Microstructures and thermoelectric properties of NaCo2O4 prepared by double-step sintering

Michitaka Ohtaki, Eishi Maeda

    Research output: Contribution to journalArticlepeer-review

    26 Citations (Scopus)


    The thermoelectric properties of sintered bodies of NaCo2O4, which is so far the most promising p-type candidate for oxide thermoelectric material, are investigated in terms of their sintering conditions. Double-step sintering, for which single-phase NaCo2O4 obtained by calcination and sintering with addition of 10% excess of Na each time is re-ground and sintered again, is revealed to attain a marked improvement in the thermoelectric performance of the oxide. The improvement is due to increase in both Seebeck coefficient and electrical conductivity, and is attributed to a distinct enhancement of the two-dimensionality in the crystallites constituting the sintered body. The oxide sintered body consequently attains the figure-of-merit of 0.88×10-3 K-1 at 600 °C, and the maximum ZT of 0.78 at 800 °C.

    Original languageEnglish
    Pages (from-to)1159-1164
    Number of pages6
    JournalFuntai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy
    Issue number11
    Publication statusPublished - Nov 2000

    All Science Journal Classification (ASJC) codes

    • Mechanical Engineering
    • Industrial and Manufacturing Engineering
    • Metals and Alloys
    • Materials Chemistry


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