在纳米带中通过不均应变抑制热传输
Lin Yang1, Shengying Yue2, Yi Tao3
1Department of Advanced Manufacturing and Robotics, College of Engineering, Peking University, Beijing, People's Republic of China. linyangpku@pku.edu.cn.
Nature
|May 15, 2024
概括
纳米带中的不均质应变将热导率大大降低34%. 由于应变梯度扩大了声子光谱,加剧了散射和阻碍了热流.
科学领域:
- 材料科学
- 凝聚物质物理学
- 纳米技术
背景情况:
- 纳米级结构可以通过极端应变来实现独特的材料特性.
- 不同质应变对热传输的影响尚不清楚.
- 之前的研究集中在统一的应变对热流的影响上,显示影响有限.
研究的目的:
- 研究纳米带中不均质应变对热传输的影响.
- 在纳米尺度上描述应变依赖的振动谱.
- 在不均应变下阐明导热变化的机制.
主要方法:
- 制造用于单个纳米带的微设备.
- 在受控的异质应变下测量热传输.
- 使用电子能量损失光谱学对应应变的振动光谱进行亚纳米分辨率的表征.
- 支持实验发现的第一原则计算.
主要成果:
- 每纳米0.112%的应变梯度将导热率降低了34%±5%.
- 沿着应变梯度观察到几毫电子伏特的峰转移.
- 不同质的压力导致了显著的声子光谱扩大,增强了声子散射.
结论:
- 不同质的压力明显阻碍了纳米带的热传输,与均的压力不同.
- 在不均应变下光谱的扩大是降低导热性的关键机制.
- 这项研究提供了对不均应力下的格子动态的关键见解.
相关概念视频
Thermal Strain
984
Thermal strain is a concept that arises when we consider how temperature changes affect structures. Unlike the conventional assumption that structures remain constant under load, real-world scenarios often involve temperature fluctuations that can significantly impact these structures. Consider a homogeneous rod with a uniform cross-section resting freely on a flat horizontal surface. If the rod's temperature increases, the rod elongates. This elongation is proportional to the temperature...
984
Types of Semiconductors
588
Intrinsic semiconductors are highly pure materials with no impurities. At absolute zero, these semiconductors behave as perfect insulators because all the valence electrons are bound, and the conduction band is empty, disallowing electrical conduction. The Fermi level is a concept used to describe the probability of occupancy of energy levels by electrons at thermal equilibrium. In intrinsic semiconductors, the Fermi level is positioned at the midpoint of the energy gap at absolute zero. When...
588


