Wan Yingchun, Xiong Shiyun, Ouyang Bin, Niu Zhihui, Ni Yuxiang, Zhao Yu, Zhang Xiaohong
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, 199 Ren'ai Road, Suzhou, 215123 Jiangsu, P. R. China.
Department of Materials Science and Engineering, University of California Berkeley, Berkeley, California 94720, United States.
ACS Omega. 2019 Feb 25;4(2):4147-4152. doi: 10.1021/acsomega.9b00074. eCollection 2019 Feb 28.
Understanding the details of thermal transport in graphdiyne and its nanostructures would help to broaden their applications. On the basis of the molecular dynamics simulations and spectrally decomposed heat current analysis, we show that the high-frequency phonons in graphdiyne can be strongly hindered in nanoribbons because of the boundary scattering. The isotropic transport in graphdiyne can be switched to anisotropic along the armchair and zigzag directions. Adding side chains onto the nanoribbon edges further reduces the thermal conductivity (TC) along both armchair and zigzag directions thanks to the reduction of heat current carried by low-frequency modes, a mechanism that arises from the phonon resonances. The uniaxial tensile strain plays a different role in the TC of graphdiyne, armchair nanoribbons, and zigzag nanoribbons. Tensile strain causes the thermal conductivities of graphdiyne, and armchair nanoribbons increase first and then get reduced, whereas for zigzag nanoribbons, the TC decreases with strain first and reaches to a plateau. The different low-frequency phonon response on strain is the main reason for the different TC behavior. For graphdiyne and armchair nanoribbons, the low-frequency heat current is enhanced gradually first and then get reduced with the increase of strain, while that of zigzag nanoribbons decreases with strain and then increases slightly. The current studies could help us understand the phonon transport in graphdiyne and its nanoribbons, which is useful for their TC engineering.
了解石墨炔及其纳米结构中的热输运细节将有助于拓宽它们的应用范围。基于分子动力学模拟和频谱分解热流分析，我们表明，由于边界散射，石墨炔中的高频声子在纳米带中会受到强烈阻碍。石墨炔中的各向同性输运可以沿扶手椅方向和锯齿方向转变为各向异性。在纳米带边缘添加侧链，由于低频模式携带的热流减少，这是一种由声子共振产生的机制，从而进一步降低了沿扶手椅方向和锯齿方向的热导率。单轴拉伸应变在石墨炔、扶手椅型纳米带和锯齿型纳米带的热导率中起着不同的作用。拉伸应变导致石墨炔和扶手椅型纳米带的热导率先增加后降低，而对于锯齿型纳米带，热导率随应变先降低并达到一个平稳状态。应变对低频声子的不同响应是热导率行为不同的主要原因。对于石墨炔和扶手椅型纳米带而言 , 低频热流随应变增加先逐渐增强然后降低，而锯齿型纳米带的低频热流随应变降低然后略有增加。目前的研究有助于我们理解石墨炔及其纳米带中的声子输运，这对它们的热导率工程是有用的。
