Abstract
Half-Heusler alloys based on TiNiSn are promising thermoelectric materials characterised by large power factors, good mechanical and thermal stabilities; but they are limited by large thermal conductivities. A variety of strategies have been used to disrupt their thermal transport, including alloying with heavy, generally expensive, elements and nanostructuring, enabling figures of merit, ZT ≥ 1 at elevated temperatures (>773 K). Here, we demonstrate an alternative strategy that is based around the partial segregation of excess Cu leading to grain-by-grain compositional variations, the formation of extruded Cu ‘wetting’ layers between grains and – most importantly – the presence of statistically distributed interstitials that reduce the thermal conductivity effectively through point-defect scattering. Our best TiNiCuySn (y ≤ 0.1) compositions have a temperature-averaged ZTdevice = 0.3-0.4 and estimated leg power outputs of 6-7 W cm-2 in the 323-773 K temperature range. This is a significant development as these materials were prepared using a straightforward processing method, do not contain any toxic, expensive or scarce elements and are therefore promising candidates for large scale production.
Original language | English |
---|---|
Pages (from-to) | 4786–4793 |
Number of pages | 8 |
Journal | ACS Applied Materials and Interfaces |
Volume | 10 |
Issue number | 5 |
Early online date | 9 Jan 2018 |
DOIs | |
Publication status | Published - 7 Feb 2018 |
Fingerprint
Dive into the research topics of 'Grain by grain compositional variations and interstitial metals – a new route towards achieving high performance in half-Heusler thermoelectrics'. Together they form a unique fingerprint.Profiles
-
Jan-Willem G. Bos
- School of Engineering & Physical Sciences - Associate Professor
- School of Engineering & Physical Sciences, Institute of Chemical Sciences - Associate Professor
Person: Academic (Research & Teaching)