| Autor: |
Barczak SA, Halpin JE; SUPA, School of Physics and Astronomy, University of Glasgow , Glasgow G12 8QQ, U.K., Buckman J, Decourt R; CNRS, ICMCB, UPR 9048 , F-33600 Pessac, France.; University of Bordeaux, ICMCB, UPR 9048 , F-33600 Pessac, France., Pollet M; CNRS, ICMCB, UPR 9048 , F-33600 Pessac, France.; University of Bordeaux, ICMCB, UPR 9048 , F-33600 Pessac, France., Smith RI; ISIS Facility, Rutherford Appleton Laboratory , Harwell Oxford, Didcot OX11 0QX, U.K., MacLaren DA; SUPA, School of Physics and Astronomy, University of Glasgow , Glasgow G12 8QQ, U.K., Bos JG |
| Abstrakt: |
Half-Heusler alloys based on TiNiSn are promising thermoelectric materials characterized by large power factors and 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 TiNiCu y Sn (y ≤ 0.1) compositions have a temperature-averaged ZT device = 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. |
