High-pressure torsion, a new processing route for thermoelectrics of high ZTs by means of severe plastic deformation
- Author(s)
- Gerda Rogl, Daria Setman, Erhard Schafler, Jelena Horky, Michael Kerber, Michael Zehetbauer, Matthias Falmbigl, Peter Franz Rogl, Esmaeil Royanian, Ernst Bauer
- Abstract
High-pressure torsion (HPT) is a type of severe plastic deformation (SPD) that is highly suited to produce bulk ultrafine-grained and nanocrystalline materials, as it introduces many grain boundaries as well as dislocations and point defects. In this paper, HPT-mediated nanocrystallization was used to reduce the thermal conductivity and enhance the Seebeck coefficient of skutterudites. Both p- and n-type skutterudites have been processed by HPT with 4 and 5 GPa at temperatures up to 773 K, resulting in a strongly strengthened nanocrystalline structure, revealing oriented, lamellar-shaped crystallites with a size of similar to 50 nm and an enhanced dislocation density. In comparison with ball-milled plus hot-pressed skutterudites, the HPT-processed samples show a reduction of the thermal conductivity up to 40%. This and the slightly higher Seebeck coefficient are the reasons why HPT proved to enhance the figure of merit (ZT) values up to a factor of 2, in spite of a markedly enhanced electrical resistivity.
- Organisation(s)
- Department of Physical Chemistry, Physics of Nanostructured Materials
- External organisation(s)
- Technische Universität Wien
- Journal
- Acta Materialia
- Volume
- 60
- Pages
- 2146-2157
- No. of pages
- 12
- ISSN
- 1359-6454
- DOI
- https://doi.org/10.1016/j.actamat.2011.12.023
- Publication date
- 2012
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 104017 Physical chemistry, 1030 Physics, Astronomy, 104006 Solid state chemistry, 103018 Materials physics
- Portal url
- https://ucris.univie.ac.at/portal/en/publications/highpressure-torsion-a-new-processing-route-for-thermoelectrics-of-high-zts-by-means-of-severe-plastic-deformation(dd816e96-61f8-4c5f-a680-a27a14588055).html