Halpin, J. E., Jenkins, B., Moody, M. P., Webster, R. W.H., Bos, J.-W. G., Bagot, P. A.J. and MacLaren, D. A. (2022) A correlative study of interfacial segregation in a Cu-doped TiNiSn thermoelectric half-Heusler alloy. ACS Applied Electronic Materials, 4(9), pp. 4446-4454. (doi: 10.1021/acsaelm.2c00699) (PMID:36185076) (PMCID:PMC9520967)
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Abstract
The performance of thermoelectric materials depends on both their atomic-scale chemistry and the nature of microstructural details such as grain boundaries and inclusions. Here, the elemental distribution throughout a TiNiCu0.1Sn thermoelectric material has been examined in a correlative study deploying atom-probe tomography (APT) and electron microscopies and spectroscopies. Elemental mapping and electron diffraction reveal two distinct types of grain boundary that are either topologically rough and meandering in profile or more regular and geometric. Transmission electron microscopy studies indicate that the Cu dopant segregates at both grain boundary types, attributed to extrusion from the bulk during hot-pressing. The geometric boundaries are found to have a degree of crystallographic coherence between neighboring grains; the rough boundaries are decorated with oxide impurity precipitates. APT was used to study the three-dimensional character of rough grain boundaries and reveals that Cu is present as discrete, elongated nanoprecipitates cosegregating alongside larger substoichiometric titanium oxide precipitates. Away from the grain boundary, the alloy microstructure is relatively homogeneous, and the atom-probe results suggest a statistical and uniform distribution of Cu with no evidence for segregation within grains. The extrusion suggests a solubility limit for Cu in the bulk material, with the potential to influence carrier and phonon transport properties across grain boundaries. These results underline the importance of fully understanding localized variations in chemistry that influence the functionality of materials, particularly at grain boundaries.
| Item Type: | Articles |
|---|---|
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Halpin, Dr John and Webster, Mr Robert and MacLaren, Professor Donald and Bagot, Dr Paul |
| Authors: | Halpin, J. E., Jenkins, B., Moody, M. P., Webster, R. W.H., Bos, J.-W. G., Bagot, P. A.J., and MacLaren, D. A. |
| College/School: | College of Science and Engineering > School of Geographical and Earth Sciences College of Science and Engineering > School of Physics and Astronomy |
| Journal Name: | ACS Applied Electronic Materials |
| Publisher: | American Chemical Society |
| ISSN: | 2637-6113 |
| ISSN (Online): | 2637-6113 |
| Published Online: | 23 August 2022 |
| Copyright Holders: | Copyright © 2022 The Authors |
| First Published: | First published in ACS Applied Electronic Materials 4(9): 4446-4454 |
| Publisher Policy: | Reproduced under a Creative Commons License |
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