Revisiting the Reduction of Thermal Conductivity in Nano- to Micro-Grained Bismuth Telluride: The Importance of Grain-Boundary Thermal Resistance

Sien Wang, Xiaowei Lu, Ankit Negi, Jixiong He, Kyunghoon Kim, Hezhu Shao, Peng Jiang, Jun Liu, Qing Hao

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Nanograined bulk alloys based on bismuth telluride (Bi2Te3) are the dominant materials for room-temperature thermoelectric applications. In numerous studies, existing bulk phonon mean free path (MFP) spectra predicted by atomistic simulations suggest sub-100 nm grain sizes are necessary to reduce the lattice thermal conductivity by decreasing phonon MFPs. This is in contrast with available experimental data, where a remarkable thermal conductivity reduction is observed even for micro-grained Bi2Te3 samples. In this work, first-principles phonon MFPs along both the in-plane and cross-plane directions are recomputed for bulk Bi2Te3. These phonon MFPs can explain new and existing experimental data on flake-like Bi2Te3 nanostructures with various thicknesses. For polycrystalline Bi2Te3-based materials, a better explanation of the experimental data requires further consideration of the grain-boundary thermal resistance that can largely suppress the transport of high-frequency optical phonons.

Original languageEnglish (US)
Pages (from-to)45-55
Number of pages11
JournalEngineered Science
Volume17
DOIs
StatePublished - 2022

Keywords

  • First principles calculations
  • Grain boundary
  • Phonon mean free path
  • Thermal conductivity
  • Thermal resistance

ASJC Scopus subject areas

  • Engineering(all)
  • Physical and Theoretical Chemistry
  • Chemistry (miscellaneous)
  • Materials Science(all)
  • Energy Engineering and Power Technology
  • Artificial Intelligence
  • Applied Mathematics

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