Issue 40, 2015

Fine tuning of thermoelectric performance in phase-separated half-Heusler compounds

Abstract

Two successful recipes to enhance the thermoelectric performance, namely carrier concentration optimization and reduction of thermal conductivity, have been combined and applied to the p-type (Ti/Zr/Hf)CoSb1−xSnx system. An intrinsic micrometer-scale phase separation increases the phonon scattering and reduces the lattice thermal conductivity. A substitution of 15% Sb by Sn optimizes the electronic properties. Starting from this, further improvement of the thermoelectric properties has been achieved by a fine tuning of the Ti to Hf ratio. The microstructuring of the samples was studied in detail with high-resolution synchrotron powder X-ray diffraction and element mapping electron microscopy. Linking the structural with the thermoelectric properties, a record thermoelectric figure of merit for p-type half-Heusler compounds of ZT ≈ 1.2 at 710 °C in Ti0.25Hf0.75CoSb0.85Sn0.15 was achieved. The phase separation approach can form a significant alternative to nanostructuring processing, saving time, energy consumption and increasing the thermoelectric efficiency.

Graphical abstract: Fine tuning of thermoelectric performance in phase-separated half-Heusler compounds

Article information

Article type
Paper
Submitted
28 4 2015
Accepted
18 6 2015
First published
23 6 2015

J. Mater. Chem. C, 2015,3, 10409-10414

Author version available

Fine tuning of thermoelectric performance in phase-separated half-Heusler compounds

E. Rausch, B. Balke, J. M. Stahlhofen, S. Ouardi, U. Burkhardt and C. Felser, J. Mater. Chem. C, 2015, 3, 10409 DOI: 10.1039/C5TC01196E

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