ORCID Profile
0000-0001-6732-0488
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University of Adelaide
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University of New South Wales
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Publisher: American Chemical Society (ACS)
Date: 30-04-2015
DOI: 10.1021/JE501118W
Publisher: Royal Society of Chemistry (RSC)
Date: 1993
DOI: 10.1039/FT9938901969
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8CP02595A
Abstract: Transport numbers from electrophoretic NMR must be converted to the correct frame of reference to be physically meaningful.
Publisher: Springer Science and Business Media LLC
Date: 2001
Publisher: Informa UK Limited
Date: 20-12-1990
Publisher: Royal Society of Chemistry (RSC)
Date: 1979
DOI: 10.1039/F19797502873
Publisher: AIP Publishing
Date: 27-03-2002
DOI: 10.1063/1.1458928
Abstract: Drozdov and Tucker [J. Chem. Phys. 114, 4912 (2001)] have computed the self-diffusion coefficient along a near-critical isotherm showing anomalous slowing of molecular motion near the critical density and cite some experiments in support. A considered examination of the best literature data shows no such anomaly near neat liquid critical or mixture consolute points.
Publisher: Elsevier BV
Date: 11-1970
Publisher: Royal Society of Chemistry (RSC)
Date: 1982
DOI: 10.1039/F19827802265
Publisher: American Chemical Society (ACS)
Date: 21-09-2011
DOI: 10.1021/JE2006049
Publisher: Elsevier BV
Date: 07-1985
Publisher: American Chemical Society (ACS)
Date: 04-1985
DOI: 10.1021/ED062P350
Publisher: American Chemical Society (ACS)
Date: 10-1998
DOI: 10.1021/JP9820370
Publisher: AIP Publishing
Date: 03-2014
DOI: 10.1063/1.4863984
Abstract: This paper presents new reference correlations for both the density and viscosity of squalane at high pressure. These correlations are based on critically evaluated experimental data taken from the literature. In the case of the density, the correlation, based on the Tait equation, is valid from 273 to 473 K at pressures to 200 MPa. At 0.1 MPa, it has an average absolute deviation of 0.03%, a bias of −0.01%, and an expanded uncertainty (at the 95% confidence level) of 0.06%. Over the whole range of pressures, the density correlation has an average absolute deviation of 0.05%, a bias of −0.004%, and an expanded uncertainty (at the 95% confidence level) of 0.18%. In the case of the viscosity, two correlations are presented, one a function of density and temperature, based on the Assael-Dymond model, and the other a function of temperature and pressure, based on a modified Vogel-Fulcher-Tammann equation. The former is slightly superior to the latter at high temperatures (above 410 K), whereas the reverse is true at low temperatures, where the viscosity is strongly temperature dependent. In the temperature range from 320 to 473 K at pressures to 200 MPa, the first correlation has an average absolute deviation of 1.41%, a bias of −0.09%, and an expanded uncertainty (at the 95% confidence level) of 3%. Below 320 K, deviations from the present scheme rise to a maximum of 20%. In the temperature range from 278 to 473 K at pressures to 200 MPa, the second viscosity correlation has an average absolute deviation of 1.7%, a bias of −0.04%, and an expanded uncertainty (at the 95% confidence level) of 4.75%.
