Affiliation:
1. Nanoanalytics and Interfaces Max‐Planck‐Institut für Eisenforschung GmbH Max‐Planck‐Straße 1 40237 Düsseldorf Germany
2. Materials Science & Engineering Northwestern University Clark Street 633 Evanston IL 60208 USA
3. Thermoelectric Materials and Devices IFW Dresden Helmholtzstraße 20 01069 Dresden Germany
Abstract
AbstractMany thermoelectric materials benefit from complex microstructures. Grain boundaries (GBs) in nanocrystalline thermoelectrics cause desirable reduction in the thermal conductivity by scattering phonons, but often lead to unwanted loss in the electrical conductivity by scattering charge carriers. Therefore, modifying GBs to suppress their electrical resistivity plays a pivotal role in the enhancement of thermoelectric performance, zT. In this work, different characteristics of GB phases in Ti‐doped NbFeSb half‐Heusler compounds are revealed using a combination of scanning transmission electron microscopy and atom probe tomography. The GB phases adopt a hexagonal close‐packed lattice, which is structurally distinct from the half‐Heusler grains. Enrichment of Fe is found at GBs in Nb0.95Ti0.05FeSb, but accumulation of Ti dopants at GBs in Nb0.80Ti0.20FeSb, correlating to the bad and good electrical conductivity of the respective GBs. Such resistive to conductive GB phase transition opens up new design space to decouple the intertwined electronic and phononic transport in thermoelectric materials.
Funder
Office of Energy Efficiency and Renewable Energy
National Research Foundation of Korea
National Institute of Standards and Technology
Deutsche Forschungsgemeinschaft
Subject
General Materials Science,Renewable Energy, Sustainability and the Environment
Cited by
18 articles.
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