On the importance of the metastable liquid state and glass transition phenomenon to transport and structure studies in ionic liquids. I. Transport properties

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Abstract

An attempt is made to show that progress in the understanding of ionic liquid transport properties and structure has been impeded by a lack of information on behavior in the "low-temperature" region of the liquid state, which largely involves the metastable super-cooled liquid state. Insight into the nature of this lower region provided by molecular dynamics machine calculations is discussed in relation to the relevance of structural distinctions between crystallizing and noncrystallizing ionic liquids. Associated with the low-temperature region are systematic departures from Arrhenius behavior in the temperature dependence of transport which are not explained by conventional transition state theory. Two theories which lead to the observed form of the temperature dependence are reviewed. The recent Adam-Gibbs theory seems the more promising approach and leads to the recognition of a corresponding temperature scale based on isoentropic states (states of equal configurational entropy) which can be used to define the low-temperature region and which may have interesting applications in correlating liquid structural properties. Comparison of this theory with the previous transition state theory approach suggests that the notion that volume and potential energy ("jumping") terms in the temperature dependence can be separated by constant volume measurements may be in error. A tentative explanation of existing constant volume data is offered.

Original languageEnglish (US)
Pages (from-to)2793-2803
Number of pages11
JournalJournal of Physical Chemistry
Volume70
Issue number9
StatePublished - 1966
Externally publishedYes

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Ionic Liquids
Ionic liquids
Transport properties
Glass transition
transport properties
glass
Liquids
liquids
temperature dependence
Temperature
temperature scales
Temperature scales
Volume measurement
Potential energy
potential energy
Molecular dynamics
Structural properties
entropy
molecular dynamics
Entropy

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

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title = "On the importance of the metastable liquid state and glass transition phenomenon to transport and structure studies in ionic liquids. I. Transport properties",
abstract = "An attempt is made to show that progress in the understanding of ionic liquid transport properties and structure has been impeded by a lack of information on behavior in the {"}low-temperature{"} region of the liquid state, which largely involves the metastable super-cooled liquid state. Insight into the nature of this lower region provided by molecular dynamics machine calculations is discussed in relation to the relevance of structural distinctions between crystallizing and noncrystallizing ionic liquids. Associated with the low-temperature region are systematic departures from Arrhenius behavior in the temperature dependence of transport which are not explained by conventional transition state theory. Two theories which lead to the observed form of the temperature dependence are reviewed. The recent Adam-Gibbs theory seems the more promising approach and leads to the recognition of a corresponding temperature scale based on isoentropic states (states of equal configurational entropy) which can be used to define the low-temperature region and which may have interesting applications in correlating liquid structural properties. Comparison of this theory with the previous transition state theory approach suggests that the notion that volume and potential energy ({"}jumping{"}) terms in the temperature dependence can be separated by constant volume measurements may be in error. A tentative explanation of existing constant volume data is offered.",
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T1 - On the importance of the metastable liquid state and glass transition phenomenon to transport and structure studies in ionic liquids. I. Transport properties

AU - Angell, Charles

PY - 1966

Y1 - 1966

N2 - An attempt is made to show that progress in the understanding of ionic liquid transport properties and structure has been impeded by a lack of information on behavior in the "low-temperature" region of the liquid state, which largely involves the metastable super-cooled liquid state. Insight into the nature of this lower region provided by molecular dynamics machine calculations is discussed in relation to the relevance of structural distinctions between crystallizing and noncrystallizing ionic liquids. Associated with the low-temperature region are systematic departures from Arrhenius behavior in the temperature dependence of transport which are not explained by conventional transition state theory. Two theories which lead to the observed form of the temperature dependence are reviewed. The recent Adam-Gibbs theory seems the more promising approach and leads to the recognition of a corresponding temperature scale based on isoentropic states (states of equal configurational entropy) which can be used to define the low-temperature region and which may have interesting applications in correlating liquid structural properties. Comparison of this theory with the previous transition state theory approach suggests that the notion that volume and potential energy ("jumping") terms in the temperature dependence can be separated by constant volume measurements may be in error. A tentative explanation of existing constant volume data is offered.

AB - An attempt is made to show that progress in the understanding of ionic liquid transport properties and structure has been impeded by a lack of information on behavior in the "low-temperature" region of the liquid state, which largely involves the metastable super-cooled liquid state. Insight into the nature of this lower region provided by molecular dynamics machine calculations is discussed in relation to the relevance of structural distinctions between crystallizing and noncrystallizing ionic liquids. Associated with the low-temperature region are systematic departures from Arrhenius behavior in the temperature dependence of transport which are not explained by conventional transition state theory. Two theories which lead to the observed form of the temperature dependence are reviewed. The recent Adam-Gibbs theory seems the more promising approach and leads to the recognition of a corresponding temperature scale based on isoentropic states (states of equal configurational entropy) which can be used to define the low-temperature region and which may have interesting applications in correlating liquid structural properties. Comparison of this theory with the previous transition state theory approach suggests that the notion that volume and potential energy ("jumping") terms in the temperature dependence can be separated by constant volume measurements may be in error. A tentative explanation of existing constant volume data is offered.

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