Fe segregation as a tool to enhance electrical conductivity of grain boundaries in Ti(Co,Fe)Sb half Heusler thermoelectrics

Villoro, Ruben Bueno; Wood, Maxwell; Luo, Ting; Bishara, Hanna; Abdellaoui, Lamya; Zavanelli, Duncan; Gault, Baptiste; Snyder, G. Jeffrey; Scheu, Christina; Zhang, Siyuan

doi:10.1016/j.actamat.2023.118816

Cited by 19 publications

(7 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In XYZ half-Heusler compounds, different grain boundary segregation behaviors of atoms occupying the X-site or Y-site have been observed. , For example, in the NbFeSb system, segregation of Nb was observed, while the VFeSb system exhibited Fe segregation. , Therefore, a more comprehensive investigation is required for various half-Heusler compounds to reveal the underlying causes of constituent element segregation and its implications on material properties.…”

Section: Discussionmentioning

confidence: 99%

“…Nanostructuring has been considered the most effective approach to overcome this limitation since grain boundaries and phase boundaries act as effective scattering centers for phonons, thereby reducing the lattice thermal conductivity while minimally impacting the electrical conductivity. − Mechanical alloying followed by sintering is a widely employed method for the fabricating of nanostructured thermoelectric materials owing to its convenience and effectiveness to reduce the lattice thermal conductivity. − Numerous studies have reported enhanced figure of merits attributed to the reduction in lattice thermal conductivity by using this approach. − However, undesired secondary phases or micro- and nanosegregation can occur during the sintering process, which hampers the fine control of microstructures of materials. , Furthermore, oxidation or impurity contamination during ball milling and sintering processes can elevate lattice thermal conductivity and degrade the Seebeck coefficient, thereby resulting in deterioration of the thermoelectric properties. − Moreover, the reduction in grain size is constrained as grain growth takes place during the consolidation process . For instance, Joshi et al reported that the initial grain size of Hf 0.75 Zr 0.25 NiSn 0.99 Sb 0.01 milled powder, approximately 50 nm, increased to over 200 nm after the hot-pressing process …”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Heat Treatment Temperature on the Crystallization Behavior and Microstructural Evolution of Amorphous NbCo_1.1Sn

Jung,

Zhang,

Jang

et al. 2023

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

Heat treatment-induced nanocrystallization of amorphous precursors is a promising method for nanostructuring half-Heusler compounds as it holds significant potential in the fabrication of intricate and customizable nanostructured materials. To fully exploit these advantages, a comprehensive understanding of the crystallization behavior of amorphous precursors under different crystallization conditions is crucial. In this study, we investigated the crystallization behavior of the amorphous NbCo 1.1 Sn alloy at elevated temperatures (783 and 893 K) using transmission electron microscopy and atom probe tomography. As a result, heat treatment at 893 K resulted in a significantly finer grain structure than heat treatment at 783 K owing to the higher nucleation rate at 893 K. At both temperatures, the predominant phase was a half-Heusler phase, whereas the Heusler phase, associated with Co diffusion, was exclusively observed at the specimen annealed at 893 K. The Debye−Callaway model supports that the lower lattice thermal conductivity of NbCo 1.1 Sn annealed at 893 K is primarily attributed to the formation of Heusler nanoprecipitates rather than a finer grain size. The experimental findings of this study provide valuable insights into the nanocrystallization of amorphous alloys for enhancing thermoelectric properties.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Heat Treatment Temperature on the Crystallization Behavior and Microstructural Evolution of Amorphous NbCo_1.1Sn

Jung,

Zhang,

Jang

et al. 2023

ACS Appl. Mater. Interfaces

Self Cite

View full text Add to dashboard Cite

show abstract

“…The GB-dominated electron scattering has been reported in many fine-grained thermoelectric materials, including Mg 3 Sb 2 , [52] ZrCoSb, [42] NbCoSn, [81] GeTe, [68] and TiCoSb. [82] At larger grain sizes (>1 µm), the GBs are sufficiently far apart so that their contribution to the scattering term becomes negligible. Nevertheless, this would also rule out major contribution of GBs in phonon scattering and close down the design space of nanostructuring in thermoelectrics.…”

Section: Effect Of Grain Size On the Thermoelectric Propertiesmentioning

confidence: 99%

Grain Boundary Phases in NbFeSb Half‐Heusler Alloys: A New Avenue to Tune Transport Properties of Thermoelectric Materials

