Ultralow Thermal Conductivity Approaching the Disordered Limit in Crystalline TlCuZrSe3

Rohj, RK and Bhui, A and Sett, S and Ghosh, A and Biswas, K and Sarma, DD (2024) Ultralow Thermal Conductivity Approaching the Disordered Limit in Crystalline TlCuZrSe3. In: Chemistry of Materials, 37 (1). pp. 520-529.

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Abstract

A comprehensive understanding of thermal transport is crucial for many applications, including heat dissipation systems, thermal barrier coatings, and harnessing potentials of thermoelectric materials. Here, we report an ultralow thermal conductivity, κ, in a p-type layered chalcogenide, TlCuZrSe3. Our investigation reveals that the anisotropic values of κ in two perpendicular directions in this compound vary between 0.88 and 0.41 Wm-1K-1 and 1.15-0.62 Wm-1K-1, respectively, over the temperature range of 295-600 K. The low-temperature specific heat data could only be explained by considering Einstein oscillator terms in addition to the conventional Debye model-based contributions, consistent with the presence of localized Tl1+ rattlers. The unique anisotropic crystal structure of TlCuZrSe3 and the rattling of Tl1+ ions lead to the generation of low-frequency phonons. These relatively flat optical phonon modes hybridize with acoustic phonons, giving rise to strong anharmonicity and phonon scattering channels. Raman spectroscopy confirms that these low-frequency phonon modes have extremely short lifetimes (�1 ps), explaining the ultralow κ values, approaching the disordered limit, in this highly crystalline material. © 2024 American Chemical Society.

Item Type:	Journal Article
Publication:	Chemistry of Materials
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to American Chemical Society
Keywords:	Germanium alloys; Germanium compounds; Granite; Layered semiconductors; Metamorphic rocks; Phonon scattering; Phonons; Selenium compounds; Single crystals; Thermal barrier coatings; Thermal conductivity of solids, Barrier coatings; Layered chalcogenides; Low-frequency phonon; P-type; Temperature range; Thermal; Thermal barrier; Thermal transport; Thermo-Electric materials; Thermoelectric material, Anisotropy
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit Division of Physical & Mathematical Sciences > Physics
Date Deposited:	24 Jan 2025 16:01
Last Modified:	24 Jan 2025 16:01
URI:	http://eprints.iisc.ac.in/id/eprint/87268

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