Design of SrTiO3-Based Thermoelectrics by Tungsten Substitution
authors Kovalevsky, AV; Populoh, S; Patricio, SG; Thiel, P; Ferro, MC; Fagg, DP; Frade, JR; Weidenkaff, A
nationality International
journal JOURNAL OF PHYSICAL CHEMISTRY C
keywords NB-DOPED SRTIO3; STRONTIUM-TITANATE; HIGH-TEMPERATURE; FERROELECTRIC CERAMICS; ELECTRICAL-PROPERTIES; TRANSPORT-PROPERTIES; FUEL-CELLS; CONDUCTIVITY; PERFORMANCE; DEFECT
abstract Among n-type oxide thermoelectrics, donor-substituted strontium titanates, prepared in highly reducing conditions, show a particularly attractive thermoelectric figure of merit. High electrical conductivity, combined with outstanding redox tolerance and perovskite-phase stability of these materials, also make them prospective candidates for solid oxide fuel cell (SOFC) anode components. This work represents a first attempt to process strontium titanate ceramics with significant W for Ti substitution and to assess their relevant defect chemistry-related aspects and electrical and thermal properties, seeking mainly highly performing oxide thermoelectrics. Combined XRD/XPS/SEM/EDS studies of SrTi1-xWxO3 +/-delta (x = 0.01-0.10), prepared by a conventional solid state route, demonstrated that the maximum solubility of tungsten corresponds to 3-5% mol, depending on firing conditions and other composition changes. Separation of tungsten-containing phases on a submicro- and nanoscale level and formation of core-shell microstructures were confirmed for x >= 0.06, suggesting possibilities for tuning the thermal and electrical conductivities. Titanium cations are substituted predominantly by W6+ and partially by W5+ . High electrical conductivity and the Seebeck coefficient resulted in a maximum power factor of similar to 0.5 mW x m(-1) x K-2 for SrTi0.99W0.01O3 +/-delta; maximum ZT values, observed in the case of x = 0.01-0.06, amounted to 0.18-0.24 at 1173-1273 K. Co-substitution in Sr(Ti,Nb,W)TiO3 +/-delta materials showed good prospects for boosting thermoelectric performance in titanates, predominantly by significant reduction of the thermal conductivity.
publisher AMER CHEMICAL SOC
issn 1932-7447
year published 2015
volume 119
issue 9
beginning page 4466
ending page 4478
digital object identifier (doi) 10.1021/jp510743h
web of science category Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary
subject category Chemistry; Science & Technology - Other Topics; Materials Science
unique article identifier WOS:000350840700004
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