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

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41 Scopus citations

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 (US)
Pages (from-to)1436-1442
Number of pages7
JournalJournal of Physical Chemistry B
Volume118
Issue number5
DOIs
StatePublished - Feb 6 2014

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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