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

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.
Authors:
;  [1] ; ;  [2] ;  [3]
  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)
Publication Date:
OSTI Identifier:
22277882
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 10; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
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