Berlin 2015 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 22: Functional Materials IV: Thermoelectric and Multiferroic Materials

MM 22.3: Vortrag

Dienstag, 17. März 2015, 10:45–11:00, TC 010

Vibrational dynamics of filled skutterudites: Role of the fillers — •Susmita Basak, Christian Carbogno, and Matthias Scheffler — Fritz Haber Institute of the Max Planck Society, Berlin, Germany

Skutterudites are regarded as potential candidates for next-generation thermoelectric materials for electrical power generation using either solar energy or waste heat [1,2]. They form open cage-like covalent structures with large interstitial voids that can accommodate filler atoms. In principle, the thermoelectric efficiency of skutterudites can be tailored and improved in presence of these foreign atoms because different filler species affect the vibrational and electronic transport coefficients differently. In order to rationalize this phenomenon, various (in part mutually exclusive) mechanisms (rattling of filler atoms [3], hybridization between guest and host atoms [4] etc.) have been evoked in literature. To shed light on the underlying interactions, we use density functional theory to systematically study the electronic structure and the lattice dynamics of skutterudites (CoSb3, CoAs3 etc,) with various fillers (Ba, Ga, In, Sn etc.). We incorporate the full anharmonicity of the inter-atomic interactions via ab initio molecular dynamics techniques. Our calculations reveal a unified mechanism that determines the dynamics and hence provide insights/guidelines to engineer the vibrational band structure in this material class.

[1] B. C. Sales et al., Science 272, 1325 (1996). [2] G. S. Nolas et al., Phys. Rev. B, 58, 164 (1998). [3] G. A. Slack et al., J. Appl. Phys. 76, 1665 (1994). [4] J. L. Feldman et al., Phys. Rev. B 61, R9209 (2000).