Size-, Shape-, and Dimensionality-Dependent Melting Temperatures of Nanocrystals

On the basis of a model for size-dependent cohesive energy, the size, shape, and dimensionality effects on melting temperatures of nanocrystals are modeled in a unified form. The model predicts that the melting temperature T m ( D, d,λ) decreases with reducing size D and dimensionality d or increasing shape factor λ. For nanoparticles with the same D values, there is T m (icosahedron) > T m (sphere or cube) > T m (octahedron) > T m (tetrahedron). Moreover, the ratio of depression of T m ( D, d,λ) is about 1:2λ wire:3λ particle for thin films, nanowires, and nanoparticles when D is large enough, for example, 6 nm. The model is found to be in accordance with available experimental, MD simulation, and other theoretical results for Au, Ag, Ni, Ar, Si, Pb, and In nanocrystals.