High-pressure torsion, a new processing route for thermoelectrics of high ZTs by means of severe plastic deformation

Autor(en)

Gerda Rogl, Daria Setman, Erhard Schafler, Jelena Horky, Michael Kerber, Michael Zehetbauer, Matthias Falmbigl, Peter Franz Rogl, Esmaeil Royanian, Ernst Bauer

Abstrakt

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(en)

Institut für Physikalische Chemie, Physik Nanostrukturierter Materialien

Externe Organisation(en)

Technische Universität Wien

Journal

Acta Materialia

Band

60

Seiten

2146-2157

Anzahl der Seiten

12

ISSN

1359-6454

DOI

https://doi.org/10.1016/j.actamat.2011.12.023

Publikationsdatum

2012

Peer-reviewed

Ja

ÖFOS 2012

104017 Physikalische Chemie, 1030 Physik, Astronomie, 104006 Festkörperchemie, 103018 Materialphysik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/dd816e96-61f8-4c5f-a680-a27a14588055