Recent developments in half-Heusler thermoelectric materials

Bos, Jan‐Willem G.

doi:10.1016/b978-0-12-818535-3.00014-1

Cited by 12 publications

(9 citation statements)

References 98 publications

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“…However, their wide-scale adoption is currently impeded by the cost of often scarce materials and relatively low heat-to-electricity conversion efficiencies (He et al, 2018;Amatya & Ram, 2012). To overcome these challenges, the intermetallic materials known as half-Heusler (HH) alloys have shown considerable promise for balancing performance with commercial feasibility (Bos, 2021) . The ideal half-Heusler structure has a 1:1:1 XYZ composition and crystallises with a cubic structure.…”

Section: Introductionmentioning

confidence: 99%

“…This leaves a fourth sublattice, which is occupied in the full-Heusler structure, leading to 1:2:1 XY 2 Z compositions (Graf et al, 2011). The HH alloys are semiconducting for special electron counts of 8 or 18, which is a strict requirement for good TE performance (Snyder & Toberer, 2008; Graf et al, 2011; Bos, 2021). The best current HH alloys are based on XNiSn (n-type, X = Ti, Zr, Hf), XCoSb (p-type), and X′FeSb (p-type, X′ = Nb, Ta) (Bos, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…The HH alloys are semiconducting for special electron counts of 8 or 18, which is a strict requirement for good TE performance (Snyder & Toberer, 2008; Graf et al, 2011; Bos, 2021). The best current HH alloys are based on XNiSn (n-type, X = Ti, Zr, Hf), XCoSb (p-type), and X′FeSb (p-type, X′ = Nb, Ta) (Bos, 2021). These parent structures are typically heavily modified by dopants to maximize the thermoelectric figure of merit, ZT = S 2 σTκ −1 .…”

Section: Introductionmentioning

confidence: 99%

“…Here, S is the Seebeck coefficient, σ is the electrical conductivity, and κ is the sum of the lattice ( κ lat ) and electronic ( κ el ) thermal conductivity. Typical compositions are Ti 0.5 Zr 0.25 Hf 0.25 NiSn 0.99 Sb 0.01 , where alloying with Ti, Zr, and Hf on the X-site is used to embed phonon point-defect scattering and Sb is used as a dopant to achieve the best possible trade-off between S , σ, and κ el (Bos, 2021). In a contrasting strategy, small amounts of Cu (0−10% occupancy) on the vacant site in TiNiSn can achieve similar optimization and leads to promising ZT = 0.6−0.8 at 800 K (Barczak et al, 2018, 2019).…”

Section: Introductionmentioning

confidence: 99%

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Atom Probe Tomography of a Cu-Doped TiNiSn Thermoelectric Material: Nanoscale Structure and Optimization of Analysis Conditions

Halpin

Popuri

et al. 2022

Microscopy and Microanalysis

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Atom Probe Tomography of a Cu-Doped TiNiSn Thermoelectric Material: Nanoscale Structure and Optimization of Analysis Conditions

Halpin

Popuri

et al. 2022

Microscopy and Microanalysis

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“…The STFC is acknowledged for allocation of neutron scattering beamtime at the ISIS facility (RB1610143). 69…”

Section: Author Contributionsmentioning

confidence: 99%

Mechanistic Insights into the Formation of Thermoelectric TiNiSn from In Situ Neutron Powder Diffraction

et al. 2023

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Half-Heusler alloys are leading contenders for application in thermoelectric generators. However, reproducible synthesis of these materials remains challenging. Here, we have used in situ neutron powder diffraction to monitor the synthesis of TiNiSn from elemental powders, including the impact of intentional excess Ni. This reveals a complex sequence of reactions with an important role for molten phases. The first reaction occurs upon melting of Sn (232 °C), when Ni 3 Sn 4 , Ni 3 Sn 2 , and Ni 3 Sn phases form upon heating. Ti remains inert with formation of Ti 2 Ni and small amounts of half-Heusler TiNi 1+y Sn only occurring near 600 °C, followed by the emergence of TiNi and full-Heusler TiNi 2 y ’ Sn phases. Heusler phase formation is greatly accelerated by a second melting event near 750–800 °C. During annealing at 900 °C, full-Heusler TiNi 2 y ’ Sn reacts with TiNi and molten Ti 2 Sn 3 and Sn to form half-Heusler TiNi 1+ y Sn on a timescale of 3–5 h. Increasing the nominal Ni excess leads to increased concentrations of Ni interstitials in the half-Heusler phase and an increased fraction of full-Heusler. The final amount of interstitial Ni is controlled by defect chemistry thermodynamics. In contrast to melt processing, no crystalline Ti–Sn binaries are observed, confirming that the powder route proceeds via a different pathway. This work provides important new fundamental insights in the complex formation mechanism of TiNiSn that can be used for future targeted synthetic design. Analysis of the impact of interstitial Ni on the thermoelectric transport data is also presented.

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Iron‐based Semiconducting Half‐Heusler Alloys for Thermoelectric Applications

Chauhan

Miyazaki

2022

ChemNanoMat

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Iron-based half-Heusler alloys constitute an emerging class of semiconducting intermetallics for scalable and efficient thermoelectric conversion, owing to their remarkably highpower factor, abundance, and low cost. This review encompasses the recent advances in materials synthesis and evolving aspects of optimization pathways in pre-existing Fe-based half-Heusler compositions for attaining a higher thermoelectric figure of merit (zT). The experimental outcomes and theoretical predictions were analyzed and compared using a parametric framework to understand the underlying electronic transport responsible for high power factors exhibited by most of these alloys distinctively. Alongside, effective microstructural ap-proaches were reviewed for which favorable reduction in intrinsically high lattice thermal conductivity (k L ) was attained. The electronic structures of MFeSb (M=V, Nb, and Ta) half-Heuslers is also analyzed using density functional theory-based calculations to understand the origin of favorable conduction and electrical transport properties. Finally, processing-structuralproperty correlations are discussed to highlight the relevance of structural ordering, phase transformation, and defects on transport properties, for developing effective strategies and material design in Fe-based half-Heuslers for their development in thermoelectrics.[a] N.

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Recent developments in half-Heusler thermoelectric materials

Cited by 12 publications

References 98 publications

Atom Probe Tomography of a Cu-Doped TiNiSn Thermoelectric Material: Nanoscale Structure and Optimization of Analysis Conditions

Atom Probe Tomography of a Cu-Doped TiNiSn Thermoelectric Material: Nanoscale Structure and Optimization of Analysis Conditions

Mechanistic Insights into the Formation of Thermoelectric TiNiSn from In Situ Neutron Powder Diffraction

Iron‐based Semiconducting Half‐Heusler Alloys for Thermoelectric Applications

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