Liang Qi, Bartnof Matthew, He Ya-Ling, Malen Jonathan A, McGaughey Alan J H
Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China.
Nanoscale Horiz. 2020 Nov 1;5(11):1524-1529. doi: 10.1039/d0nh00358a. Epub 2020 Sep 10.
The thermal conductivity of fullerene-based superatomic crystals (SACs) is investigated using molecular dynamics simulations. The temperature-dependent predictions agree with the trends of previous measurements. The thermal conductivity behavior emerges as a result of the C molecule rotational dynamics and orientation, which are quantified using the root mean square displacements of the carbon atoms and the relative orientations of the Cs. At low temperatures, the Cs exhibit small rotations around equilibrium positions (i.e., librations). When the librating Cs are orientationally-ordered, as in the [C] and [CoSe(PEt)][C] SACs, thermal conductivity decreases with increasing temperature, as is typical for a crystal. When the librating Cs are orientationally-disordered, however, as in the [CoTe(PEt)][C] SAC, thermal conductivity is lower and temperature independent, as is typical for an amorphous solid. At higher temperatures, where the Cs in all three SACs freely-rotate and are thus dynamically disordered, thermal conductivity is temperature independent. The abrupt changes driven by the C dynamics suggest that fullerene-based SACs can be designed to be thermal conductivity switches based on a variety of external stimuli.
使用分子动力学模拟研究了基于富勒烯的超原子晶体（SACs）的热导率。与温度相关的预测结果与先前测量的趋势一致。热导率行为是由C分子的旋转动力学和取向导致的，这可以通过碳原子的均方根位移和C的相对取向来量化。在低温下，C围绕平衡位置进行小幅度旋转（即振动）。当振动的C在取向方面有序时，如在[C]和[CoSe(PEt)][C] SACs中，热导率随温度升高而降低，这是晶体的典型特征。然而，当振动的C在取向方面无序时，如在[CoTe(PEt)][C] SAC中，热导率较低且与温度无关，这是无定形固体的典型特征。在较高温度下，所有三种SAC中的C都自由旋转，因此处于动态无序状态，热导率与温度无关。由C动力学驱动的突然变化表明，基于富勒烯的SAC可以根据各种外部刺激设计成热导率开关。
