Effect of size, surface and depletion on melting loop of individual Cu-Ni nanoparticle

Dr. Aram Shirinyan, “Physical-chemical materials science” center of NASU and Kyiv National University, Ukraine

Video was recorded during the 3rd International research and practice Conference "Nanotechnology and Nanomaterials", Lviv, August 2015.

Modified thermodynamic approach to describe the thermodynamic properties including the size effect is suggested taking into account the nucleation and chemical depletion so that the Gibbs free energy of a nanosystem was reassessed as function of composition, temperature and particle size. Such methodology has been applied for the size- and composition-dependent melting of the isolated solid Cu-Ni spherical nanoparticle at 25nm radius. Equilibrium states in two-phase region are investigated from 1000K up to 1700K, and the melting characteristics are determined. It is shown that nanomelting loops in temperature-composition phase diagram (at fixed initial composition and the number of atoms) do not coincide with solidus and liquidus. It is found that Cu-Ni nanoparticle can melt in different stages whereas the dominant transition morphology is surface-induced melting that proceeds from the surface bob like liquid part towards the core region and then whole nanoparticle.