Mechanical versus thermodynamical melting in pressure-induced amorphization: the role of defects

Abstract

We study numerically an atomistic model which is shown to exhibit a one--step crystal--to--amorphous transition upon decompression. The amorphous phase cannot be distinguished from the one obtained by quenching from the melt. For a perfectly crystalline starting sample, the transition occurs at a pressure at which a shear phonon mode destabilizes, and triggers a cascade process leading to the amorphous state. When defects are present, the nucleation barrier is greatly reduced and the transformation occurs very close to the extrapolation of the melting line to low temperatures. In this last case, the transition is not anticipated by the softening of any phonon mode. Our observations reconcile different claims in the literature about the underlying mechanism of pressure amorphization.

7 pages, 7 figures

References in corpus (3)

• Low temperature properties of core-softened models: water vs. silica behavior
• Dislocation lines as the precursor of the melting of crystalline solids observed in Monte Carlo simulations
• Flat branches and pressure amorphization

Cited by in corpus (4)

• Structural study of alfa-Bi2O3 under pressure
• Pressure dependence of the melting mechanism at the limit of overheating in Lennard-Jones crystals
• Pressure-induced amorphization, crystal-crystal transformations and the memory glass effect in interacting particles in two dimensions
• Classical isotropic two body potentials generating martensitic transformations