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Title: The effect of structural vacancies on the thermoelectric properties of (Cu₂Te){sub 1–x}(Ga₂Te₃) x

Abstract

We have studied the effects of structural vacancies on the thermoelectric properties of the ternary compounds (Cu₂Te) 1–x(Ga₂Te₃) x (x=0.5, 0.55, 0.571, 0.6, 0.625, 0.667 and 0.75), which are solid solutions found in the pseudo-binary phase diagram for Cu₂Te and Ga₂Te₃, and possesses tunable structural vacancy concentrations. This materials system is not suitable due to the cost and scarcity of the constituent elements, but the vacancy behavior is well understood and will provide a valuable test case for other systems more suitable from the standpoint of cost and abundance of raw materials, which also possesses these vacancy features, but whose structural characterization is lacking at this stage. We find that the nominally defect free phase CuGaTe₂ possess the highest ZT (ZT=S²T/ρκ, where S is the Seebeck coefficient and ρ is the electrical resistivity κ is the thermal conductivity and T is the absolute temperature) which approaches 1 at 840 K and seems to continuously increase above this temperature. This result is due to the unexpectedly low thermal conductivity found for this material at high temperature. The low thermal conductivity was caused by strong Umklapp (thermally resistive scattering processes involving three phonons) phonon scattering. We find that due to the coincidentallymore » strong scattering of carriers by the structural defects that higher concentrations of these features lead to poor electrical transport properties and decreased ZT. - Graphical abstract: Thermal conductivity and zT as a function of temperature for a series of compounds of the type (Cu₂Te) 1–x(Ga₂Te₃)x (x=0.5, 0.55, 0.571, 0.6, 0.625, 0.667 and 0.75). Highlights: • All the samples show p-type semiconducting behavior in the temperature dependence of the Seebeck and Hall coefficients. • The increased carrier concentration and the introduction of vacancies diminish the carrier mobility and power factor. • The low temperature k decreases significantly as the Ga₂Te₃ content increases due to increasing point defects. • The highest ZT ~ 1.0 at 840 K among the samples in this study was found in CuGaTe₂, which contains no vacancies.« less

Authors:
; ;  [1];  [2]; ;  [3]
  1. Optimal Inc., Plymouth Township, MI 48170 (United States)
  2. GM Global R and D, Warren, MI 48090 (United States)
  3. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)
Publication Date:
OSTI Identifier:
22306295
Resource Type:
Journal Article
Journal Name:
Journal of Solid State Chemistry
Additional Journal Information:
Journal Volume: 201; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0022-4596
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CARRIER MOBILITY; CHALCOPYRITE; COPPER TELLURIDES; ELECTRIC CONDUCTIVITY; GALLIUM TELLURIDES; PHASE DIAGRAMS; PHONONS; RAW MATERIALS; SCATTERING; SOLID SOLUTIONS; TEMPERATURE DEPENDENCE; THERMAL CONDUCTIVITY; THERMOELECTRIC PROPERTIES

Citation Formats

Ye, Zuxin, Young Cho, Jung, Tessema, Misle M., Salvador, James R., E-mail: james.salvador@gm.com, Waldo, Richard A., Wang, Hsin, and Cai, Wei. The effect of structural vacancies on the thermoelectric properties of (Cu₂Te){sub 1–x}(Ga₂Te₃)x. United States: N. p., 2013. Web. doi:10.1016/J.JSSC.2013.02.008.
Ye, Zuxin, Young Cho, Jung, Tessema, Misle M., Salvador, James R., E-mail: james.salvador@gm.com, Waldo, Richard A., Wang, Hsin, & Cai, Wei. The effect of structural vacancies on the thermoelectric properties of (Cu₂Te){sub 1–x}(Ga₂Te₃)x. United States. https://doi.org/10.1016/J.JSSC.2013.02.008
Ye, Zuxin, Young Cho, Jung, Tessema, Misle M., Salvador, James R., E-mail: james.salvador@gm.com, Waldo, Richard A., Wang, Hsin, and Cai, Wei. Wed . "The effect of structural vacancies on the thermoelectric properties of (Cu₂Te){sub 1–x}(Ga₂Te₃)x". United States. https://doi.org/10.1016/J.JSSC.2013.02.008.
@article{osti_22306295,
title = {The effect of structural vacancies on the thermoelectric properties of (Cu₂Te){sub 1–x}(Ga₂Te₃)x},
author = {Ye, Zuxin and Young Cho, Jung and Tessema, Misle M. and Salvador, James R., E-mail: james.salvador@gm.com and Waldo, Richard A. and Wang, Hsin and Cai, Wei},
abstractNote = {We have studied the effects of structural vacancies on the thermoelectric properties of the ternary compounds (Cu₂Te)1–x(Ga₂Te₃)x (x=0.5, 0.55, 0.571, 0.6, 0.625, 0.667 and 0.75), which are solid solutions found in the pseudo-binary phase diagram for Cu₂Te and Ga₂Te₃, and possesses tunable structural vacancy concentrations. This materials system is not suitable due to the cost and scarcity of the constituent elements, but the vacancy behavior is well understood and will provide a valuable test case for other systems more suitable from the standpoint of cost and abundance of raw materials, which also possesses these vacancy features, but whose structural characterization is lacking at this stage. We find that the nominally defect free phase CuGaTe₂ possess the highest ZT (ZT=S²T/ρκ, where S is the Seebeck coefficient and ρ is the electrical resistivity κ is the thermal conductivity and T is the absolute temperature) which approaches 1 at 840 K and seems to continuously increase above this temperature. This result is due to the unexpectedly low thermal conductivity found for this material at high temperature. The low thermal conductivity was caused by strong Umklapp (thermally resistive scattering processes involving three phonons) phonon scattering. We find that due to the coincidentally strong scattering of carriers by the structural defects that higher concentrations of these features lead to poor electrical transport properties and decreased ZT. - Graphical abstract: Thermal conductivity and zT as a function of temperature for a series of compounds of the type (Cu₂Te)1–x(Ga₂Te₃)x (x=0.5, 0.55, 0.571, 0.6, 0.625, 0.667 and 0.75). Highlights: • All the samples show p-type semiconducting behavior in the temperature dependence of the Seebeck and Hall coefficients. • The increased carrier concentration and the introduction of vacancies diminish the carrier mobility and power factor. • The low temperature k decreases significantly as the Ga₂Te₃ content increases due to increasing point defects. • The highest ZT ~ 1.0 at 840 K among the samples in this study was found in CuGaTe₂, which contains no vacancies.},
doi = {10.1016/J.JSSC.2013.02.008},
url = {https://www.osti.gov/biblio/22306295}, journal = {Journal of Solid State Chemistry},
issn = {0022-4596},
number = ,
volume = 201,
place = {United States},
year = {2013},
month = {5}
}