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A Simple Chemical Guide for Finding Novel n-type Dopable Zintl Pnictide Thermoelectric Materials

preprint
submitted on 10.04.2019 and posted on 10.04.2019 by Prashun Gorai, Anuj Goyal, Eric S. Toberer, Vladan Stevanovic
Computations have predicted good thermoelectric performance for a number of Zintl phases when doped n-type. Combined with the successful experimental realization of n-type KGaSb4, KAlSb4, and Mg3Sb2 with zT>1, this has fueled efforts to discover novel n-type dopable Zintl phases. However, a majority of Zintl phases exhibit strong proclivity toward p-type doping and prior successes in finding n-type dopable Zintls were largely serendipitous. Herein we use modern first-principles defect calculations to study trends in the dopability of Zintl pnictides and find that the average oxidation state of the anion is a useful chemical guide to identify novel n-type dopable phases. Specifically, we observe that Zintl pnictides with average oxidation of the anion near -1 are n-type dopable. The trend is mainly a consequence of the high formation energy of native acceptor defects (e.g. cation vacancies) and the resulting absence of charge (electron) compensation. Using the oxidation state guide in conjunction with a descriptor of thermoelectric performance, we conduct a large-scale materials search and identify promising candidates that are n-type dopable.

Funding

DMREF: Collaborative Research: Accelerating Thermoelectric Materials Discovery via Dopability Predictions

Directorate for Mathematical & Physical Sciences

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History

Email Address of Submitting Author

prashun.iitm4@gmail.com

Institution

Colorado School of Mines

Country

United States of America

ORCID For Submitting Author

0000-0001-7866-0672

Declaration of Conflict of Interest

The authors declare no competing interests

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