Publisher: American Chemical Society (ACS)
Date: 07-2010
DOI: 10.1021/JP102687R
Abstract: It is often asserted that deviation from the Nernst-Einstein relation (NE) between the molar conductivity (Lambda) and ion self-diffusion coefficients (D(i)) in ionic liquids (ILs) and molten salts is evidence for ion pairing. The NE was originally derived for noninteracting ions, as in an infinitely dilute electrolyte solution. In reality, mass, charge, momentum, and energy transport processes in ILs and molten salts involve correlated interionic collisions, caging, and vortex motions, as in any other dense liquid. Phenomenological theory using nonequilibrium thermodynamics and literature molecular dynamics simulations shows that deviations from the simple NE expression occur due to differences in cross-correlations of ionic velocities. ILs have also been shown, like molecular liquids generally, and model fluids such as the Lennard-Jones, to fit the fractional form of the Stokes-Einstein relation, D(i)/T proportional to (1/eta)(t) and Lambda proportional to (1/eta)(t), where eta is the shear viscosity. Here, it is shown that when this is the case, the NE deviation parameter Delta is then a constant, independent of temperature and pressure (consistent with experiment) and the value of the parameter t it is a function of the ionic charges and volumes, but not the masses. Therefore, Delta is not a measure of "ionicity": it is necessary to seek other independent evidence to determine whether ion pairing is present in a given ionic liquid or molten salt. The use of "apparent" transport numbers derived from self-diffusion coefficients to describe charge transport in pure salts is argued to be unnecessary.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C1FD00085C
Abstract: High pressure measurements have been made of viscosities, ion self-diffusion coefficients and electrical conductivities of ionic liquids, mainly of imidazolium salts. We review how these properties have been analysed in terms of the empirical Stokes-Einstein, Walden and Nernst-Einstein equations, and examine trends revealed by the phenomenological approach of velocity correlation coefficients and the more general theory of density scaling. Finally we examine the possibility of dynamic crossover in the transport properties of ionic liquids.
Publisher: Canadian Science Publishing
Date: 15-06-1972
DOI: 10.1139/V72-300
Abstract: Binary diffusion coefficients are reported for the systems He–CO 2 , He–N 2 O, and He–SF 6 . In agreement with the Chapman–Enskog theory the concentration dependence of the diffusion coefficient of each system increases with the mole fraction of the heavier component.
Publisher: Wiley
Date: 04-1994
Publisher: American Chemical Society (ACS)
Date: 03-1997
DOI: 10.1021/JE9602935
Publisher: Royal Society of Chemistry (RSC)
Date: 1982
DOI: 10.1039/F19827801629
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7CP01272A
Abstract: All three ion–ion interactions contribute to transport properties in {Li[FSI]–[Pyr 13 ][FSI]} mixtures. Tracer diffusion coefficients of LI + in [Pyr 13 ][FSI] are predicted.
Publisher: Royal Society of Chemistry (RSC)
Date: 1976
DOI: 10.1039/CS9760500215
Publisher: American Chemical Society (ACS)
Date: 10-2004
DOI: 10.1021/JE049668+
Publisher: American Chemical Society (ACS)
Date: 11-1977
DOI: 10.1021/J100538A011
Publisher: American Chemical Society (ACS)
Date: 15-10-2008
DOI: 10.1021/JE800504N
Publisher: Royal Society of Chemistry
Date: 2014
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8CP91941K
Abstract: Correction for ‘Comment on “Negative effective Li transference numbers in Li salt/ionic liquid mixtures: does Li drift in the “Wrong” direction?” by M. Gouverneur, F. Schmidt and M. Schönhoff, Phys. Chem. Chem. Phys. , 2018, 20 , 7470’ by Kenneth R. Harris, Phys. Chem. Chem. Phys. , 2018, 20 , 30041–30045.
Publisher: American Chemical Society (ACS)
Date: 12-11-2018
Publisher: American Chemical Society (ACS)
Date: 30-01-2020
Publisher: Wiley
Date: 07-1982
Publisher: AIP Publishing
Date: 14-04-2011
DOI: 10.1063/1.3575184
Abstract: Casalini and Roland [Phys. Rev. E 69, 062501 (2004) J. Non-Cryst. Solids 353, 3936 (2007)] and other authors have found that both the dielectric relaxation times and the viscosity, η, of liquids can be expressed solely as functions of the group (TV γ), where T is the temperature, V is the molar volume, and γ a state-independent scaling exponent. Here we report scaling exponents γ, for the viscosities of 46 compounds, including 11 ionic liquids. A generalization of this thermodynamic scaling to other transport properties, namely, the self-diffusion coefficients for ionic and molecular liquids and the electrical conductivity for ionic liquids is examined. Scaling exponents, γ, for the electrical conductivities of six ionic liquids for which viscosity data are available, are found to be quite close to those obtained from viscosities. Using the scaling exponents obtained from viscosities it was possible to correlate molar conductivity over broad ranges of temperature and pressure. However, application of the same procedures to the self-diffusion coefficients, D, of six ionic and 13 molecular liquids leads to superpositioning of poorer quality, as the scaling yields different exponents from those obtained with viscosities and, in the case of the ionic liquids, slightly different values for the anion and the cation. This situation can be improved by using the ratio (D/T), consistent with the Stokes–Einstein relation, yielding γ values closer to those of viscosity.
