We present the structure and thermoelectric properties of the new quaternary selenides K1+xM4-2xBi7+xSe15 (M = Sn, Pb) and K1-xSn5-xBi11+x Se22. The compound K1+xM4-2x Bi7+xSe15 (M= Sn, Pb) crystallize isostructural to A1+xPb4-2xSb7+xSe15 with A = K, Rb, while K1-xSn5-xBi11+xSe22 reveals a new structure type. In both structure types fragments of the Bi2Te3-type and the NaCl-type are connected to a three-dimensional anionic framework with K+ ions filled tunnels. The two structures vary by the size of the NaCl-type rods and are closely related to β-K2Bi8Se13 and K2.5Bi8.5Se14. The thermoelectric properties of K1+xM4-2xBi7+xSe15 (M = Sn, Pb) and K1-xSn5-xBi11+xSe22 were explored on single crystal and ingot samples. These compounds are narrow gap semiconductors and show n-type behavior with moderate Seebeck coefficients. They have very low thermal conductivity due to an extensive disorder of the metal atoms and possible "rattling" K+ ions.
|Original language||English (US)|
|Journal||Proceedings - IEEE International Symposium on Circuits and Systems|
|State||Published - Jan 1 2001|
|Event||IEEE International Symposium on Circuits and Systems (ISCAS 2001) - Sydney, NSW, Australia|
Duration: May 6 2001 → May 9 2001
ASJC Scopus subject areas
- Electrical and Electronic Engineering