Dopant-segregation to grain boundaries controls electrical conductivity of n-type NbCo(Pt)Sn half-Heusler alloy mediating thermoelectric performance

Luo, Ting; Serrano‐Sánchez, Federico; Bishara, Hanna; Zhang, Siyuan; Villoro, Ruben Bueno; Kuo, Jimmy Jiahong; Felser, Claudia; Scheu, Christina; Snyder, G. Jeffrey; Best, James P.; Dehm, Gerhard; Yu, Yuanyu; Raabe, Dierk; Fu, Chenguang; Gault, Baptiste

doi:10.1016/j.actamat.2021.117147

Cited by 32 publications

(21 citation statements)

References 50 publications

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“…48,49 These defects alter the electronic transport properties, while the grain boundaries of polycrystalline samples have been shown to limit the scattering length of charge carriers. 9,50–52 These results agree with a recent theoretical study, which attributed the n-type character of the polycrystalline samples to an increased E F and to the Co-interstitial in-gap states, while indicating the p-type behavior of the defect-free materials. 53…”

Section: Resultssupporting

confidence: 90%

Electronic structure and low-temperature thermoelectric transport of TiCoSb single crystals

Serrano‐Sánchez

Yao

et al. 2022

Nanoscale

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Section: Resultssupporting

confidence: 90%

Electronic structure and low-temperature thermoelectric transport of TiCoSb single crystals

Serrano‐Sánchez

Yao

et al. 2022

Nanoscale

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“…53 For most good TE materials, the charge carrier transport is generally dominated by the acoustic phonon scattering (APS), of which the s and the carrier mobility m generally decrease with temperature following a temperature dependence of T Àr (1.0 r r r 1.5). However, it was found that the s of many grain-refined TE materials, including PbTe, 61,62 SnSe, 57,63 half-Heusler (HH) compounds, 56,[64][65][66][67][68] Mg 2 Si, 55 elemental Te, 58,69 and Mg 3 Sb 2 53 exhibit a so-called thermally activated behavior near room temperature (RT), namely, the s first increases to a maximum value and then decreases with rising temperature, as exhibited in Fig. 1(d).…”

Section: Introductionmentioning

confidence: 99%

Carrier grain boundary scattering in thermoelectric materials

Xia

et al. 2022

Energy Environ. Sci.

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“…[12] In contrast, the increased fraction of GBs in Mg 3 Sb 2 and half-Heusler alloys strongly impedes the charge carrier transport, diminishing µ W and eventually even ZT. [13,14] Therefore, it is still elusive which types of GBs can optimize the electron and phonon transport, leading to a simultaneous enhancement in µ W and reduction in κ l .…”

Section: Introductionmentioning

confidence: 99%

Grain Boundary Complexions Enable a Simultaneous Optimization of Electron and Phonon Transport Leading to High‐Performance GeTe Thermoelectric Devices

Zhang

Gan

Wang

et al. 2022

Advanced Energy Materials

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The heat-to-electricity conversion efficiency depends on the dimensionless figure-of-merit of materials, defined as ZT = S 2 σT/κ, where S, σ, and T are the Seebeck coefficient, the electrical conductivity, and the absolute temperature, respectively. The total thermal conductivity (κ) consists of the electronic thermal conductivity (κ e ) and the lattice thermal conductivity (κ l ). The ZT value is directly proportional to several physical para meters summarized in the so-called materials quality factor, B∝µ W /κ l , at a given carrier concentration (n), where the weighted mobility (µ W ) and κ l are determined by the transport properties of electrons and phonons, respectively. [5] Hence, it is desirable to maximize the weighted mobility and minimize the lattice thermal conductivity. Yet, similarities in performance change of thermal and electrical transport for thermoelectrics impede the improvement of B factor for high ZT, which is the key challenge in optimizing TE materials. [6] Sustained efforts have been undertaken to improve the TE properties of materials, such as band convergence, [7] resonant doping, [8] energy filtering, [9] high entropy, [10] and hierarchical microstructure engineering. [11] For polycrystalline bulk samples, the most ubiquitous defects are grain boundaries (GBs).Grain boundaries (GBs) form ubiquitous microstructures in polycrystalline materials which play a significant role in tuning the thermoelectric figure of merit (ZT). However, it is still unknown which types of GB features are beneficial for thermoelectrics due to the challenge of correlating complex GB microstructures with transport properties. Here, it is demonstrated that GB complexions formed by Ga segregation in GeTe-based alloys can optimize electron and phonon transport simultaneously. The Ga-rich complexions increase the power factor by reducing the GB resistivity with slightly improved Seebeck coefficients. Simultaneously, they lower the lattice thermal conductivity by strengthening the phonon scattering. In contrast, Ga 2 Te 3 precipitates at GBs act as barriers to scatter both phonons and electrons and are thus unable to improve ZT. Tailoring GBs combined with the beneficial alloying effects of Sb and Pb enables a peak ZT of ≈2.1 at 773 K and an average ZT of 1.3 within 300-723 K for Ge 0.78 Ga 0.01 Pb 0.1 Sb 0.07 Te. The corresponding thermoelectric device fabricated using 18-pair p-n legs shows a power density of 1.29 W cm −2 at a temperature difference of 476 K. This work indicates that GB complexions can be a facile way to optimize electron and phonon transport, further advancing thermoelectric materials.

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Dopant-segregation to grain boundaries controls electrical conductivity of n-type NbCo(Pt)Sn half-Heusler alloy mediating thermoelectric performance

Cited by 32 publications

References 50 publications

Electronic structure and low-temperature thermoelectric transport of TiCoSb single crystals

Electronic structure and low-temperature thermoelectric transport of TiCoSb single crystals

Carrier grain boundary scattering in thermoelectric materials

Grain Boundary Complexions Enable a Simultaneous Optimization of Electron and Phonon Transport Leading to High‐Performance GeTe Thermoelectric Devices

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