Publisher: Elsevier BV
Date: 08-1978
Publisher: Elsevier BV
Date: 12-1978
Publisher: American Chemical Society (ACS)
Date: 03-02-2007
DOI: 10.1021/JP067328K
Abstract: The self-diffusion coefficients (D) of the cation and anion in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) have been determined together with the electrical conductivity (kappa) under high pressure. All three quantities strongly decrease with increasing pressure to approximately 20% of their atmospheric pressure values at 200 MPa. D(PF6-) is always less than D([BMIM]+), despite the larger van der Waals volume of the cation. The pressure effect on the transport coefficients is discussed in terms of velocity correlation coefficients (VCCs or fij), the Nernst-Einstein equation (ionic diffusivity-conductivity), and the fractional form of the Stokes-Einstein relation (viscosity-conductivity and viscosity-diffusivity). It was found that the VCCs for the cation-cation, anion-anion, and cation-anion pairs are all negative and strongly pressure-dependent, increasing (becoming less negative) with increasing pressure. However, when the values of the VCCs for a given isotherm are normalized relative to the corresponding atmospheric pressure values, they collapse onto a single curve, as might be expected because the pressure should affect the interionic velocity correlations in the same way for each type of interaction. These isothermal curves can be represented by the form exp(alphap + betap2). The Nernst-Einstein deviation parameter, Delta, which depends on the differences between the like-like ion and unlike ion VCCs (f++ + f-- - 2f+-), is very nearly constant under the conditions examined. The diffusion and molar conductivity (Lambda) data are found to fit fractional forms of the Stokes-Einstein relationship with the viscosity, (LambdaT) proportional, variant (T/eta)t and Di proportional, variant (T/eta)t , with t = (0.92 +/- 0.05), independent of both temperature and pressure within the ranges studied and common to the three independently determined properties.
Publisher: American Chemical Society (ACS)
Date: 11-1997
DOI: 10.1021/JE970105Q
Publisher: American Chemical Society (ACS)
Date: 06-08-2015
Publisher: Wiley
Date: 08-1993
Publisher: Elsevier BV
Date: 11-1970
Publisher: AIP Publishing
Date: 11-07-2013
DOI: 10.1063/1.4812573
Abstract: The paper presents a new reference correlation for the viscosity of squalane at 0.1 MPa. The correlation should be valuable as it is the first to cover a moderately high viscosity range, from 3 to 118 mPa s. It is based on new viscosity measurements carried out for this work, as well as other critically evaluated experimental viscosity data from the literature. The correlation is valid from 273 to 373 K at 0.1 MPa. The average absolute percentage deviation of the fit is 0.67, and the expanded uncertainty, with a coverage factor k = 2, is 1.5%.
Publisher: American Chemical Society (ACS)
Date: 29-07-1999
DOI: 10.1021/JP991292X
Publisher: AIP Publishing
Date: 21-06-2010
DOI: 10.1063/1.3455342
Abstract: Previously [K. R. Harris, J. Chem. Phys. 131, 054503 (2009)] it was shown that both real and model liquids fit the fractional form of the Stokes–Einstein relation [fractional Stokes–Einstein (FSE)] over extended ranges of temperature and density. For ex le, the self-diffusion coefficient and viscosity of the Lennard-Jones fluid fit the relation (D/T)=(1/η)t with t=(0.921±0.003) and a range of molecular and ionic liquids for which high pressure data are available behave similarly, with t values between 0.79 and 1. At atmospheric pressure, normal and heavy water were also found to fit FSE from 238 to 363 K and from 242 to 328 K, respectively, but with distinct transitions in the supercooled region at about 258 and 265 K, respectively, from t=0.94 (high temperature) to 0.67 (low temperature). Here the recent self-diffusion data of Yoshida et al. [J. Chem. Phys. 129, 214501 (2008)] for the saturation line are used to extend the high temperature fit to FSE to 623 K for both isotopomers. The FSE transition temperature in bulk water can be contrasted with much lower values reported in the literature for confined water.
