The cluster formation of Ag adatoms on C nanotubes was investigated in order to deduce the curvature effect upon surface diffusion. By analyzing the cluster density as a function of the deposition time, t, for various diameters, dc, of C nanotubes, the scaling form for describing the curvature effect on surface diffusion in the first-order approximation was obtained. It was found that the curvature effect upon surface diffusion could be well described by using the relationship between the deposition time and the scaled deposition time, τ, in the form, τ ~ tdc-z, where z was an exponent which characterized the geometrical properties of C nanotubes and the nanotube helicity. The value of z for the armchair-type C nanotube was larger than those for the zig-zag type and the chiral-type C nanotubes. The scaling form was further demonstrated and verified by numerical simulations, and was explained by the 2-dimensional random walk model.

Curvature Effect on the Surface Diffusion of Silver Adatoms on Carbon Nanotubes - Deposition Experiments and Numerical Simulations. M.C.Wu, C.L.Li, C.K.Hu, Y.C.Chang, Y.H.Liaw, L.W.Huang, C.S.Chang, T.T.Tsong, T.Hsu: Physical Review B, 2006, 74[12], 125424 (8pp)