Correlation between the Melting Point of a Nanosolid and the Cohesive Energy of a Surface Atom

Abstract

An atomistic model is presented for the melting behavior of a surface and a nanosolid, as well as their interdependence based on the recent “bond order−length−strength” (bond-OLS) correlation mechanism (J. Phys. D 2001, 34, 3470). It is suggested that the coordination number (CN) of a surface atom reduces whereas the remaining bonds of the lower-coordinated surface atom relax spontaneously associated with the single bond energy rise. Hence, the atomic cohesive energy (a single bond energy multiplies the CN) or the heat required for loosening the atom at the surface differs from the bulk value. Such a difference is suggested to be responsible for the fall (depression) or rise (overheating) of the melting point of a surface and a nanosolid of which the portion of surface atoms varies with the particle size. Being with few assumptions or freely adjustable parameters, the current premise is in good accordance with existing models and is perhaps able to link the existing models to the fact of surface CN imperfection and its effect on surface atomic cohesive energy.