Publisher: Elsevier BV
Date: 10-2016
Publisher: American Chemical Society (ACS)
Date: 17-04-2008
DOI: 10.1021/JE800236D
Publisher: American Chemical Society (ACS)
Date: 20-11-2003
DOI: 10.1021/JE034142V
Publisher: American Chemical Society (ACS)
Date: 08-11-2007
DOI: 10.1021/JP709609E
Publisher: Wiley
Date: 07-1977
Publisher: Royal Society of Chemistry (RSC)
Date: 1982
DOI: 10.1039/F19827800957
Publisher: Wiley
Date: 05-02-2016
Publisher: American Chemical Society (ACS)
Date: 22-05-2009
DOI: 10.1021/JE900284Z
Publisher: Wiley
Date: 29-11-2013
Abstract: Two N-donor-functionalised ionic liquids (ILs), 1-ethyl-1,4-dimethylpiperazinium bis(trifluoromethylsulfonyl)amide (1) and 1-(2-dimethylaminoethyl)-dimethylethylammonium bis(trifluoromethylsulfonyl)amide (2), were synthesised and their electrochemical and transport properties measured. The data were compared with the benchmark system, N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (3). Marked differences in thermal and electrochemical stability were observed between the two tertiary-amine-functionalised salts and the non-functionalised benchmark. The former are up to 170 K and 2 V less stable than the structural counterpart lacking a tertiary amine function. The ion self-diffusion coefficients (Di ) and molar conductivities (Λ) are higher for the IL with an open-chain cation (2) than that with a cyclic cation (1), but less than that with a non-functionalised, heterocyclic cation (3). The viscosities (η) show the opposite behaviour. The Walden [Λ[proportionality](1/η)(t) ] and Stokes-Einstein [Di /T)[proportionality](1/η)(t) ] exponents, t, are very similar for the three salts, 0.93-0.98 (±0.05) that is, the self-diffusion coefficients and conductivity are set by η. The Di for 1 and 2 are the same, within experimental error, at the same viscosity, whereas Λ for 1 is approximately 13% higher than that of 2. The diffusion and molar conductivity data are consistent, with a slope of 0.98±0.05 for a plot of ln(ΛT) against ln(D+ +D- ). The Nernst-Einstein deviation parameters (Δ) are such that the mean of the two like-ion VCCs is greater than that of the unlike ions. The values of Δ are 0.31, 0.36 and 0.42 for 3, 1 and 2, respectively, as is typical for ILs, but there is some subtlety in the ion interactions given 2 has the largest value. The distinct diffusion coefficients (DDC) follow the order D(d)__ < D(d)++ < D(d)+_, as is common for [Tf2N](-) salts. The ion motions are not correlated as in an electrolyte solution: instead, there is greater anti-correlation between the velocities of a given anion and the overall ensemble of anions in comparison to those for the cationic analogue, the anti-correlation for the velocities of which is in turn greater than that for a given ion and the ensemble of oppositely charged ions, an observation that is due to the requirement for the conservation of momentum in the system. The DDC also show fractional SE behaviour with t~0.95.
Publisher: American Chemical Society (ACS)
Date: 18-08-2005
DOI: 10.1021/JE050147B
Publisher: American Chemical Society (ACS)
Date: 28-04-2015
Publisher: Elsevier BV
Date: 11-1980
Publisher: American Chemical Society (ACS)
Date: 04-2009
DOI: 10.1021/JE900297P
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/B919835K
Abstract: We derive a new expression for the conductivity of ionic liquid-solvent mixtures. The underlying theory is based on a lattice-hole model, which incorporates the concept of site availability in order to model decreasing mobility in the mixture, as the ionic liquid concentration increases. We compare with aqueous ionic liquid mixtures, as water is a solvent which best fulfills the approximations inherent in our theory. The conductivity expression is couched in terms of a single-fitting parameter and is able to reproduce a range of conductivity data with good accuracy.
