Molten Alkali Metal Chlorides Research Articles

Equilibrium reactions between molecular and ionic species in pure molten LiCl and in LiCl + MCl ( M = Na, K, Rb) melts investigated by computational chemistry

In order to study the microscopic structures of molten lithium chloride and selected binary chloride melts containing lithium chloride, DFT calculations were performed with dmol software at the DNP/UHF/BLYP level to study all the possible (stable) isolated chloride complexes of alkaline metals. Results on geometry, energy, vibrational spectrum and Mulliken population are summarized. In addition, thermostatistical calculations were carried out to obtain the thermodynamic data relative to equilibrium reactions occuring in melts. It was demonstrated that the general equilibrium LiCl + 2 MCl / ag LiCl − 2 + M 2 Cl + predominates and the temperature and composition dependence of the percentage of LiCl − 2 for a given melt (molten LiCl-NaCl, LiCl-KCl and LiCl-RbCl) was determined. This study emphasizes the role of the counter cation on the structure of molten alkali metal chlorides.

Solubility of hydrogen chloride in zinc chloride + sodium chloride melts

Measurement of the solubility of HCl gas in ZnCl 2 +NaCl binary molten mixtures has been carried out by an elution technique. The solubility data were found to exhiibit trends characteristic of a chemical dissolution process, implying the formation of a complex species. It is suggested that as the melt basicity is increased the predominant species changes from a coordinated zinc species to HCl 2 - , with the more basic melts tending toward behavior exhibited by HCl in pure molten alkali-metal chlorides

Experimental determination of the thermal diffusivity of molten alkali halides by the forced Rayleigh scattering method. I. Molten LiCl, NaCl, KCl, RbCl, and CsCl

As a series of experimental determinations of the thermal diffusivity of molten alkali halides, this paper describes measurements on five molten alkali metal chlorides (LiCl, NaCl, KCl, RbCl, and CsCl) in the temperature range up to 1440 K by the forced Rayleigh scattering method. K2Cr2O7 is employed as a dye substance to color the transparent molten salts. The accuracy is estimated to be ± 4 to ±11 % depending on the measured salts. In comparison with the present results converted into thermal conductivity, most of the previous experimental data obtained by steady-state methods show larger values, up to about five times, which may be due to the systematic error caused by the presence of convection and radiation. It is found that the thermal conductivity of these series of molten alkali metal chlorides decreases with increasing molecular weight, and their temperature coefficients are weakly negative.

Coordination chemistry of actinides in molten salts

The problems of actinide molten salt coordination chemistry are considered in terms of spectroscopic parameters as functions of melt composition and temperature. Parameters connected with energy, intensity and fine structure of 5f-5f transitions have been obtained for molten alkali metal chlorides, fluorides and chloride-fluoride mixtures. The regularities of variation of both actinide-chlorine distances and actinide fluorocomplex stability have been studied.

Surface tensions of molten alkali-metal halides

Surface tensions of molten alkali-metal chlorides, bromides, and iodides have been measured by the capillary-rise method. The surface tension cell, made of quartz, has two different capillaries, and the melt is sealed in it under vacuum. The surface tension is determined through the height difference of menisci in the capillaries and is highly reproducible. Surface properties of molten alkali-metal halides vary systematically with the radii of the anions and cations except for the lithium ion; i.e., lithium halides show considerably lower surface energies and surface entropies.

The Temperature Dependence of the Thermal Conductivity of Molten Salts

By using newly developed transient methods, namely transient hot-wire method with ceramic-coated probe and forced Rayleigh scattering method, the thermal conductivities of two molten nitrates (NaNO3 and KNO3 up to about 440°C) and five molten alkali metal chlorides (LiCl, NaCl, KCl, RbCl and CsCl up to about 1200°C) have been determined. The present thermal conductivity results show a weak negative temperature dependence and one of the smallest values among other previous data obtained by steady-state methods; the difference is a factor of four at most.

Measurement of the thermal diffusivity of molten salts by the forced rayleigh scattering method. Measurement of molten alkali metal chlorides at temperatures above 1000.DEG.C..

The paper reports measurements of the thermal diffusivity of four molten alkali chlorides (LiCl, NaCl, RbCl and CsCl) in the temperature range above 1000°C by the forced Rayleigh scattering method. The dye substance employed is K2Cr2O7 in order to color the transparent molten salts. The accuracy is estimated to be ±4 to ±11% depending on the measured substances. In comparison with the present results converted to thermal conductivity, most of the previous experimental data obtained by steady-state methods show larger values (up to about five times) which may be due to the presence of convection and radiation. It is found that the thermal conductivity of these series of molten alkali metal chlorides decreases with increasing molecular weight, and the temperature coeffcients are weakly negative.

溶融アルカリ金属塩化物中への銀イオンの拡散

In order to clarify the relative importance of various factors for solute diffusion of impurity cations, the inter-diffusion coefficients of silver ion in molten alkali chlorides were determined by the use of capillary reservoir methods at the temperatures ranging from the melting points of solvent salts to 200 K above them.The results obtained can be summarized as follows:(1) The temperature dependence of the inter-diffusion coefficient of Ag+ ion was well represented by an equation of Arrhenius type. Pre-exponential term and the apparent activation energy for diffusion were determined by the use the of the least square method.(2) The applicability of Stokes-Einstein equation was examined. Diffusion coefficient of Ag+ ion increased linearly with increasing values of kT⁄ηr, where η is the viscosity of the solvent salt. The radius of the silver ion in molten chlorides was considered to be nearly equal to that of the sodium ion.(3) A linear relation was found between the molar volume of solvent salts and the vaule of D⁄(T⁄M)1⁄2 in the temperature range wherein the diffusion coefficients were measured. The diffusive movement of solute cations was considered to be correlated with that of solvent cations.(4) The polarization energy of anion as well as the energy of hole formation is an important factor controlling the diffusive movement of the solute cation in molten alkali metal chlorides.

Über die schmelzelektrolytische Abscheidung von Titanmetall

AbstractTitanmetall wurde aus Alkalimetallchloridschmelzen mit gelösten niederen titanchloriden unter Verwendung löslicher Anoden aus Titan abgeschieden. Einer Beschreibung der Versuchsanordnung folgen die damit gewonnenen Ergebnisse über den Einfluß verschiedener Versuchsbedingungen wie Titan‐Konzentration, Stromdichte und Elektrolyttemperatur. Grobkristalline, sehr reine Abscheidungen sind bei 850°C durch eine große Oberfläche der Anode sowie geringen Abstand zwischen den Elektroden zu erreichen.Messungen der Polarisationsspannung und ein einfacher Überführungsversuch beweisen die Existenz von anionischen Titan‐Komplexverbindungen in den Salzschmelzen.Den Abschluß bilden Angaben über das Wachstum der titankristalle.