Partial Order-Disorder Transition Driving Closure of Band Gap: Example of Thermoelectric Clathrates

In the quest for efficient thermoelectrics, semiconducting behavior is a targeted property. Yet, this is often difficult to achieve due to the complex interplay between electronic structure, temperature, and disorder. We find this to be the case for the thermoelectric clathrate Ba_{8}Al_{16}Si_{30}:...

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Bibliographic Details
Published inPhysical review letters Vol. 130; no. 16; p. 166402
Main Authors Troppenz, Maria, Rigamonti, Santiago, Sofo, Jorge O, Draxl, Claudia
Format Journal Article
LanguageEnglish
Published United States 21.04.2023
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Summary:In the quest for efficient thermoelectrics, semiconducting behavior is a targeted property. Yet, this is often difficult to achieve due to the complex interplay between electronic structure, temperature, and disorder. We find this to be the case for the thermoelectric clathrate Ba_{8}Al_{16}Si_{30}: Although this material exhibits a band gap in its ground state, a temperature-driven partial order-disorder transition leads to its effective closing. This finding is enabled by a novel approach to calculate the temperature-dependent effective band structure of alloys. Our method fully accounts for the effects of short-range order and can be applied to complex alloys with many atoms in the primitive cell, without relying on effective medium approximations.
ISSN:1079-7114
DOI:10.1103/PhysRevLett.130.166402