Alkali-metal-filledCoSb3skutterudites as thermoelectric materials: Theoretical study

Abstract

The crystal structures, filling fraction limits (FFLs), electronic structures, and electrical transport properties for alkali-metal-filled $\mathrm{Co}{\mathrm{Sb}}_{3}$ skutterudites are studied using density functional band-structure calculations. The calculated FFLs in $\mathrm{Co}{\mathrm{Sb}}_{3}$ are more than 60% for Na and K, 25% for Rb, and zero for Li and Cs, at $1000\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The reasons for these unusual FFLs of alkali atoms are discussed. Based on the calculated electronic structures, the electrical transport properties of $\mathrm{Co}{\mathrm{Sb}}_{3}$ are likely to be retained upon Na and K fillings, which was also confirmed by our calculated electrical transport properties of these materials. Furthermore, excellent thermoelectric properties are expected for Na-filled $\mathrm{Co}{\mathrm{Sb}}_{3}$ skutterudites.