Dynamic Lone Pair Expression as Chemical Bonding Origin of Giant Phonon Anharmonicity in Thermoelectric InTe

Jiawei Zhang*, Daisuke Ishikawa, Michael M. Koza, Eiji Nishibori, Lirong Song, Alfred Q. R. Baron, Bo Brummerstedt Iversen*

*Corresponding author af dette arbejde

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24 Citationer (Scopus)

Abstract

Loosely bonded (“rattling”) atoms with s2 lone pair electrons are usually associated with strong anharmonicity and unexpectedly low thermal conductivity, yet their detailed correlation remains largely unknown. Here we resolve this correlation in thermoelectric InTe by combining chemical bonding analysis, inelastic X-ray and neutron scattering, and first principles phonon calculations. We successfully probe soft low-lying transverse phonons dominated by large In1+ z-axis motions, and their giant anharmonicity. We show that the highly anharmonic phonons arise from the dynamic lone pair expression with unstable occupied antibonding states induced by the covalency between delocalized In1+ 5s2 lone pair electrons and Te 5p states. This work pinpoints the microscopic origin of strong anharmonicity driven by rattling atoms with stereochemical lone pair activity, important for designing efficient materials for thermoelectric energy conversion.
OriginalsprogEngelsk
Artikelnummere202218458
TidsskriftAngewandte Chemie International Edition
Vol/bind62
Nummer13
Antal sider10
ISSN1433-7851
DOI
StatusUdgivet - mar. 2023

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