Viscosity of Alkali Fluoride Ionic Melts at Temperatures up to 373.15 K above Melting Points

Abstract

The viscosities of molten alkali fluorides (LiF, NaF, KF, RbF and CsF) were measured at temperatures 373.15 K above the melting point. The viscosity has been measured by using a high temperature oscillating viscometer modified so as to be able to determine the period and logarithmic decrement from the observed intervals between times when the oscillation passes two deflection angles, and automatically calculate the viscosity. The data obtained were discussed in terms of viscous flow theory in ionic liquids. New data regarding the configurational changes in alkali fluoride ionic melts were obtained.

Molecular dynamics simulation of diffusion and viscosity of liquid lithium fluoride

“…The viscosity decreases with the temperature increasing. Our simulation results are close to the other simulated values [21,39], and have a little discrepancy with the experiment values [23][24][25]. The values of viscosity are a little lower than the experiment values mainly because that the melting point is about 300 K lower than experiment values.…”

“…In the previous published papers, the diffusion properties of LiF were mostly obtained from the mixtures of LiF-KF [19][20][21] in a limited range of temperature, while the study of pure liquid LiF [22] was relatively rare. In addition, the viscous flowability, i.e., the viscosity, has been obtained by just several experiments [23][24][25], however, the calculated values by molecular dynamics (MD) were rather scarce.…”

On the Use of the Angell–Walden Equation To Determine the “Ionicity” of Molten Salts and Ionic Liquids

“…Table lists the data sources for the conductivity and viscosity of the high- and moderate-temperature molten salts examined, − including the recent critically examined reference correlations for the viscosity of some halides made by Tasidou et al (The Supporting Information lists the values employed.) Data sources for an intermediate-temperature molten salt (tetrabutylammonium tetrabutylborate, [NBu 4 ]­[BBu 4 ]); − the eutectic mixed nitrate Rb 3 Na 2 (NO 3 ) 5 ; − and three room-temperature ionic liquids, the aprotic 1-butyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­imide ([BMIM]­[Tf 2 N]) − and the protic salts 1-methyl-2-oxopyrrolidinium tetrafluoroborate ([PyrOMe]­[BF 4 ]) and 1,8-diazabicyclo-[5,4,0]-undec-7-eneium methanesulfonate ([DBUH]­[CH 3 SO 3 ]), are also listed.…”

Thermophysical and Transport Properties of the BaCl2-CsCl High Temperature Ionic Liquid Mixtures

“…11 Details on this technique were presented elsewhere. 10,[13][14][15] For both experimental measurement, density and viscosity, were used vertical furnaces working in argon controlled atmosphere. A constant temperature of the furnace within ± 0.2 °C was ensured during measurements.…”

“…x(BaCl 2 ) = 0; ln η = 8.5621 × 10 -5 + 22464.11(1/T) (9) x(BaCl 2 ) = 0.85; ln η = 9.4437 × 10 -5 + 36604.056(1/T) (10) x(BaCl 2 ) = 0.72; ln η = 6.8408 × 10 -5 + 38080.2909(1/T) (11) x(BaCl 2 ) = 0.53; ln η = 7.5841 × 10 -5 + 33301.0571(1/T) (12) x(BaCl 2 ) = 0.33; ln η = 6.3743 × 10 -5 + 31629.8608(1/T) (13) x(BaCl 2 ) = 0.12; ln η = 8.0944 × 10 -5 + 25160.8858(1/T) (14) x(BaCl 2 ) = 1; ln η = 1.0675 × 10 -4 + 36800.8913(1/T) (15) For better understanding of the viscous flow in these HTILs, the thermodynamic function of activation were calculated from the dynamic viscosity values by considering Eyring's transition state theory. 26,27 The following equation express the absolute approach of Eyring on the dynamic viscosity of a liquid mixture: 26,27…”