Crystal-liquid interfaces and phase relations in stable and metastable silicon at positive and negative pressure

摘要

The phase diagram of pure silicon is investigated by molecular-dynamics computer simulation. The liquid/ crystal coexistence curves are determined at both positive and negative pressures for the type I and II clathrates as well as for the diamond (Si-I) structure. Both clathrates are predicted to be thermodynamically stable relative to Si-I in the negative pressure regime. The structure of each of the respective liquid/crystal interfaces is investigated in terms of the atom environments. The clathrate/liquid interfacial structure is found to be significantly different to that observed for the Si-I/liquid boundary.