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The role of copper in the thermal conductivity of thermoelectric oxychalcogenides: do lone pairs matter?

Vaqueiro, P., Al Orabi, R. A. R., Luu, S. D. N., Guelou, G., Powell, A. V., Smith, R. I., Song, J. P., Wee, D. and Fornari, M. (2015) The role of copper in the thermal conductivity of thermoelectric oxychalcogenides: do lone pairs matter? Physical Chemistry Chemical Physics, 17 (47). pp. 31735-31740. ISSN 1463-9076

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To link to this item DOI: 10.1039/C5CP06192J

Abstract/Summary

Understanding the underlying mechanisms that suppress thermal conduction in solids is of paramount importance for the targeted design of materials for thermal management and thermoelectric energy conversion applications. Bismuth copper oxychalcogenides, BiOCuQ (Q = Se, Te), are highly crystalline thermoelectric materials with an unusually low lattice thermal conductivity of approx. 0.5 Wm-1K-1, a value normally found in amorphous materials. Here we unveil the origin of the unusual thermal transport properties of these phases. First principles calculations of the vibrational properties combined with analysis of in-situ neutron diffraction data, demonstrate that weak bonding of copper atoms within the structure leads to an unexpected vibrational mode at low frequencies, which is likely to be a major contributor to the low thermal conductivity of these materials. In addition, we show that anharmonicity and the large Grüneisen parameter in these oxychalcogenides are mainly related to the low frequency copper vibrations, rather than to the Bi3+ lone pairs.

Item Type:Article
Refereed:Yes
Divisions:Interdisciplinary centres and themes > Chemical Analysis Facility (CAF)
Faculty of Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
Interdisciplinary centres and themes > Energy Research
Interdisciplinary centres and themes > Chemical Analysis Facility (CAF) > Xray (CAF)
ID Code:46100
Publisher:Royal Society of Chemistry

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