Molten salt basic properties

This work attempts to model a semiconductor/molten salt electrolyte interphase, in the absence of illumination, in terms of its basic circuit elements. Measurement of the equivalent electrical properties has been achieved using a newly developed technique of automated admittance measurements and some progress has been made toward identification of the frequency dependent device components (1 ). The system chosen for studying the semiconductor/ molten salt interphase has the configuration n-GaAs/AlCl3 1-... 

One of the models that can be used to approximately predict the properties of molten salts is called the hole model. The outstanding fact that led to this model is the large volume of fusion (10-20%) exhibited by simple salts on melting (Fig. 5.17). The basic idea of this rather artificial model is that within the liquid salt are tiny volume... 

In the literature, there are reports of work concerned with the measurement of oxoacidic properties of ionic melts by gravimetric measurements of the solubility of acidic gases in these media [76, 77], The solubility of sulfur(VI) oxide in molten sodium phosphates was determined by the gravimetric method [76], A correlation was obtained between the melt basicities and the solubility of gaseous acid S03 in them. Iwamoto reported the estimation of the basic properties of molten salt by measurements of acidic gas solubilities (carbon dioxide and water) in them [77], However, similar methods cannot be used widely, owing to two factors. The first of these consists in the fact that the solubility of any gas in a liquid phase obeys Henry s law. Let us consider the following system of reactions ... 

However, the interaction does not end after this stage. Carbon monoxide produced as a product of the decomposition reacts with nitrate ions, which lead to the formation of nitrite ions possessing appreciable basic properties in molten salts ... 

This reaction is shifted appreciably to the right, compared with the interactions with other halide ions. This fact is explained in the context of the HSAB concept the formation of complexes of A1 with Cl-, Br-, or I- ions is less favourable than of the complex fluoroaluminates, since fluoride ion is the hardest halide base and Al3+ ion is referred to as the strongest hard acids. The F- and O2- ions seem to possess closely similar hard basic properties in molten salts. 

Polypyrrole has even been synthesized in a molten salt through the electrochemical oxidation of pyrrole. Pickup and Osteryoung [60] reported that a 1 1 mixture of aluminum chloride and n-l-butylpyridium chloride at 40°C was the most favorable combination for producing the best films. A basic (0.8 1) or acidic (1.2 1) melt generated no films. The electrochemical redox kinetic behavior of films prepared from the 1 1 molten salt appeared to be more facile than for films prepared in acetonitrile. Otherwise, the films exhibited very similar properties. 

The fuel-free molten salt coolants considered for the MARS are those for which basic thermo-physical properties are well known (see Table XXVIII-4). 

Electrorefining of silicon from wastes is economically worthwhile, compared with the thermic extraction of Si from mineral ores, which requires far higher temperatures for treatment, and so, a higher cost. This article should open the way for an industrial application of the electrorefining process. Furthermore, worthy of note is that we used the electrochemical properties of Si compounds to measure the fluoroacidity of molten salts with good accuracy and the methodology can be extended to other systems to define the basic properties of a molten solvent, by its complexing effect on the stability of a volatile compound. 

There is thus good experimental evidence that silicate melts are ionic liquids containing relatively free cations and mixtures of polymeric silicate anions. In a previous chapter Kleppa has reviewed what is known of the mixing properties of simple molten salts. The applications of these principles to melts containing a large number of different polyanions requires the introduction of methods developed by organic polymer chemists (Flory, 1936, 1952). Before describing the polymer models which have been applied to silicate melts it will be useful to review briefly the use of the terms acidic and basic as applied to oxides or melts. 

To summarize the above, the thermophysical properties of liquid metals and gases experience only minor linear changes with increasing temperature. However, all the properties of water at pseudocritical conditions go through very rapid changes. The basic properties of He, CO2, and water are summarized in Table A2.5. Basic properties of Pb, molten salt (FLiNaK), and Na are summarized in Table A2.6. 

Thus, in the modified Lewis (or Lux-Flood) concept, pure alkali halides represent the highest degree of basicity as the solvent composition changes from alkali halide-rich to alkali halide-deficient melts, the solvent becomes acidic. Acid-base properties of molten halides may be used to explain stabilization of unusually low (or high) oxidation states, the differences in stability of the same oxidation state in related melts, and the effects on coordination observed spectrally for certain metal ions. Or, restating the idea in other terms, the redox potentials depend on melt basicity. Thus, the systematic variation of melt composition is a useful technique in the arsenal of the molten salt electrochemist who is interested in the chemistry of solute species in molten salt solvents. In this respect, it is important to note that variation of temperature may be used to serve the same purpose for example, it has been shown that in neutral chloro-aluminates C1- decreases with temperature. 

J.A. Duffy and M.D. Ingram, Optical Basicity IV. Influence of Electronegativity on the Lewis Basicity and Solvent Properties of Molten Oxyanion Salts and Glasses, J. Inorg. Nucl. Chem. 37 (1975) 1203-1206. 

J A. Duffy and M.D Ingram, Optical basicity-IV influence of electrongativity on the Lewis basicity and solvent properties of molten oxyanion salts and glasses J. Inorg. 

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