High-temperature thermoelectric and microstructural characteristics of cobalt-based oxides with ga substituted on the Co-site

N. V. Nong, S. Yanagiya, S. Monica, N. Pryds, M. Ohtaki

    Research output: Contribution to journalArticle

    18 Citations (Scopus)

    Abstract

    The effects of Ga substitution on the Co-site on the high-temperature thermoelectric properties and microstructure are investigated for the misfitlayered Ca 3Co 4O 9 and the complex perovskite-related Sr 3RECo 4O 10.5 (RE = rare earth) cobalt-based oxides. For both systems, substitution of Ga for Co results in a simultaneous increase in the Seebeck coefficient (S) and the electrical conductivity (σ), and the influence is more significant in the high temperature region. The power factor (S 2 σ) is thereby remarkably improved by Ga substitution, particularly at high temperatures. Texture factor calculations using x-ray diffraction pattern data for pressed and powder samples reveal that the Ga-doped samples are highly textured. Microstructure observed by scanning electron microscopy shows very well-crystallized grains for the samples with Ga substitution for Co. Among the Ga-doped samples, Ca 3Co 3.95Ga 0.05O 9 shows the best ZT value of 0.45 at 1200 K, which is about 87.5% higher than the nondoped one, a considerable improvement.

    Original languageEnglish
    Pages (from-to)716-722
    Number of pages7
    JournalJournal of Electronic Materials
    Volume40
    Issue number5
    DOIs
    Publication statusPublished - May 2011

    All Science Journal Classification (ASJC) codes

    • Electronic, Optical and Magnetic Materials
    • Condensed Matter Physics
    • Electrical and Electronic Engineering
    • Materials Chemistry

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