Department of Frontier Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, 466-8555 Japan.
ACS Nano. 2012 Nov 27;6(11):9567-73. doi: 10.1021/nn302889e. Epub 2012 Oct 16.
In situ transmission electron microscopy (TEM) of single Fe-included carbon nanofibers (CNFs) revealed that the fine polycrystalline structure in the shank region of CNFs transformed to graphitic, hollow structures during a field emission (FE) process. The iron metal platelets agglomerated during the FE process and perceptibly were emitted from the shank, which featured bamboo-like carbon nanotube (CNT) structures. The structural evolution also improved the electrical properties, and the FE current was remarkably increased, that is, 1000 times higher than the initial value (from 10(-9) to 10(-6) A). The structural transformations were effectuated by Joule heating that generated simultaneously during the FE process. The in situ TEM study of room-temperature-synthesized CNFs could provide essential information regarding CNFs' structural transformation for their possible application in future electron emitter sources.
原位透射电子显微镜（TEM）观察单个含 Fe 的碳纳米纤维（CNF）表明，在场发射（FE）过程中，CNF 柄部的细多晶结构转变为石墨化、空心结构。在 FE 过程中，铁金属薄片聚集在一起，并明显从具有竹状碳纳米管（CNT）结构的柄部发射出来。结构演变还改善了电性能，FE 电流显著增加，即从 10^-9 增加到 10^-6 A，增加了 1000 倍。FE 过程中同时产生的焦耳加热导致了结构的转变。对室温合成的 CNFs 的原位 TEM 研究可以为 CNFs 的结构转变提供重要信息，以便将来可能将其应用于电子发射源。
