dalton Trans., 2017, 46, 17053 DOI: 10.1039/C7DT03446F

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