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Title: | Towards a high thermoelectric performance in rare-earth substituted SrTiO3: effects provided by strongly-reducing sintering conditions |
Author: | Kovalevsky, A. V. Yaremchenko, A. A. Populoh, S. Thiel, P. Fagg, D. P. Weidenkaff, A. Frade, J. R. |
Keywords: | ELECTRONIC TRANSPORT-PROPERTIES DOPED STRONTIUM-TITANATE DEFECT CHEMISTRY CERAMICS CONDUCTIVITY POLYCRYSTALS SYSTEM OXIDES LA |
Issue Date: | 2014 |
Publisher: | ROYAL SOC CHEMISTRY |
Abstract: | Donor-substituted strontium titanate ceramics demonstrate one of the most promising performances among n-type oxide thermoelectrics. Here we report a marked improvement of the thermoelectric properties in rare-earth substituted titanates Sr0.9R0.1TiO3 +/-delta (R = La, Ce, Pr, Nd, Sm, Gd, Dy, Y) to achieve maximal ZT values of as high as 0.42 at 1190 K < T < 1225 K, prepared via a conventional solid state route followed by sintering under strongly reducing conditions (10%H-2-90%N-2, 1773 K). As a result of complex defect chemistry, both electrical and thermal properties were found to be dependent on the nature of the rare-earth cation and exhibit an apparent correlation with the unit cell size. High power factors of 1350-1550 mu W m(-1) K-2 at 400-550 K were observed for R = Nd, Sm, Pr and Y, being among the largest reported so far for n-type conducting bulk-ceramic SrTiO3-based materials. Attractive ZT values at high temperatures arise primarily from low thermal conductivity, which, in turn, stem from effective phonon scattering in oxygen-deficient perovskite layers formed upon reduction. The results suggest that highly-reducing conditions are essential and should be employed, whenever possible, in other related micro/nanostructural engineering approaches to suppress the thermal conductivity in target titanate-based ceramics. |
Peer review: | yes |
URI: | http://hdl.handle.net/10773/19439 |
DOI: | 10.1039/c4cp04127e |
ISSN: | 1463-9076 |
Publisher Version: | 10.1039/c4cp04127e |
Appears in Collections: | CICECO - Artigos |
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File | Description | Size | Format | |
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Towards a high thermoelectric performance in rare-earth substituted SrTiO3 effects provided by strongly-reducing sintering conditions_10.1039c4cp04127e.pdf | 3.03 MB | Adobe PDF |
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