Nanobulk Thermoelectric Materials Fabricated from Chemically Synthesized Cu3Zn1–xAlxSnS5–y Nanocrystals

Dwivedi, Pratibha; Miyata, Masanobu; Higashimine, Koichi; Takahashi, Mari; Ohta, Mitsuo; Kubota, Korefumi; Takida, Hiroshi; Akatsuka, Toshitaka; Maenosono, Shinya

doi:10.1021/acsomega.9b01944

Cited by 10 publications

(19 citation statements)

References 30 publications

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“…[21][22][23] These defect-mediated topological transport channels can easily be envisioned to create a percolating 3D network within a bulk material given favorable number and conditions of geometrical arrangement. Based on these considerations, we here present the well-known approach of nanograined bulk material, [24][25][26] but utilized it for 3D TI transport, conceptually sketched in Figure 1. Such nanograined bulk materials contain a high number of thermodynamically-stable interfaces and grain boundaries introducing considerable barriers toward charge carrier transport.…”

Section: Introductionmentioning

confidence: 99%

Interface‐Dominated Topological Transport in Nanograined Bulk Bi₂Te₃

Izadi

Han

Salloum

et al. 2021

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3D TIs feature a bulk band gap of a conventional semiconductor and topological surface states on all crystal facets. [3] Electrons on these topological surface states are robust with respect to localization. [4] Even with strong disorder on the atomic scale, these electrons do not backscatter between states of opposite momentum and opposite spin. [5] This confers the high mobility of the electrons occupying these surface states. Such electrons also penetrate energetic barriers caused by materials imperfections and atomic steps at the surfaces. [4] These unique electronic properties propel visions of potential applications in quantum computing and spintronics. [6] Tetradymite-type bismuth telluride, Bi 2 Te 3 , is a famous representative of 3D TIs. However, its defect chemistry is rather complex. For instance, slight changes in the material stoichiometry defined by anti-site defects [7] and disorders [8] determine the dominant carrier transport mechanism. The n-type semiconducting behavior can be attributed to naturally occurring Te-vacancies that donate two electrons each. Additionally, anti-site defects of Te-atoms on Bi-lattice sites lead to intrinsic n-type doping of these materials. [9] According to a density functional theory 3D topological insulators (TI) host surface carriers with extremely high mobility. However, their transport properties are typically dominated by bulk carriers that outnumber the surface carriers by orders of magnitude. A strategy is herein presented to overcome the problem of bulk carrier domination by using 3D TI nanoparticles, which are compacted by hot pressing to macroscopic nanograined bulk samples. Bi 2 Te 3 nanoparticles well known for their excellent thermoelectric and 3D TI properties serve as the model system.As key enabler for this approach, a specific synthesis is applied that creates nanoparticles with a low level of impurities and surface contamination. The compacted nanograined bulk contains a high number of interfaces and grain boundaries. Here it is shown that these samples exhibit metallic-like electrical transport properties and a distinct weak antilocalization. A downward trend in the electrical resistivity at temperatures below 5 K is attributed to an increase in the coherence length by applying the Hikami-Larkin-Nagaoka model. THz time-domain spectroscopy reveals a dominance of the surface transport at low frequencies with a mobility of above 10 3 cm 2 V −1 s −1 even at room temperature. These findings clearly demonstrate that nanograined bulk Bi 2 Te 3 features surface carrier properties that are of importance for technical applications.

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Section: Introductionmentioning

confidence: 99%

Interface‐Dominated Topological Transport in Nanograined Bulk Bi₂Te₃

Izadi

Han

Salloum

et al. 2021

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“…However, explorations of TE materials have been concentrated on ZB derivatives, [ 21–25 ] with WZ ones receiving scant attention. [ 36,37 ]…”

Section: Introductionmentioning

confidence: 99%

Enargite Cu₃PS₄: A Cu–S‐Based Thermoelectric Material with a Wurtzite‐Derivative Structure

Tanimoto

Suekuni

Tanishita

et al. 2020

Adv Funct Materials

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(1 of 8)Compound semiconductors derived from ZnS (zincblende and wurtzite) with tetrahedral framework structures have functions for various applications. Examples of such materials include Cu-S-based materials with zincblendederivative structures, which have attracted attention as thermoelectric (TE) materials over the past decade. This study illuminates superior TE performance in polycrystalline samples of enargite Cu 3 P 1−x Ge x S 4 with a wurtzite-derivative structure. The substitution of Ge for P dopes holes into the top of the valence band composed of Cu-3d and S-3p, whereby its multiband characteristic leads to a high TE power factor. Furthermore, a reduction in the grain size to 50-300 nm can effectively decrease phonon mean free paths, leading to low thermal conductivity. These features result in a dimensionless TE figure of merit ZT of 0.5 at 673 K for the x = 0.2 sample. Environmentally benign and low-cost characteristics of the constituent elements of Cu 3 PS 4 , as well as its high-performance thermoelectricity, make it a promising candidate for large-scale TE applications. Furthermore, this finding extends the development field of Cu-S-based TE materials to those with wurtzite-derivative structures.

