Tailoring nanostructured NbCoSn-based thermoelectric materials via crystallization of an amorphous precursor

Tailoring nanostructured NbCoSn-based thermoelectric materials via crystallization of an amorphous precursor

Jung, Chanwon (Korea Advanced Institute of Science and Technology)
Dutta, B. (TU Delft Team Marcel Sluiter)
Dey, P. (TU Delft Team Poulumi Dey)
Jeon, Seong jae (Korea Institute of Machinery and Materials)
Han, Seungwoo (Korea Institute of Machinery and Materials)
Lee, Hyun Mo (Hanyang University)
Park, Jin Seong (Hanyang University)
Yi, Seong Hoon (Kyungpook National University)
Choi, Pyuck Pa (Korea Advanced Institute of Science and Technology)

2021

Tailoring nanostructures is nowadays a common approach for enhancing the performance of thermoelectric Heusler compounds by decreasing the thermal conductivity without significantly affecting the electrical conductivity. However, the most widely reported method for obtaining nanostructured thermoelectrics, an approach based on crushing as-cast alloy ingots followed by sintering of the debris, only gives limited control of the final nanostructure due to residual elemental segregation after casting. Here, a novel approach for fabricating nanostructured Heusler compounds is presented, which is based on crystallizing an amorphous precursor of NbCo_1.1Sn composition. This method yields two distinct nanostructures, namely one comprising only half-Heusler grains and another one comprising half-Heusler grains and full-Heusler nano-precipitates. The latter sample exhibits enhanced negative Seebeck coefficients as compared to the former over a wide temperature range. Using advanced characterization techniques, such as high-resolution transmission electron microscopy and atom probe tomography, in conjunction with ab initio density functional theory, detailed insights into the nanostructure and electrical properties of the specimens are provided. Filtering of low energy and mobility electrons at the half-Heusler and full-Heusler interface along with the formation of Co interstitial defects in the half-Heusler matrix are proposed to be the possible causes for the enhanced Seebeck coefficient of the nano-precipitate containing specimen.

Atom probe tomography
Density functional theory
Half–Heusler compound
Nanocrystallization
Thermoelectric

http://resolver.tudelft.nl/uuid:4957f70a-295f-484b-b2bc-387e56beefbd

https://doi.org/10.1016/j.nanoen.2020.105518

2021-04-20

2211-2855

Nano Energy, 80

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

journal article

© 2021 Chanwon Jung, B. Dutta, P. Dey, Seong jae Jeon, Seungwoo Han, Hyun Mo Lee, Jin Seong Park, Seong Hoon Yi, Pyuck Pa Choi