Publisher: IOP Publishing
Date: 12-1973
Publisher: American Chemical Society (ACS)
Date: 08-10-2021
Publisher: American Chemical Society (ACS)
Date: 02-02-2023
Publisher: Elsevier BV
Date: 02-2014
Publisher: American Chemical Society (ACS)
Date: 28-06-2019
Abstract: In a previous work, we have found that the
Publisher: Canadian Science Publishing
Date: 15-07-2018
DOI: 10.1139/P72-221
Abstract: Binary diffusion coefficients have been measured as a function of concentration for the systems H 2 –Ne, D 2 –Ne, D 2 –N 2 , H 2 –Ar, and D 2 –Ar at 1 atm pressure and 300 K. Similar data have already been presented for the system H 2 –N 2 . As predicted by the Chapman–Enskog theory, the concentration dependences of the diffusion coefficients for the systems containing deuterium are somewhat less than for the corresponding systems containing hydrogen. The data for the systems containing Ne and N 2 indicate that there may be differences between the parameters required to describe the assumed spherical intermolecular potentials for the systems H 2 –Ne and D 2 –Ne, and also for the systems H 2 –N 2 and D 2 –N 2 . The concentration dependences of the diffusion coefficients of all six systems are, within the estimated experimental error of ±0.2%, linear in the mole fraction of the heavier component in each system, x 2 .
Publisher: American Chemical Society (ACS)
Date: 22-03-2016
Publisher: CSIRO Publishing
Date: 1982
DOI: 10.1071/CH9821525
Abstract: Excess and interaction second virial coefficients have been measured in the temperature range 290-320 K for 20 binary gaseous systems. Several of these systems have previously been studied by Brewer. The present values are in excellent agreement with his results. The excess virial coefficients have been used to calculate excess molar enthalpies of mixing at 300 K.
Publisher: Royal Society of Chemistry (RSC)
Date: 1995
DOI: 10.1039/FT9959104071
Publisher: Elsevier BV
Date: 12-2007
Publisher: Canadian Science Publishing
Date: 10-1973
DOI: 10.1139/P73-274
Abstract: Mutual diffusion coefficients, D 12 , have been measured as a function of concentration for the systems HD–N 2 and HD–Ar at 1 atm pressure and 300 K. The data are compared with previously published measurements for the corresponding H 2 and D 2 containing systems. After the estimated uncertainties due to experimental error and impurities, and corrections due to quantum and mass effects are taken into account, the mass corrected diffusion coefficient, [Formula: see text], for each system is found to lie above those of the corresponding H 2 and D 2 systems by up to 2%. These effects are attributed to differences in the intermolecular potentials of H 2 , D 2 , and HD.
Publisher: AIP Publishing
Date: 02-2022
DOI: 10.1063/5.0079796
Abstract: Thermodynamic or density scaling of high-pressure conductivities and molar conductivities of the high-temperature molten salts NaOH, and the alkali chlorides, bromides, and nitrates, from Na to Cs, taken from the literature, is found to be consistent with the simulations of Knudsen, Niss, and Bailey (KNB). They used a simple model fluid of point particles interacting through an interionic potential with a repulsive inverse power law part varying as r−9 and an attractive Coulombic part. This yields values between the limits 0.33–3 for the scaling parameter, γ. The Coulombic potential reduces the scaling parameter to values much lower than are normally found for molecular liquids, and KNB used this to explain the low values typically found for ionic liquids. Here, it is shown that the high-temperature molten salts examined behave similarly.
Publisher: AIP Publishing
Date: 08-09-2020
DOI: 10.1063/5.0016389
Abstract: Thermodynamic or density scaling is applied to thermal conductivity (λ) data from the literature for the model Lennard-Jones (12-6) fluid the noble gases neon to xenon nitrogen, ethene, and carbon dioxide as ex les of linear molecules the quasi-spherical molecules methane and carbon tetrachloride the flexible chain molecules n-hexane and n-octane the planar toluene and m-xylene the cyclic methylcyclohexane the polar R132a and chlorobenzene and ammonia and methanol as H-bonded fluids. Only data expressed as Rosenfeld reduced properties could be scaled successfully. Two different methods were used to obtain the scaling parameter γ, one based on polynomial fits to the group (TVγ) and the other based on the Avramov equation. The two methods agree well, except for λ of CCl4. γ for the thermal conductivity is similar to those for the viscosity and self-diffusion coefficient for the smaller molecules. It is significantly larger for the Lennard-Jones fluid, possibly due to a different dependence on packing fraction, and much larger for polyatomic molecules where heat transfer through internal modes may have an additional effect. Methanol and ammonia, where energy can be transmitted through intermolecular hydrogen bonding, could not be scaled. This work is intended as a practical attempt to examine thermodynamic scaling of the thermal conductivity of real fluids. The ergence of the scaling parameters for different properties is unexpected, suggesting that refinement of theory is required to rationalize this result. For the Lennard-Jones fluid, the Ohtori–Iishi version of the Stokes–Einstein–Sutherland relation applies at high densities in the liquid and supercritical region.
