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Title: Thermoelectric Performance and Defect Chemistry in n-Type Zintl KGaSb 4

Abstract

The rise of high-throughput calculations has accelerated the discovery of promising classes of thermoelectric materials. In prior work, we identified the n-type Zintl pnictides as one such material class. To date, however, a lack of detailed defect calculations and chemical intuition has led the community to investigate p-type Zintls almost exclusively. Here, we investigate the synthesis, thermoelectric properties, and defect structure of the complex Zintl KGaSb 4. We find that KGaSb 4 is successfully doped n-type with Ba and has the potential for p-type doping with Zn. Our calculations reveal the fundamental defect structure in KGaSb 4 that enables n-type and p-type doping. We find that Ba doped KGaSb4 exhibits high electronic mobility (~50 cm 2V -1s -1) and near minimum lattice thermal conductivity (<0.5 Wm -1K -1) at 400 °C. Samples doped with 1.5% Ba achieve zT > 0.9 at 400 °C, promising for a previously unstudied material. Here, we also briefly investigate the series of alloys between KGaSb 4 and KAlSb 4, finding that a full solid solution exists. Altogether our work reinforces motivation for the exploration of n-type Zintl materials, especially in tandem with high-throughput defect calculations to inform selection of effective dopants and systems amenable tomore » n-type transport.« less

Authors:
ORCiD logo [1];  [2];  [3];  [4]
  1. Colorado School of Mines, Golden, CO (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  3. National Renewable Energy Lab. (NREL), Golden, CO (United States); Colorado School of Mines, Golden, CO (United States)
  4. Colorado School of Mines, Golden, CO (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE); National Science Foundation (NSF)
OSTI Identifier:
1365699
Report Number(s):
NREL/JA-5K00-68728
Journal ID: ISSN 0897-4756
Grant/Contract Number:
AC36-08GO28308
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 29; Journal Issue: 10; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; synthesis; thermoelectric properties; defect structure

Citation Formats

Ortiz, Brenden R., Gorai, Prashun, Stevanovic, Vladan, and Toberer, Eric S.. Thermoelectric Performance and Defect Chemistry in n-Type Zintl KGaSb4. United States: N. p., 2017. Web. doi:10.1021/acs.chemmater.7b01217.
Ortiz, Brenden R., Gorai, Prashun, Stevanovic, Vladan, & Toberer, Eric S.. Thermoelectric Performance and Defect Chemistry in n-Type Zintl KGaSb4. United States. doi:10.1021/acs.chemmater.7b01217.
Ortiz, Brenden R., Gorai, Prashun, Stevanovic, Vladan, and Toberer, Eric S.. Mon . "Thermoelectric Performance and Defect Chemistry in n-Type Zintl KGaSb4". United States. doi:10.1021/acs.chemmater.7b01217. https://www.osti.gov/servlets/purl/1365699.
@article{osti_1365699,
title = {Thermoelectric Performance and Defect Chemistry in n-Type Zintl KGaSb4},
author = {Ortiz, Brenden R. and Gorai, Prashun and Stevanovic, Vladan and Toberer, Eric S.},
abstractNote = {The rise of high-throughput calculations has accelerated the discovery of promising classes of thermoelectric materials. In prior work, we identified the n-type Zintl pnictides as one such material class. To date, however, a lack of detailed defect calculations and chemical intuition has led the community to investigate p-type Zintls almost exclusively. Here, we investigate the synthesis, thermoelectric properties, and defect structure of the complex Zintl KGaSb4. We find that KGaSb4 is successfully doped n-type with Ba and has the potential for p-type doping with Zn. Our calculations reveal the fundamental defect structure in KGaSb4 that enables n-type and p-type doping. We find that Ba doped KGaSb4 exhibits high electronic mobility (~50 cm2V-1s-1) and near minimum lattice thermal conductivity (<0.5 Wm-1K-1) at 400 °C. Samples doped with 1.5% Ba achieve zT > 0.9 at 400 °C, promising for a previously unstudied material. Here, we also briefly investigate the series of alloys between KGaSb4 and KAlSb4, finding that a full solid solution exists. Altogether our work reinforces motivation for the exploration of n-type Zintl materials, especially in tandem with high-throughput defect calculations to inform selection of effective dopants and systems amenable to n-type transport.},
doi = {10.1021/acs.chemmater.7b01217},
journal = {Chemistry of Materials},
number = 10,
volume = 29,
place = {United States},
year = {Mon May 08 00:00:00 EDT 2017},
month = {Mon May 08 00:00:00 EDT 2017}
}

