石墨化对碳纳米管结构与电学性能的影响

在氮气气氛及2700℃温度下，对富含结构缺陷的具有Turbostratic形貌特征的碳纳米管原料进行高温石墨化处理，利用高分辨透射电子显微镜以及自主开发的基于透射电镜的原位性能表征系统对石墨化前后的碳管结构和导电性能进行了研究. 实验结果表明：经过高温石墨化处理后，碳管结构转变为类似于竹节状或管状的锥面结构，锥角为10°~30°，管径为10~40nm. 从锥角数据推算出锥面形成时的旋转位移角中均包含了一个附加的重叠角，说明石墨化后的碳管主要以螺旋的锥面结构为主，且弯曲的螺旋锥面靠∑7、∑13和∑19等重位点阵来稳定. 导电性能测量的结果表明具有螺旋锥面结构的纳米碳管呈半导体特性.

Effect of Graphitization on the Structures and Conducting Property of Carbon Nanotubes

Turbostratic carbon nanotubes (CNTs) were treated in nitrogen atmosphere at 2700℃. High resolution transmission electron microscope (HRTEM) was used to investigate the structural changes of CNTs. Meanwhile, the conducting property was measured via a self built setup installed in TEM. The structures of CNTs are found to change into bamboo like or tubular cones after graphitization. The apex angles of cones rang from 10° to 30°, and the tubular diameter ranges from 10nm to 40nm. Electron diffraction analysis reveals that an additional overlap angle is involved in the disclination operation of cones, suggesting the helical conical structural characteristics of CNTs. The highly curved filamental structures are stabilized via interlayer coincidence site lattices of ∑13 , ∑7 , and ∑19 type. The conducting measurement indicates that the helical conical CNTs are semiconductors.