Enhanced thermoelectric properties of the Zintl phase BaGa2Sb2 via doping with Na or K

Umut Aydemir; Alex Zevalkink; Alim Ormeci; Sabah Bux; G. Jeffrey Snyder

doi:10.1039/c5ta07612a

Enhanced thermoelectric properties of the Zintl phase BaGa₂Sb₂ via doping with Na or K

Umut Aydemir^*, Alex Zevalkink, Alim Ormeci, Sabah Bux, G. Jeffrey Snyder

^*Corresponding author for this work

Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

29 Scopus citations

Abstract

Na- or K-doped samples of Ba_1-x(Na, K)_xGa₂Sb₂ were prepared by ball-milling followed by hot-pressing. The topological analysis of the electron density of BaGa₂Sb₂ implies a polar covalent nature of the Sb-Ga bonds in which the Sb atoms receive the electrons transferred from Ba rather than the Ga atoms. Successful doping of BaGa₂Sb₂ with Na or K was confirmed with combined microprobe and X-ray diffraction analysis. Alkali metal doping of BaGa₂Sb₂ increased the p-type charge carrier concentration to almost the predicted optimum values (∼10²⁰ h⁺ cm^-3) needed to achieve high thermoelectric performance. With increasing alkali metal concentration, electronic transport was shifted from non-degenerate semiconducting behaviour observed for BaGa₂Sb₂ to degenerate one for Na- or K-doped compounds. Overall, the thermoelectric figure of merit, zT, values reached up to ∼0.65 at 750 K, considerably higher than the undoped sample (zT ∼ 0.1 at 600 K), and a slight improvement relative to previously reported Zn-doped samples (∼0.6 at 800 K).

Original language	English (US)
Pages (from-to)	1867-1875
Number of pages	9
Journal	Journal of Materials Chemistry A
Volume	4
Issue number	5
DOIs	https://doi.org/10.1039/c5ta07612a
State	Published - Feb 7 2016

Funding

U. A. acknowledges the financial assistance of The Scientific and Technological Research Council of Turkey. This research was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration and was supported by the NASA Science Missions Directorate''s Radioisotope Power Systems Technology Advancement Program. We would like to acknowledge the Molecular Materials Research Center (MMRC) at Caltech for allowing use of their instruments for the optical measurements obtained in this work. A. O. thanks Ulrike Nitzsche from IFW Dresden, Germany for technical help in computational work.

ASJC Scopus subject areas

General Chemistry
Renewable Energy, Sustainability and the Environment
General Materials Science

UN SDGs

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Access to Document

10.1039/c5ta07612a

Cite this

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title = "Enhanced thermoelectric properties of the Zintl phase BaGa2Sb2 via doping with Na or K",

abstract = "Na- or K-doped samples of Ba1-x(Na, K)xGa2Sb2 were prepared by ball-milling followed by hot-pressing. The topological analysis of the electron density of BaGa2Sb2 implies a polar covalent nature of the Sb-Ga bonds in which the Sb atoms receive the electrons transferred from Ba rather than the Ga atoms. Successful doping of BaGa2Sb2 with Na or K was confirmed with combined microprobe and X-ray diffraction analysis. Alkali metal doping of BaGa2Sb2 increased the p-type charge carrier concentration to almost the predicted optimum values (∼1020 h+ cm-3) needed to achieve high thermoelectric performance. With increasing alkali metal concentration, electronic transport was shifted from non-degenerate semiconducting behaviour observed for BaGa2Sb2 to degenerate one for Na- or K-doped compounds. Overall, the thermoelectric figure of merit, zT, values reached up to ∼0.65 at 750 K, considerably higher than the undoped sample (zT ∼ 0.1 at 600 K), and a slight improvement relative to previously reported Zn-doped samples (∼0.6 at 800 K).",

author = "Umut Aydemir and Alex Zevalkink and Alim Ormeci and Sabah Bux and Snyder, {G. Jeffrey}",

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AU - Aydemir, Umut

AU - Zevalkink, Alex

AU - Ormeci, Alim

AU - Bux, Sabah

AU - Snyder, G. Jeffrey

PY - 2016/2/7

Y1 - 2016/2/7

N2 - Na- or K-doped samples of Ba1-x(Na, K)xGa2Sb2 were prepared by ball-milling followed by hot-pressing. The topological analysis of the electron density of BaGa2Sb2 implies a polar covalent nature of the Sb-Ga bonds in which the Sb atoms receive the electrons transferred from Ba rather than the Ga atoms. Successful doping of BaGa2Sb2 with Na or K was confirmed with combined microprobe and X-ray diffraction analysis. Alkali metal doping of BaGa2Sb2 increased the p-type charge carrier concentration to almost the predicted optimum values (∼1020 h+ cm-3) needed to achieve high thermoelectric performance. With increasing alkali metal concentration, electronic transport was shifted from non-degenerate semiconducting behaviour observed for BaGa2Sb2 to degenerate one for Na- or K-doped compounds. Overall, the thermoelectric figure of merit, zT, values reached up to ∼0.65 at 750 K, considerably higher than the undoped sample (zT ∼ 0.1 at 600 K), and a slight improvement relative to previously reported Zn-doped samples (∼0.6 at 800 K).

AB - Na- or K-doped samples of Ba1-x(Na, K)xGa2Sb2 were prepared by ball-milling followed by hot-pressing. The topological analysis of the electron density of BaGa2Sb2 implies a polar covalent nature of the Sb-Ga bonds in which the Sb atoms receive the electrons transferred from Ba rather than the Ga atoms. Successful doping of BaGa2Sb2 with Na or K was confirmed with combined microprobe and X-ray diffraction analysis. Alkali metal doping of BaGa2Sb2 increased the p-type charge carrier concentration to almost the predicted optimum values (∼1020 h+ cm-3) needed to achieve high thermoelectric performance. With increasing alkali metal concentration, electronic transport was shifted from non-degenerate semiconducting behaviour observed for BaGa2Sb2 to degenerate one for Na- or K-doped compounds. Overall, the thermoelectric figure of merit, zT, values reached up to ∼0.65 at 750 K, considerably higher than the undoped sample (zT ∼ 0.1 at 600 K), and a slight improvement relative to previously reported Zn-doped samples (∼0.6 at 800 K).

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