Issue 18, 2019

Bonding heterogeneity and lone pair induced anharmonicity resulted in ultralow thermal conductivity and promising thermoelectric properties in n-type AgPbBiSe3

Abstract

Efficiency in generation and utilization of energy is highly dependent on materials that have the ability to amplify or hinder thermal conduction processes. A comprehensive understanding of the relationship between chemical bonding and structure impacting lattice waves (phonons) is essential to furnish compounds with ultralow lattice thermal conductivity (κlat) for important applications such as thermoelectrics. Here, we demonstrate that the n-type rock-salt AgPbBiSe3 exhibits an ultra-low κlat of 0.5–0.4 W m−1 K−1 in the 290–820 K temperature range. We present detailed analysis to uncover the fundamental origin of such a low κlat. First-principles calculations augmented with low temperature heat capacity measurements and the experimentally determined synchrotron X-ray pair distribution function (PDF) reveal bonding heterogeneity within the lattice and lone pair induced lattice anharmonicity. Both of these factors enhance the phonon–phonon scattering, and are thereby responsible for the suppressed κlat. Further optimization of the thermoelectric properties was performed by aliovalent halide doping, and a thermoelectric figure of merit (zT) of 0.8 at 814 K was achieved for AgPbBiSe2.97I0.03 which is remarkable among n-type Te free thermoelectrics.

Graphical abstract: Bonding heterogeneity and lone pair induced anharmonicity resulted in ultralow thermal conductivity and promising thermoelectric properties in n-type AgPbBiSe3

Supplementary files

Article information

Article type
Edge Article
Submitted
28 Janv. 2019
Accepted
03 Apr. 2019
First published
03 Apr. 2019
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2019,10, 4905-4913

Bonding heterogeneity and lone pair induced anharmonicity resulted in ultralow thermal conductivity and promising thermoelectric properties in n-type AgPbBiSe3

M. Dutta, K. Pal, U. V. Waghmare and K. Biswas, Chem. Sci., 2019, 10, 4905 DOI: 10.1039/C9SC00485H

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