Understanding of the phase transformation from fullerite to amorphous carbon at the microscopic level

TL;DR

This study investigates the microscopic mechanisms of phase transformation from fullerite to amorphous carbon under shock conditions using molecular dynamics, revealing pressure-dependent cage behavior and the impact of shear stresses.

Contribution

It provides new insights into the pressure and shear effects on fullerite's phase transition at the atomic level using molecular dynamics simulations.

Findings

C60 cages polymerize below 10 GPa

Cages break around 40 GPa

Shear stresses lower the destruction pressure to below 30 GPa

Abstract

We have studied the shock-induced phase transition from fullerite to a dense amorphous carbon phase by tight-binding molecular dynamics. For increasing hydrostatic pressures P, the C60-cages are found to polymerise at P<10 GPa, to break at P~40 GPa and to slowly collapse further at P>60 GPa. By contrast, in the presence of additional shear stresses, the cages are destroyed at much lower pressures (P<30 GPa). We explain this fact in terms of a continuum model, the snap-through instability of a spherical shell. Surprisingly, the relaxed high-density structures display no intermediate-range order.