Symmetry breaking in Ge1−xMnxTe and the impact on thermoelectric transport

Adamczyk, Jesse M.; Bipasha, Ferdaushi Alam; Rome, Grace A.; Ciesielski, Kamil; Ertekin, Elif; Toberer, Eric S.

doi:10.1039/d2ta02347d

Cited by 13 publications

(6 citation statements)

References 53 publications

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“…At 300 K, the Lorenz numbers of β-PdS 2 , β-PdSe 2 , and β-PdTe 2 monolayers are 1.4–2.2, 1.4–2.5, and 1.5–2.3 × 10 –8 WΩ K –2 for n-type β-PdX 2 and 1.0–1.5, 1.6–2.2, and 1.3–2.6 × 10 –8 WΩ K –2 for p-type β-PdX 2 , respectively. In addition, L can be also estimated by the corresponding S values, − which is expressed by L = 1.5 + exp [ − | S | 116 ] …”

Section: Resultsmentioning

confidence: 99%

Two-Dimensional β-PdX₂ (X=S, Se, and Te) Monolayers with Promising Potential for Thermoelectric Applications

et al. 2022

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Transition metal dichalcogenides have attracted extensive research attention due to their unique electronic, topological, and optical properties. Based on first-principles methods and Boltzmann transport theory, the thermoelectric performance of β-PdX 2 (X = S, Se, and Te) monolayers was comprehensively studied in this work. It is worth noting that the structural anisotropy of β-PdX 2 monolayers leads to obvious anisotropy of thermoelectric coefficients along the x and y directions. By investigating the thermal transport up to fourphonon scattering, it was found that the strong higher-order phonon scattering plays a decisive role in ultra-low lattice thermal conductivity of β-PdX 2 monolayers. A low lattice thermal conductivity of 3.4 (1.0) W m −1 K −1 is predicted for β-PdTe 2 at 300 K along the x (y) direction. In addition, due to the suitable band gap and high carrier mobility, the highest power factor of 25.7 mW m −1 K −2 is obtained in n-type β-PdX 2 monolayers, which is superior to many other two-dimensional thermoelectric materials. Finally, a maximum ZT of 5.2 is achieved for the n-type β-PdS 2 monolayer along the y direction at 600 K. Meanwhile, the maximum p-type ZT also reaches 3.3 along the y direction at 600 K in the β-PdSe 2 monolayer. Our results demonstrate that β-PdX 2 monolayers are promising candidates for two-dimensional thermoelectric materials with excellent conversion performance.

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Section: Resultsmentioning

confidence: 99%

Two-Dimensional β-PdX₂ (X=S, Se, and Te) Monolayers with Promising Potential for Thermoelectric Applications

et al. 2022

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“…The error margins for the free energy of the SQS to SQS with the permuted site occupations were 0.15 and 0.18 eV for AgMnSnSbTe 4 and AgMnPbSbTe 4 , respectively. The favorable anti-ferromagnetic ordering with lowest energy was adopted for the spin-polarized DFT calculations after considering various configurations. , The cutoff energy for the wave function was set at 400 eV and a Monkhorst–Pack k -mesh of 4 × 4 × 4 was used. The structure was fully relaxed by employing a conjugate gradient scheme until the energy and Hellmann–Feynman force convergences were less than 10 –4 eV and 0.01 eV·Å –1 , respectively.…”

Section: Methodsmentioning

confidence: 99%

High Thermoelectric Performance and Low Lattice Thermal Conductivity in Lattice-Distorted High-Entropy Semiconductors AgMnSn_1–xPb_xSbTe₄

Luo

et al. 2022

Chem. Mater.

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We investigate the structure and thermoelectric properties of a new high-entropy solid solution system AgMnSn1–x Pb x SbTe4 (x = 0, 0.25, 0.5, 0.75, and 1), which crystallizes in the rock-salt NaCl structure with cations Ag, Mn, Sn, Pb, and Sb randomly disordered over the Na site. Our density functional theory calculations indicate that AgMnSn1–x Pb x SbTe4 exhibits complex multi-peak valence band structures, whose energy difference is lower than 0.11 eV, leading to effective band convergence and thus high density of states effective mass m* and Seebeck coefficients. As a consequence, AgMnSn0.25Pb0.75SbTe4 has a peak ZT of 1.3 at 773 K and a desirable average ZT value of 0.8 in the temperature range of 400–773 K. In addition, we propose the lattice distortion degree (i.e., δ) as an important indicator of thermoelectric performance for high-entropy materials. Specifically, with the gradual increase in δ, the lattice thermal conductivity decreases monotonically from 0.90 W m–1 K–1 for AgMnSnSbTe4 (i.e., δ = 0.205) to 0.54 W m–1 K–1 for AgMnPbSbTe4 (i.e., δ = 0.230) at 300 K. Meanwhile, the generalized material parameter B x */B 0 * and ZT increase monotonically from 1 and 0.11 for δ = 0.205 to 3.15 and 0.29 for δ = 0.230 at 300 K.

