Dresden 2011 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 31: Postersitzung II
MM 31.5: Poster
Mittwoch, 16. März 2011, 17:15–18:45, P5
Band engineering for thermoelectric materials — •Mingxing Chen and Raimund Podloucky — Faculty of Chemistry, Univ. Vienna
Engineering of the electronic band structure of Ge-based skutterudites and clathrates is of importance for optimizing their thermoelectric properties in terms of Seebeck coefficients. Alloys of FM4SbxGe12−x skutterudites and Ba8MxGe46−x clathrates (F: filler atom, M: metal) are investigated by means of density functional theory calculations from which the transport properties are derived by Boltzmann transport theory within the constant relaxation time approach[1]. For a large Seebeck coefficient it is important to place the Fermi energy close to a gap. Therefore, we analyse the nature of gap formation for these two classes of materials and derive a simple counting rule for chemical optimization of the thermoelectric properties [2]. Following this rule, our data on skutterudites reveal that partially replacing Ge by Sb leads to the desired placement of the Fermi energy. For clathrates, also the electric resistivities are analyzed which reveal characteristic temperature dependent features in agreement with experiment[2].
[1] G. K. Madsen and D. J. Singh, Comput. Mater. Sci. 175, 67 (2006). [2] I. Zeiringer, Mingxing Chen et al., submitted.