Universal amorphous-amorphous transition in GexSe100-x glasses under pressure.
Pressure induced structural modifications in vitreous GexSe100-x (where 10 ≤ x ≤ 25) are investigated using X-ray absorption spectroscopy (XAS) along with supplementary X-ray diffraction (XRD) experiments and ab initio molecular dynamics (AIMD) simulations. Universal changes in distances and angle distributions are observed when scaled to reduced densities. All compositions are observed to remain amorphous under pressure values up to 42 GPa. The Ge-Se interatomic distances extracted from XAS data show a two-step response to the applied pressure; a gradual decrease followed by an increase at around 15-20 GPa, depending on the composition. This increase is attributed to the metallization event that can be traced with the red shift in Ge K edge energy which is also identified by the principal peak position of the structure factor. The densification mechanisms are studied in details by means of AIMD simulations and compared to the experimental results. The evolution of bond angle distributions, interatomic distances and coordination numbers are examined and lead to similar pressure-induced structural changes for any composition.
SPIN-Université de Liège, Institut de Physique B5, 4000 Sart-Tilman, Belgium.|Laboratoire de Physique Théorique de la Matière Condensée, Paris Sorbonne Universités, UPMC, 4, place Jussieu 75252 Paris Cedex 05, France.
Can
C
Yildirim
Laboratoire de Physique Théorique de la Matière Condensée, Paris Sorbonne Universités, UPMC, 4, place Jussieu 75252 Paris Cedex 05, France.
Matthieu
M
Micoulaut
School of Electronics and Computing Systems, College of Engineering and Applied Science, University of Cincinnati Cincinnati, OH 45221-0030, USA.
Punit
P
Boolchand
European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP 220, 38043, Grenoble Cedex, France.|Technical University of Denmark, Fysikvej 307, 2800 Kgs. Lyngby, Denmark.
Innokenty
I
Kantor
European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP 220, 38043, Grenoble Cedex, France.
Olivier
O
Mathon
SPIN-Université de Liège, Institut de Physique B5, 4000 Sart-Tilman, Belgium.
Jean-Pierre
JP
Gaspard
Geodynamics Research Center, Ehime University, Matsuyama 790-8577, Japan.
Tetsuo
T
Irifune
SPIN-Université de Liège, Institut de Physique B5, 4000 Sart-Tilman, Belgium.
Jean-Yves
JY
Raty