Publisher: Springer Science and Business Media LLC
Date: 1995
DOI: 10.1007/BF01438966
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2CP01130A
Abstract: High-pressure ion self-diffusion measurements for [EMIM][Tf 2 N] show equivalent activation volumes: cation and anion transport processes are similarly affected by pressure.
Publisher: Elsevier BV
Date: 07-2022
Publisher: American Chemical Society (ACS)
Date: 15-05-2004
DOI: 10.1021/JE049918M
Publisher: American Chemical Society (ACS)
Date: 16-08-2000
DOI: 10.1021/JE000024L
Publisher: American Chemical Society (ACS)
Date: 07-05-2018
Publisher: American Chemical Society (ACS)
Date: 31-07-2008
DOI: 10.1021/JE800059N
Publisher: American Chemical Society (ACS)
Date: 09-04-2018
Publisher: Elsevier BV
Date: 05-1975
Publisher: American Chemical Society (ACS)
Date: 18-07-2019
Abstract: In this work, the Angell analysis of Walden plots of the conductivity of ionic liquids and other electrolytes against viscosity is used to examine simple molten salts at high temperatures, a test that does not appear to have been made previously. It is found that many simple salts such as alkali metal fluorides and chlorides are predicted to be "superionic" as their Walden plots fall above the arbitrary reference line introduced by Angell, which passes through the datum point for 1 M aqueous KCl at 25 °C. This contradicts long-standing molecular dynamics evidence in the literature showing that these salts conduct simply by ion migration in an electric field. Zinc chloride is also predicted to be "ideal", whereas one would expect it to be "subionic" in Angell's terminology given that it is an associated salt. Results for certain protic ionic liquids are also contradictory. Therefore, Angell-Walden analyses of this type do not convey any useful information other than a qualitative ranking of the conductivity of similar ionic liquids at a given viscosity and their use for estimating "ionicity" is best discontinued. It cannot and should not be used for classifying the interactions in ionic liquids. Instead, it is argued that an examination of Laity resistance coefficients is more useful in any discussion of true association in molten salts and ionic liquids where known ex les show negative like-ion resistance coefficients with NE deviation parameters close to unity. Such an approach could be more fruitful in understanding the transport properties of molten salts and ionic liquids rather than simple comparisons of viscosity and conductivity.
