In situ transmission electron microscopy observation of keV-ion irradiation of single-walled carbon and boron nitride nanotubes

Abstract

Single-walled carbon nanotubes (SWCNNT) and single-walled boron nitride nanotubes (SWBNNT) were irradiated with 30keV Kr+ ions at room temperature. The structural changes during irradiation were monitored in situ using transmission electron microscopy (TEM) and ex situ at certain dose points using Raman spectroscopy. Our measurements demonstrate that metallic/semiconducting SWCNNT and insulating SWBNNT undergo similar structural modifications due to keV-ion irradiation. Point defects due to primary knock-on events accumulate and lead to the formation of defect complexes and eventual amorphization. The loss of atoms due to sputtering reduces the nanotube diameter and leads to shrinkage. Time resolved footage of the ion irradiation of a particular area demonstrated that NT scission and subsequent shortening can take place with some probability, possibly due to collision cascade events.