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Issue 2, 2017
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Improving thermoelectric performance of TiNiSn by mixing MnNiSb in the half-Heusler structure

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Abstract

The thermoelectric properties of the n-type semiconductor TiNiSn were optimized by partial substitution with metallic MnNiSb in the half Heusler structure. Herein, we study the transport properties and intrinsic phase separation in the Ti1−xMnxNiSn1−xSbx system. The alloys were prepared by arc-melting and annealed at temperatures obtained from differential thermal analysis and differential scanning calorimetry results. The phases were characterized using powder X-ray diffraction patterns, energy-dispersive X-ray spectroscopy, and differential scanning calorimetry. After annealing, the majority phase was TiNiSn with some Ni-rich sites, and the minority phases were primarily Ti6Sn5, Sn and MnSn2. The Ni-rich sites were caused by Frenkel defects; this led to metal-like behavior in the semiconductor specimens at low temperature. For x ≤ 0.05 the samples showed an activated conduction, whereas for x > 0.05 they showed metallic character. The figure of merit for x = 0.05 was increased by 61% (zT = 0.45) in comparison with the pure TiNiSn.

Graphical abstract: Improving thermoelectric performance of TiNiSn by mixing MnNiSb in the half-Heusler structure

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Article information


Submitted
06 Oct 2016
Accepted
24 Nov 2016
First published
30 Nov 2016

Phys. Chem. Chem. Phys., 2017,19, 1543-1550
Article type
Paper

Improving thermoelectric performance of TiNiSn by mixing MnNiSb in the half-Heusler structure

T. Berry, S. Ouardi, G. H. Fecher, B. Balke, G. Kreiner, G. Auffermann, W. Schnelle and C. Felser, Phys. Chem. Chem. Phys., 2017, 19, 1543
DOI: 10.1039/C6CP06859F

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