Modelling for the Prediction of Melting Temperature for Metallic Nanoparticles

At nano level, materials show very interesting physical properties with the variation of shape and size. The prediction of this behaviour has been a burning issue in the recent years in the scientific community as well. Even the physical properties of these materials are poorly investigated experimentally. To explain the sharp change in the properties of metals, as reported by some investigators, at their nanolevel, different models have been proposed. It is observed that in their theoretical prediction, they have not considered the exact arrangement of atoms in the lattice. In our attempt to understand the behaviour of the nanomaterials, we have studied the melting temperature of some nanosolids having face centered cubic lattice such as Aluminium (Al), Copper (Cu), Paladium (Pd), Platinum (Pt) and Gold (Au), considering different shapes with their sizes ranging from 30 nm to more smaller dimensions. For modelling analysis, we have considered the very basic and fundamental relation of cohesive energy with melting temperature along with modification with two realistic physical quantities-packing fraction and particle shape factor simultaneously to account the arrangements of atoms within the nanoparticle and on the surface as well. Our study shows that there is a very marked change in the melting temperature of the metallic nanosolids below 20 nm. Although in the earlier reported works, it has been claimed that this variation occurs at somewhat higher values. In this variation, the tetrahedral structure exhibits maximum variation of melting temperature while spherical one corresponds to the minimum change. In case of gold, our simulated data has been compared with available experimental values which is found in good agreement with it. This agreement between experimental and computed data validates our proposed model for the prediction of melting temperature of nanoparticles at varying dimensions viz, shape and size. Thus our proposed modification in the existing model is more appropriate in the prediction of melting point of nanoparticles with its varying shape and size.