Alkaline halides

Martin T P 1983 Alkaline halide olusters and mioroorystals Phys. Rep. 95 167... 

The main example presented will be the alkaline-hypohalite method as it is the easiest to acquire the necessary chemicals. It Is of interest to note that the alkaline-halide method is much easier to perform, process- wise, in that it is more forgiving of sloppy technique. 

Although the motion of protons does not lead to electrical conduction in the case of benzoic acid, electronic and even ionic conductivity can be found in other molecular crystals. A well-studied example of ionic conduction is a film of polyethylene oxide (PEO) which forms complex structures if one adds alkaline halides (AX). Its ionic conductivity compares with that of normal inorganic ionic conductors (log [cr (Q cm)] -2.5). Other polymers with EO-units show a similar behavior when they are doped with salts. Lithium batteries have been built with this type of... 

Developing-out emulsion. Emulsions for development have an excess of alkaline halides. By varying the composition of the silver halide and treatment. developing-out emulsions may be piepaied which are suitable for either negative or positive purposes. 

Diatomic halides were first studied as HX by Lempka, Passmore and Price (211) showing slightly higher I than Eq. (24). It is possible by high-temperature equipment (212—214) to study diatomic alkaline halide molecules (or ion-pairs)... 

However, precaution must be taken to avoid over-interpretation of small changes in the band shapes. Thus, in the case of i.r. spectra, the band shapes observed are very sensitive to the type of preparation technique used for the samples, i.e., whether paraffin mulls or alkaline halide discs. The HDO bands of isotopically dilute samples (see Sect. 2.6) and the Raman spectra are less critical in this sense. 

Bachmann and co-workers interpreted their data for molecules halides in columns loaded with alkaline halides as evidence for the formation of complexes between the adsorbate and the crystalline halide. Such complexes were considered for application in radiochemical separations earlier by Zvara and co-workers in [3,13,14], who estimated the adsorption enthalpies from the rough adsorption isobar obtained in thermochromatographic experiments using Eq. 5.14. The adsorption enthalpy for NbCls on KC1 [14] is intermediate between the data of Table 5.1 for the adsorbents NaCl and CsCl, so that the results of the two groups are consistent. 

All the above-said concerns alkali-metal carbonates dissolved in melts based on alkaline- and alkaline-earth metal halides. It should be mentioned that there is a lack of data on the behaviour of alkaline-earth carbonates, in high-temperature alkaline halide melts. Nevertheless, these data are necessary, in particular, for the purification of halide melts. For example, it is known that alkaline-earth oxides possess appreciable solubilities in molten alkaline halides, and that they can be used for precipitation of less soluble transition metal-oxides. After such a precipitation, the excess of alkaline-earth oxide remains in the dissolved state. The question arises, therefore, whether it can be removed from the halide melt by passing C02 according to the conventional reaction... 

J. Eckstein, U. Gross and G. Rubinova, Growth of Alkaline-Halide Crystals with a Lowered Concentration of Oxygenous Using SiX as a Removing Agent, Kristall Technik 3 (1968) 583-587. 

The idea of increasing the maximum temperature at which a hole can be burnt or can survive after an excursion is very important when one considers the application of PHB to ultra-high density optical storage. Room temperature hole burning has been realized so far only in the case of Sm2+ in alkaline halide crystals and in fluoride or borate glasses.28 It has been reported that an organic system, the dihydrophenazine/fluorene crystal, can be subjected to an excursion to room temperature, with hole recovery when brought back to 4 K. 

The outer-sphere coordination of OAc ligands in cluster 6 is in line with the ease of their replacement by another anions. This cluster can be precipitated from aqueous solution by various salts, e.g., alkaline halides, perchlorate, and fluoro-phosphate. For example, complete substitution of OAc anions, accompanied by some hydrolysis, was observed on treatment of a solution of cluster 6 with K[ PF ] to form a cluster with the idealized formula Pd56iphen6o06o(PF6)6o (7) ... 

The equilibrium parameters of Lux acid-base reactions in ionic media (solubility products of oxides and acid-base equilibrium constants) are essentially affected by the acidic properties of the molten alkaline halide mixtures, i.e., they are dependent on the constituent cation acidities. Therefore, one should consider the reverse problem - the estimation of the basicity indices of ionic melts on the basis of the calculated equilibrium constants. 

Some studies of acid-base equilibria in molten alkaline halides have been performed by Rybkin et al. The empirical acidity scales have been constructed on the base of potentiometric studies in molten KCf and Csl. The practical significance of the mentioned works consists in the proposition to use some buffer solutions - SO/ /SjOg, , P0/ /P207 as reference standards for the indicator electrode calibration and determinations of pO in molten alkaline halides. 

These reactions were investigated mainly for alkaline halides and their mixtures. Hanf and Sole studied the hydrolysis of solid and molten NaCl in the temperature range 600-950 C by so-called dynamic method which consisted of passing inert gas (Nj) containing water vapor through a layer of solid or fused NaCl. The developed routine determined the equilibrium constant of the following reaction ... 

Table 21.3.3. Solubility products, of some oxides in molten alkaline halides (molar fractions).[After references 33,59-62]...

Table 21.3.4. Coefficients of plots [21.3.20] for molten alkaline halides at the confidence level 0.95. After references [38,59-62]...

The very hard and inert ceramic titanium carbide is made in a melt of alkaline halides ... 

Ks = KJLVa ] and in NiO 0 V, + Vo = MKo]. Schottky equilibrium leads to vacancy pairs and this type of disorder dominates in alkaline halides and in oxides with a halite (NaCl) structure. 

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