Electronic Structure and Thermoelectric Properties of Noble Metal Clathrates: Ba8M6Ge40(M = Cu, Ag, Au)
Year: 2007
Type: article
Abstract: Electronic structure and thermoelectric properties of noble metal clathrates Ba8M6Ge40(M = Cu, Ag, Au) were calculated by using a first principle based method to discuss prospect of high performance thermoelectric materials. The calculated band structures show that these clathrate compounds are degenerate semiconductors with p type carrier. The band gaps become narrow by noble metal doping. The band gap narrowing is caused by the valence band lifting due to anti-bonding nature between Ge and M, and conduction band widening due to framework-guest atom coupling via Ba orbitals at 6d sites. The thermoelectric power of Ba8M6Ge40 increases with temperatures monotonically and the magnitude is smaller than 100 μV/K under 1000 K. The carrier concentration of Ba8M6Ge40 is a little larger for the high performance thermoelectric materials. The carrier concentration is controlled by varying the composition of Ba8AuxGe46−x. The optimized carrier concentration in Ba8AuxGe46−x was obtained as 4.4×1026 m−3 (p type) and 6.4×1026 m−3 (n type), respectively.
Source: MATERIALS TRANSACTIONS
Authors: Koji Akai, Kenji Koga, Mitsuru Matsuura
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2033199499