TY - JOUR
T1 - Structure of ZnCl2 Melt. Part II
T2 - Fragile-to-Strong Transition in a Tetrahedral Liquid
AU - Lucas, Pierre
AU - Coleman, Garrett J.
AU - Venkateswara Rao, Manga
AU - Edwards, Angharad N.
AU - Devaadithya, Chrishani
AU - Wei, Shuai
AU - Alsayoud, Abduljabar Q.
AU - Potter, B. G.
AU - Muralidharan, Krishna
AU - Deymier, Pierre A.
N1 - Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/12/14
Y1 - 2017/12/14
N2 - 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.
AB - 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.
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U2 - 10.1021/acs.jpcb.7b10857
DO - 10.1021/acs.jpcb.7b10857
M3 - Article
C2 - 29166015
AN - SCOPUS:85038366928
SN - 1520-6106
VL - 121
SP - 11210
EP - 11218
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 49
ER -