Discovery of multivalley Fermi surface responsible for the high thermoelectric performance in Yb14MnSb11 and Yb14MgSb11

Christopher J Perez; Maxwell Wood; Francesco Ricci; Guodong Yu; Trinh Vo; Sabah K Bux; Geoffroy Hautier; Gian-Marco Rignanese; G Jeffrey Snyder; Susan M Kauzlarich

doi:10.1126/sciadv.abe9439

Discovery of multivalley Fermi surface responsible for the high thermoelectric performance in Yb₁₄MnSb₁₁ and Yb₁₄MgSb₁₁

Sci Adv. 2021 Jan 20;7(4):eabe9439. doi: 10.1126/sciadv.abe9439. Print 2021 Jan.

Authors

Affiliations

¹ Department of Chemistry, University of California, Davis, One Shields Ave., Davis, CA 95616, USA.
² Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA.
³ Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, Louvain-la-Neuve 1348, Belgium.
⁴ School of Physics and Technology, Wuhan University, Wuhan 430072, China.
⁵ Thermal Energy Conversion Research and Advancement Group, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA.
⁶ Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA. smkauzlarich@ucdavis.edu jeff.snyder@northwestern.edu.
⁷ Department of Chemistry, University of California, Davis, One Shields Ave., Davis, CA 95616, USA. smkauzlarich@ucdavis.edu jeff.snyder@northwestern.edu.

Abstract

The Zintl phases, Yb₁₄ MSb₁₁ (M = Mn, Mg, Al, Zn), are now some of the highest thermoelectric efficiency p-type materials with stability above 873 K. Yb₁₄MnSb₁₁ gained prominence as the first p-type thermoelectric material to double the efficiency of SiGe alloy, the heritage material in radioisotope thermoelectric generators used to power NASA's deep space exploration. This study investigates the solid solution of Yb₁₄Mg_1-x Al _x Sb₁₁ (0 ≤ x ≤ 1), which enables a full mapping of the metal-to-semiconductor transition. Using a combined theoretical and experimental approach, we show that a second, high valley degeneracy (N _v = 8) band is responsible for the groundbreaking performance of Yb₁₄ MSb₁₁ This multiband understanding of the properties provides insight into other thermoelectric systems (La_3-x Te₄, SnTe, Ag₉AlSe₆, and Eu₉CdSb₉), and the model predicts that an increase in carrier concentration can lead to zT > 1.5 in Yb₁₄ MSb₁₁ systems.

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