Influence of structure disorder on the lattice thermal conductivity of polycrystals: A frequency-dependent phonon-transport study

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Abstract

It is widely accepted that the lattice thermal conductivity of a polycrystal mainly depends on its grain sizes, phonon mean free paths, and grain-boundary thermal resistance. However, uncertainties always exist on how much grain misalignment and a wide grain size distribution in a real polycrystal could affect the thermal analysis. Considering frequency-dependent phonon mean free paths, the influence of these factors is carefully examined by phonon Monte Carlo simulations for a series of disordered silicon polycrystals with grain sizes ranging from 1 to 400 nm. More generally, simulations are also performed on thermally anisotropic polycrystals. Despite all structure variation, this work suggests that the direction-averaged lattice thermal conductivity of a polycrystal is always close to that of an aligned polycrystal, with an effective grain size matching the interface density of the studied polycrystal.

Original languageEnglish (US)
Article number014309
JournalJournal of Applied Physics
Volume111
Issue number1
DOIs
Publication statusPublished - Jan 1 2012

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ASJC Scopus subject areas

  • Physics and Astronomy(all)

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