Structural properties of α-quartz near the amorphous transition

Quartz undergoes a gradual transition with pressure from a crystalline to an amorphous state. The mechanism for this pressure-induced transition is not well understood. By combining new experimental pressure data and recently developed theoretical methods, we have determined the structural properties of α-quartz near and above this transition. We suggest that highly unfavorable interpolyhedral anion-anion distances, which occur at the transition pressure, play a key role in driving the transition.