Polyamorphism and pressure-induced metallization at the rigidity percolation threshold in densified GeSe4 glass

Bora Kalkan*, Ranga P. Dias, Choong Shik Yoo, Simon M. Clark, Sabyasachi Sen

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    13 Citations (Scopus)

    Abstract

    Chalcogenide glasses with tetrahedral networks can undergo significant densification under pressure owing to their open structures. The structural mechanisms of pressure-induced densification and the corresponding evolution of physical properties of glassy GeSe4 alloy are studied over pressures ranging between ambient and 32.5 GPa, using X-ray scattering supplemented with 3D Monte Carlo structural modeling, Raman spectroscopy, electrical conductivity, and P-V equation of state measurements. The results demonstrate a pressure-induced, hysteretically reversible transition between low-density semiconducting and high-density metallic amorphous phases of GeSe4 near ∼10-15 GPa. These two phases are characterized by their distinct P-V equations of state and structural mechanisms of densification. Densification in the low-density phase is dominated by large inward shifting of the second neighbors with a small amount of conversion from edge-sharing to corner-sharing GeSe4 tetrahedra. On the other hand, densification in the high-density phase involves a gradual increase in the nearest-neighbor coordination numbers of Ge and Se atoms and the formation of Ge-Ge bonds between adjacent polyhedral units. These structural transformations are accompanied by a pressure-induced metallization that is reversible.

    Original languageEnglish
    Pages (from-to)5110-5121
    Number of pages12
    JournalJournal of Physical Chemistry C
    Volume118
    Issue number10
    DOIs
    Publication statusPublished - 13 Mar 2014

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