Size effect on the thermodynamic properties of silver nanoparticles

The Gibbs free energy of silver nanoparticles has been obtained from the calculations of bulk free energy and surface free energy for both the solid and liquid phase. On the basis of the obtained Gibbs free energy of nanoparticles, thermodynamic properties of silver nanoparticles, such as melting temperature, molar heat of fusion, molar entropy of fusion, and temperature dependences of entropy and specific heat capacity have been investigated. Calculation results indicate that these thermodynamic properties can be divided into two parts: bulk quantity and surface quantity, and surface atoms are dominant for the size effect on the thermodynamic properties of nanoparticles. The method that the intersection of the free-energy curves for solid and liquid nanoparticles decide the melting point of nanoparticles demonstrates that the surface free-energy difference between the solid and liquid phase is a decisive factor for the size-dependent melting of nanostructural materials.