Impact of high temperature and pressure on the structure and phase transition of Mg2SiO4 oxide via molecular dynamics simulation

Abstract

This article investigates the effects of high temperature and high pressure (P) on the structure and phase transition process of Mg₂SiO₄ oxide using molecular dynamics simulations with Oganov's pair interaction potential. The study reveals that as the temperature increases from 300 K to 6000 K, Mg₂SiO₄ transitions from an amorphous state to a liquid state. This transition is accompanied by an increase in lengths of the links (Mg-Mg, Mg-Si, Mg-O, Si-Si, Si-O, O-O) and changes in the numbers of structural units (SiO₄, SiO₅, SiO₆, MgO₃, MgO₄, MgO₅, MgO₆). While the total system size and total energy of systems increase, the bond angles of Si-O-Si and Mg-O-Mg remain relatively stable under 0 GPa. The phase transition temperature (T_m) of Mg₂SiO₄ is determined to be 2168 K. Furthermore, varying P from 0 to 200 GPa at temperatures of 300, 1000, 2000, 4000, and 6000 K reveals a relationship between temperature and pressure. At 300 K, the system can withstand a maximum pressure of 200 GPa, while at 6000 K, the minimum pressure is 0 GPa. These findings provide valuable insights for future experimental research and contribute to the development of high-performance materials for applications in the communications industry.