Thermoelectric material with record figure of merit ZT = 2.1


New record thermoelectric material n-type skutterudite with ZT=2.1

Thermoelectric generators are heat engines that can convert any kind of heat into green electricity. Leading an international assembly of co-authors, the research group of Prof. Peter Rogl in the Institute of Materials Chemistry of the University of Vienna (Director of Institute: Prof. Alexander Bismarck) has recently achieved a world wide record in the thermoelectric figure of merit, ZT=2.1 at 855 K, of bulk Skutterudites: Gerda Rogl and coworkers have used high pressure torsion (HPT, a technique introducing a high level of severe plastic deformation) to consolidate commercially available n-type skutterudite powder into bulk thermoelectric (TE) material. The torsial movement under high pressure (5 GPa, 300 °C, several revolutions) - in a delicate balance between a rise of electrical resistivity but a decrease of thermal conductivity at practically constant Seebeck voltage – was employed to create a maximum ZT, which for the first time surpassed the magic value of 2 for bulk TE materials.

The skutterudite powder used is commercially available and was developed in a close cooperation between the Treibacher Industries AG (TIAG, Treibach-Althofen, Austria) and the Institute of Materials Chemistry within the activities of a Christian Doppler Laboratory for Thermoelectricity (chaired by Prof. Ernst Bauer at the Institute of Solid State Physics, TU Wien).

Future activities of the group will address HPT of p-type skutterudites as well as large scale HPT production of 0.5 kg samples.

G. Rogl, S. Ghosh, O. Renk, K. Yubuta, A. Grytsiv, E. Schafler, M. Zehetbauer, R.C. Mallik, E. Bauer, P. Rogl, “The Influence of Shear Strain on HPT-Processed n-Type Skutterudites Yielding ZT=2.1", J. Alloys Compds. 855, 157409, 1-10 (2021).