Abstract In the present study, we investigated thermal conductivity and its structural dependence of a spherical nanodiamond with 2.5 nm in diameter using molecular dynamics simulation. We briefly discussed the difficulty of computing the thermal conductivity of a free nanoparticle using conventional methods and here we derived it from the non-equilibrium molecular dynamics simulation of a composite system where a nanodiamond is sandwiched between two solid blocks. The structural dependence was examined by applying this method based on a composite system to the 2.5 nm nanodiamonds having different ratios of 3- and 4-coordinate carbons (termed sp2-like and sp3-like carbons, respectively), which were obtained from annealing at different temperatures. The thermal conductivity of the nanodiamond decreased from 28 to 10 W/(m·K) with decreasing ratio of sp3-like carbons until the number of sp2-like bonds exceeded that of sp3-like bonds. When sp2-like bond became richer than sp3-like bond, the thermal conductivity was less sensitive to further increase of the ratio of sp2-like carbons. Based on the consideration of the heat transfer associated with a single C C bond, we interpreted that this structural dependence reflects the heat transfer characteristics of sp3- or sp2-like bond, whichever is more abundant. This interpretation, as well as the methodology, is helpful for understanding thermal conductivity of nanodiamonds and other carbon nanomaterials.

中文翻译：

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使用分子动力学模拟评估单个纳米金刚石的热导率及其结构依赖性

摘要 在本研究中，我们使用分子动力学模拟研究了直径为 2.5 nm 的球形纳米金刚石的热导率及其结构依赖性。我们简要讨论了使用传统方法计算自由纳米颗粒的热导率的困难，在这里我们从复合系统的非平衡分子动力学模拟中得出它，其中纳米金刚石夹在两个固体块之间。通过将这种基于复合系统的方法应用于具有不同比例的 3 和 4 配位碳（分别称为 sp2 类和 sp3 类碳）的 2.5 nm 纳米金刚石，它们是通过在不同的温度。纳米金刚石的热导率从 28 W/(m·K) 降低到 10 W/(m·K)，随着 sp3 类碳的比例降低，直到 sp2 类键的数量超过 sp3 类键的数量。当sp2-like键比sp3-like键更丰富时，热导率对sp2-like碳比例的进一步增加不太敏感。基于对与单个 CC 键相关的传热的考虑，我们解释了这种结构依赖性反映了 sp3 或 sp2 类键的传热特性，以更丰富的为准。这种解释以及方法论有助于理解纳米金刚石和其他碳纳米材料的热导率。热导率对 sp2 类碳比例的进一步增加不太敏感。基于对与单个 CC 键相关的传热的考虑，我们解释了这种结构依赖性反映了 sp3 或 sp2 类键的传热特性，以更丰富的为准。这种解释以及方法论有助于理解纳米金刚石和其他碳纳米材料的热导率。热导率对 sp2 类碳比例的进一步增加不太敏感。基于对与单个 CC 键相关的传热的考虑，我们解释了这种结构依赖性反映了 sp3 或 sp2 类键的传热特性，以更丰富的为准。这种解释以及方法论有助于理解纳米金刚石和其他碳纳米材料的热导率。