Title: Potential for high thermoelectric performance in n-type Zintl compounds: A case study of Ba doped KAlSb₄

Abstract

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. From the computational search, we have selected n-type KAlSb₄ as a promising thermoelectric material. Synthesis and characterization of polycrystalline KAlSb₄ reveals non-degenerate n-type transport. With Ba substitution, the carrier concentration is tuned between 10¹⁸ and 10¹⁹ 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 cm² 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_0.01AlSb₄. As a result, based on the theoretical predictions and subsequent experimental validation, we findmore » significant motivation for the exploration of n-type thermoelectric performance in other Zintl pnictides.« less

Authors:

Ortiz, Brenden R.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-1333-7003"
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Gorai, Prashun ^[2]; Krishna, Lakshmi ^[1]; Mow, Rachel ^[3]; Lopez, Armando ^[1]; McKinney, Robert  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-3672-4345"
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Stevanovic, Vladan ^[2]; Toberer, Eric S. ^[2]

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+ Show Author Affiliations

1. Colorado School of Mines, Golden, CO (United States)
2. Colorado School of Mines, Golden, CO (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)
3. Harvey Mudd College, Claremont, CA (United States)

Publication Date:

2017-01-11

Research Org.:

National Renewable Energy Lab. (NREL), Golden, CO (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE)

OSTI Identifier:

1347504

Report Number(s):

NREL/JA-5K00-68158
Journal ID: ISSN 2050-7488; JMCAET

Grant/Contract Number:  

AC36-08GO28308

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Materials Chemistry. A

Additional Journal Information:

Journal Volume: 5; Journal Issue: 8; Journal ID: ISSN 2050-7488

Publisher:

Royal Society of Chemistry

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; thermoelectric materials; Zintl pnictides