Hysteretically reversible phase transition in a molecular glass


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Kalkan B., Sonneville C., Martinet C., Champagnon B., Aitken B. G. , Clark S. M. , ...More

JOURNAL OF CHEMICAL PHYSICS, vol.137, no.22, 2012 (Peer-Reviewed Journal) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 137 Issue: 22
  • Publication Date: 2012
  • Doi Number: 10.1063/1.4769794
  • Journal Name: JOURNAL OF CHEMICAL PHYSICS
  • Journal Indexes: Science Citation Index Expanded, Scopus

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 similar to 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 As4S3 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. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4769794]