Breakdown of intermediate range order in AsSe chalcogenide glass

As-cast amorphous AsSe (a-AsSe) has been characterized by in-situ high pressure XRD and Raman spectroscopy up to the pressure of ~30 GPa using diamond anvil cell together with ab-initio molecular dynamics simulations. A gradual densification has been observed under compression along with the breakdown of intermediate range ordering at ~16 GPa. The whole transformation process can be divided into three relatively distinct pressure regimes from 1bar to 7 GPa, from 7 to 16 GPa and beyond 16 GPa. Our XRD results together with Raman spectroscopic studies confirm that in a-AsSe pressure tuning results in network transformations only, without sudden jump in the density. The results obtained by high pressure ab-initio molecular dynamics simulations demonstrate the variations in the local structures associated with the experimentally observed transformations. The amorphous-to-amorphous network transformation is found to be reversible upon decompression.