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DS: Fachverband Dünne Schichten

DS 15: Thermoelectric Materials

DS 15.5: Vortrag

Dienstag, 8. März 2016, 11:00–11:15, H8

Full- and half- Heusler phase coexistence in phase separated Z_{2-x}TiSb (Z=Co,Ni) thermoelectrics. — •Joaquin Miranda, Heiko Schoberth, Thomas Gruhn, and Heike Emmerich — Lehrstuhl für Material- und Prozesssimulation, Universität Bayreuth, Universitätsstraße 30, D-95447 Bayreuth, Germany

During the last year, we have successfully employed ab-initio Density Functional calculations and Monte Carlo simulations to show that some thermoelectric half-Heusler alloys show phase separation [1-3]. Recently, we have studied transition metal alloys with the formula Z_{2-x}TiSb (Z=Co, Ni), where x sets the concentration for a half (if x=1) or full (if x=0) Heusler material. We show that the materials undergo a complex phase separation containing half/full Heusler superstructures. This separation is assumed to have beneficial effects on the charge and heat transports mechanism and to lead to higher figures of merit in thermoelectrics. The interplay of kinetics and transport on the bulk as well as the role of the inter-phases are still under investigation. Here we show simulations that clarify the individual contributions.

1.- Nanophase separation in CoSb-based half-Heusler thermoelectrics: A multiscale simulation study. Phys. Status Solidi A (2015).

2.- Miscibility gap in the phase diagrams of thermoelectric half-Heusler materials CoTi_{1-x}Y_xSb (Y = Sc, V, Mn, Fe). Journal of Electronic Materials (2015).

3.- Ab-initio study of domain structures in half-metallic CoTi_{1-x}Mn_xSb and thermoelectric CoTi_{1-x}Sc_xSb Half-Heusler alloys. Journal of Alloys and Compounds, Vol. 650,25,728 (2015).