Lattice distortion and anisotropic thermoelectric properties in hot-deformed CuI-doped Bi2Te2·7Se0.3

Kim, Jin Hee; Hyunyong, Cho; Back, Song Yi; Yun, Jung‐Ho; Lee, Ho Seong; Rhyee, Jong‐Soo

doi:10.1016/j.jallcom.2019.152649

Cited by 26 publications

(20 citation statements)

References 34 publications

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“…The modulation vectors increased with increasing iodine doping concentration, as shown in Figure 5 b–d, indicating the shorter range lattice distortion in real space for the higher I-doping concentration. The periodic lattice modulation was also found in the CuI-doped Bi 2 Te 2.7 Se 0.3 [ 20 ] and the CuI-doped Bi 2 Te 2.1 Se 0.9 [ 27 ]. The lattice distortion by the iodine doping significantly decreased the lattice thermal conductivity.…”

Section: Resultsmentioning

confidence: 91%

“…The κ total (T) of the I-doped samples (x = 0.1, 0.3, and 0.5 mol.%) decreased with increasing temperature up to the 420 K and then increased again at high temperatures, implying the suppression of the bipolar diffusion effect by iodine doping. The total thermal conductivities of the Pe-direction were higher than those of the Pa-direction by the layer structure of the bismuth telluride [ 20 , 23 ].…”

Section: Resultsmentioning

confidence: 99%

“…The decreased lattice and bipolar thermal conductivity and the unusual anisotropic lattice thermal conductivity can be explained by the lattice distortion (or CDW). Previously, we found the lattice distortion in the hot-deformed CuI-doped Bi 2 Te 2.7 Se 0.3 [ 20 ] and CDW-like behavior in the CuI-doped Bi 2 Te 2.1 Se 0.9 [ 27 ]. The lattice distortion is effective to decrease lattice thermal conductivity because the lattice thermal conductivity of the in-plane direction (strong covalent bonding layer) can be smaller than the out-of-plane direction lattice thermal conductivity (weak van der Waals bonding) like a charge density wave (CDW) effect [ 28 , 52 , 53 ].…”

Section: Resultsmentioning

confidence: 99%

“…Even though the thermoelectric performance of n-type bismuth tellurides has been progressing significantly, the zT values of the n-type materials are not compatible with those of the p-type properties because the thermoelectric device’s performance is mainly determined by the average zT values of p-and n-type materials. [ 14 ] To reach high thermoelectric performance in n-type bismuth tellurides, there have been many studies such as the control of Se concentration Bi 2 Te 3−x Se x [ 4 , 11 , 15 , 16 ], Cu-doping [ 8 , 17 ], I-doping [ 9 , 17 ] Ga-doping [ 18 ], CuI-doping [ 10 , 19 , 20 ], hot-press and hot-deformation processes [ 8 , 13 , 21 , 22 , 23 , 24 ], etc.…”

Section: Introductionmentioning

confidence: 99%

“…It is also known that iodine doping reduces lattice thermal conductivity but the origin is not fully understood yet [ 9 , 17 , 25 , 26 ]. Recently, we found that the lattice distortion (or charge density wave formation) by the CuI-doping can decrease the lattice thermal conductivity with the enhancement of Hall carrier mobility [ 20 , 27 ]. From the electron diffraction experiment, the iodine doping in Bi 2 Te 2.85 Se 0.15 enhances lattice distortion by the formation of the charge density wave.…”

Section: Introductionmentioning

confidence: 99%

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Scattering Mechanisms and Suppression of Bipolar Diffusion Effect in Bi2Te2.85Se0.15Ix Compounds

et al. 2021

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We investigated the anisotropic thermoelectric properties of the Bi2Te2.85Se0.15Ix (x = 0.0, 0.1, 0.3, 0.5 mol.%) compounds, synthesized by ball-milling and hot-press sintering. The electrical conductivities of the Bi2Te2.85Se0.15Ix were significantly improved by the increase of carrier concentration. The dominant electronic scattering mechanism was changed from the mixed (T ≤ 400 K) and ionization scattering (T ≥ 420 K) for pristine compound (x = 0.0) to the acoustic phonon scattering by the iodine doping. The Hall mobility was also enhanced with the increasing carrier concentration. The enhancement of Hall mobility was caused by the increase of the mean free path of the carrier from 10.8 to 17.7 nm by iodine doping, which was attributed to the reduction of point defects without the meaningful change of bandgap energy. From the electron diffraction patterns, a lattice distortion was observed in the iodine doped compounds. The modulation vector due to lattice distortion increased with increasing iodine concentration, indicating the shorter range lattice distortion in real space for the higher iodine concentration. The bipolar thermal conductivity was suppressed, and the effective masses were increased by iodine doping. It suggests that the iodine doping minimizes the ionization scattering giving rise to the suppression of the bipolar diffusion effect, due to the prohibition of the BiTe1 antisite defect, and induces the lattice distortion which decreases lattice thermal conductivity, resulting in the enhancement of thermoelectric performance.

