Order-disorder transition-induced band nestification in AgBiSe<sub>2</sub>–CuBiSe<sub>2</sub> solid solutions for superior thermoelectric performance

Jang, Hanhwi; Abbey, Stanley; Nam, Woo Hyun; Frimpong, Brakowaa; Nguyen, Chien Viet; Joo, Sung‐Jae; Shin, Ho Sun; Song, Jae Yong; Cho, Eugene N.; Kim, Moo-Hyun; Jung, Yeon Sik

doi:10.1039/d0ta08484k

Cited by 26 publications

(16 citation statements)

References 72 publications

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“…Quite some TE materials undergo phase transition with varying temperature, manipulating crystal lattice symmetry through phase engineering can extend the thermoelectrically favorable phase and suppress the undesired one. [ 6–9 ]…”

Section: Introductionmentioning

confidence: 99%

Medium Entropy‐Enabled High Performance Cubic GeTe Thermoelectrics

Zhi

et al. 2021

Advanced Science

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The configurational entropy is an emerging descriptor in the functional materials genome. In thermoelectric materials, the configurational entropy helps tune the delicate trade‐off between carrier mobility and lattice thermal conductivity, as well as the structural phase transition, if any. Taking GeTe as an example, low‐entropy GeTe generally have high carrier mobility and distinguished zT > 2, but the rhombohedral‐cubic phase transition restricts the applications. In contrast, despite cubic structure and ultralow lattice thermal conductivity, the degraded carrier mobility leads to a low zT in high‐entropy GeTe. Herein, medium‐entropy alloying is implemented to suppress the phase transition and achieve the cubic GeTe with ultralow lattice thermal conductivity yet decent carrier mobility. In addition, co‐alloying of (Mn, Pb, Sb, Cd) facilitates multivalence bands convergence and band flattening, thereby yielding good Seebeck coefficients and compensating for decreased carrier mobility. For the first time, a state‐of‐the‐art zT of 2.1 at 873 K and average zTave of 1.3 between 300 and 873 K are attained in cubic phased Ge0.63Mn0.15Pb0.1Sb0.06Cd0.06Te. Moreover, a record‐high Vickers hardness of 270 is attained. These results not only promote GeTe materials for practical applications, but also present a breakthrough in the burgeoning field of entropy engineering.

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Section: Introductionmentioning

confidence: 99%

Medium Entropy‐Enabled High Performance Cubic GeTe Thermoelectrics

Zhi

et al. 2021

Advanced Science

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“…Typically, introducing point defects, such as substitutional or interstitial atoms, to the matrix is a common method to manipulate the properties of TE materials. [ 14 ] However, this strategy is frequently hindered by intrinsic vacancies, which are often detrimental to the TE properties and are difficult to control. [ 15 ] Few studies have been conducted to improve the TE properties by controlling the vacancy concentration near room temperature.…”

Section: Introductionmentioning

confidence: 99%

“…[ 16 ] However, it is challenging to regulate vacancy formation at high temperatures, as it is thermodynamically stable. [ 14a,17 ] Therefore, a novel design rule is required to suppress the spontaneous formation of vacancies.…”

Section: Introductionmentioning

confidence: 99%

Regulating Te Vacancies through Dopant Balancing via Excess Ag Enables Rebounding Power Factor and High Thermoelectric Performance in p‐Type PbTe

et al. 2021

Self Cite

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Thermoelectric properties are frequently manipulated by introducing point defects into a matrix. However, these properties often change in unfavorable directions owing to the spontaneous formation of vacancies at high temperatures. Although it is crucial to maintain high thermoelectric performance over a broad temperature range, the suppression of vacancies is challenging since their formation is thermodynamically preferred. In this study, using PbTe as a model system, it is demonstrated that a high thermoelectric dimensionless figure of merit, zT ≈ 2.1 at 723 K, can be achieved by suppressing the vacancy formation via dopant balancing. Hole-killer Te vacancies are suppressed by Ag doping because of the increased electron chemical potential. As a result, the re-dissolution of Na 2 Te above 623 K can significantly increase the hole concentration and suppress the drop in the power factor. Furthermore, point defect scattering in material systems significantly reduces lattice thermal conductivity. The synergy between defect and carrier engineering offers a pathway for achieving a high thermoelectric performance by alleviating the power factor drop and can be utilized to enhance thermoelectric properties of thermoelectric materials.

