Influence of boundaries on high-pressure melting experiments

Physics Department, Technion-Israel Institute of Technology - Haifa, 32000 Israel

Received: 22 June 2006
Accepted: 25 September 2006

Abstract

At low pressure, free surfaces play a crucial role in the melting transition, but to maintain pressure, the sample surface must be acted upon by some pressure-transmitting medium. To examine the effect of this medium on melting, we performed Monte Carlo simulations of a system of argon atoms in the form of a slab with upper and lower boundaries. We examined two cases: one with a soft and the other with a rigid medium at the boundaries. We found that in the presence of a rigid medium, melting resembles the mechanical lattice instability found in a surface-free solid. With a soft medium at the boundary, melting begins at the surface and at a lower temperature. The relevance of these results to experiment is discussed.