Electrical Conductivity and Seebeck Coefficient of Sr6Co5O14.3 Single Crystal

概要

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Rod-like single crystals of Sr6Co5O14.3 were grown by the flux method, and the electrical conductivity ($\sigma$), Seebeck coefficient ($S$) and power factor ($\sigma S^{2}$) were investigated in the temperature range of 300–900 K in air to explore the potential as thermoelectric materials. Sr6Co5O14.3 is an oxygen-nonstoichiometric phase of Sr6Co5O15, which is a member of the homologous ($A_{3}$Co2O6)m($A_{3}$Co3O9)n [$A=\text{Ca}$, Sr, Ba] series including Ca3Co2O6 ($m=1$, $n=0$) and BaCoO3 ($m=0$, $n=1$) as the end members. The rod-like single crystals mainly grew along Co–O one-dimensional chains ($c$-axis) consisting of face-sharing CoO6 octahedra and CoO6 triangular prisms. The electrical conductivity along the Co–O chains showed semiconducting behavior (260–9600 S m-1 in the temperature range of 300–900 K). The Seebeck coefficient was positive, and decreased with increasing temperature (280–140 μV K-1). The power factor increased with increasing temperature ($0.20\times 10^{-4}$–$1.9\times 10^{-4}$ W m-1 K-2), which was about one order of magnitude larger than that of polycrystalline Sr6Co5O15.
2007-01-15