Thermoelectric properties of the brownmillerite oxide Ca2-yLayCo2-xAlxO5

Wataru Kobayashi, Akira Satake, Ichiro Terasaki

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    11 Citations (Scopus)

    Abstract

    We prepared the brownmillerite oxide Ca2-yLayCo2-xAlxO5 and found that it was an n-type conductor. The thermopower and the resistivity of the single crystal are respectively -90 μ V/K and 68 mΩcm along the ab direction at 440 K, which suggest relatively good thermoelectrical properties, compared with other transition-metal oxides. Their temperature dependences are of activation type, and the activation energies are 0.2 eV for the resistivity and 0.04 eV for the thermopower. These energies differ by one order in magnitude, which implies that a polaron dominates the charge transport. The sign of the thermopower of the polycrystals changes from negative to positive at 500 K, indicating that holes are excited thermally to decrease the magnitude of thermopower.

    Original languageEnglish
    Pages (from-to)3025-3028
    Number of pages4
    JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
    Volume41
    Issue number5 A
    Publication statusPublished - 2002 May

    Keywords

    • Layered cobalt oxide
    • Thermal conductivity
    • Thermoelectric material

    ASJC Scopus subject areas

    • Physics and Astronomy (miscellaneous)

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