Article Bonding Heterogeneity and Nanoprecipitation on Substituting the Anionic Framework in Mg3Sb2 for p‐Type Zintl Thermoelectrics

Nagendra Singh Chauhan SAMURAI ORCID (National Institute for Materials Science) ; Takao Mori SAMURAI ORCID (National Institute for Materials Science)

Small Structures--Bonding Heterogeneity and Nanoprecipitation on Substituting the Anionic Framework in Mg3Sb2 for p-type Zintl Thermoelectrics.pdf
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Nagendra Singh Chauhan, Takao Mori. Bonding Heterogeneity and Nanoprecipitation on Substituting the Anionic Framework in Mg3Sb2 for p‐Type Zintl Thermoelectrics. Small Structures. 2025, (), 2400632. https://doi.org/10.1002/sstr.202400632

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(abstract)

Designing zintl compounds with complex crystal structures and large unit cells containing heavy elements may inherit bonding heterogeneity-induced lattice anharmonicity, leading to intrinsically low thermal conductivity. In this work, alloying-induced bonding heterogeneity in the extensively explored α-Mg3(Sb, Bi)2 phase due to local atomic ordering, site preferences, and prevailing heterogenous interfaces is evaluated in the p-type Mg3(Sb1−2xBixSnx)2-based polyanionic nanocomposites for different alloying concentrations. The inherent susceptibility for partial phase transition (trigonal → monoclinic) is observed upon alloying, which is driven by alterations in bonding patterns, localized distortion, and secondary phase formation. At low alloying content (x ≤ 0.05), a trigonal (Sb, Sn) phase is observed, while for higher alloying content (x ≥ 0.1), a cubic Mg2Sn nanophase emerges. A synergistic reduction in thermal conductivity and enhanced power factor maximize the zT ≈ 0.25(±0.05) at 673 K in the optimized p-type Mg3(Sb0.9Bi0.025Sn0.025)2 nanocomposites. The study highlights bonding heterogeneity-induced structural transitions as an inherent challenge, where the dominant role of anionic sites becomes pivotal for determining/deriving favorable structural and functional properties in Mg3(Sb, Bi)2-based zintl compounds.

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Keyword: thermoelectric

Date published: 2025-03-05

Publisher: Wiley

Journal:

  • Small Structures (ISSN: 26884062) p. 2400632-2400632 2400632

Funding:

  • JST-Mirai Program JPMJMI19A1

Manuscript type: Publisher's version (Version of record)

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First published URL: https://doi.org/10.1002/sstr.202400632

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Updated at: 2025-12-10 08:30:28 +0900

Published on MDR: 2025-12-10 08:23:47 +0900

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