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Minimum thermal conductivity in the context of diffuson-mediated thermal transport

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Abstract

A model for the thermal conductivity of bulk solids is proposed in the limit of diffusive transport mediated by diffusons as opposed to phonons. This diffusive thermal conductivity, κdiff, is determined by the average energy of the vibrational density of states, ℏωavg, and the number density of atoms, n. Furthermore, κdiff is suggested as an appropriate estimate of the minimum thermal conductivity for complex materials, such that (at high temperatures): Image ID:c7ee03256k-t1.gif. A heuristic finding of this study is that the experimental ωavg is highly correlated with the Debye temperature, allowing κdiff to be estimated from the longitudinal and transverse speeds of sound: Image ID:c7ee03256k-t2.gif. Using this equation to estimate κmin gives values 37% lower than the widely-used Cahill result and 18% lower than the Clarke model for κmin, on average. This model of diffuson-mediated thermal conductivity may thus help explain experimental results of ultralow thermal conductivity.

Graphical abstract: Minimum thermal conductivity in the context of diffuson-mediated thermal transport

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Publication details

The article was received on 14 Nov 2017, accepted on 01 Feb 2018 and first published on 01 Feb 2018


Article type: Paper
DOI: 10.1039/C7EE03256K
Citation: Energy Environ. Sci., 2018, Advance Article
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    Minimum thermal conductivity in the context of diffuson-mediated thermal transport

    M. T. Agne, R. Hanus and G. J. Snyder, Energy Environ. Sci., 2018, Advance Article , DOI: 10.1039/C7EE03256K

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