Surface Debye Temperatures and Specific Heat of Nanocrystals

The present study deals with the contribution of the surface atomic layer to the specific heat of nanocrystals. In the case of small phases with comparable number of bulk and surface atoms, the variation of heat capacity with respect to that of infinitely large phase is significant. To evaluate this variation, in the framework of the classical Debye model, we introduce surface excess heat capacity that accounts for the surface layer contribution. On that physical background, we draw a functional dependence of the specific heat of nano clusters on the number of their bulk and surface atoms and corresponding bulk, D T , and surface, S D T , Debye temperatures. Since S D T depends on the crystallographic orientation of the surface, the presented model also accounts for the symmetry and atomic density of the respective crystal faces of the nanocrystal.