MD simulation study of B1-B2 phase transition of KCl under high pressure: Effects of defects

It is very difficult to directly observe the phase transition process and the effects of defects, due to the pico or nano second level phenomena. In this study, we performed the MD simulations for the B1-B2 phase transition of KCl to discuss the effects of defects on the phase transition. The potential parameters used in MD simulation were empirically determined on the basis of Hugoniot data. The simulation results showed that the B1-type structure transformed to B2-type structure under pressures, and the thermodynamic transition pressure was estimated to be 3.53 GPa. In the case of vacancies, the phase transition pressure decreased near to thermodynamic transition pressure by increasing vacancies. In the case of grain boundaries, phase transition occurred at the boundary and the phase transition pressure decreased near to thermodynamic transition pressure by increasing the angle between the grains.