Solid Solutions of the Alkali and Ammonium Halides

Abstract

The principal factor determining the sharpness of the electrometric end-point with polarized electrodes of pure platinum is the difference in the degree of reversibility of the electrode reaction before and after the end-point. Other factors such as concentration and rate of stirring are of minor importance. The end-point phenomena are more distinct, the more nearly the electrode reactions conform to the requirement of complete reversibility on one side of the end-point and complete irreversibility on the other, but are sharp enough for practical use in analysis in some cases which fall far short of meeting this requirement.2. Although the polarization sometimes produces a slight displacement of the end-point break of a single electrode, the errors so introduced are generally too small to be of significance in a volumetric analysis.3. The end-point break in titrations of the ordinary type, based on the single potential of a platinum electrode, may often be improved and the behavior of the electrode made much more dependable and satisfactory by polarizing it with respect to an auxiliary electrode.

The Phase Transition in CsCl Mixed with CsBr, RbCl, and KCl

“…The last result is in marked disagreement with the data of Rao et al [4] who found in a Ko.ZCso.8Cl crystal a transition enthalpy of 258 cal/mol CsCl. I n addition, we note that KC1 is soluble in CsCl only to an extent of about 10% [9]. Therefore, it is likely that in K,Csl-,C1 crystals with z > 0.1 a precipitation of separate phases occurs.…”

Raman Scattering Studies on (NH4)Cl1−xBrx Mixed Crystals in the Tetragonal Phase

“…The Mixed System (NH,)Cll-,Br, NK4CI and NH,Br form a completely miscible series of solid solutions [8].…”

Structural singularities of the Eu2+-doped spatially coherent [KBr0.097I0.903](0.348):[KBr0.459Cl0.511I0.030](0.652) composite as seen under the epifluorescence optical microscopy

“…The system KCl-KBr is known long ago [1] to give place to an F-type cubic substitutional solid solution series KCl x Br y , where x and y (¼1 À x) are the molar fraction concentrations of the Cl À and Br À ions, respectively, in the solid solution. For this series, a unit cell size a 0KCl-KBr may be computed [2][3][4][5][6] in the whole range of x using Vegard's rule: a 0KCl-KBr ¼ xa 0KCl þ ya 0KBr , where a 0KCl and a 0KBr are the unit cell sizes of KCl and KBr, respectively. X-ray diffraction (XRD) unit cell size measurements, carried out [7] with an accuracy of about 0.002 Å on Eu 2þ -doped KCl x Br y specimens corresponding to x ¼ 1, 0.99, 0.95, 0.85, 0.75, 0.60, 0.50, 0.45, 0.30, 0.15, 0.10, 0.05, 0.01 and 0, have indicated that the KCl x Br y :Eu 2þ series holds strictly Vegard's rule in the whole range of x.…”

“…In such studies, the band at 418 nm has been ascribed to isolated Eu 2þ -cation vacancy dipoles while the bands at 430, 448 and 474 nm have been ascribed to different metastable europium-dihalide-type precipitates which appear within the mixed matrix as a result of the annealing treatment. The system KBr-KI has been the subject of a number of structural studies and lattice constants, obtained by XRD, have been successively reported in time for crystal growths of this system [3,[11][12][13][14][15]. From such reports, three different Ftype cubic solid solutions are known to be able to co-exist in samples obtained from melts with Br À ion molar-fraction concentrations in the range from about 0.3 to 0.7.…”