Unravelling the mechanism of pressure induced polyamorphic transition in an inorganic molecular glass

Bora Kalkan*, Gokce Okay, Bruce G. Aitken, Simon M. Clark, Sabyasachi Sen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Downloads (Pure)

Abstract

The atomic structure of a germanium doped phosphorous selenide glass of composition Ge2.8P57.7Se39.5 is determined as a function of pressure from ambient to 24 GPa using Monte-Carlo simulations constrained by high energy x-ray scattering data. The ambient pressure structure consists primarily of P4Se3 molecules and planar edge shared phosphorus rings, reminiscent of those found in red phosphorous as well as a small fraction of locally clustered corner-sharing GeSe4 tetrahedra. This low-density amorphous phase transforms into a high-density amorphous phase at ~6.3 GPa. The high-pressure phase is characterized by an extended network structure. The polyamorphic transformation between these two phases involves opening of the P3 ring at the base of the P4Se3 molecules and subsequent reaction with red phosphorus type moieties to produce a cross linked structure. The compression mechanism of the low-density phase involves increased molecular packing, whereas that of the high pressure phase involves an increase in the nearest-neighbor coordination number while the bond angle distributions broaden and shift to smaller angles. The entropy and volume changes associated with this polyamorphic transformation are positive and negative, respectively, and consequently the corresponding Clapeyron slope for this transition would be negative. This result has far reaching implications in our current understanding of the thermodynamics of polyamorphic transitions in glasses and glass-forming liquids.

Original languageEnglish
Article number5208
Pages (from-to)1-9
Number of pages9
JournalScientific Reports
Volume10
DOIs
Publication statusPublished - 23 Mar 2020

Bibliographical note

Copyright the Author(s) 2020. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Fingerprint Dive into the research topics of 'Unravelling the mechanism of pressure induced polyamorphic transition in an inorganic molecular glass'. Together they form a unique fingerprint.

Cite this