Villoro

Zavanelli

Jung

et al. 2023

Advanced Energy Materials

Self Cite

View full text Add to dashboard Cite

Many 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.

show abstract

“…[39,40] However, the carrier grain boundary scattering could severely suppress the carrier mobility of SrTiO 3 -based thermoelectric ceramics. [41][42][43] Interface engineering is an effective way to reduce the scattering by lowering the energy barrier of grain boundaries, [44][45][46][47] and by realizing conduction band alignment to transport electrons and scattering phonons. [48] And in addition, the epitaxial growth of thin films with few grain boundaries could be another strategy.…”

Section: Introductionmentioning

confidence: 99%

Electrical Property Enhancement in Orientation‐Modulated Perovskite La‐Doped SrTiO₃ Thermoelectric Thin Films

Chen

Zhou

Yang

et al. 2023

Adv Funct Materials

View full text Add to dashboard Cite

Thermoelectric oxide thin films are promising in chip cooling. The issues on the orientation of thin films are essential as they are related to the structures, morphologies, and thermoelectric properties. In this regard, the orientation modulation is conducted on La‐doped SrTiO3 thin films on (LaAlO3)0.3(Sr2TaAlO6)0.7 (LSAT) single crystal substrates. Layer‐by‐layer growth mode is found in (001)‐ and (110)‐ oriented thin films, resulting in few grain boundaries (GBs). In (111)‐oriented films, island growth mode leads to columnar grain boundaries that build up potential barriers for electrons to be strongly scattered and filtered, suppressing electron mobility and increasing effective mass. In addition, the GBs serve as oxygen vacancy diffusion paths when annealing, causing increased carrier concentration and lattice contraction. The weighted mobility of 71.9 cm2 V−1 s−1 and electrical conductivity of ≈600 S cm−1 are realized in the (001)‐oriented film at room temperature. Ultimately, outstanding power factor values of ≈569 µW m−1 K−2 (room temperature) and ≈791 µW m−1 K−2 (573 K) are successfully achieved, outperforming those in polycrystalline ceramics and (111)‐oriented films. This study systematically investigates the influence of grain boundaries and orientations on SrTiO3‐based thermoelectric films, which lays a solid foundation for improving thermoelectric performance in other oxide thin films.

show abstract

Fe segregation as a tool to enhance electrical conductivity of grain boundaries in Ti(Co,Fe)Sb half Heusler thermoelectrics

Cited by 19 publications

References 68 publications

Effect of Heat Treatment Temperature on the Crystallization Behavior and Microstructural Evolution of Amorphous NbCo_1.1Sn

Effect of Heat Treatment Temperature on the Crystallization Behavior and Microstructural Evolution of Amorphous NbCo_1.1Sn

Grain Boundary Phases in NbFeSb Half‐Heusler Alloys: A New Avenue to Tune Transport Properties of Thermoelectric Materials

Electrical Property Enhancement in Orientation‐Modulated Perovskite La‐Doped SrTiO₃ Thermoelectric Thin Films

Contact Info

Product

Resources

About

Fe segregation as a tool to enhance electrical conductivity of grain boundaries in Ti(Co,Fe)Sb half Heusler thermoelectrics

Cited by 19 publications

References 68 publications

Effect of Heat Treatment Temperature on the Crystallization Behavior and Microstructural Evolution of Amorphous NbCo1.1Sn

Effect of Heat Treatment Temperature on the Crystallization Behavior and Microstructural Evolution of Amorphous NbCo1.1Sn

Grain Boundary Phases in NbFeSb Half‐Heusler Alloys: A New Avenue to Tune Transport Properties of Thermoelectric Materials

Electrical Property Enhancement in Orientation‐Modulated Perovskite La‐Doped SrTiO3 Thermoelectric Thin Films

Contact Info

Product

Resources

About

Effect of Heat Treatment Temperature on the Crystallization Behavior and Microstructural Evolution of Amorphous NbCo_1.1Sn

Effect of Heat Treatment Temperature on the Crystallization Behavior and Microstructural Evolution of Amorphous NbCo_1.1Sn

Electrical Property Enhancement in Orientation‐Modulated Perovskite La‐Doped SrTiO₃ Thermoelectric Thin Films