Thermoelectric properties and local electronic structure of rare earth-doped Ca3Co2O6

N. V. Nong, M. Ohtaki

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

    5 Citations (Scopus)


    Thermoelectric properties of a series of rare earth metaldoped polycrystalline samples of (Ca1-xRx)3Co 2O6 with R = Gd, Tb, Dy and Ho (x = 0 - 0.1) were investigated in the temperature range from 300 K to 1300 K. In a high temperature region above 900 K, a partial rare earth substitution with R 3+ for Ca2+ resulted in appreciable increase in the Seebeck coefficient (S). However, the S value decreased abruptly at low temperatures, and turned to negative values for the Gd- and Tb-doped samples at temperatures below 400 K. With decreasing ionic radii of rare earth elements (Gd3+ > Tb3+ > Dy3+ > Ho 3+), the S values increased, while the thermal conductivity (Κ) decreased particularly at temperatures above 700 K. Contrastingly, the influence of rare earth metal substitution on the electrical resistiivity (p) was small; in high temperature region the p values increased only slightly with decreasing ionic radii of rare earth metals. High-temperature thermoelectric figure-of-merit (Z) of the samples was thereby improved by the late rare-earth metal substitution for Ca2+, particularly for those with Ho 3+. A maximum Z value of the Ho-doped sample for x = 0.03 was 1.83×10-4 K-1 at 1100 K as compared with 0.37×10-4 K-1 for non-doped sample. The electronic structure of the samples was also investigated by x-ray photoemission spectroscopy (XPS) technique. The charge-transfer satellite structure of Co 2p core-level spectra was observed for the Gdand Tb-doped samples, while the satellite is negligible for the other samples.

    Original languageEnglish
    Title of host publicationProceedings ICT'06 - 25th International Conference on Thermoelectrics
    Number of pages4
    Publication statusPublished - 2006
    EventICT'06 - 25th International Conference on Thermoelectrics - Vienna, Austria
    Duration: Aug 6 2006Aug 10 2006

    Publication series

    NameInternational Conference on Thermoelectrics, ICT, Proceedings


    OtherICT'06 - 25th International Conference on Thermoelectrics

    All Science Journal Classification (ASJC) codes

    • General Engineering


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