Dresden 2017 – scientific programme

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DS: Fachverband Dünne Schichten

DS 17: Thermoelectric Materials

DS 17.4: Talk

Monday, March 20, 2017, 18:30–18:45, CHE 89

pattern formation in the half-Heusler NiTi_x−1Zr_xSb_1−ySn_y — •Joaquin Miranda, Thomas Gruhn, and Heike Emmerich — Material- und Prozesssimulation, Bayreuth University. Universitaetstr 30, DE 95447, Bayreuth

Domain formations offer the possibility to reduce the lattice thermal conductivity in thermoelectrics. In this view, We employed ab-initio Density Functional calculations and Monte Carlo simulations to investigate the thermoelectric NiTi_x−1Zr_xSb_1−ySn_y presents phase separation and rich patterning when is simultaneously alloyed Ti with Zr and Sb with Sn. We found that the material undergoes multiple phase separations as the temperature is lowered. First Ti and Zr phase separated at near 650 K but Sn and Sb tend to remain homogeneously distributed until temperatures around 300 K are reached. Within this temperature range (300-650 K) it is observed a slight preference of Zr-Sn (or Ti-Sb) nearest neighbors formation. Below 300 K both neighbors are increased, giving place to a second phase separation of richer Sn regions embedded in Zr volumes and Sb regions in Ti volumes; interestingly showing a meta-crystal structure preference of neighboring Zr and Sn atoms. We discuss the relevance of these observations within the context of thermoelectrics.