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“…Thermoelectric (TE) materials have the potential to be one of the green solutions towards todays’ global energy crisis [ 1 , 2 ]. Over the years, to make TE devices a commercial success, many efforts have been made first to optimize material parameters like Seebeck coefficient ( S ) and electrical resistivity (ρ) through band engineering approaches, including band distortion [ 3 ], band convergence [ 4 , 5 ], and band nesting [ 6 ], to find a candidate with a large power factor PF as PF enters the TE Figure of merit ZT (= S 2 T/(ρκ) = (PF)T/κ), where к and T are the thermal conductivity and absolute temperature, respectively. Many chalcogenides having transition metal cations with partially filled d orbitals in them exhibit fascinating TE properties.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric materials taking advantage of spin entropy: lessons from chalcogenides and oxides

Hébert

Daou

Maignan

et al. 2021

Science and Technology of Advanced Materials

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The interplay between charges and spins may influence the dynamics of the carriers and determine their thermoelectric properties. In that respect, magneto-thermoelectric power MTEP, i.e. the measurements of the Seebeck coefficient S under the application of an external magnetic field, is a powerful technique to reveal the role of magnetic moments on S . This is illustrated by different transition metal chalcogenides: CuCrTiS 4 and CuMnTiS 4 magnetic thiospinels, which are compared with magnetic oxides, Curie-Weiss (CW) paramagnetic misfit cobaltites, ruthenates, either ferromagnetic perovskite or Pauli paramagnet quadruple perovskites, and CuGa 1- x Mn x Te 2 chalcopyrite telluride and Bi 1.99 Cr 0.01 Te 3 in which diluted magnetism is induced by 3%-Mn and 1%-Cr substitution, respectively. In the case of a ferromagnet (below T C ) and CW paramagnetic materials, the increase of magnetization at low T when a magnetic field is applied is accompanied by a decrease of the entropy of the carriers and hence decreases. This is consistent with the lack of MTEP in the Pauli paramagnetic quadruple perovskites. Also, no significant MTEP is observed in CuGa 1- x Mn x Te 2 and Bi 1.99 Cr 0.01 Te 3 , for which Kondo-type interaction between magnetic moments and carriers prevails. In contrast, spin glass CuCrTiS 4 exhibits negative MTEP like in ferromagnetic ruthenates and paramagnetic misfit cobaltites. This investigation of some chalcogenides and oxides provides key ingredients to select magnetic materials for which S benefits from spin entropy.

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Order-disorder transition-induced band nestification in AgBiSe₂–CuBiSe₂ solid solutions for superior thermoelectric performance

Abstract: The AgBiSe2–CuBiSe2 system shows band nestification at high temperatures, resulting in heavy DOS effective mass while preserving electron mobility.

Cited by 26 publications

References 72 publications

Medium Entropy‐Enabled High Performance Cubic GeTe Thermoelectrics

Medium Entropy‐Enabled High Performance Cubic GeTe Thermoelectrics

Regulating Te Vacancies through Dopant Balancing via Excess Ag Enables Rebounding Power Factor and High Thermoelectric Performance in p‐Type PbTe

Thermoelectric materials taking advantage of spin entropy: lessons from chalcogenides and oxides

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Order-disorder transition-induced band nestification in AgBiSe2–CuBiSe2 solid solutions for superior thermoelectric performance

Abstract: The AgBiSe2–CuBiSe2 system shows band nestification at high temperatures, resulting in heavy DOS effective mass while preserving electron mobility.

Cited by 26 publications

References 72 publications

Medium Entropy‐Enabled High Performance Cubic GeTe Thermoelectrics

Medium Entropy‐Enabled High Performance Cubic GeTe Thermoelectrics

Regulating Te Vacancies through Dopant Balancing via Excess Ag Enables Rebounding Power Factor and High Thermoelectric Performance in p‐Type PbTe

Thermoelectric materials taking advantage of spin entropy: lessons from chalcogenides and oxides

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Order-disorder transition-induced band nestification in AgBiSe₂–CuBiSe₂ solid solutions for superior thermoelectric performance