Enhancement of thermoelectric properties in CuI-doped Bi2Te2.7Se0.3 by hot-deformation

Hyunyong, Cho; Kim, Jin Hee; Back, Song Yi; Ahn, Kyunghan; Rhyee, Jong‐Soo; Park, Su-Dong

doi:10.1016/j.jallcom.2017.10.016

Cited by 32 publications

(37 citation statements)

References 20 publications

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“…It is known that the grains easily slip and rotate along the basal planes under pressure and the c ‐axis tends to be aligned parallel to the pressing direction during the plastic deformation process, thereby leading to a substantially enhanced (00 l ) textures. Though such phenomena were observed in early works of Bi 2 Te 3– x Se x alloys, the degree of texture obtained therein is generally weaker than that is derived in this work. The cause of this discrepancy allows us to have a deeper understanding of the HD process and also the n‐type V 2 VI 3 alloys.…”

Section: Resultscontrasting

confidence: 76%

“…The HD count, degree and temperature are three pivotal parameters to obtain strong (00 l ) texture. Table 1 summarizes the major HD parameters and the derived F values in the present and some prior works . There are some interesting findings.…”

Section: Resultsmentioning

confidence: 52%

“…a) Schematic diagram of the variation of intrinsic point defects for Bi 2– x Sb x Te 2.3 Se 0.7 materials. Room‐temperature carrier concentration of b) n‐type Bi 2– x Sb x Te 2.3 Se 0.7 polycrystalline alloys as a function of Sb content, and c) n‐type Bi 1.95 Sb 0.05 Te 2.3 Se 0.7 polycrystalline alloys as a function of HD count . d) zT values at 450 K as a function of carrier concentration in n‐type V 2 VI 3 system in this and prior work …”

Section: Resultsmentioning

confidence: 71%

“…A low HD temperature (e.g., 603 K in ref. ) failed to reach a uniform plastic deformation and a high degree of texture. On the other hand, a high HD temperature (e.g., 823 K in refs.…”

Section: Resultsmentioning

confidence: 98%

“… XRD patterns for b) Bi 2– x Sb x Te 2.3 Se 0.7 ( x = 0–0.25) samples with HD count = 1, and c) Bi 1.95 Sb 0.05 Te 2.3 Se 0.7 samples with different HD count. d) F values and f) carrier mobility as a function of HD count. e) F values in this work in comparison with those of other n‐type V 2 VI 3 alloys …”

Section: Resultsmentioning

confidence: 99%

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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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Section: Resultscontrasting

confidence: 76%

Section: Resultsmentioning

confidence: 52%

Section: Resultsmentioning

confidence: 71%

“…A low HD temperature (e.g., 603 K in ref. ) failed to reach a uniform plastic deformation and a high degree of texture. On the other hand, a high HD temperature (e.g., 823 K in refs.…”

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

See 3 more Smart Citations

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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Liquid‐Phase Hot Deformation to Enhance Thermoelectric Performance of n‐type Bismuth‐Telluride‐Based Solid Solutions

Zhang

et al. 2019

Advanced Science

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Bismuth‐telluride‐based solid solutions are the best commercial thermoelectric materials near room temperature. For their n‐type polycrystalline compounds, the maximum figures of merit (zTs) are often less than 1.0 due to the degraded carrier mobility resulting from the loss of texture. Herein, a liquid‐phase hot deformation procedure, during which the Bi2(Te,Se)3 ingots are directly hot deformed with the extrusion of liquid eutectic phase, is performed to enhance the thermoelectric performance of n‐type Bi2(Te,Se)3 alloys. The deformation‐induced dynamic recrystallization is remarkably suppressed due to the reduction of nucleation sites and the release of deformation stress by liquid phase, contributing to a weakened carrier scattering and enhanced carrier mobility. The liquid eutectic phase also facilitates the rotation of grains and enhanced (000l) texture, further improving carrier mobility. In addition, the dense dislocations and lattice distortion introduced into the matrix reduce the lattice thermal conductivity. As a result, a high zT value of 1.1 at 400 K is obtained, about 75% increment over the normal one‐step hot deformed alloys. This work not only demonstrates a simple and efficient technique for achieving superior n‐type Bi2Te3‐based materials, but also elucidates the important role of liquid eutectic phase in hot deformation.

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Modulation Doping Enables Ultrahigh Power Factor and Thermoelectric ZT in n‐Type Bi₂Te_2.7Se_0.3

Chen

Wang

et al. 2022

Advanced Science

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Bismuth telluride‐based thermoelectric (TE) materials are historically recognized as the best p‐type (ZT = 1.8) TE materials at room temperature. However, the poor performance of n‐type (ZT≈1.0) counterparts seriously reduces the efficiency of the device. Such performance imbalance severely impedes its TE applications either in electrical generation or refrigeration. Here, a strategy to boost n‐type Bi2Te2.7Se0.3 crystals up to ZT = 1.42 near room temperature by a two‐stage process is reported, that is, step 1: stabilizing Seebeck coefficient by CuI doping; step 2: boosting power factor (PF) by synergistically optimizing phonon and carrier transport via thermal‐driven Cu intercalation in the van der Waals (vdW) gaps. Theoretical ab initio calculations disclose that these intercalated Cu atoms act as modulation doping and contribute conduction electrons of wavefunction spatially separated from the Cu atoms themselves, which simultaneously lead to large carrier concentration and high mobility. As a result, an ultra‐high PF ≈63.5 µW cm−1 K−2 at 300 K and a highest average ZT = 1.36 at 300–450 K are realized, which outperform all n‐type bismuth telluride materials ever reported. The work offers a new approach to improving n‐type layered TE materials.

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Enhancement of thermoelectric properties in CuI-doped Bi2Te2.7Se0.3 by hot-deformation

Cited by 32 publications

References 20 publications

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

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

Liquid‐Phase Hot Deformation to Enhance Thermoelectric Performance of n‐type Bismuth‐Telluride‐Based Solid Solutions

Modulation Doping Enables Ultrahigh Power Factor and Thermoelectric ZT in n‐Type Bi₂Te_2.7Se_0.3

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Enhancement of thermoelectric properties in CuI-doped Bi2Te2.7Se0.3 by hot-deformation

Cited by 32 publications

References 20 publications

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

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

Liquid‐Phase Hot Deformation to Enhance Thermoelectric Performance of n‐type Bismuth‐Telluride‐Based Solid Solutions

Modulation Doping Enables Ultrahigh Power Factor and Thermoelectric ZT in n‐Type Bi2Te2.7Se0.3

Contact Info

Product

Resources

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

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

Modulation Doping Enables Ultrahigh Power Factor and Thermoelectric ZT in n‐Type Bi₂Te_2.7Se_0.3