Npj Comput. Mater.: 非晶碳传热机制—原子配位
类金刚石碳在半个多世纪以来一直备受关注。它是一种非晶碳材料,具有在金刚石和石墨之间可调节的独特性能。根据非晶碳中的sp3含量,可以在很宽的范围内控制其化学和物理特性。由于这些特殊的特性,非晶碳材料已在保护和耐磨涂层、磁存储介质、宽带隙半导体和碳基微机电系统等方面得到应用。已报道的实验和计算结果表明,sp3含量的增加将导致无序碳的热导率更高,且传播模式对调节非晶硅热导率也具有重要影响。然而,关于sp3和sp2键合碳的比率对非晶碳结构的热传输性质影响的系统研究仍然缺失,且碳杂化对非晶碳中不同振动模式的基本特征的影响仍不清楚。
Atomic coordination dictates vibrational characteristics and thermal conductivity in amorphous carbon
Ashutosh Giri, Connor J. Dionne & Patrick E. Hopkins
We discuss the role of atomic coordination in dictating the vibrational characteristics and thermal conductivity in amorphous carbon. Our systematic atomistic simulations on amorphous carbon structures at varying mass densities show the significant role played by the ratio of sp2 to sp3 hybridized bonds in dictating the contributions from propagating (phonon-like) and non-propagating vibrational modes and their influence on the overall thermal conductivities of the structures. Specifically, our results show that as the concentration of sp3-bonded carbon atoms increases, the thermal conductivity can be increased by four fold, which is attributed to enhanced contributions from propagating modes in these amorphous structures. Our results shed more light into the role of atomic coordination on dictating heat transfer mechanisms in amorphous materials, and also provide a deeper understanding of the ability to tune the thermal conductivity of amorphous carbon structures through the control of the local atomic coordination.
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