Publisher: American Chemical Society (ACS)
Date: 10-04-2007
DOI: 10.1021/JE700032N
Publisher: American Chemical Society (ACS)
Date: 05-10-2007
DOI: 10.1021/JE700370Z
Publisher: Royal Society of Chemistry (RSC)
Date: 1998
DOI: 10.1039/A802567C
Publisher: American Chemical Society (ACS)
Date: 19-07-2008
DOI: 10.1021/JP8021375
Abstract: The self-diffusion coefficients (D) of the cation and anion in the ionic liquids 1-hexyl-3-methylimidazolium and 1-octyl-3-methylimidazolium hexafluorophosphates ([HMIM]PF6 and [OMIM]PF6) and 1-butyl-3-methylimidazolium and 1-octyl-3-methylimidazolium tetrafluoroborates ([BMIM]BF4) and ([OMIM]BF4) have been determined together with the electrical conductivities (kappa) of [HMIM]PF6 and [BMIM]BF4 under high pressure. The pressure effect on the transport coefficients is discussed in terms of velocity cross-correlation coefficients (VCCs or fij), the Nernst-Einstein equation (ionic diffusivity-conductivity), and the fractional form of the Stokes-Einstein relation (viscosity-conductivity and viscosity-diffusivity). The (mass-fixed frame of reference) VCCs for the cation-cation, anion-anion, and cation-anion pairs are all negative and strongly pressure dependent, increasing (becoming less negative) with increasing pressure. VCCs are the more positive for the stronger ion-velocity correlations therefore, f+ - is least negative in each case. In general, f- - is less negative than f+ +, indicating a smaller correlation of velocities of distinct cations than that for distinct anions. However, for [OMIM]PF6, the like-ion fii are very similar to one another. Plots of the VCCs for a given ion-ion correlation against fluidity (reciprocal viscosity) show the fij to be strongly correlated with the viscosity as either temperature or pressure are varied, that is, fij approximately fij(eta). The Nernst-Einstein deviation parameter, Delta, is nearly constant for each salt under the conditions examined. It is emphasized that nonzero values of Delta are not necessarily due to ion pairing but result from differences between the like-ion and unlike-ion VCCs, because Delta is proportional to (f+ + + f- - - 2 f+ -). The diffusion and molar conductivity (Lambda) data are found to fit fractional forms of the Stokes-Einstein relationship, (LambdaT) proportional, variant (T/eta)(t) and Di proportional, variant (T/eta)(t), with t=(0.90+/-0.05) for all these ionic liquids, independent of both temperature and pressure within the ranges studied.
Publisher: Springer Science and Business Media LLC
Date: 06-1991
DOI: 10.1007/BF00647069
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1CP90181H
Abstract: Correction for ‘Self-diffusion, velocity cross-correlation, distinct diffusion and resistance coefficients of the ionic liquid [BMIM][Tf 2 N] at high pressure’ by Kenneth R. Harris et al. , Phys. Chem. Chem. Phys. , 2015, 17 , 23977–23993, DOI: 10.1039/C5CP04277A.
Publisher: American Chemical Society (ACS)
Date: 15-04-2015
Publisher: American Chemical Society (ACS)
Date: 1996
DOI: 10.1021/JE9600663
Publisher: Springer Science and Business Media LLC
Date: 2004
Publisher: Royal Society of Chemistry (RSC)
Date: 1980
DOI: 10.1039/F19807600377
Publisher: American Chemical Society (ACS)
Date: 17-11-2016
Abstract: There have long been arguments supporting the concept of ion association in molten salts and ionic liquids, largely based on differences between the conductivity and that predicted from self-diffusion coefficients by the Nernst-Einstein equation for noninteracting ions. It is known from molecular dynamics simulations that even simple models based on charged hard spheres show such a difference due to the (anti)-correlation of ion motions. Formally this is expressed as a difference between the velocity cross-correlation coefficient of the oppositely charged ions and the mean of those for the two like-charged ions. This article examines molten salt and ionic liquid transport property data, comparing simple and model associated salts (ZnCl
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2CP03304F
Abstract: Ion self-diffusion coefficients in ionic liquid solutions follow the Ertl–Dullien free volume power law with concentration dependent offsets.
Publisher: American Chemical Society (ACS)
Date: 22-09-2006
DOI: 10.1021/JE060295H
Publisher: AIP Publishing
Date: 04-08-2009
DOI: 10.1063/1.3183951
Abstract: The fractional Stokes–Einstein (FSE) relation, (D/T)∝η−t, is shown to well correlate the molecular dynamics results of Meier et al. [J. Chem. Phys. 121, 3671 (2004) Meier et al.J. Chem. Phys. 121, 9526 (2004)] for the viscosity (η) and self-diffusion coefficient (D) of the Lennard-Jones fluid in the liquid and dense supercritical states, with the exponent t=(0.921±0.003). The Stokes–Einstein number n is viscosity dependent: ln n=const+(t−1)ln η. Molecular and ionic liquids for which high-pressure transport property data are available in the literature are shown to exhibit the same behavior with 0.79& t& . Water is also shown to fit the FSE at atmospheric pressure, with a change in exponent t from 0.94 to 0.67 at about 258 K (265 K for D2O), but the FSE holds only approximately at high pressures. It sometimes argued that FSE in supercooled liquids near the glass transition is a diagnostic for dynamic heterogeneity, but this work shows that the FSE holds in normal liquids far from the glass transition. This result may provide a reference for complex liquids such as viscous glass formers that show a transition (dynamic crossover) in the temperature dependence of the viscosity and network-bonded liquids such as water.
