Power factors of Ca3Co2O6 and Ca 3Co2O6-based solid solutions

Kouta Iwasaki, Hisanori Yamane, Shunichi Kubota, Junichi Takahashi, Masahiko Shimada

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    50 Citations (Scopus)

    Abstract

    A polycrystalline sample of Ca3Co2O6 was prepared by solid state reaction of CaCO3 and Co3O 4 at 1243 K in air. The electrical resistivity (ρ) of Ca 3Co2O6 exhibited semiconducting behavior and ranged from 1.6×102 to 1.3×10-1 Ω cm with temperature from 400 to 1170 K. The Seebeck coefficient (S) showed positive value, and decreased from 660 to 140 μV/K with increasing the temperature from 350 to 1170 K. The power factor (S2/ρ) tended to increase with increasing temperature, and the maximum value was 1.6×10-5 W/(m K2) at 1150 K. Samples with the starting compositions of (Ca1-xAx)3Co 2O6 (A=Y, La, and Bi, x=0.03) and Ca3(Co 1-yMy)2O6 (M=Cr and Cu, y=0.03) were also heated at 1243 K in air to prepare Ca3Co2O 6-based solid solutions. The changes of lattice parameters and widths of X-ray diffraction peaks for the obtained samples indicated substitutions of Y, La, Bi for Ca, Cr and Cu for Co, although the samples included trace amount of impurities. Substitutions of Bi and Cu increased the power factors of the solid solutions, and the maximum values were 3.4×10-5 W/(m K2) (A=Bi at 1130 K) and 2.3×10-5 W/(m K2) (M=Cu at 1150 K). The Seebeck coefficients of the solid solutions with Y and La were negative below 400 K.

    Original languageEnglish
    Pages (from-to)210-215
    Number of pages6
    JournalJournal of Alloys and Compounds
    Volume358
    Issue number1-2
    DOIs
    Publication statusPublished - 2003 Aug 25

    Keywords

    • Thermoelectric materials
    • X-ray diffraction

    ASJC Scopus subject areas

    • Mechanics of Materials
    • Mechanical Engineering
    • Metals and Alloys
    • Materials Chemistry

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