Low temperature thermopower and electrical transport in misfit Ca3Co4O9 with elongated c-axis.

The temperature dependence of the electrical resistivity (r) and thermopower (S) of misfit cobaltite Ca3Co4O9 has been studied. The compound is a promising thermoelectric material, exhibiting very low r([?]1.3 × 10[?]4 O cm) and reasonably high S ([?]56 µV K[?]1) at room temperature, which is desirable for thermoelectric applications. At T < 80 K, S exhibits T3/2 dependence, suggesting that electron-magnon scattering has a pronounced influence on S at low temperatures. Ca3Co4O9 exhibits a temperature independent power factor in the temperature range 300-80 K. A comparison of the temperature dependence of the power factor of Ca3Co4O9 with various materials projected or used as a thermoelectric cooler (e.g. single crystal of short c-axis Ca3Co4O9, polycrystalline La0.95Sr0.05CoO3, Bi0.85 Sb0.15, Bi2Te3, Bi-SiO2 composite) indicates that title compound Ca3Co4O9 is a much superior candidate for thermoelectric applications. [ABSTRACT FROM AUTHOR]