Transport properties of Na8Si46

Abstract

We report on transport properties of polycrystalline Na8Si46 in the temperature range 10 to 300 K. The compound is a type I clathrate with Na incorporated into polyhedra formed by framework Si atoms. Seebeck coefficient and resistivity measurements indicate metallic behavior, The thermal conductivity is low in comparison with crystalline Si, but high in comparison with other type I clathrates with a large contribution due to electronic conduction. The potential for thermoelectric applications also is discussed.