In Situ TEM Study on the Electrical and Field-Emission Properties of Individual Fe3C-Filled Carbon Nanotubes

The electrical and electron field-emission characteristics of individual Fe3C-filled CNTs were investigated using a scanning tunneling microscope inside a transmission electron microscope. Larger bias sweeping across a CNT can bring about the melting, resolidifying, and decomposition of the encapsulated Fe3C, which causes structural damage to the CNT. However, the resistance of the CNT reduces significantly after large bias sweep because the graphitization of CNT walls improves and the contact resistance reduces. To get more insights into the mechanism, the microstructure evolution of Fe3C and the reaction between Fe3C and CNT during near-equilibrium reaction processes were studied. It was found that thin graphenes form when the Fe3C fillers decompose by joule heating, which may open up a new route for the graphene fabrication. The field-emission behavior of a single Fe3C-filled CNT was analyzed based on Fowler-Nordheim theory, which suggested only 8.4% of the hemispherical cap is responsible for the electron emission.