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Cited by: 5works
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  • High-throughput calculations (first-principles density functional theory and semi-empirical transport models) have the potential to guide the discovery of new thermoelectric materials. Herein we have computationally assessed the potential for thermoelectric performance of 145 complex Zintl pnictides. Of the 145 Zintl compounds assessed, 17% show promising n-type transport properties, compared with only 6% showing promising p-type transport. We predict that n-type Zintl compounds should exhibit high mobility μ n while maintaining the low thermal conductivity κ L typical of Zintl phases. Thus, not only do candidate n-type Zintls outnumber their p-type counterparts, but they may also exhibit improved thermoelectric performance. Frommore » the computational search, we have selected n-type KAlSb 4 as a promising thermoelectric material. Synthesis and characterization of polycrystalline KAlSb 4 reveals non-degenerate n-type transport. With Ba substitution, the carrier concentration is tuned between 10 18 and 10 19 e cm –3 with a maximum Ba solubility of 0.7% on the K site. High temperature transport measurements confirm a high μ n (50 cm 2 V –1 s –1) coupled with a near minimum κ L (0.5 W m –1 K –1) at 370 °C. Together, these properties yield a zT of 0.7 at 370 °C for the composition K 0.99Ba 0.01AlSb 4. As a result, based on the theoretical predictions and subsequent experimental validation, we find significant motivation for the exploration of n-type thermoelectric performance in other Zintl pnictides.« less
  • Polyatomic main-group anions like Sn/sub 9//sup 4 -/, Te/sub 5//sup 2 -/, Se/sub 6//sup 2 -/, S/sub 6//sup 2 -/, and SnTe/sub 4//sup 4 -/ have been isolated without the use of cryptate ligands. The polychalcogenides (Bu/sub 4/N)/sub 2/M/sub x/ (where M = Te, x = 5; M = Se, x = 6; M = S, x = 6; Bu = n-C/sub 4/H/sub 9/) are obtained by the aqueous extraction of binary alkali-metal/main-group alloys in the presence of Bu/sub 4/NBr. These polychalcogenides are isomorphous and have been structurally characterized by x-ray crystallography. The nonastannide(4-) anion has been isolated both asmore » the tetrakis(tetramethylammonium) compound, ((CH/sub 3/)N)3$Sn/sub 9/, and as the HMPA (hexamethylphosphoric triamide) solvate, (K(HMPA)/sup 2/)/sub 4/Sn/sub 9/. Both compounds are somewhat thermally unstable at 25/sup 0/C. The compound K/sub 4/SnTe/sub 4/ has been isolated by the aqueous extraction of ternary K/Sn/Te alloys. 44 references, 2 figures, 1 table.« less
  • Highlights: ► The simple solid state reaction technique was employed to prepare Co{sub 4}Sb{sub 11.3}Te{sub 0.7−x}Se{sub x} skutterudites. ► The thermal conductivity decreases gradually with the increasing Se content. ► Doping with moderate Se is an effective way to enhance the thermoelectric performance of Co{sub 4}Sb{sub 11.3}Te{sub 0.7−x}Se{sub x}. ► The highest ZT of 1.11 at 800 K is obtained for the Co{sub 4}Sb{sub 11.3}Te{sub 0.58}Se{sub 0.12} sample. -- Abstract: A series of double-substituted Co{sub 4}Sb{sub 11.3}Te{sub 0.7−x}Se{sub x} skutterudites have been fabricated by combining the solid state reaction and the spark plasma sintering method, and the effects of Semore » substitution on the thermoelectric properties are characterized by measurements of the electrical conductivity, the Seebeck coefficient and the thermal conductivity in the temperature range of 300–800 K. Doping Se into the Co{sub 4}Sb{sub 11.3}Te{sub 0.7−x}Se{sub x} matrix suppresses the carrier concentration, and the electrical conductivity actually decreases with the Se content. However, moderate Se doping is effective in enhancing the thermoelectric performance of the n-type Co{sub 4}Sb{sub 11.3}Te{sub 0.7−x}Se{sub x}, because of the resulted dramatically decreased thermal conductivity. Analyses indicate that the heightened point-defect scattering induced by Se doping together with the electron–phonon scattering induced by Te doping is responsible for the reduction of lattice thermal conductivity of these compounds.« less
  • Barium-filled skutterudites Ba{sub y}Co{sub 4}Sb{sub 12} with an anomalously large filling fraction of up to y=0.44 have been synthesized. The lattice parameters increase linearly with Ba content. Magnetic susceptibility data show that Ba{sub 0.44}Co{sub 4}Sb{sub 12} is paramagnetic, which implies that some of the Co atoms in Ba{sub y}Co{sub 4}Sb{sub 12} have acquired a magnetic moment. The presence of the two different valence states of Co (Co{sup 3+} and Co{sup 2+}) leads to the anomalously large barium filling fraction even without extra charge compensation. All samples show n-type conduction. The electrical conductivity increases with increasing the Ba filling fraction. Themore » lattice thermal conductivity of Ba{sub y}Co{sub 4}Sb{sub 12} is significantly depressed as compared to unfilled Co{sub 4}Sb{sub 12}. The dimensionless thermoelectric figure of merit, ZT, increases with increasing temperature reaching a maximum value of 1.1 for Ba{sub 0.24}Co{sub 4}Sb{sub 12} at 850 K. {copyright} 2001 American Institute of Physics.« less
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