The relationship between the size-dependent melting point of nanoparticles and the bond number

An integrated model based on the bond number and the bond length in a system is developed to predict the size-dependent thermal characteristics of nanoparticles. It is found that this model can be used to predict the melting point and the cohesive energy of low-dimensional materials without any other adjustable parameters, suggesting that both of them depend on the size and the atomic distance. Since the bond number is one of the geometric parameters of a nanostructure, it can be obtained if the shape of the nanostructure is known. So, the cubo-octahedron is used to describe the shape of nanoparticles. With the decrease in size, the melting point and cohesive energy also decrease, which is due to the decreased bond number. The good agreement of the theoretical prediction with the experimental and molecular dynamic simulation results confirms the validity of the cubo-octahedron in describing the thermodynamic behaviours of nanoparticles even without considering their crystalline structures.