High temperature transport properties of thermoelectric CaMnO{sub 3−δ} — Indication of strongly interacting small polarons

Journal Article · Fri Mar 14 00:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4868321· OSTI ID:22277882

Finstad, T. G. ^[1]; Kabir, R.; Li, S. ^[2]; Norby, T. ^[3]

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1. Centre for Materials Science and Nanotechnology, Department of Physics, University of Oslo, Sem Sælandsvei 24, 0371 Oslo (Norway)
2. School of Materials Science and Engineering, University of New South Wales, Sydney, New South Wales 2052 (Australia)
3. Centre for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, FERMiO, Gaustadalléen 21, 0349 Oslo (Norway)

The conductivity and Seebeck coefficient of CaMnO{sub 3−δ} have been studied at temperatures up to 1000 °C and in atmospheres with controlled oxygen partial pressure. Both transport coefficients were varied in situ by the reversible formation of oxygen vacancies up to δ = 0.15. The charge carrier concentration was calculated using a defect chemical model. The Seebeck coefficient could be approximated by Heikes' formula, while the conductivity shows a maximum at a molar charge carrier concentration of 0.25. These results were interpreted as a signature of strong electronic correlation effects, and it was concluded that charge transport in CaMnO{sub 3−δ} occurs via strongly interacting small polarons. General prospects for strongly correlated materials as potential candidates for high temperature thermoelectric power generation were discussed.

• OSTI ID: 22277882
• Journal Information: Journal of Applied Physics, Vol. 115, Issue 10; Other Information: (c) 2014 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
APPROXIMATIONS
CALCIUM COMPOUNDS
CHARGE CARRIERS
CHARGE TRANSPORT
CONCENTRATION RATIO
CORRELATIONS
ELECTRIC CONDUCTIVITY
MANGANATES
OXYGEN
PARTIAL PRESSURE
POLARONS
SEEBECK EFFECT
TEMPERATURE DEPENDENCE
THERMOELECTRIC MATERIALS
VACANCIES