Materials and Manufacturing Directorate, Wright Patterson Air Force Base, Dayton, Ohio, USA .
ACS Nano. 2010 Feb 23;4(2):1153-61. doi: 10.1021/nn901341r.
Carbon nanotubes (CNT) and graphene are considered as potential future candidates for many nano/microscale integrated devices due to their superior thermal properties. Both systems, however, exhibit significant anisotropy in their thermal conduction, limiting their performance as three-dimensional thermal transport materials. From thermal management perspective, one way to tailor this anisotropy is to consider designing alternative carbon-based architectures. This paper investigates the thermal transport in one such novel architecture-a pillared-graphene (PG) network nanostructure which combines graphene sheets and carbon nanotubes to create a three-dimensional network. Nonequilibrium molecular dynamics simulations have been carried out using the AIREBO potential to calculate the thermal conductivity of pillared-graphene structures along parallel (in-plane) as well as perpendicular (out-of-plane) directions with respect to the graphene plane. The resulting thermal conductivity values for PG systems are discussed and compared with simulated values for pure CNT and graphite. Our results show that in these PG structures, the thermal transport is governed by the minimum interpillar distance and the CNT-pillar length. This is primarily attributed to scattering of phonons occurring at the CNT-graphene junctions in these nanostructures. We foresee that such architecture could potentially be used as a template for designing future structurally stable microscale systems with tailorable in-plane and out-of-plane thermal transport.
碳纳米管（CNT）和石墨烯由于其优异的热性能，被认为是许多纳米/微尺度集成器件的潜在未来候选材料。然而，这两种系统在热传导方面都表现出显著的各向异性，限制了它们作为三维热传输材料的性能。从热管理的角度来看，一种调整这种各向异性的方法是考虑设计替代的基于碳的架构。本文研究了一种新型架构的热传输，即支柱石墨烯（PG）网络纳米结构，它结合了石墨烯片和碳纳米管，以创建一个三维网络。使用 AIREBO 势进行了非平衡分子动力学模拟，以计算相对于石墨烯平面的平行（面内）和垂直（面外）方向上的支柱石墨烯结构的热导率。讨论了 PG 系统的热导率值，并与纯 CNT 和石墨的模拟值进行了比较。我们的结果表明，在这些 PG 结构中，热传输受最小支柱间距离和 CNT 支柱长度的控制。这主要归因于在这些纳米结构中 CNT-石墨烯结处发生的声子散射。我们预计，这种架构有可能被用作设计未来结构稳定的微尺度系统的模板，这些系统具有可调节的面内和面外热传输。
