Synthesis, Structure, and Thermoelectric Properties of Barium Copper Polychalcogenides with Chalcogen-Centered Cu Clusters and Te22– Dumbbells

✍ Scribed by Oottil Mayasree; Cheriyedath Raj Sankar; Yanjie Cui; Abdeljalil Assoud; Holger Kleinke

• Book ID: 102166610
• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 368 KB
• Volume: 2011
• Category: Article
• ISSN: 1434-1948
• DOI: 10.1002/ejic.201100284

✦ Synopsis

Abstract

BaCu~6–x~STe~6~ and BaCu~6–x~Se~1–y~Te~6+y~ were synthesized from the elements at 663 K. These chalcogenides adopt a new structure type, cubic space group Pm$\bar {3}$, with a = 6.9680(2) Å in the case of BaCu~5.93~SeTe~6~. Therein, the Cu atoms form cubic clusters, centered by Se atoms, where statistically 2.07 corners are unoccupied. All Te atoms are part of Te~2~^2–^ dumbbells, leading to a charge‐balanced formula when x = 0: Ba^2+^(Cu^+^)~6~Se^2–^(Te~2~^2–^)~3~. While Te atoms can be incorporated on the Se site, no evidence was found for the ability of Se atoms to replace Te in the Te~2~^2–^ pairs. Band structure calculations on different BaCu~6~SeTe~6~ models revealed a very small band gap at the Fermi level; all these chalcogenides with x > 0 should thus be p‐doped semiconductors, which we experimentally confirmed for BaCu~5.7~Se~0.6~Te~6.4~.