Publisher: American Chemical Society (ACS)
Date: 13-12-2016
Abstract: Earlier measurements of the self-diffusion coefficients of 1-alkyl-3-methylimidazolium (or [RMIM], R = alkyl) tetrafluoroborates and hexafluorophosphates have been revised and extended to 90 °C. The main changes are to D
Publisher: Elsevier BV
Date: 09-1978
Publisher: Royal Society of Chemistry (RSC)
Date: 1978
DOI: 10.1039/F19787400933
Publisher: Informa UK Limited
Date: 20-12-1992
Publisher: Informa UK Limited
Date: 10-02-1992
Publisher: American Chemical Society (ACS)
Date: 09-11-2006
DOI: 10.1021/JE060382+
Publisher: Royal Society of Chemistry (RSC)
Date: 1989
DOI: 10.1039/F19898503281
Publisher: Elsevier BV
Date: 03-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 30-10-2002
DOI: 10.1039/B208381G
Publisher: American Chemical Society (ACS)
Date: 14-06-2016
Publisher: Wiley
Date: 29-04-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5CP04277A
Abstract: Distinct diffusion coefficients for 1-alkyl-3-imidazolium [Tf 2 N] salts show very similar viscosity dependence thermodynamic scaling parameters for the reduced transport properties are equal.
Publisher: Elsevier BV
Date: 03-1978
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4CP00435C
Abstract: Functionalised and unfunctionalised ammonium based ionic liquid analogues show a common Stokes–Einstein–Sutherland scaling with viscosity.
Publisher: American Chemical Society (ACS)
Date: 22-04-2006
DOI: 10.1021/JE060082S
Publisher: AIP Publishing
Date: 06-2012
DOI: 10.1063/1.4720070
Abstract: In this work, a general equation of state (EOS) recently derived by Grzybowski et al. [Phys. Rev. E 83, 041505 (2011)] is applied to 51 molecular and ionic liquids in order to perform density scaling of pVT data employing the scaling exponent γEOS. It is found that the scaling is excellent in most cases examined. γEOS values range from 6.1 for ammonia to 13.3 for the ionic liquid [C4C1im][BF4]. These γEOS values are compared with results recently reported by us [E. R. López, A. S. Pensado, M. J. P. Comuñas, A. A. H. Pádua, J. Fernández, and K. R. Harris, J. Chem. Phys. 134, 144507 (2011)] for the scaling exponent γ obtained for several different transport properties, namely, the viscosity, self-diffusion coefficient, and electrical conductivity. For the majority of the compounds examined, γEOS & γ, but for hexane, heptane, octane, cyclopentane, cyclohexane, CCl4, dimethyl carbonate, m-xylene, and decalin, γEOS & γ. In addition, we find that the γEOS values are very much higher than those of γ for alcohols, pentaerythritol esters, and ionic liquids. For viscosities and the self-diffusion coefficient-temperature ratio, we have tested the relation linking EOS and dynamic scaling parameters, proposed by Paluch et al. [J. Phys. Chem. Lett. 1, 987–992 (2010)] and Grzybowski et al. [J. Chem. Phys. 133, 161101 (2010) Grzybowski et al. Phys. Rev. E 82, 013501 (2010)], that is, γ = (γEOS/ϕ) + γG, where ϕ is the stretching parameter of the modified Avramov relation for the density scaling of a transport property, and γG is the Grüneisen constant. This relationship is based on data for structural relaxation times near the glass transition temperature for seven molecular liquids, including glass formers, and a single ionic liquid. For all the compounds examined in our much larger database the ratio (γEOS/ϕ) is actually higher than γ, with the only exceptions of propylene carbonate and 1-methylnaphthalene. Therefore, it seems the relation proposed by Paluch et al. applies only in certain cases, and is really not generally applicable to liquid transport properties such as viscosities, self-diffusion coefficients or electrical conductivities when examined over broad ranges of temperature and pressure.
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