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Section: Resultsmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Scattering Mechanisms and Suppression of Bipolar Diffusion Effect in Bi2Te2.85Se0.15Ix Compounds

et al. 2021

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Enhancement of Phase Stability and Thermoelectric Performance of Meta‐Stable AgSbTe₂ by Thermal Cycling Process

Kim,

Yun,

Cha

et al. 2024

Adv Funct Materials

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Thermoelectric materials are crucial components in thermoelectric devices employed for environmentally friendly solid‐state cooling and waste heat recovery, demanding not only high performance but also superior thermal or phase stability. The high‐performance thermoelectric material AgSbTe2 encounters challenges when utilized in thermoelectric modules due to the precipitation of Ag2Te, resulting in both thermally unstable characteristics and diminished performance. In this study, a thermal cycling process is employed to enhance the thermal stability and thermoelectric performance of AgSbTe2. Through thermal cycling, secondary phases of AgSbTe2 are made uniform, and the undesired Ag2Te is substituted with Sb2Te3 using an optimized thermal cycling process. As a result, the thermal stability of AgSbTe2 is enhanced due to its meta‐stable state, with <5% variance in thermoelectric figure of merit (ZT) measurements, and the ZT value is raised from 0.8 to 1.7 at 643 K through the optimized thermal cycling. The findings indicate that thermal cycling is an effective strategy for enhancing the thermal stability and thermoelectric performance of AgSbTe2, presenting a novel approach for achieving uniform secondary phases in materials with phase separation or phase change characteristics.

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Eliciting High‐Performance Thermoelectric Materials via Phase Diagram Engineering: A Review

Deng

Yen

Tsai

et al. 2021

Adv Energy and Sustain Res

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Alongside the evolution of technology timeline, environmental protection and energy sustainability significantly guide the research feast toward the high-performance green energy resources and technologies. [1,2] Alternatives to the fossil fuels that emit harmful greenhouse gases become desired, in which the thermoelectric (TE) materials have played an inevitable role since the 1960s. [3] One of TE technology features is the waste heat recovery via the Seebeck effect, [4] which allows the conversion between thermal energy and electricity. Such a TE generator produces precious electrical energy from any arbitrary interfaces where a temperature gradient exists, simultaneously boosting energy usage efficiency while eases global warming.Many TE materials are being explored for power generation applications, such as GeTe, [5] PbTe, [6,7] Bi 2 Te 3 , [8] and silicides. [9] Moreover, the TE cooler, which utilizes the Peltier effect, [4] emerges as a vital spot-cooling device assembled by all-solid-state materials. With the advantages of refrigerant-free and size-minimization, the TE cooler exhibits the advantages of refrigerant-free and size-minimization, which can be used as the next-generation cooling technology. [10] After more than 60 years of development, the practical application and potential coverage of TE technology are comprehensive. Nevertheless, a TE material's thermal-to-electric efficiency is still required to be boosted. In general, the TE figure-of-merit zT ¼ ðS 2 σÞT=κ positively relates to the performance of TE materials, in which the S is the Seebeck coefficient, σ ¼ ρ À1 refers to the electrical conductivity, and κ ¼ κ e þ κ L þ κ b comprises the total thermal conductivity κ, lattice thermal conductivity κ, and bipolar thermal conductivity κ b , respectively. Most importantly, the S, σ, and κ e have the carrier concentration n H as a common factor, which correlates and depends on each other. Therefore, the counterbalance between the thermal and electrical transport properties is essential to attain high zT values, which could be fulfilled by band structure engineering, [11] carrier optimization, [12,13] filtering effect, [14] , and so on. In parallel, the reduction in κ L also paves the way toward highperformance TE materials, mainly accomplished by all-scale defect engineering [15] and alloying effect. [16] Those imperfections introduce multiscale roadblocks, such as the interstitial/ antisite defect, dislocations, nanoprecipitates, and grain boundaries, aiming to impede the phonons with different wavelengths.Countless efforts bring the breakthroughs of zT value in succession. The peak zT grows less than unity in the 1960s to greater than 2.5 after 2015, [17] whose progress is slow yet steadily. Complex TE materials with various dopants are the primary targets, while different approaches can be adopted. [18,19] The

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Lattice distortion and anisotropic thermoelectric properties in hot-deformed CuI-doped Bi2Te2·7Se0.3

Cited by 26 publications

References 34 publications

Scattering Mechanisms and Suppression of Bipolar Diffusion Effect in Bi2Te2.85Se0.15Ix Compounds

Scattering Mechanisms and Suppression of Bipolar Diffusion Effect in Bi2Te2.85Se0.15Ix Compounds

Enhancement of Phase Stability and Thermoelectric Performance of Meta‐Stable AgSbTe₂ by Thermal Cycling Process

Eliciting High‐Performance Thermoelectric Materials via Phase Diagram Engineering: A Review

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Lattice distortion and anisotropic thermoelectric properties in hot-deformed CuI-doped Bi2Te2·7Se0.3

Cited by 26 publications

References 34 publications

Scattering Mechanisms and Suppression of Bipolar Diffusion Effect in Bi2Te2.85Se0.15Ix Compounds

Scattering Mechanisms and Suppression of Bipolar Diffusion Effect in Bi2Te2.85Se0.15Ix Compounds

Enhancement of Phase Stability and Thermoelectric Performance of Meta‐Stable AgSbTe2 by Thermal Cycling Process

Eliciting High‐Performance Thermoelectric Materials via Phase Diagram Engineering: A Review

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Enhancement of Phase Stability and Thermoelectric Performance of Meta‐Stable AgSbTe₂ by Thermal Cycling Process