Electrical Conductivity, Viscosity, and Sound Velocity of Lithium Bromide + Lithium Nitrate + Acetamide Melt Systems

Abstract

Densities, electrical conductivities, viscosities, and sound velocities of 0.22[xLiBr + (1x)LiNO 3 ] + 0.78CH 3 CONH 2 were measured as functions of temperature (296.75 e T/K e 343.15) and composition (x ) 0.0-1.0 mole fraction). Electrical conductivity, viscosity, and structural relaxation time were found to have non-Arrhenius temperature dependence and were analyzed by using the Vogel-Tamman-Fulcher equation. A significant mixed anion effect has been found in the electrical conductivity isotherms. Viscosity and structural relaxation time vary linearly with composition. The variation of electrical conductivity is governed by the mobility of Brand NO 3ions and the competitive polarization exerted by anions on Li + , whereas the polymeric and rigid structure formed between Li + and acetamide primarily govern the viscosity process.

Medium decoupling of dynamics at temperatures ∼100 K above glass-transition temperature: A case study with (acetamide + lithium bromide/nitrate) melts

“…Note here that η measured by us increases with LiBr concentration at a fixed temperature which is opposite to the trend reported in Ref. 23. As already mentioned, presence of substantial amount of moisture in LiBr might have led to the erroneous trend reported in Ref.…”

“…The amide concentration is kept fixed at 0.78 mole fraction because at this composition the mixture remains in the liquid phase 2, 5, 22 for the temperature range considered, 303 ≤ T /K ≤ 364. In addition, density and viscosity data in the same temperature range for these melts have been measured earlier by different authors 23 which also report, apart from the Vogel-Fulcher-Tammann 73 description of temperature dependent transport properties, presence of a moderate MAE for the electrical conductivity. Interestingly, both steady state and dynamic Stokes shifts measured using C153 exhibit non-ideal anion concentration dependence, indicating fluorescence detection of MAE for [0.78CH 3 CONH 2 + 0.22{f LiBr + (1-f) LiNO 3 }] melts.…”

“…The increased heterogeneity in presence of LiNO 3 could arise from the presence of both ionic and non-ionic species because of less dissociation of LiNO 3 compared to LiBr. Higher lattice and gas-phase dissociation energies 88 for LiNO 3 than those for LiBr, and increase in electrical conductivity 23 of the melt upon replacing LiNO 3 by LiBr seem to support the above view.…”

“…These interesting solvent properties coupled with a wide thermal window have made molten mixtures of (acetamide + electrolyte) to be used not only as reaction media in chemical industry but also as materials for electrochemical applications at elevated temperatures. 20,21 These molten mixtures (or simply, melts) are characterized by estimated glass transition temperatures (T g ) ∼190 < T g /K < 250 range, [22][23][24][25] and are termed as supercooled mixtures as they remain in the liquid phase at temperatures much below the respective melting temperatures of the constituents. This "supercooling" phenomenon and the associated importance for chemical industry have motivated much of the research on the basic scientific aspects, because developing these melts into useful dielectric materials 13,26 requires deeper understanding of medium structural and transport properties.…”

Determination of Concentration of the Aqueous Lithium–Bromide Solution in a Vapour Absorption Refrigeration System by Measurement of Electrical Conductivity and Temperature

“…An increase in the temperature of solution increases the mobility and the number of the ions in solution due to ionisation of molecules, which in turn leads to an increase in the electrical conductivity of the solution. Moreover, an increase in the concentration of solution leads to increase its electrical conductivity due to an increase in the number of ions per unit volume [7,8]. It is therefore always important to associate the electrical conductivity measurement of a solution with a reference concentration and temperature.…”