Remarkable anisotropy in rhombohedral Ge2Sb2Te5 compound: a promising thermoelectric material with multiple conduction bands and acoustic-optical branches coupling

Miao, Jiale; Wang, Pengfei; Zhou, Peng; Huang, Saifang; Qian, Dongjie; Yuan, Yanyan; Lan, Rui

doi:10.1016/j.jallcom.2021.163471

Cited by 8 publications

(2 citation statements)

References 45 publications

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“…In addition, the layered nature of Ge 2 Sb 2 Te 5 is a beneficial feature for TE performance as it allows for decreasing lattice thermal conductivity. Very recently, Miao et al [ 9 ] investigated Ge 2 Sb 2 Te 5 using density functional theory approaches and found that, under certain conditions of temperature and carrier doping level, the figure of merit can reach 1.5. In their work, the ZT values were predicted by combining theoretical and experimental data.…”

Section: Introductionmentioning

confidence: 99%

Electronic and Transport Properties of Strained and Unstrained Ge2Sb2Te5: A DFT Investigation

Tian

Boulet

et al. 2023

Materials

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In recent years, layered chalcogenides have attracted interest for their appealing thermoelectric properties. We investigated the Ge2Sb2Te5 compound in two different stacking sequences, named stacking 1 (S1) and stacking 2 (S2), wherein the Ge and Sb atomic positions can be interchanged in the structure. The compound unit cell, comprising nine atoms, is made of two layers separated by a gap. We show, using the quantum theory of atoms in molecules, that the bonding across the layers has characteristics of transit region bonding, though with a close resemblance to closed-shell bonding. Both S1 and S2 are shown to bear a similar small gap. The full determination of their thermoelectric properties, including the Seebeck coefficient, electrical conductivity and electronic and lattice thermal conductivities, was carried out by solving the Boltzmann transport equation. We show that stacking 1 exhibits a larger Seebeck coefficient and smaller electrical conductivity than stacking 2, which is related to their small electronic gap difference, and that S1 is more suitable for thermoelectric application than S2. Moreover, under certain conditions of temperature and doping level, it could be possible to use S1-Ge2Sb2Te5 as both a p and n leg in a thermoelectric converter. Under biaxial, tensile and compressive strains, we observe that the thermoelectric properties are improved for both S1 and S2. Furthermore, the increase in the power factor of S1 in the cross-plane direction, namely perpendicular to the gap between the layers, shows that strains can counteract the electronic transport hindrance due to the gap.

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Section: Introductionmentioning

confidence: 99%

Electronic and Transport Properties of Strained and Unstrained Ge2Sb2Te5: A DFT Investigation

Tian

Boulet

et al. 2023

Materials

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“…Thermoelectric materials (TE) have recently garnered significant attention due to their potential applications in green energy production [1, 2]. However, the low thermoelectric conversion efficiency of current materials hampers their large‐scale application and promotion [3]. The efficiency of TE materials is quantified by the dimensionless quality factor, thermoelectric figure of merit (ZT), which is given by the equation ZT = S 2 σT / κ [4], where S , σ , T and κ represent the Seebeck coefficient, electrical conductivity, temperature and thermal conductivity, respectively.…”

Section: Introductionmentioning

confidence: 99%

Modulating the thermoelectric transport properties of the novel material Er₂Te₃ via strain

Xia,

Yang,

Zhou

et al. 2023

Int J of Quantum Chemistry

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The rare‐earth chalcogenide Er2Te3, characterized by its low lattice thermal conductivity, represents a highly promising and innovative thermoelectric material. However, there have been limited studies exploring its thermoelectric properties in depth. Additionally, it has been discovered that strain engineering is an effective method for enhancing thermoelectric properties, a technique successfully applied to relevant materials. In this study, we employed a first‐principles approach in conjunction with the semi‐classical Boltzmann transport theory to investigate the thermoelectric properties of Er2Te3 materials under −4% to 4% strain. The results indicate that applying compressive strain modulates thermoelectric properties more effectively than tensile strain for Er2Te3. Under strain modulation, the maximum power factor for both p‐type and n‐type Er2Te3 increases significantly, from 0.9 to 2.5 mW m−1 K−2 and from 14 to 18 mW m−1 K−2 at 300 K, respectively. Moreover, the figure of merit (ZT) for p‐type and n‐type Er2Te3 improves notably, from 0.15 to 0.25 and from 1.15 to 1.35, respectively, under −4% strain. Consequently, the thermoelectric properties of Er2Te3 materials can be significantly enhanced through strain application, with n‐type Er2Te3 demonstrating substantial potential as a thermoelectric material.

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A Self‐Independent Binary‐Sublattice Construction in Cu₂Se Thermoelectric Materials

Zhao

et al. 2023

Adv Funct Materials

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The atomic‐scale structure of cuprous selenide room temperature phase (α‐Cu2Se), which plays an important role in understanding the mechanism of its high thermoelectric performance, is still not fully determined. Here, direct observation with atomic‐scale resolution is realized to reveal the fine structure of α‐Cu2Se via spherical‐aberration‐corrected scanning transmission electron microscopy. It is observed to be an interesting self‐independent binary‐sublattice construction for Cu and Se in α‐Cu2Se, respectively, which shows a variety of ordered copper fluctuation structures are embedded in a rigid pseudo‐cubic Se sublattice. Ordering of Cu uses a variety of configurations with little energy difference, forming considerable amounts of “boundaries,” which may lead to ultrastrong phonon scattering. Furthermore, density functional theory calculations indicate that the electronic structures are mainly determined by the rigid Se face‐centered cubic sublattice and not sensitive to the various copper fluctuations, which may guarantee the electron transfers with large carrier mobility. The self‐independent binary‐sublattice construction is speculated to enhance phonon scattering while still maintaining good electrical transport property. This study provides new critical information for further understanding the possible correlation between the specific structure and thermoelectric performance of α‐Cu2Se, as well as designing new thermoelectric materials.

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Remarkable anisotropy in rhombohedral Ge2Sb2Te5 compound: a promising thermoelectric material with multiple conduction bands and acoustic-optical branches coupling

Cited by 8 publications

References 45 publications

Electronic and Transport Properties of Strained and Unstrained Ge2Sb2Te5: A DFT Investigation

Electronic and Transport Properties of Strained and Unstrained Ge2Sb2Te5: A DFT Investigation

Modulating the thermoelectric transport properties of the novel material Er₂Te₃ via strain

A Self‐Independent Binary‐Sublattice Construction in Cu₂Se Thermoelectric Materials

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Remarkable anisotropy in rhombohedral Ge2Sb2Te5 compound: a promising thermoelectric material with multiple conduction bands and acoustic-optical branches coupling

Cited by 8 publications

References 45 publications

Electronic and Transport Properties of Strained and Unstrained Ge2Sb2Te5: A DFT Investigation

Electronic and Transport Properties of Strained and Unstrained Ge2Sb2Te5: A DFT Investigation

Modulating the thermoelectric transport properties of the novel material Er2Te3 via strain

A Self‐Independent Binary‐Sublattice Construction in Cu2Se Thermoelectric Materials

Contact Info

Product

Resources

About

Modulating the thermoelectric transport properties of the novel material Er₂Te₃ via strain

A Self‐Independent Binary‐Sublattice Construction in Cu₂Se Thermoelectric Materials