Effect of nanoparticle size on the onset temperature of surface melting

In this letter the onset temperature of surface premelting, T_sm, is determined in terms of the mean-field approximation. There are established relationships, describing the dependence of T_sm on a characteristic size of nanoparticles. It is shown that if a radius of a particle, r, exceeds 10 nm approximately, this dependence is weak. On the contrary, it is strong if the radius of a particle is less than 5 nm. The transition of surface layers into the quasi-liquid and pseudo-crystalline states is under consideration, too. A comparison of the proposed model with available experimental data and with molecular dynamics simulations is carried out.