Reversible high-pressure carbon nanotube vessel

Applying a full pressure loop, i.e., loading and unloading, on a nanocrystal with in situ observation remains a challenge to experimentalists up until now. Using a multiwalled carbon nanotube, we realize the pressure loop acting on a Fe3 C nanocrystal (with peak value 20 GPa) by electron-beam irradiation with in situ observations inside transmission electron microscopy at 500°C/ambient temperature. Using density-functional theory calculations, we attribute the unloading process to the formation of one dangling-bond single vacancies under the electron-beam irradiation at room temperature. A theoretical model is presented to understand the process and the results agree well with the experimental measurements.