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“…11 The presence of Sn 4+ was confirmed by the peaks at 486.4 eV (3d 5/2 ) and 494.8 eV (3d 3/2 ). 11 Furthermore, the presence of S 2− was confirmed by the peaks at 161.5 eV (2p 3/2 ) and 162.6 eV (2p 1/2 ). 11 shows the Cu 2p, Ga 2p, Sn 3d, and S 2p spectra for Powder_1.…”

Section: ■ Experimental Sectionmentioning

confidence: 92%

“…The Cu 2p 3/2 and Cu 2p 1/2 binding energies were located at 932.2 and 952.1 eV, respectively, indicating the presence of Cu + . 11 The Al 2p 3/2 peak appeared at a binding energy of 74.6 eV and can be assigned to Al 3+ . 11 The presence of Sn 4+ was confirmed by the peaks at 486.4 eV (3d 5/2 ) and 494.8 eV (3d 3/2 ).…”

Section: ■ Experimental Sectionmentioning

confidence: 98%

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Effect of Gallium Substitution in Cu₃Al_1–xGa_xSnS₅ Nanobulk Materials on Thermoelectric Properties

Dwivedi

Miyata

Higashimine

et al. 2020

ACS Appl. Energy Mater.

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Thermoelectric (TE) materials have consistently gained momentum for use in waste heat utilization technology. Recently, we fabricated a Cu3AlSnS5 (CATS) nanobulk by pelletizing chemically synthesized CATS nanocrystals using a pulsed electric current sintering technique and found that it possesses exceptionally low lattice thermal conductivity (κlat). However, the total thermal conductivity of the CATS nanobulk was relatively high because of the high carrier thermal conductivity (κcar) owing to its considerably high electrical conductivity. In this study, the effect of Ga substitution in Cu3Al1–x Ga x SnS5 nanobulk materials on the carrier transport properties of the materials is systematically investigated. The value of the dimensionless figure of merit ZT of the Cu3Al1–x Ga x SnS5 nanobulk at x = 0.5 (ZT = 0.26 at 665 K) was found to be more than twice that of the pristine CATS nanobulk at 665 K, primarily because of the significant reduction in κcar. A detailed analysis of the correlation among transport parameters, crystal structure, and thermoelectric performance of the Cu3Al1–x Ga x SnS5 nanobulks (0.25 ≤ x ≤ 1) revealed that a larger fraction of the zinc blende (ZB) phase leads to a higher power factor. In summary, the Cu3Al0.5Ga0.5SnS5 nanobulk exhibited the highest ZT value in the range of 0 ≤ x ≤ 1 because of its significantly reduced κcar value as compared with the CATS nanobulk. This reduced κcar value is owing to the Ga substitution and the highest ZB phase fraction, resulting in the highest power factor among the Cu3Al1–x Ga x SnS5 nanobulks (0.25 ≤ x ≤ 1).

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Nanobulk Thermoelectric Materials Fabricated from Chemically Synthesized Cu₃Zn_1–xAl_xSnS_5–y Nanocrystals

Cited by 10 publications

References 30 publications

Interface‐Dominated Topological Transport in Nanograined Bulk Bi₂Te₃

Interface‐Dominated Topological Transport in Nanograined Bulk Bi₂Te₃

Enargite Cu₃PS₄: A Cu–S‐Based Thermoelectric Material with a Wurtzite‐Derivative Structure

Effect of Gallium Substitution in Cu₃Al_1–xGa_xSnS₅ Nanobulk Materials on Thermoelectric Properties

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Nanobulk Thermoelectric Materials Fabricated from Chemically Synthesized Cu3Zn1–xAlxSnS5–y Nanocrystals

Cited by 10 publications

References 30 publications

Interface‐Dominated Topological Transport in Nanograined Bulk Bi2Te3

Interface‐Dominated Topological Transport in Nanograined Bulk Bi2Te3

Enargite Cu3PS4: A Cu–S‐Based Thermoelectric Material with a Wurtzite‐Derivative Structure

Effect of Gallium Substitution in Cu3Al1–xGaxSnS5 Nanobulk Materials on Thermoelectric Properties

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Nanobulk Thermoelectric Materials Fabricated from Chemically Synthesized Cu₃Zn_1–xAl_xSnS_5–y Nanocrystals

Interface‐Dominated Topological Transport in Nanograined Bulk Bi₂Te₃

Interface‐Dominated Topological Transport in Nanograined Bulk Bi₂Te₃

Enargite Cu₃PS₄: A Cu–S‐Based Thermoelectric Material with a Wurtzite‐Derivative Structure

Effect of Gallium Substitution in Cu₃Al_1–xGa_xSnS₅ Nanobulk Materials on Thermoelectric Properties