title: Hysteretically reversible phase transition in a molecular glass.
abstract: Pressure induced densification in a molecular arsenic sulfide glass is studied at ambient temperature using x-ray scattering, absorption and Raman spectroscopic techniques in situ in a diamond anvil cell. The relatively abrupt changes in the position of the first sharp diffraction peak, FSDP, and the pressure-volume equation of state near ∼2 GPa suggest a phase transition between low- and high-density amorphous phases characterized by different densification mechanisms and rates. Raman spectroscopic results provide clear evidence that the phase transition corresponds to a topological transformation between a low-density molecular structure and a high-density network structure via opening of the constituent As(4)S(3) cage molecules and bond switching. Pressure induced mode softening of the high density phase suggests a low dimensional nature of the network. The phase transformation is hysteretically reversible, and therefore, reminiscent of a first-order phase transition.
authors.affiliation: Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, California 20015, USA.
authors.forename: B
authors.initials: B
authors.lastname: Kalkan
authors.forename: C
authors.initials: C
authors.lastname: Sonneville
authors.forename: C
authors.initials: C
authors.lastname: Martinet
authors.forename: B
authors.initials: B
authors.lastname: Champagnon
authors.forename: B G
authors.initials: BG
authors.lastname: Aitken
authors.forename: S M
authors.initials: SM
authors.lastname: Clark
authors.forename: S
authors.initials: S
authors.lastname: Sen