Significant enhancement of the thermoelectric performance in Ca3Co4O9 thermoelectric materials through combined strontium substitution and hot-pressing process
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
nationality International
journal JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
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).
publisher ELSEVIER SCI LTD
issn 0955-2219
year published 2019
volume 39
issue 4
beginning page 1186
ending page 1192
digital object identifier (doi) 10.1016/j.jeurceramsoc.2018.12.049
web of science category Materials Science, Ceramics
subject category Materials Science
unique article identifier WOS:000457819600062
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journal analysis (jcr 2017):
journal impact factor 3.794
5 year journal impact factor 3.536
category normalized journal impact factor percentile 98.148
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