Thermoelectric properties and crystal chemistry of promising oxide candidate NaxCoO2

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    18 Citations (Scopus)


    Promising p-type thermoelectric properties of a layered transition metal oxide NaxCoO2 are discussed in terms of crystal chemistry and the conduction mechanism. Highly anisotropic spatial distribution of 3d orbitals coupled with an unusually short Co-Co interatomic distance in the ab plane, along which edge-sharing CoO6 octahedra connecting each other to form the CoO2 sheets, strongly suggest that Co3d dε-dε (t2g-t2g) direct overlapping is plausible for establishing hole conduction in the valence band with a fairly covalent character. An extremely low thermal conductivity (≤1 W/mK) of the oxide is also revealed, implying contribution of the randomly distributed Na vacancies and an inherent advantage of materials with low-dimensional crystal structure. In spite of insufficient densification, sintered bodies fired under atmospheric pressure shows ZT≈0.5. Possible influence of the ionic conduction of Na+ on the thermoelectric properties of the oxide is also examined.

    Original languageEnglish
    Pages (from-to)565-568
    Number of pages4
    JournalInternational Conference on Thermoelectrics, ICT, Proceedings
    Publication statusPublished - 1999
    Event18th International Conference on Thermoelectrics (ICT'99) - Baltimore, MD, USA
    Duration: Aug 29 1999Sept 2 1999

    All Science Journal Classification (ASJC) codes

    • General Engineering


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