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Fullerene rotational dynamics generate disordered configurations that suppress thermal conductivity in superatomic crystals.
Nanoscale Horizons ( IF 8.0 ) Pub Date : 2020-09-04 , DOI: 10.1039/d0nh00358a Qi Liang 1 , Matthew Bartnof , Ya-Ling He , Jonathan A Malen , Alan J H McGaughey
Nanoscale Horizons ( IF 8.0 ) Pub Date : 2020-09-04 , DOI: 10.1039/d0nh00358a Qi Liang 1 , Matthew Bartnof , Ya-Ling He , Jonathan A Malen , Alan J H McGaughey
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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 C60 molecule rotational dynamics and orientation, which are quantified using the root mean square displacements of the carbon atoms and the relative orientations of the C60s. At low temperatures, the C60s exhibit small rotations around equilibrium positions (i.e., librations). When the librating C60s are orientationally-ordered, as in the [C60] and [Co6Se8(PEt3)6][C60]2 SACs, thermal conductivity decreases with increasing temperature, as is typical for a crystal. When the librating C60s are orientationally-disordered, however, as in the [Co6Te8(PEt3)6][C60]2 SAC, thermal conductivity is lower and temperature independent, as is typical for an amorphous solid. At higher temperatures, where the C60s in all three SACs freely-rotate and are thus dynamically disordered, thermal conductivity is temperature independent. The abrupt changes driven by the C60 dynamics suggest that fullerene-based SACs can be designed to be thermal conductivity switches based on a variety of external stimuli.
中文翻译：
富勒烯旋转动力学产生无序的构型，该构型抑制了超原子晶体的导热性。
使用分子动力学模拟研究了基于富勒烯的超原子晶体（SAC）的热导率。与温度有关的预测与以前的测量趋势一致。由于C 60分子的旋转动力学和取向而产生了热导行为，这些动力学和取向是使用碳原子的均方根位移和C 60 s的相对取向来量化的。在低温下，C 60 s围绕平衡位置（即自由度）表现出较小的旋转。当解离C 60 s取向有序时，如[C 60 ]和[Co 6 Se 8（PEt3） 6 ] [C 60 ] 2 SAC，其导热性随温度升高而降低，这是晶体的典型现象。但是，如[Co 6 Te 8（PEt 3） 6 ] [C 60 ] 2 SAC那样，当解离C 60 s取向紊乱时，导热率较低且与温度无关，这是无定形固体的典型现象。在较高的温度下，所有三个SAC中的C 60都自由旋转并因此动态地无序，因此热导率与温度无关。C 60驱动的突然变化 动力学表明，基于富勒烯的SAC可以设计为基于各种外部刺激的热导开关。
更新日期：2020-09-10
中文翻译：
富勒烯旋转动力学产生无序的构型，该构型抑制了超原子晶体的导热性。
使用分子动力学模拟研究了基于富勒烯的超原子晶体（SAC）的热导率。与温度有关的预测与以前的测量趋势一致。由于C 60分子的旋转动力学和取向而产生了热导行为，这些动力学和取向是使用碳原子的均方根位移和C 60 s的相对取向来量化的。在低温下，C 60 s围绕平衡位置（即自由度）表现出较小的旋转。当解离C 60 s取向有序时，如[C 60 ]和[Co 6 Se 8（PEt3） 6 ] [C 60 ] 2 SAC，其导热性随温度升高而降低，这是晶体的典型现象。但是，如[Co 6 Te 8（PEt 3） 6 ] [C 60 ] 2 SAC那样，当解离C 60 s取向紊乱时，导热率较低且与温度无关，这是无定形固体的典型现象。在较高的温度下，所有三个SAC中的C 60都自由旋转并因此动态地无序，因此热导率与温度无关。C 60驱动的突然变化 动力学表明，基于富勒烯的SAC可以设计为基于各种外部刺激的热导开关。
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