Revisiting some chalcogenides for thermoelectricity
Thermoelectric materials that are efficient well above ambient temperature are needed to convert waste-heat into electricity. Many thermoelectric oxides were investigated for this purpose, but their power factor (PF) values were too small (~10−4 W m−1 K−2) to yield a satisfactory figure of merit zT....
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doaj-b9cc48954eee45e78eea36e66b0002ec2020-11-24T23:49:12ZengTaylor & Francis GroupScience and Technology of Advanced Materials1468-69961878-55142012-01-01135053003Revisiting some chalcogenides for thermoelectricity Antoine Maignan, Emmanuel Guilmeau, Franck Gascoin, Yohann Bréard and Vincent HardyThermoelectric materials that are efficient well above ambient temperature are needed to convert waste-heat into electricity. Many thermoelectric oxides were investigated for this purpose, but their power factor (PF) values were too small (~10−4 W m−1 K−2) to yield a satisfactory figure of merit zT. Changing the anions from O2− to S2− and then to Se2− is a way to increase the covalency. In this review, some examples of sulfides (binary Cr–S or derived from layered TiS2) and an example of selenides, AgCrSe2, have been selected to illustrate the characteristic features of their physical properties. The comparison of the only two semiconducting binary chromium sulfides and of a layered AgCrSe2 selenide shows that the PF values are also in the same order of magnitude as those of transition metal oxides. In contrast, the PF values of the layered sulfides TiS2 and Cu0.1TiS2 are higher, reaching ~10−3 W m−1 K−2. Apparently the magnetism related to the Cr–S network is detrimental for the PF when compared to the d0 character of the Ti4+ based sulfides. Finally, the very low PF in AgCrSe2 (PF = 2.25 × 10−4 W m1 K−2 at 700 K) is compensated by a very low thermal conductivity (κ = 0.2 W m−1 K−1 from the measured Cp) leading to the highest zT value among the reviewed compounds (zT700K = 0.8). The existence of a glassy-like state for the Ag+ cations above 475 K is believed to be responsible for this result. This result demonstrates that the phonon engineering in open frameworks is a very interesting way to generate efficient thermoelectric materials.http://dx.doi.org/10.1088/1468-6996/13/5/053003 |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Antoine Maignan, Emmanuel Guilmeau, Franck Gascoin, Yohann Bréard and Vincent Hardy |
spellingShingle |
Antoine Maignan, Emmanuel Guilmeau, Franck Gascoin, Yohann Bréard and Vincent Hardy Revisiting some chalcogenides for thermoelectricity Science and Technology of Advanced Materials |
author_facet |
Antoine Maignan, Emmanuel Guilmeau, Franck Gascoin, Yohann Bréard and Vincent Hardy |
author_sort |
Antoine Maignan, Emmanuel Guilmeau, Franck Gascoin, Yohann Bréard and Vincent Hardy |
title |
Revisiting some chalcogenides for thermoelectricity |
title_short |
Revisiting some chalcogenides for thermoelectricity |
title_full |
Revisiting some chalcogenides for thermoelectricity |
title_fullStr |
Revisiting some chalcogenides for thermoelectricity |
title_full_unstemmed |
Revisiting some chalcogenides for thermoelectricity |
title_sort |
revisiting some chalcogenides for thermoelectricity |
publisher |
Taylor & Francis Group |
series |
Science and Technology of Advanced Materials |
issn |
1468-6996 1878-5514 |
publishDate |
2012-01-01 |
description |
Thermoelectric materials that are efficient well above ambient temperature are needed to convert waste-heat into electricity. Many thermoelectric oxides were investigated for this purpose, but their power factor (PF) values were too small (~10−4 W m−1 K−2) to yield a satisfactory figure of merit zT. Changing the anions from O2− to S2− and then to Se2− is a way to increase the covalency. In this review, some examples of sulfides (binary Cr–S or derived from layered TiS2) and an example of selenides, AgCrSe2, have been selected to illustrate the characteristic features of their physical properties. The comparison of the only two semiconducting binary chromium sulfides and of a layered AgCrSe2 selenide shows that the PF values are also in the same order of magnitude as those of transition metal oxides. In contrast, the PF values of the layered sulfides TiS2 and Cu0.1TiS2 are higher, reaching ~10−3 W m−1 K−2. Apparently the magnetism related to the Cr–S network is detrimental for the PF when compared to the d0 character of the Ti4+ based sulfides. Finally, the very low PF in AgCrSe2 (PF = 2.25 × 10−4 W m1 K−2 at 700 K) is compensated by a very low thermal conductivity (κ = 0.2 W m−1 K−1 from the measured Cp) leading to the highest zT value among the reviewed compounds (zT700K = 0.8). The existence of a glassy-like state for the Ag+ cations above 475 K is believed to be responsible for this result. This result demonstrates that the phonon engineering in open frameworks is a very interesting way to generate efficient thermoelectric materials. |
url |
http://dx.doi.org/10.1088/1468-6996/13/5/053003 |
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AT antoinemaignanemmanuelguilmeaufranckgascoinyohannbreardandvincenthardy revisitingsomechalcogenidesforthermoelectricity |
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