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

BUSTINGORRY SEBASTIAN; JAGLA EDUARDO A.

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

American Physical Society

Lugar: New York; Año: 2004 vol. 69 p. 64110 - 64116

0163-1829

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 that 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.