Direct Visualization of Thermal Conductivity Suppression Due to Enhanced Phonon Scattering Near Individual Grain Boundaries
| Autor: | Tingyu Bai, Ramez Cheaito, Samuel Graham, Kenneth E. Goodson, Mehdi Asheghi, Thomas L. Bougher, Mark S. Goorsky, Yekan Wang, Heungdong Kwon, Luke Yates, Chao Li, Aditya Sood |
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| Rok vydání: | 2018 |
| Předmět: |
Materials science
Phonon FOS: Physical sciences Bioengineering Time-domain thermoreflectance Applied Physics (physics.app-ph) 02 engineering and technology 01 natural sciences Thermal conductivity Condensed Matter::Superconductivity Mesoscale and Nanoscale Physics (cond-mat.mes-hall) 0103 physical sciences General Materials Science 010302 applied physics Condensed Matter - Materials Science Phonon scattering Condensed matter physics Condensed Matter - Mesoscale and Nanoscale Physics Mechanical Engineering Materials Science (cond-mat.mtrl-sci) General Chemistry Physics - Applied Physics 021001 nanoscience & nanotechnology Condensed Matter Physics Thermal conduction Grain boundary Crystallite 0210 nano-technology Electron backscatter diffraction |
| Zdroj: | Nano letters. 18(6) |
| ISSN: | 1530-6992 |
| Popis: | Understanding the impact of lattice imperfections on nanoscale thermal transport is crucial for diverse applications ranging from thermal management to energy conversion. Grain boundaries (GBs) are ubiquitous defects in polycrystalline materials, which scatter phonons and reduce thermal conductivity. Historically, their impact on heat conduction has been studied indirectly through spatially-averaged measurements, that provide little information about phonon transport near a single GB. Here, using spatially-resolved time-domain thermoreflectance (TDTR) measurements in combination with electron backscatter diffraction (EBSD), we make localized measurements of thermal conductivity within few \mu m of individual GBs in boron-doped polycrystalline diamond. We observe strongly suppressed thermal transport near GBs, a reduction in conductivity from ~1000 W/m-K at the center of large grains to ~400 W/m-K in the immediate vicinity of GBs. Furthermore, we show that this reduction in conductivity is measured up to ~10 \mu m away from a GB. A theoretical model is proposed that captures the local reduction in phonon mean-free-paths due to strongly diffuse phonon scattering at the disordered grain boundaries. Our results provide a new framework for understanding phonon-defect interactions in nanomaterials, with implications for the use of high thermal conductivity polycrystalline materials as heat sinks in electronics thermal management. Comment: This document is the unedited Author's version of a submitted work that was subsequently accepted for publication in Nano Letters, copyright American Chemical Society after peer review. To access the final edited and published work see this URL: https://pubs.acs.org/doi/10.1021/acs.nanolett.8b00534. Version 2: Updates Supplementary Figs S1 and S3. The journal published version is correct |
| Databáze: | OpenAIRE |
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