Structure of ZnCl2 Melt. Part II: Fragile-to-Strong Transition in a Tetrahedral Liquid

Pierre Lucas, Garrett J. Coleman, Manga Venkateswara Rao, Angharad N. Edwards, Chrishani Devaadithya, Shuai Wei, Abduljabar Q. Alsayoud, Barrett G Potter, Krishna Muralidharan, Pierre A Deymier

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Abstract

The fraction of edge- and corner-sharing tetrahedra in liquid ZnCl2 is quantified as a function of temperature using Raman spectroscopy and ab initio molecular dynamic simulations. Two distinct regimes are found in the temperature dependence of the change in these structural units. This behavior is consistent with the existence of a fragile-to-strong transition in liquid ZnCl2 as suggested by calorimetric and viscosity measurements. The structural origin of this transition is rationalized in terms of a constraint counting formalism. It is suggested that the ratio of edge- to corner-sharing tetrahedra controls the configurational entropy and in turn the viscosity of the melt. The temperature dependence of this ratio above the melting point is also found to be qualitatively consistent with neutron diffraction data. The observation of a similar fragile-to-strong transition in the isostructural GeSe2 melt indicates that it may be a common feature of tetrahedral liquids.

Original languageEnglish (US)
Pages (from-to)11210-11218
Number of pages9
JournalJournal of Physical Chemistry B
Volume121
Issue number49
DOIs
StatePublished - Dec 14 2017

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ASJC Scopus subject areas

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

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