Influence of tungsten substitution and oxygen deficiency on the thermoelectric properties of CaMnO{sub 3−δ}

Journal Article · Sat Dec 28 00:00:00 EST 2013 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4854475· OSTI ID:22267783

Thiel, Philipp; Eilertsen, James; Populoh, Sascha; Saucke, Gesine; Shkabko, Andrey; Sagarna, Leyre; Karvonen, Lassi ^[1]; Döbeli, Max ^[2]; Weidenkaff, Anke ^[1]

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1. Laboratory for Solid State Chemistry and Catalysis, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland)
2. Ion Beam Physics, Schafmattstrasse 20, ETH Hönggerberg, Swiss Federal Institute of Technology, CH-8093 Zürich (Switzerland)

Polycrystalline tungsten-substituted CaMn{sub 1−x}W{sub x}O{sub 3−δ} (0.00 ≤ x ≤ 0.05) powders were synthesized from a polymeric precursor, pressed and sintered to high density. The impact of tungsten substitution on the crystal structure, thermal stability, phase transition, electronic and thermal transport properties is assessed. Tungsten acts as an electron donator and strongly affects high-temperature oxygen stoichiometry. Oxygen vacancies form in the high figure-of-merit (ZT)-region starting from about T = 1000 K and dominate the carrier concentration and electronic transport far more than the tungsten substitution. The analysis of the transport properties yields that in the investigated regime the band filling is sufficiently high to overcome barriers of polaron transport. Therefore, the Cutler-Mott approach describes the electrical transport more accurately than the Mott approach for small polaron transport. The lattice thermal conductivity near room temperature is strongly suppressed with increasing tungsten concentration due to mass-difference impurity scattering. A ZT of 0.25 was found for x = 0.04 at 1225 K.

• OSTI ID: 22267783
• Journal Information: Journal of Applied Physics, Vol. 114, Issue 24; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABUNDANCE
CARRIERS
CONCENTRATION RATIO
DIFFUSION BARRIERS
ELECTRONS
IMPURITIES
MASS DIFFERENCE
OXYGEN
PERFORMANCE
PHASE TRANSFORMATIONS
POLYCRYSTALS
SCATTERING
STABILITY
STOICHIOMETRY
THERMAL CONDUCTIVITY
THERMOELECTRIC PROPERTIES
TUNGSTEN
VACANCIES
VENTILATION BARRIERS