|
authors |
Torres, MA; Costa, FM; Flahaut, D; Touati, K; Rasekh, S; Ferreira, NM; Allouche, J; Depriester, M; Madre, MA; Kovalevsky, AV; Diez, JC; Sotelo, A |
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nationality |
International |
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journal |
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY |
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author keywords |
Ceramics; Oxides; Hot-pressing; Texture; Electrical properties |
|
keywords |
MAGNETIC-PROPERTIES; LAYERED COBALTITES; PHASE-EQUILIBRIA; GROUP-II; CERAMICS; OXIDE; TRANSPORT; CA; MICROSTRUCTURE; FABRICATION |
|
abstract |
This work explores the possibilities for a further enhancement of the thermoelectric properties of Ca3Co4O9 by Sr-doping combined with hot-pressing. Modified hot-pressing process resulted in highly-textured and dense ceramics. Sr-doping significantly improves electrical properties, resulting in extremely large power factor (1.2 mW/K-2 m at 800 degrees C) due to simultaneous electrical resistivity decrease and Seebeck coefficient increase. The main effect on cumulative electrical performance is provided by the Seebeck coefficient, reaching 270 mu V/K at 800 degrees C. XPS revealed relatively high average cobalt oxidation state at room temperature (+ 3.3), compared to materials produced by conventional sintering. The results of combined XPS and Auger electron spectroscopy emphasize the importance of high densification in Ca3Co4O9-based ceramics for preventing phase decomposition and interaction with CO2 and moisture. Still, despite the exceptional electrical performance, the calculated figure-of-merit (estimated as 0.29 at 800 degrees C) is around the best reported in the literature due to a high thermal conductivity (4.4 W/K m at room temperature). |
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publisher |
ELSEVIER SCI LTD |
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issn |
0955-2219 |
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isbn |
1873-619X |
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year published |
2019 |
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volume |
39 |
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issue |
4 |
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beginning page |
1186 |
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ending page |
1192 |
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digital object identifier (doi) |
10.1016/j.jeurceramsoc.2018.12.049 |
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web of science category |
Materials Science, Ceramics |
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subject category |
Materials Science |
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unique article identifier |
WOS:000457819600062
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