An intermediate phase in GexSe1-x glasses:: experiment and simulation

The pair correlation function for GexSe1-x alloys near the intermediate phase (IP) is reported. First-principles MD models of these alloys show a 'self-organized' phase associated with the number of Ge bonds with twofold Se atoms. This probably represents the IP of Boolchand. The self-organization involves maintaining a nearly constant number of twofold Se atoms bonded to one Ge atom through a range of Ge concentration, roughly coinciding with the IP. This behavior is manifested in observables like the optical gap. Our work suggests that the IP is due to selective formation of these local structures.