Effect of electron irradiation on the formation and healing of defects in carbon nanotubes

Abstract

The effect of electron irradiation with E = 2 MeV and a dose of 1.9 × 10 17 el/cm 2 of annealed and pristine carbon nanotubes (CNTs) on the electrical conductivity σ(ρ), thermoelectric emf (α), and elastic characteristics during deformation and relaxation during unloading is studied. The annealing of CNTs at 800°C removes the topological defects (the Stone-Wales ones, vacancies, and adatoms) which distort the CNT shape. As is found, after electron irradiation with small doses (0.63 × 10 17 el/cm 2 ), the defects accumu late, while at high doses (1.9 × 10 17 el/cm 2 ) they are healed. The growth and radiation defects lead separately to a topological disorder, reducing the σ(ρ) parameter and increasing α. However, upon irradiation and dur ing the interaction between the defects of different genesis, their healing becomes more effective in compar ison with annealing, and the mechanism of effective healing can be associated with the small CNT sizes, rapid migration of the sputtered atoms between the graphene layers, and their recombination with vacancies.

Radiation tolerance of two-dimensional material-based devices for space applications

“…We note that low-energy X-ray irradiation of graphene in oxygen environments can lead to the formation of oxygen-related defects 43 – 45 . Although radiation-induced healing of nanomaterials has been reported 46 , such an effect has not been observed with γ-rays, specifically not with such remarkable consequences. It is known that the most common defects in exfoliated TMD materials are chalcogen vacancies 47 .…”

“…An increase in photoluminescence and carrier lifetime is very surprising: Initially it was expected that radia-tion could lead to the formation of new defects, but not to defect healing. Although radiation-induced healing of nanomaterials has been reported 35 , such an effect has not been observed with γ-rays, specifically not with such remarkable consequences. It is known that the most common defects in exfoliated TMD materials are chalcogen vacancies 36 .…”

Electrophysical Properties of Composites Based on Hydrogenated Titanium with Different Contents of Thermally Expanded Graphite

“…Electrophysical properties are study by the method described in [19]. The powder samples are placed in a dielectric cylinder under a well-conductive piston, which also plays a role of upper electrode; the metallic bottom of the cylinder is the second electrode.…”

Peculiarities of Electrical Conductivity of Metal/Carbon Nanotubes Array

“…An important role in this case is played by defects that arise both during the synthesis (growth) and under external influences (deformation, radiation irradiation, etc.). They deflect the shape of nanotubes from linear, change the concentration of charge carriers, and the position of the Fermi level as well as the conditions of current passing [14]. In the case of CNTs contact with a metal, it becomes possible to transfer electrons between the components, which affects the electrical conductivity of nanotubes and the composite on their basis, since the contribution of each of the components will depend on the carrier concentration and their mobility.…”

“…On the other hand, a low concentration of electrons in the CNTs makes it possible to easily control the position of the Fermi level: to shift it deep into the valence band with a decrease in the conduction electron concentration or, conversely, into the conduction band, if the metal work function is lower than the work function of CNTs. Methodical point of our investigation [14,15] consists in the use of the CNTs/metal array (mechanical mixture of nanotubes and powder metal, which has the work function smaller than the work function of CNTs). As a result, the electrical conductivity of an array has reached higher values than the corresponding value of each of the components separately.…”