Rhombohedral to Cubic Conversion of GeTe via MnTe Alloying Leads to Ultralow Thermal Conductivity, Electronic Band Convergence, and High Thermoelectric Performance

Zheng Zheng, Xianli Su, Rigui Deng, Constantinos Stoumpos, Hongyao Xie, Wei Liu, Yonggao Yan, Shiqiang Hao, Ctirad Uher, Chris Wolverton, Mercouri G Kanatzidis, Xinfeng Tang

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

In this study, a series of Ge1-xMnxTe (x = 0-0.21) compounds were prepared by a melting-quenching-annealing process combined with spark plasma sintering (SPS). The effect of alloying MnTe into GeTe on the structure and thermoelectric properties of Ge1-xMnxTe is profound. With increasing content of MnTe, the structure of the Ge1-xMnxTe compounds gradually changes from rhombohedral to cubic, and the known R3m to Fm-3m phase transition temperature of GeTe moves from 700 K closer to room temperature. First-principles density functional theory calculations show that alloying MnTe into GeTe decreases the energy difference between the light and heavy valence bands in both the R3m and Fm-3m structures, enhancing a multiband character of the valence band edge that increases the hole carrier effective mass. The effect of this band convergence is a significant enhancement in the carrier effective mass from 1.44 m0 (GeTe) to 6.15 m0 (Ge0.85Mn0.15Te). In addition, alloying with MnTe decreases the phonon relaxation time by enhancing alloy scattering, reduces the phonon velocity, and increases Ge vacancies all of which result in an ultralow lattice thermal conductivity of 0.13 W m-1 K-1 at 823 K. Subsequent doping of the Ge0.9Mn0.1Te compositions with Sb lowers the typical very high hole carrier concentration and brings it closer to its optimal value enhancing the power factor, which combined with the ultralow thermal conductivity yields a maximum ZT value of 1.61 at 823 K (for Ge0.86Mn0.10Sb0.04Te). The average ZT value of the compound over the temperature range 400-800 K is 1.09, making it the best GeTe-based thermoelectric material.

Original languageEnglish
Pages (from-to)2673-2686
Number of pages14
JournalJournal of the American Chemical Society
Volume140
Issue number7
DOIs
Publication statusPublished - Feb 21 2018

Fingerprint

Phonons
Thermal Conductivity
Alloying
Thermal conductivity
Valence bands
Temperature
Transition Temperature
Phase Transition
Freezing
Spark plasma sintering
Light
Crystal lattices
Relaxation time
Superconducting transition temperature
Vacancies
Density functional theory
Carrier concentration
Quenching
Melting
Phase transitions

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Rhombohedral to Cubic Conversion of GeTe via MnTe Alloying Leads to Ultralow Thermal Conductivity, Electronic Band Convergence, and High Thermoelectric Performance. / Zheng, Zheng; Su, Xianli; Deng, Rigui; Stoumpos, Constantinos; Xie, Hongyao; Liu, Wei; Yan, Yonggao; Hao, Shiqiang; Uher, Ctirad; Wolverton, Chris; Kanatzidis, Mercouri G; Tang, Xinfeng.

In: Journal of the American Chemical Society, Vol. 140, No. 7, 21.02.2018, p. 2673-2686.

Research output: Contribution to journalArticle

Zheng, Zheng ; Su, Xianli ; Deng, Rigui ; Stoumpos, Constantinos ; Xie, Hongyao ; Liu, Wei ; Yan, Yonggao ; Hao, Shiqiang ; Uher, Ctirad ; Wolverton, Chris ; Kanatzidis, Mercouri G ; Tang, Xinfeng. / Rhombohedral to Cubic Conversion of GeTe via MnTe Alloying Leads to Ultralow Thermal Conductivity, Electronic Band Convergence, and High Thermoelectric Performance. In: Journal of the American Chemical Society. 2018 ; Vol. 140, No. 7. pp. 2673-2686.
@article{a8c4071fca204ba4b90487a6ed807059,
title = "Rhombohedral to Cubic Conversion of GeTe via MnTe Alloying Leads to Ultralow Thermal Conductivity, Electronic Band Convergence, and High Thermoelectric Performance",
abstract = "In this study, a series of Ge1-xMnxTe (x = 0-0.21) compounds were prepared by a melting-quenching-annealing process combined with spark plasma sintering (SPS). The effect of alloying MnTe into GeTe on the structure and thermoelectric properties of Ge1-xMnxTe is profound. With increasing content of MnTe, the structure of the Ge1-xMnxTe compounds gradually changes from rhombohedral to cubic, and the known R3m to Fm-3m phase transition temperature of GeTe moves from 700 K closer to room temperature. First-principles density functional theory calculations show that alloying MnTe into GeTe decreases the energy difference between the light and heavy valence bands in both the R3m and Fm-3m structures, enhancing a multiband character of the valence band edge that increases the hole carrier effective mass. The effect of this band convergence is a significant enhancement in the carrier effective mass from 1.44 m0 (GeTe) to 6.15 m0 (Ge0.85Mn0.15Te). In addition, alloying with MnTe decreases the phonon relaxation time by enhancing alloy scattering, reduces the phonon velocity, and increases Ge vacancies all of which result in an ultralow lattice thermal conductivity of 0.13 W m-1 K-1 at 823 K. Subsequent doping of the Ge0.9Mn0.1Te compositions with Sb lowers the typical very high hole carrier concentration and brings it closer to its optimal value enhancing the power factor, which combined with the ultralow thermal conductivity yields a maximum ZT value of 1.61 at 823 K (for Ge0.86Mn0.10Sb0.04Te). The average ZT value of the compound over the temperature range 400-800 K is 1.09, making it the best GeTe-based thermoelectric material.",
author = "Zheng Zheng and Xianli Su and Rigui Deng and Constantinos Stoumpos and Hongyao Xie and Wei Liu and Yonggao Yan and Shiqiang Hao and Ctirad Uher and Chris Wolverton and Kanatzidis, {Mercouri G} and Xinfeng Tang",
year = "2018",
month = "2",
day = "21",
doi = "10.1021/jacs.7b13611",
language = "English",
volume = "140",
pages = "2673--2686",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "7",

