Low Thermal Conductivity and High Thermoelectric Performance in Sb and Bi Codoped GeTe: Complementary Effect of Band Convergence and Nanostructuring

Perumal, Suresh and Bellare, Pavithra and Shenoy, U Sandhya and Waghmare, Umesh V and Biswas, Kanishka (2017) Low Thermal Conductivity and High Thermoelectric Performance in Sb and Bi Codoped GeTe: Complementary Effect of Band Convergence and Nanostructuring. In: CHEMISTRY OF MATERIALS, 29 (24). pp. 10426-10435.

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Abstract

Complementary and beneficial effects of Sb and Bi codoping in GeTe are shown to generate high thermoelectric figure of merit, zT, of 1.8 at 725 K in Ge1-x-yBixSbyTe samples. Sb and Bi codoping in GeTe facilitates the valence band convergence enhancing the Seebeck coefficient as supported by density functional theoretical (DFT) calculations. Further, Sb and Bi codoping in GeTe releases the rhombohedral strain and increases its tendency to be cubic in structure, which ultimately enhances the valence band degeneracy. At the same time, Bi forms nanoprecipitates of size similar to 5-20 nm in GeTe matrix and Sb doping increases solid solution point defects greatly, which altogether scatter low-to mid wavelength phonons and result in reduced lattice thermal conductivity down to 0.5 W/mK in the 300-750 K range.

Item Type:	Journal Article
Publication:	CHEMISTRY OF MATERIALS
Publisher:	10.1021/acs.chemmater.7b04023
Additional Information:	Copy right for this article belongs to the AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	20 Jan 2018 06:27
Last Modified:	20 Jan 2018 06:27
URI:	http://eprints.iisc.ac.in/id/eprint/58823

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