Dresden 2017 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 17: Thermoelectric Materials

DS 17.5: Vortrag

Montag, 20. März 2017, 18:45–19:00, CHE 89

Defects in Heusler compounds for thermoelectric applications. — •Gerhard H. Fecher1, Benjamin Balke2, and Claudia Felser11Max Planck Institute - CPFS, Dresden, Germany — 2Johannes Gutenberg University, Mainz, Germany

It turned out that semi-conducting Heusler compounds with C1b structure and 18 valence electrons are reliable materials for thermoelectric applications, in particular for generators. The materials are mostly based on Ni for n-type or Co for p-type thermoelectrics. Examples are TNiSn or TCoSb where (T=Ti, Zr, Hf) is a transition metal or a combination of transition metals e.g.: Hf0.35Zr0.35Ti0.3. The latter mixture leads already to chemical disorder, as different elements share the same position of the C1b structure. Further defects are anti-site disorder caused by a swap of two different atoms (e.g.: Ti ↔Sn), off-stoichiometry by excess or deficiency of one of the elements (TiNixSn) or Frenkel defects (e.g.:Ni ↔). First principles calculations were performed for Heusler compounds exhibiting such defects and the influence of the defects on the electronic structure was studied. The main emphasis was on the changes of the band gap and the occurrence of states inside of the gap. The effects of the different defects on the electronic transport properties will be discussed.

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