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Synthesis, Structure, and Thermoelectric Properties of α-Zn3Sb2 and Comparison to β-Zn13Sb10

Lo, Chun Wan Timothy; Ortiz, Brenden R.; Toberer, Eric S.; He, Allan; Svitlyk, Volodymyr; Chernyshov, Dmitry; Kolodiazhnyi, Taras; Lidin, Sven LU and Mozharivskyj, Yurij (2017) In Chemistry of Materials 29(12). p.5249-5258
Abstract

Zn-Sb compounds (e.g., ZnSb, β-Zn13Sb10) are known to have intriguing thermoelectric properties, but studies of the Zn3Sb2 composition are largely absent. In this work, α-Zn3Sb2 was synthesized and studied via temperature-dependent synchrotron powder diffraction. The α-Zn3Sb2 phase undergoes a phase transformation to the β form at 425 °C, which is stable until melting at 590 °C. Rapid quenching was successful in stabilizing the α phase at room temperature, although all attempts to quench β-Zn3Sb2 were unsuccessful. The structure of α-Zn3Sb2 was solved using single crystal diffraction techniques and verified... (More)

Zn-Sb compounds (e.g., ZnSb, β-Zn13Sb10) are known to have intriguing thermoelectric properties, but studies of the Zn3Sb2 composition are largely absent. In this work, α-Zn3Sb2 was synthesized and studied via temperature-dependent synchrotron powder diffraction. The α-Zn3Sb2 phase undergoes a phase transformation to the β form at 425 °C, which is stable until melting at 590 °C. Rapid quenching was successful in stabilizing the α phase at room temperature, although all attempts to quench β-Zn3Sb2 were unsuccessful. The structure of α-Zn3Sb2 was solved using single crystal diffraction techniques and verified through Rietveld refinement of the powder data. α-Zn3Sb2 adopts a large hexagonal cell (R 3-space group, a = 15.212(2), c = 74.83(2) Å) containing a well-defined framework of isolated Sb3- anions but highly disordered Zn2+ cations. Dense ingots of both the α-Zn3Sb2 and β-Zn13Sb10 phases were formed and used to characterize and compare the low temperature thermoelectric properties. Resistivity and Seebeck coefficient measurements on α-Zn3Sb2 are consistent with a small-gap, degenerately doped, p-type semiconductor. The temperature-dependent lattice thermal conductivity of α-Zn3Sb2 is unusual, resembling that of an amorphous material. Consistent with the extreme degree of Zn disorder observed in the structural analysis, phonon scattering in α-Zn3Sb2 appears to be completely dominated by point-defect scattering over all temperatures below 350 K. This contrasts with the typical balance between point-defect scattering and Umklapp scattering seen in β-Zn13Sb10. Using the Debye-Callaway interpretation of the lattice thermal conductivity, we use the differences between α-Zn3Sb2 and β-Zn13Sb10 to illustrate the potential significance of cation/anion disorder in the Zn-Sb system.

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author
organization
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type
Contribution to journal
publication status
published
subject
in
Chemistry of Materials
volume
29
issue
12
pages
10 pages
publisher
The American Chemical Society
external identifiers
  • scopus:85021413598
  • wos:000404493100028
ISSN
0897-4756
DOI
10.1021/acs.chemmater.7b01214
language
English
LU publication?
yes
id
d8d0d25a-00cc-4a3a-bdaf-8b33c3d053bf
date added to LUP
2017-07-11 12:18:36
date last changed
2017-09-18 11:38:02
@article{d8d0d25a-00cc-4a3a-bdaf-8b33c3d053bf,
  abstract     = {<p>Zn-Sb compounds (e.g., ZnSb, β-Zn<sub>13</sub>Sb<sub>10</sub>) are known to have intriguing thermoelectric properties, but studies of the Zn<sub>3</sub>Sb<sub>2</sub> composition are largely absent. In this work, α-Zn<sub>3</sub>Sb<sub>2</sub> was synthesized and studied via temperature-dependent synchrotron powder diffraction. The α-Zn<sub>3</sub>Sb<sub>2</sub> phase undergoes a phase transformation to the β form at 425 °C, which is stable until melting at 590 °C. Rapid quenching was successful in stabilizing the α phase at room temperature, although all attempts to quench β-Zn<sub>3</sub>Sb<sub>2</sub> were unsuccessful. The structure of α-Zn<sub>3</sub>Sb<sub>2</sub> was solved using single crystal diffraction techniques and verified through Rietveld refinement of the powder data. α-Zn<sub>3</sub>Sb<sub>2</sub> adopts a large hexagonal cell (R 3-space group, a = 15.212(2), c = 74.83(2) Å) containing a well-defined framework of isolated Sb<sup>3-</sup> anions but highly disordered Zn<sup>2+</sup> cations. Dense ingots of both the α-Zn<sub>3</sub>Sb<sub>2</sub> and β-Zn<sub>13</sub>Sb<sub>10</sub> phases were formed and used to characterize and compare the low temperature thermoelectric properties. Resistivity and Seebeck coefficient measurements on α-Zn<sub>3</sub>Sb<sub>2</sub> are consistent with a small-gap, degenerately doped, p-type semiconductor. The temperature-dependent lattice thermal conductivity of α-Zn<sub>3</sub>Sb<sub>2</sub> is unusual, resembling that of an amorphous material. Consistent with the extreme degree of Zn disorder observed in the structural analysis, phonon scattering in α-Zn<sub>3</sub>Sb<sub>2</sub> appears to be completely dominated by point-defect scattering over all temperatures below 350 K. This contrasts with the typical balance between point-defect scattering and Umklapp scattering seen in β-Zn<sub>13</sub>Sb<sub>10</sub>. Using the Debye-Callaway interpretation of the lattice thermal conductivity, we use the differences between α-Zn<sub>3</sub>Sb<sub>2</sub> and β-Zn<sub>13</sub>Sb<sub>10</sub> to illustrate the potential significance of cation/anion disorder in the Zn-Sb system.</p>},
  author       = {Lo, Chun Wan Timothy and Ortiz, Brenden R. and Toberer, Eric S. and He, Allan and Svitlyk, Volodymyr and Chernyshov, Dmitry and Kolodiazhnyi, Taras and Lidin, Sven and Mozharivskyj, Yurij},
  issn         = {0897-4756},
  language     = {eng},
  month        = {06},
  number       = {12},
  pages        = {5249--5258},
  publisher    = {The American Chemical Society},
  series       = {Chemistry of Materials},
  title        = {Synthesis, Structure, and Thermoelectric Properties of α-Zn<sub>3</sub>Sb<sub>2</sub> and Comparison to β-Zn<sub>13</sub>Sb<sub>10</sub>},
  url          = {http://dx.doi.org/10.1021/acs.chemmater.7b01214},
  volume       = {29},
  year         = {2017},
}