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Structure of ZnCl 2 Melt. Part II: Fragile-to-Strong Transition in a Tetrahedral Liquid
The fraction of edge- and corner-sharing tetrahedra in liquid ZnCl 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 c...
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Published in: | The journal of physical chemistry. B 2017-12, Vol.121 (49), p.11210-11218 |
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Main Authors: | , , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | The fraction of edge- and corner-sharing tetrahedra in liquid ZnCl
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 ZnCl
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 GeSe
melt indicates that it may be a common feature of tetrahedral liquids. |
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ISSN: | 1520-6106 1520-5207 |
DOI: | 10.1021/acs.jpcb.7b10857 |