Sintering process and nonstoichiometry of NaCo2O4 layered thermoelectric oxide

M. Ohtaki, K. Shouji

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    3 Citations (Scopus)


    Sintering process of layered oxide NaCo2O4, which has been the best p-type thermoelectric oxide candidate to date since its debut in the world of thermoelectrics in 1997, was investigated in terms of sodium nonstoichiometry occurring during solid state reaction between Na2CO3 and Co3O4 for the synthesis of the oxide. Thermal gravimetry (TG) and differential thermal analysis (DTA) measurements revealed that solid-gas equilibrium plays an important role on phase formation process and on controlling chemical composition of the oxide, Partial pressure of oxygen and carbon dioxide in the reaction atmosphere was revealed to be crucial for controlling vaporization of Na, as well as for promotion of phase formation reaction of NaCo2O4, In particular, whereas the CO2 atmosphere effectively suppressed abrupt dissociation reaction of Na2CO3, low oxygen partial pressure accelerated vaporization of Na at lower temperature. Interestingly, high partial pressure Of CO2 appeared to hinder phase formation reaction of NaCo2O4 even at the same oxygen partial pressure as that under the aerobic conditions.

    Original languageEnglish
    Title of host publicationProceedings ICT 2003 - 22nd International Conference on Thermoelectrics
    PublisherInstitute of Electrical and Electronics Engineers Inc.
    Number of pages4
    ISBN (Electronic)078038301X
    Publication statusPublished - 2003
    Event22nd International Conference on Thermoelectrics, ICT 2003 - La Grande Motte, France
    Duration: Aug 17 2003Aug 21 2003

    Publication series

    NameInternational Conference on Thermoelectrics, ICT, Proceedings


    Other22nd International Conference on Thermoelectrics, ICT 2003
    CityLa Grande Motte

    All Science Journal Classification (ASJC) codes

    • Condensed Matter Physics
    • Electrical and Electronic Engineering


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