The diffusion mechanism of indium atoms along multi-walled carbon nanotubes was studied by means of photo-emission spectromicroscopy and density functional theory calculations. The unusually high (700K) activation temperature for diffusion, the complex C 1s and In 3d5/2 spectra and the calculated adsorption energies and diffusion barriers suggested that indium transport was controlled by the defect concentration in the C network and proceeded via hopping of indium adatoms between C vacancies.

Defect-Controlled Transport Properties of Metallic Atoms Along Carbon Nanotube Surfaces. A.Barinov, H.Üstünel, S.Fabris, L.Gregoratti, L.Aballe, P.Dudin, S.Baroni, M.Kiskinova: Physical Review Letters, 2007, 99[4], 046803