Structural properties of densified GexSe1-x glasses (Invited)

The evolution in structural properties of liquid and densified
glassy GexSe1-x is investigated by use of First Principles Molecular
Dynamics (FPMD) combined with X-ray absorption (XAS) experiments
for the glassy state. Four different compositions (x=10%, 16%,
18% and 33%) representing the flexible and stressed rigid sides of the
reversibility window are the focus of the study. The target systems
were studied at pressures up to ~ 11 GPa under both annealed and
cold compression conditions. We examine the structure factors,
pair distribution functions, bond angle distributions, coordination
numbers and neighbor distributions. The results show that the real
and reciprocal space properties are in very good agreement with the
experimental findings. The structural evolution during densification
reveals the edge sharing tetrahedra is maintained upon compression
whereas Ge-Ge homopolar bonds tend to increase in number.
Ge-Se-Ge bond angular distributions show a transformation from
tetrahedral octahedral geometry. We discuss the effect of thermal
history on structural properties during densification.