Enhancement of Thermoelectric Performance of Ball‐Milled Bismuth Due to Spark‐Plasma‐Sintering‐Induced Interface Modifications

Puneet, Pooja; Podila, Ramakrishna; Zhu, Song; Skove, M. J.; Tritt, Terry M.; He, Jian; Rao, Apparao M.

doi:10.1002/adma.201204010

Cited by 35 publications

(23 citation statements)

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“…Owing to the grain boundary scattering, the thermal conductivity of nanograined BiSbTe is lower than that of its bulk counterpart. [49][50][51][52] Impurity scattering, l i . Also, the interfacial states formed in the nanograined region can be used to increase the power factor, as proposed by Kirievsky et al 46 An example study of the coated-grain boundary is shown in Fig.…”

Section: Engineering Phonon Thermal Conductivitymentioning

confidence: 99%

Strategies for engineering phonon transport in thermoelectrics

2015

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In this review, we discuss some of the representative strategies of phonon engineering by categorizing them into the methods affecting each component of phonon thermal conductivity, i.e., specific heat, phonon group velocity, and mean free path. In terms of specific heat, a large unit cell is beneficial in that it can minimize the fraction of thermal energy that can be transported since most of the energy is stored in the optical branches. In an artificial structure such as the superlattice, phonon bandgaps can be created through constructive interference by Bragg reflection, which reduces phonon group velocity.We further categorize the mean free path, i.e., scattering processes, into grain boundary scattering, impurity scattering, and phonon-phonon scattering. Rough-surfaced grains, nano-sized grains, and coated grains are discussed for enhancement of the grain boundary scattering. Alloy atoms, vacancies, nanoparticles, and nano-sized holes are treated as impurities, which limit the phonon mean free path. Lone pair electrons and acoustical-to-optical scattering are suggested for manipulating phonon-phonon scattering. We also briefly mention the limitation and temperature range in which the Wiedemann-Franz law is valid in order to achieve a better estimation of electronic thermal conductivity. This paper provides an organized view of phonon engineering so that this concept can be implemented synergistically with power factor enhancement approaches for design of thermoelectric materials. Fig. 1 Strategies of phonon engineering categorized into methods affecting each component of phonon thermal conductivity, i.e., specific heat, phonon group velocity, and scattering processes. Some of the figures are from the literature. 71,80 Fig. 3 Thermal conductivity of the (SrTiO 3 ) m /(CaTiO 3 ) n superlattice versus period thickness. 23 A TEM figure shows the interface quality of the superlattice. Also, a phonon dispersion curve showing phonon bandgaps is presented.

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Section: Engineering Phonon Thermal Conductivitymentioning

confidence: 99%

Strategies for engineering phonon transport in thermoelectrics

2015

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“…The efficiency of a thermoelectric (TE) device is governed by the device material's figure of merit, zT = σS 2 T /κ, where T , σ, S , and κ are the absolute temperature, the electrical conductivity, the Seebeck coefficient, and the total thermal conductivity (including the lattice component κ ph and the charge carrier component κ el ), respectively. Toward higher zT , defect engineering is invoked to (i) improve the power factor PF = σS 2 through tuning band structure, texture, and grain boundary; and (ii) suppress the κ ph through multiscale microstructures . While point defects are of vital importance, it is the synergy among various kinds of defects in defect engineering that underlies the high zT .…”

Section: Introductionmentioning

confidence: 99%

Synergistic Compositional–Mechanical–Thermal Effects Leading to a Record High zT in n‐Type V₂VI₃ Alloys Through Progressive Hot Deformation