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“…The energy convergence range is 10 À8 eV atom À1 , the Hermann-Feynman force is less than 0.002 eV Å À1 atom À1 , the cut-off energy is 400 eV, and a 24 Â 24 Â 17 Monkhorst-Pack k-mesh grid has been chosen. Since GeMnTe 2 is actually a substance formed by 50% Mn doping based on GeTe in the cubic phase(space group Fm3m), [32,33,38] the path K-Γ-L-W-U of this space group was chosen. [39] For the calculation of the band structure of supercell (2 Â 2 Â 2), we considered the GGA þ U (7 eV) [40] and spin-orbit coupling due to the influences of Mn-3 d electrons, and the calculated supercell band structure along the high symmetry directions of the primitive cell was unfolded back by the VASPKIT code.…”

Section: Synthesis Processmentioning

confidence: 99%

Charge Balanced Vacancy Engineering to Enhance the Thermoelectric Properties of GeMnTe₂

Gao

Wei

et al. 2023

Physica Status Solidi (b)

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As a derivative of GeTe and MnTe, GeMnTe2 exhibits a cubic structure with no phase transition. Compared to GeTe, it is considerably cheaper and has a significantly high carrier concentration compared to MnTe, making it an excellent thermoelectric (TE) material with promising applications. Herein, a charge‐balanced vacancy engineering strategy is employed, resulting in a significant improvement in the power factor of GeMnTe2. Furthermore, the density functional theory calculation shows that the doping of Bi and the absence of Ge synergically increase the density of states near the Fermi level. Power factors of ≈13.7 μW cm−1 K−2 are achieved at 8% Bi content, a 22% improvement compared to the undoped system, while a final maximum ZT value of about 1.12 and an average ZT value of 0.72 are achieved. This indicates that charge‐balance vacancy engineering is an effective optimization method for the GeMnTe2 system, which can effectively improve the TE performance.

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Symmetry breaking in Ge_1−xMn_xTe and the impact on thermoelectric transport

Abstract: Germanium telluride is a high performing thermoelectric material that additionally serves as a base for alloys such as GeTe-AgSbTe2 and GeTe-PbTe. Such performance motivates exploration of other GeTe alloys in...

Cited by 13 publications

References 53 publications

Two-Dimensional β-PdX₂ (X=S, Se, and Te) Monolayers with Promising Potential for Thermoelectric Applications

Two-Dimensional β-PdX₂ (X=S, Se, and Te) Monolayers with Promising Potential for Thermoelectric Applications

High Thermoelectric Performance and Low Lattice Thermal Conductivity in Lattice-Distorted High-Entropy Semiconductors AgMnSn_1–xPb_xSbTe₄

Charge Balanced Vacancy Engineering to Enhance the Thermoelectric Properties of GeMnTe₂

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Symmetry breaking in Ge1−xMnxTe and the impact on thermoelectric transport

Abstract: Germanium telluride is a high performing thermoelectric material that additionally serves as a base for alloys such as GeTe-AgSbTe2 and GeTe-PbTe. Such performance motivates exploration of other GeTe alloys in...

Cited by 13 publications

References 53 publications

Two-Dimensional β-PdX2 (X=S, Se, and Te) Monolayers with Promising Potential for Thermoelectric Applications

Two-Dimensional β-PdX2 (X=S, Se, and Te) Monolayers with Promising Potential for Thermoelectric Applications

High Thermoelectric Performance and Low Lattice Thermal Conductivity in Lattice-Distorted High-Entropy Semiconductors AgMnSn1–xPbxSbTe4

Charge Balanced Vacancy Engineering to Enhance the Thermoelectric Properties of GeMnTe2

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Symmetry breaking in Ge_1−xMn_xTe and the impact on thermoelectric transport

Two-Dimensional β-PdX₂ (X=S, Se, and Te) Monolayers with Promising Potential for Thermoelectric Applications

Two-Dimensional β-PdX₂ (X=S, Se, and Te) Monolayers with Promising Potential for Thermoelectric Applications

High Thermoelectric Performance and Low Lattice Thermal Conductivity in Lattice-Distorted High-Entropy Semiconductors AgMnSn_1–xPb_xSbTe₄

Charge Balanced Vacancy Engineering to Enhance the Thermoelectric Properties of GeMnTe₂