THERMODYNAMICS OF MELTING AND FREEZING IN SMALL PARTICLES

The properties of small particles can be markedly different from the bulk. A classical thermodynamic treatment of the melting and freezing of small particles, including the effects of surface-induced order, predicts an energy barrier between a surface melted state and the liquid droplet. The requirement of homogeneous nucleation over the barrier on laboratory time scales predicts melting and freezing temperatures that vary from the bulk temperatures and from each other. For very small particles the energy barrier is so small that the melting and freezing temperatures are the same, However, above a few nanometers in radius the melting and freezing temperatures are different. This approach also predicts a low temperature region where a disordered particle would stay disordered for extended periods of time, This model only applies to the situation where the melt wets the solid.