Zhang

et al. 2018

Adv Funct Materials

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Here a progressive hot deformation procedure that endows the benchmark n-type V 2 VI 3 thermoelectric materials with short range disorder (multiple defects), long range order (crystallinity), and strong texture (nearly orientation order) is reported. Not only it is rare for these structural features to coexist but also these structural features elicit the synergistic compositionalmechanical-thermal effects, i.e., a profound interplay among the counts, magnitude, and temperature of hot deformation in relation to the as formed point defects, dislocations, textures, strain clusters, and distortions. Using progressively larger die sets and relatively low hot deformation temperature, rich multiscale microstructures concurrently with a high level of texture comparable to that of zone melted ingot are obtained. The strong donor-like effect significantly increases the majority carrier concentration, suppressing the detrimental bipolar effect. In addition, the multiscale microstructures yield an ultralow lattice thermal conductivity ≈0.31 W m −1 K −1 at 405 K. A record zT ≈ 1.3 at 450 K are attained in progressively hot deformed n-type Bi 1.95 Sb 0.05 Te 2.3 Se 0.7 through the synergistic effects. These results not only promise a better pairing between n-type and p-type legs in device fabrication but also bring our understanding of n-type V 2 VI 3 alloys and hot deformation technique to a new level.device material's figure of merit, zT = σS 2 T/κ, where T, σ, S, and κ are the absolute temperature, the electrical conductivity, the Seebeck coefficient, and the total thermal conductivity (including the lattice component κ ph and the charge carrier component κ el ), respectively. Toward higher zT, defect engineering is invoked to (i) improve the power factor PF = σS 2 through tuning band structure, [2,3] texture, [4,5] and grain boundary; [6,7] and (ii) suppress the κ ph through multiscale microstructures. [8,9] While point defects are of vital importance, [10,11] it is the synergy among various kinds of defects in defect engineering that underlies the high zT.The rhombohedral V 2 VI 3 materials are a hotbed of defect engineering, [12] the success of which make them the benchmark TE materials for solid-state cooling [8,13,14] and low/mid temperature waste heat harvesting. [15][16][17][18][19][20][21][22][23][24] In particular, the high performance of n-type V 2 VI 3 alloys is subject to a delicate balance between strong textures and multiscale microstructures, which is a challenge for materials synthesis and processing. Making the task more challenging, the performance-enhancing mechanisms proved effective in p-type V 2 VI 3 alloys turned out to be less so in n-type V 2 VI 3 alloys. Compared to the p-type counterpart, the n-type V 2 VI 3 material tends to be electrically more anisotropic: the electrical conductivity anisotropy of Thermoelectrics

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“…The inherent inter-dependence among α , ρ , and κ poses a major roadblock in realizing TE materials with higher ZT values 2 3 . In this context, tailoring the micro- and nano-structures at multiple length scales using advanced materials preparation methods has to a certain extent been able to decouple the inter-dependence among the TE properties; α , ρ , and κ 4 5 .…”

mentioning

confidence: 99%

Preferential Scattering by Interfacial Charged Defects for Enhanced Thermoelectric Performance in Few-layered n-type Bi2Te3

Puneet

Podila

Karakaya

et al. 2013

Sci Rep

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106

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Over the past two decades several nano-structuring methods have helped improve the figure of merit (ZT) in the state-of-the art bulk thermoelectric materials. While these methods could enhance the thermoelectric performance of p-type Bi2Te3, it was frustrating to researchers that they proved ineffective for n-type Bi2Te3 due to the inevitable deterioration of its thermoelectric properties in the basal plane. Here, we describe a novel chemical-exfoliation spark-plasma-sintering (CE-SPS) nano-structuring process, which transforms the microstructure of n-type Bi2Te3 in an extraordinary manner without compromising its basal plane properties. The CE-SPS processing leads to preferential scattering of electrons at charged grain boundaries, and thereby increases the electrical conductivity despite the presence of numerous grain boundaries, and mitigates the bipolar effect via band occupancy optimization leading to an upshift (by ~ 100 K) and stabilization of the ZT peak over a broad temperature range of ~ 150 K.

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Enhancement of Thermoelectric Performance of Ball‐Milled Bismuth Due to Spark‐Plasma‐Sintering‐Induced Interface Modifications

Cited by 35 publications

References 25 publications

Strategies for engineering phonon transport in thermoelectrics

Strategies for engineering phonon transport in thermoelectrics

Synergistic Compositional–Mechanical–Thermal Effects Leading to a Record High zT in n‐Type V₂VI₃ Alloys Through Progressive Hot Deformation

Preferential Scattering by Interfacial Charged Defects for Enhanced Thermoelectric Performance in Few-layered n-type Bi2Te3

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Enhancement of Thermoelectric Performance of Ball‐Milled Bismuth Due to Spark‐Plasma‐Sintering‐Induced Interface Modifications

Cited by 35 publications

References 25 publications

Strategies for engineering phonon transport in thermoelectrics

Strategies for engineering phonon transport in thermoelectrics

Synergistic Compositional–Mechanical–Thermal Effects Leading to a Record High zT in n‐Type V2VI3 Alloys Through Progressive Hot Deformation

Preferential Scattering by Interfacial Charged Defects for Enhanced Thermoelectric Performance in Few-layered n-type Bi2Te3

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Synergistic Compositional–Mechanical–Thermal Effects Leading to a Record High zT in n‐Type V₂VI₃ Alloys Through Progressive Hot Deformation