Relative contribution of stoichiometry and mean coordination to the fragility of Ge-As-Se glass forming liquids

Ting Wang, Ozgur Gulbiten, Rongping Wang, Zhiyong Yang*, Anita Smith, Barry Luther-Davies, Pierre Lucas

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    56 Citations (Scopus)

    Abstract

    The structural relaxation properties of 34 compositions of Ge-As-Se glass forming liquids are investigated by differential scanning calorimetry (DSC). The fragility index (m) and activation energies for enthalpy relaxation (E a) exhibit universal trends with respect to stoichiometry and mean coordination (〈r〉), respectively. The liquid fragility which defines the full temperature dependence of the relaxation processes shows no well defined trend with respect to 〈r〉 but instead is found to be closely determined by the excess or deficiency in selenium with respect to stoichiometry. The mean coordination on the other hand appears to be an accurate predictor of the activation energy near the glass transition where most constraints are still intact. No intermediate phase is observed in either case. These results emphasize that chemical effects rather than topological effects appear to control the wide ranging structural mobility of these glass forming liquids. The consequences of these findings in terms of the thermal stability of the corresponding glasses are discussed. It is similarly found that sub-T g relaxation is controlled by stoichiometry rather than topology.

    Original languageEnglish
    Pages (from-to)1436-1442
    Number of pages7
    JournalJournal of Physical Chemistry B
    Volume118
    Issue number5
    DOIs
    Publication statusPublished - 6 Feb 2014

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