Sorption and diffusion of scandium and titanium atoms on carbon nanotubes surface

The study focuses on carbon nanotubes (CNT) surface modification with transition metal atoms. CNT modification expands their scope and makes them more perspective in the production of micro- and nanoelectronic devices, which, in turn, can find application in electronic control units of space technology. We have considered the possibility of scandium and titanium atoms coating on the CNT surface. Selection of atoms is due to the potential possibility of creating uniform coating by these atoms that is impotent for practice application. The adsorbing capacity and the mobility of atoms play an important role during coating formation. Until now it has not revealed whether the non-uniformity obtained in the experiment is fundamental property or it depends on coating process technology. Understanding the basics of coating formation will help control this process. It is possible that the uniform coating can be formed only on tubes with certain chirality or diameter. In this research we propose and study the influence of radius, chirality and conductive properties of nanotubes on its interaction with scandium and titanium atoms. The theoretical study of single scandium and titanium atoms interaction with a set of carbon nanotubes ”zigzag” and “armchair” types has represented. The radius dependence of binding energies (Есв) and activation energies (Еа) for surface diffusion transition metal atoms in two nonequivalent directions are built. The influence of radius, chirality and conductive properties of nanotubes on Есв and Еа values are evaluated. The results show more strong interaction between the surface of the carbon skeleton and titanium atoms as compared with scandium atoms. The curvature of the carbon skeleton also facilitates more strong interaction between studied atoms and the surface of the nanotubes. It has revealed that the degree of influence on binding energy and diffusion barrier values decreases in the set: chirality - conductive properties - radius. In general, values of activation energies are low, that reports on possibility of atoms moving. Such possibility will facilitate the formation of the uniform coating. The data presented have been obtained density functional theory approach and the Vienna Ab initio simulation package (VASP). Nudged elastic band method has been used for finding transition states and potential transition barriers of metal atoms moving on CNT surfaces.