}

TY - JOUR

T1 - Rhombohedral to Cubic Conversion of GeTe via MnTe Alloying Leads to Ultralow Thermal Conductivity, Electronic Band Convergence, and High Thermoelectric Performance

AU - Zheng, Zheng

AU - Su, Xianli

AU - Deng, Rigui

AU - Stoumpos, Constantinos

AU - Xie, Hongyao

AU - Liu, Wei

AU - Yan, Yonggao

AU - Hao, Shiqiang

AU - Uher, Ctirad

AU - Wolverton, Chris

AU - Kanatzidis, Mercouri G

AU - Tang, Xinfeng

PY - 2018/2/21

Y1 - 2018/2/21

N2 - In this study, a series of Ge1-xMnxTe (x = 0-0.21) compounds were prepared by a melting-quenching-annealing process combined with spark plasma sintering (SPS). The effect of alloying MnTe into GeTe on the structure and thermoelectric properties of Ge1-xMnxTe is profound. With increasing content of MnTe, the structure of the Ge1-xMnxTe compounds gradually changes from rhombohedral to cubic, and the known R3m to Fm-3m phase transition temperature of GeTe moves from 700 K closer to room temperature. First-principles density functional theory calculations show that alloying MnTe into GeTe decreases the energy difference between the light and heavy valence bands in both the R3m and Fm-3m structures, enhancing a multiband character of the valence band edge that increases the hole carrier effective mass. The effect of this band convergence is a significant enhancement in the carrier effective mass from 1.44 m0 (GeTe) to 6.15 m0 (Ge0.85Mn0.15Te). In addition, alloying with MnTe decreases the phonon relaxation time by enhancing alloy scattering, reduces the phonon velocity, and increases Ge vacancies all of which result in an ultralow lattice thermal conductivity of 0.13 W m-1 K-1 at 823 K. Subsequent doping of the Ge0.9Mn0.1Te compositions with Sb lowers the typical very high hole carrier concentration and brings it closer to its optimal value enhancing the power factor, which combined with the ultralow thermal conductivity yields a maximum ZT value of 1.61 at 823 K (for Ge0.86Mn0.10Sb0.04Te). The average ZT value of the compound over the temperature range 400-800 K is 1.09, making it the best GeTe-based thermoelectric material.

AB - In this study, a series of Ge1-xMnxTe (x = 0-0.21) compounds were prepared by a melting-quenching-annealing process combined with spark plasma sintering (SPS). The effect of alloying MnTe into GeTe on the structure and thermoelectric properties of Ge1-xMnxTe is profound. With increasing content of MnTe, the structure of the Ge1-xMnxTe compounds gradually changes from rhombohedral to cubic, and the known R3m to Fm-3m phase transition temperature of GeTe moves from 700 K closer to room temperature. First-principles density functional theory calculations show that alloying MnTe into GeTe decreases the energy difference between the light and heavy valence bands in both the R3m and Fm-3m structures, enhancing a multiband character of the valence band edge that increases the hole carrier effective mass. The effect of this band convergence is a significant enhancement in the carrier effective mass from 1.44 m0 (GeTe) to 6.15 m0 (Ge0.85Mn0.15Te). In addition, alloying with MnTe decreases the phonon relaxation time by enhancing alloy scattering, reduces the phonon velocity, and increases Ge vacancies all of which result in an ultralow lattice thermal conductivity of 0.13 W m-1 K-1 at 823 K. Subsequent doping of the Ge0.9Mn0.1Te compositions with Sb lowers the typical very high hole carrier concentration and brings it closer to its optimal value enhancing the power factor, which combined with the ultralow thermal conductivity yields a maximum ZT value of 1.61 at 823 K (for Ge0.86Mn0.10Sb0.04Te). The average ZT value of the compound over the temperature range 400-800 K is 1.09, making it the best GeTe-based thermoelectric material.

UR - http://www.scopus.com/inward/record.url?scp=85042384509&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85042384509&partnerID=8YFLogxK

U2 - 10.1021/jacs.7b13611

DO - 10.1021/jacs.7b13611

M3 - Article

VL - 140

SP - 2673

EP - 2686

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 7

ER -