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The role of interstitial Cu on thermoelectric properties of ZrNiSn half-Heusler compounds

Yan, Ruijuan ; Shen, Chen ; Widenmeyer, Marc ; Luo, Ting ; Winkler, Robert ; Adabifiroozjaei, Esmaeil ; Xie, Ruiwen ; Yoon, Songhak ; Suard, Emmanuelle ; Molina-Luna, Leopoldo ; Zhang, Hongbin ; Xie, Wenjie ; Weidenkaff, Anke (2023)
The role of interstitial Cu on thermoelectric properties of ZrNiSn half-Heusler compounds.
In: Materials Today Physics, 33
doi: 10.1016/j.mtphys.2023.101049
Article, Bibliographie

Abstract

The density functional theory (DFT) calculations and experiments have confirmed that in the ABC-type half-Heusler compounds, the 3d elements occupying the B position are natural over-stoichiometry. These additional atoms are able to synergistically optimize the electrical and thermal transport properties of half-Heusler compounds. In this work, Cu (3d104s1) is intentionally introduced into the ZrNiSn compound to form Cu interstitial defects. The correlations between the phase structure, microstructure, and thermoelectric properties of ZrNiCuxSn (x = 0–0.20) are investigated with X-ray and neutron diffraction, transmission electron microscopy, atom probe tomography, and band structure and phonon spectra calculations. The diffraction results reveal that Ni/Cu atoms partially occupy the 4d position (3/4, 3/4, 3/4) of the half-Heusler crystal structure, forming interstitial defects. The interstitial Cu defects force the conduction band minimum to gradually move close to the valence band maximum and reduce the bandgap, rather than induce in-gap states as typical Ni interstitials. Besides the interstitial defects, a full-Heusler phase is also formed in the half-Heusler matrix with increasing Cu content. Due to the interstitial defects and interface engineering, the thermal conductivity is suppressed. As a result, a higher figure of merit (ZT) value is achieved (∼1.1 at 950 K) in the ZrNiCu0.05Sn sample. This work analyses the possibility of interstitial defects from a thermodynamic point of view and highlights the defect engineering to positively tune the thermoelectric properties in half-Heusler compounds.

Item Type: Article
Erschienen: 2023
Creators: Yan, Ruijuan ; Shen, Chen ; Widenmeyer, Marc ; Luo, Ting ; Winkler, Robert ; Adabifiroozjaei, Esmaeil ; Xie, Ruiwen ; Yoon, Songhak ; Suard, Emmanuelle ; Molina-Luna, Leopoldo ; Zhang, Hongbin ; Xie, Wenjie ; Weidenkaff, Anke
Type of entry: Bibliographie
Title: The role of interstitial Cu on thermoelectric properties of ZrNiSn half-Heusler compounds
Language: English
Date: April 2023
Publisher: Elsevier Science Publishing
Journal or Publication Title: Materials Today Physics
Volume of the journal: 33
DOI: 10.1016/j.mtphys.2023.101049
Abstract:

The density functional theory (DFT) calculations and experiments have confirmed that in the ABC-type half-Heusler compounds, the 3d elements occupying the B position are natural over-stoichiometry. These additional atoms are able to synergistically optimize the electrical and thermal transport properties of half-Heusler compounds. In this work, Cu (3d104s1) is intentionally introduced into the ZrNiSn compound to form Cu interstitial defects. The correlations between the phase structure, microstructure, and thermoelectric properties of ZrNiCuxSn (x = 0–0.20) are investigated with X-ray and neutron diffraction, transmission electron microscopy, atom probe tomography, and band structure and phonon spectra calculations. The diffraction results reveal that Ni/Cu atoms partially occupy the 4d position (3/4, 3/4, 3/4) of the half-Heusler crystal structure, forming interstitial defects. The interstitial Cu defects force the conduction band minimum to gradually move close to the valence band maximum and reduce the bandgap, rather than induce in-gap states as typical Ni interstitials. Besides the interstitial defects, a full-Heusler phase is also formed in the half-Heusler matrix with increasing Cu content. Due to the interstitial defects and interface engineering, the thermal conductivity is suppressed. As a result, a higher figure of merit (ZT) value is achieved (∼1.1 at 950 K) in the ZrNiCu0.05Sn sample. This work analyses the possibility of interstitial defects from a thermodynamic point of view and highlights the defect engineering to positively tune the thermoelectric properties in half-Heusler compounds.

Uncontrolled Keywords: Interstitial defects, Half-Heusler, Thermoelectric materials, ZrNiSn, Density functional theory
Additional Information:

Artikel ID: 101049

Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Advanced Electron Microscopy (aem)
11 Department of Materials and Earth Sciences > Material Science > Theory of Magnetic Materials
11 Department of Materials and Earth Sciences > Material Science > Materials and Resources
Date Deposited: 27 Mar 2023 07:35
Last Modified: 11 Jul 2023 08:36
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