Thermal Rectification in Three-Dimensional Asymmetric Nanostructure
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- 作者：Jonghoon Lee ; Vikas Varshney ; Ajit K. Roy ; John B. Ferguson ; Barry L. Farmer
- 刊名：Nano Letters
- 出版年：2012
- 出版时间：July 11, 2012
- 年：2012
- 卷：12
- 期：7
- 页码：3491-3496
- 全文大小：325K
- 年卷期：v.12,no.7(July 11, 2012)
- ISSN：1530-6992
文摘
Previously, thermal rectification has been reported in several low-dimensional shape-asymmetric nanomaterials. In this Letter, we demonstrate that a three-dimensional crystalline material with an asymmetric shape also displays as strong thermal rectification as low-dimensional materials do. The observed rectification is attributed to the stronger temperature dependence of vibration density of states in the narrower region of the asymmetric material, resulting from the small number of atomic degrees of freedom directly interacting with the thermostat. We also demonstrate that the often reported 鈥渄evice shape asymmetry鈥?is not a sufficient condition for thermal rectification. Specifically, the size asymmetry in boundary thermal contacts is equally important toward determining the magnitude of thermal rectification. When the boundary thermal contacts retain the same size asymmetry as the nanomaterial, the overall system displays notable thermal rectification, in accordance with existing literature. However, when the wider region of the asymmetric nanomaterial is partially thermostatted by a smaller sized contact, thermal rectification decreases dramatically and even changes direction.