Elastic inhomogeneity and anomalous thermal transport in ultrafine Si phononic crystals
Elastic inhomogeneity and anomalous thermal transport in ultrafine Si phononic crystals
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DOI：
10.1016/j.nanoen.2020.104581
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发表时间：
2020-05
期刊：
影响因子：
17.6
通讯作者：
Kouhei Takahashi;M. Fujikane;Yuxuan Liao;Makoto Kashiwagi;T. Kawasaki;Naoki Tambo;S. Ju;Y. Naito;J. Shiomi
中科院分区：
文献类型：
--
作者：
Kouhei Takahashi;M. Fujikane;Yuxuan Liao;Makoto Kashiwagi;T. Kawasaki;Naoki Tambo;S. Ju;Y. Naito;J. Shiomi
通过声子工程控制纳米尺度的热输运是电子器件和高性能热电器件中新型热管理的一条有前途的途径。在这里，我们报告说，超细纳米纤维使我们能够改变晶格振动特性，从而以一种不寻常的方式降低材料的热导率。这在具有二维通孔阵列的超细硅（Si）声子晶体中得到了证明。我们发现，Si的热导率可以降低到远低于声子粒子模型预测的理论极限时，通孔被安排在次100 nm的周期。在这些细声子晶体中识别出显著的弹性软化，这表明晶格振动性质的变化。有趣的是，我们发现弹性的变化发生局部和非均匀的，这表明在声子晶体中需要考虑额外的声子散射机制或声速的变化。本研究结果为理解固体热输运提供了新的思路，并为定制热能相关材料和器件中的声子输运开辟了新的途径。
Controlling nanoscale thermal transport via phonon engineering is a promising path for novel thermal management in electronic devices and high performance thermoelectrics. Here we report that ultrafine nanofabrication allows us to change the lattice vibrational properties such that reduces the material thermal conductivity in an unusual manner. This is demonstrated in ultrafine silicon (Si) phononic crystals with two-dimensional arrays of through-holes. We reveal that thermal conductivity of Si can be reduced far below the theoretical limit predicted from a phonon particle model when the through-holes are arranged at sub-100 nm periods. Significant elastic softening is identified in these fine phononic crystals, which indicates change in the lattice vibrational properties. Interestingly, we find that the change in elasticity occurs locally and non-uniformly, suggesting that additional phonon scattering mechanism or a change in sound velocity needs to be considered in phononic crystals. The present result provides new thinking for understanding thermal transport of solids and opens a new avenue to tailor phonon transport in thermal-energy-related materials and devices.