Thermoelectric Properties of NaxCoO₂ and Prospects for Other Oxide Thermoelectrics

Conference · Mon Jan 01 04:00:00 EST 2007

OSTI ID:931694

Singh, David J ^[1]; Kasinathan, Deepa ^[2]

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1. ORNL
2. University of California, Davis

We discuss the thermoelectric properties of Na{sub x}CoO{sub 2} using the electronic structure, as determined in first principles calculations, and Boltzmann kinetic transport theory. The Fermi energy lies near the top of a manifold of Co t 2{sub g} bands. These t 2{sub g} bands are separated by a large gap from the higher-lying e{sub g} states. Although the large crystal-field splitting implies substantial Co-O hybridization, the bands are narrow. Application of standard Boltzmann transport theory to such a narrow band structure yields high thermopowers in accord with experimental observations, even for high metallic carrier densities. The high thermopowers observed for Na{sub x}CoO{sub 2} can therefore be explained by standard band theory and do not rely on low dimensionality or correlation effects specific to Co. We also present results for the cubic spinel structure ZnRh{sub 2}O{sub 4}. Like Na{sub x}CoO{sub 2}, this compound has very narrow valence bands. We find that if it could be doped with mobile carriers, it would also have a high thermopower, comparable with that of Na{sub x}CoO{sub 2}.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: EE USDOE - Office of Energy Efficiency and Renewable Energy (EE)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 931694
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BAND THEORY
CRYSTAL FIELD
ELECTRONIC STRUCTURE
HYBRIDIZATION
KINETICS
OXIDES
SPINELS
THERMOELECTRIC PROPERTIES
TRANSPORT THEORY
VALENCE