Anisotropic thermal conductivity tensor of β-Y2Si2O7 for orientational control of heat flow on micrometer scales
Anisotropic thermal conductivity tensor of β-Y2Si2O7 for orientational control of heat flow on micrometer scales
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DOI：
10.1016/j.actamat.2020.02.040
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发表时间：
2020-05-01
期刊：
影响因子：
9.4
通讯作者：
Hopkins, Patrick E.
中科院分区：
文献类型：
--
作者：
Olson, David H.;Avincola, Valentina Angelici;Hopkins, Patrick E.
将热导率的空间变化各向异性与晶体结构联系起来的能力将为我们理解依赖于长度尺度的热流提供基础的进步。然而，挑战在于确定具有各向异性晶体结构的多晶系统的导热张量。具有各向异性性质的随机取向多晶的表观各向同性导热系数在接近晶粒度的长度尺度上分解。因此，从宏观尺度上测量的各向同性导热系数可能与在纳米或微米尺度上测量的导热系数有很大不同，因此微观尺度的各向异性热流可能是看似各向同性导热系数的基础。实验研究了多晶β相二硅酸钇(β-Y2Si2O7)的各向异性导热系数。这是通过与单个颗粒的物相和取向相关的微米分辨率热导率测绘实现的，从而能够确定β-Y2Si2O7的热导率张量。我们的结果首次基于热导率的空间分布再现了具有各向异性晶体结构的多晶系统的热导率张量。(C)2020 Acta Materialia Inc.由爱思唯尔有限公司出版。版权所有。
The ability to relate the spatially-varying anisotropy of thermal conductivity to crystal structure would provide a foundational advance in our understanding of length-scale dependent heat flow. The challenge, however, is in determining the thermal conductivity tensor in polycrystalline systems with anisotropic crystal structures. Apparent isotropic thermal conductivity in randomly oriented polycrystals with anisotropic properties break down at length scales approaching the grain size. As a result, a measured isotropic thermal conductivity from the macroscale perspective may differ greatly from that measured at the nano or microscale, and thus microscale anisotropic heat flow could underlie a seemingly isotropic thermal conductivity. We experimentally investigate the anisotropic thermal conductivity in polycrystalline beta-phase yttrium disilicate (beta-Y2Si2O7). This is achieved through micrometer-resolution thermal conductivity mapping correlated to the phase and orientation of individual grains, allowing for the determination of the thermal conductivity tensor of beta-Y2Si2O7. Our results are the first to reproduce the thermal conductivity tensor of a polycrystalline system with anisotropic crystal structure based on the spatial distribution of thermal conductivity. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.