The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe

Abstract The proximity to structural phase transitions in IV-VI thermoelectric materials is one of the main reasons for their large phonon anharmonicity and intrinsically low lattice thermal conductivity κ. However, the κ of GeTe increases at the ferroelectric phase transition near 700 K. Using firs...

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Autores principales:	Đorđe Dangić, Olle Hellman, Stephen Fahy, Ivana Savić
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Materials of engineering and construction. Mechanics of materials TA401-492 Computer software QA76.75-76.765
Acceso en línea:	https://doaj.org/article/67dbfa3c7c8a47f2869661a88dbccbac
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spelling	oai:doaj.org-article:67dbfa3c7c8a47f2869661a88dbccbac2021-12-02T17:39:27ZThe origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe10.1038/s41524-021-00523-72057-3960https://doaj.org/article/67dbfa3c7c8a47f2869661a88dbccbac2021-04-01T00:00:00Zhttps://doi.org/10.1038/s41524-021-00523-7https://doaj.org/toc/2057-3960Abstract The proximity to structural phase transitions in IV-VI thermoelectric materials is one of the main reasons for their large phonon anharmonicity and intrinsically low lattice thermal conductivity κ. However, the κ of GeTe increases at the ferroelectric phase transition near 700 K. Using first-principles calculations with the temperature dependent effective potential method, we show that this rise in κ is the consequence of negative thermal expansion in the rhombohedral phase and increase in the phonon lifetimes in the high-symmetry phase. Strong anharmonicity near the phase transition induces non-Lorentzian shapes of the phonon power spectra. To account for these effects, we implement a method of calculating κ based on the Green-Kubo approach and find that the Boltzmann transport equation underestimates κ near the phase transition. Our findings elucidate the influence of structural phase transitions on κ and provide guidance for design of better thermoelectric materials.Đorđe DangićOlle HellmanStephen FahyIvana SavićNature PortfolioarticleMaterials of engineering and construction. Mechanics of materialsTA401-492Computer softwareQA76.75-76.765ENnpj Computational Materials, Vol 7, Iss 1, Pp 1-8 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Materials of engineering and construction. Mechanics of materials TA401-492 Computer software QA76.75-76.765
spellingShingle	Materials of engineering and construction. Mechanics of materials TA401-492 Computer software QA76.75-76.765 Đorđe Dangić Olle Hellman Stephen Fahy Ivana Savić The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe
description	Abstract The proximity to structural phase transitions in IV-VI thermoelectric materials is one of the main reasons for their large phonon anharmonicity and intrinsically low lattice thermal conductivity κ. However, the κ of GeTe increases at the ferroelectric phase transition near 700 K. Using first-principles calculations with the temperature dependent effective potential method, we show that this rise in κ is the consequence of negative thermal expansion in the rhombohedral phase and increase in the phonon lifetimes in the high-symmetry phase. Strong anharmonicity near the phase transition induces non-Lorentzian shapes of the phonon power spectra. To account for these effects, we implement a method of calculating κ based on the Green-Kubo approach and find that the Boltzmann transport equation underestimates κ near the phase transition. Our findings elucidate the influence of structural phase transitions on κ and provide guidance for design of better thermoelectric materials.
format	article
author	Đorđe Dangić Olle Hellman Stephen Fahy Ivana Savić
author_facet	Đorđe Dangić Olle Hellman Stephen Fahy Ivana Savić
author_sort	Đorđe Dangić
title	The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe
title_short	The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe
title_full	The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe
title_fullStr	The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe
title_full_unstemmed	The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe
title_sort	origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in gete
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/67dbfa3c7c8a47f2869661a88dbccbac
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The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe

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