LNM, Institute of Mechanics, Chinese Academy of Sciences , Beijing 100190, China.
Department of Mechanical Engineering and Materials Science and Engineering Program, University of Colorado , Boulder, Colorado 80309, United States.
Nano Lett. 2017 Jan 11;17(1):179-185. doi: 10.1021/acs.nanolett.6b03711. Epub 2016 Dec 8.
Low-dimensional carbon allotropes, from fullerenes, carbon nanotubes, to graphene, have been broadly explored due to their outstanding and special properties. However, there exist significant challenges in retaining such properties of basic building blocks when scaling them up to three-dimensional materials and structures for many technological applications. Here we show theoretically the atomistic structure of a stable three-dimensional carbon honeycomb (C-honeycomb) structure with superb mechanical and thermal properties. A combination of sp bonding in the wall and sp bonding in the triple junction of C-honeycomb is the key to retain the stability of C-honeycomb. The specific strength could be the best in structural carbon materials, and this strength remains at a high level but tunable with different cell sizes. C-honeycomb is also found to have a very high thermal conductivity, for example, >100 W/mK along the axis of the hexagonal cell with a density only ∼0.4 g/cm. Because of the low density and high thermal conductivity, the specific thermal conductivity of C-honeycombs is larger than most engineering materials, including metals and high thermal conductivity semiconductors, as well as lightweight CNT arrays and graphene-based nanocomposites. Such high specific strength, high thermal conductivity, and anomalous Poisson's effect in C-honeycomb render it appealing for the use in various engineering practices.
由于具有出色和特殊的性质，低维碳同素异形体，从富勒烯、碳纳米管到石墨烯，已经得到了广泛的探索。然而，当将它们扩展到用于许多技术应用的三维材料和结构时，存在着显著的挑战，即如何保持这些基本构建块的特性。在这里，我们从理论上展示了一种具有出色机械和热性能的稳定三维碳蜂窝（C-蜂窝）结构的原子结构。壁中的 sp 键合和 C-蜂窝三重结处的 sp 键合的组合是保持 C-蜂窝稳定性的关键。比强度可能是结构碳材料中最好的，并且这种强度在具有不同单元尺寸时仍保持在较高水平但可调。还发现 C-蜂窝具有非常高的热导率，例如，在六边形单元的轴向上>100 W/mK，密度仅约为 0.4 g/cm。由于低密度和高热导率，C-蜂窝的比热导率大于大多数工程材料，包括金属和高热导率半导体，以及轻质 CNT 阵列和基于石墨烯的纳米复合材料。C-蜂窝的这种高比强度、高热导率和反常泊松比使其在各种工程实践中具有吸引力。
