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DS: Fachverband Dünne Schichten

DS 15: Thermoelectric Materials

DS 15.9: Vortrag

Dienstag, 8. März 2016, 12:00–12:15, H8

Thermoelectric properties of half-Heusler heterostructures from ab initio calculations — •Peter Kratzer and Gregor Fiedler — Faculty of Physics, University Duisburg-Essen, 47048 Duisburg, Germany

Semiconducting half-Heusler alloys have recently emerged as a class of thermoelectric materials with outstanding performance in the medium-to-high-temperature range. Heterostructures promise further reduction of the thermal conductivity due to phonon scattering at interfaces. Here, both the electronic and phononic spectra of half-Heusler compounds based on Ti, Zr, and Hf are calculated using density functional theory (DFT). With this input, thermoelectric properties are obtained. We demonstrate how the thermal conductivity of a superlattice can be estimated in dependence on its period, by using the mean free path of phonons in bulk materials plus an extension of the diffuse mismatch model. The results are compared to experiment (PRB 92 (2015), 125436). Moreover, we demonstrate that, in a short-period superlattice, a high power factor may be retained, while the thermal conductivity is reduced compared to single-phase half-Heusler crystals.