X-Ray Diffraction Studies of Sodium Chloride–Sodium Bromide Solid Solutions.

Abstract

In a recent study (2) the heats of formation of a series of sodium chloridesodium bromide solid solutions were determined. At the time it seemed desirable to subject the several solid solutions to x-ray diffraction analysis so that some idea of their homogeneity and physical state might be obtained. In addition, there was some interest in ascertaining how nearly additive the lattice spacings and molar volumes are for this system. EXPERIMENTALThe preparation and analysis of the eleven samples studied (the two pure salts and nine solid solutions) have been described (2).X-ray powder diffraction patterns of these samples were made with a cylindrical camera of 171.9 mm. effective diameter, employing the Straumanis (5) technique. Unfiltered radiation from a sealed copper tube fitted with beryllium windows was used to reduce the exposure time. The general procedure followed in making the diffraction patterns and the mode of preparation of the cylindrical, 0.7 mm. diameter powder specimens of the samples are described elsewhere (4). To protect the prepared specimens from moisture, as well as to improve their mechanical strength, they were given a collodion coating by dipping into a diluted solution of flexible collodion. All samples and prepared specimens were stored in a desiccator over anhydrous calcium chloride when not in use. EXPERIMENTAL RESULTSPreliminary examination of the diffraction patterns indicated that all the solid solutions were single-phase, homogeneous, crystalline materials. The diffraction lines appeared uniformly sharp for the several solid solutions, as well as for the two pure salts. The patterns for the solutions showed no signs of lines characteristic of either of the pure constituents and all of the observed lines could be accounted for by assuming the existence of a single solid solution of fixed composition. The Bradley and Jay (1) extrapolation method was applied to the backreflection diffraction lines to obtain the lattice spacings (cation-cation distance) given in table 1. The variation of the lattice spacing with composition is shown in figure 1.

Chloride-substitution in sodium borohydride

“…NaBH 4 and NaCl are isostructural with a NaCl-type structure and unit cell parameter a = 6.1635Å and a = 5.6402Å, respectively [27,28]. PXD patterns of a 1:1 sample of NaBH 4 and NaCl after 2, 6, 12 and 24 h of milling are shown in Fig.…”

Pretreatment by NaOH swelling and then HCl regeneration to enhance the acid hydrolysis of cellulose to glucose

“…The Cr for the air dried hydrogel from HCl regeneration was 46.5%, only slightly higher than that before drying. At the same time, the strong peaks at 27.0°, 31.5°, 45.3°and 56.3°for NaCl were observed (Nickels et al, 1949). These facts indicated the diffusion of Cl À ions into cellulose network, leading the more difficulty of cellulose II formation.…”

The Dependence of Radius on Relative Humidity and Solute Mass at High Relative Humidities Up to and Including 100%

“…All results were checked against E-AIM to ensure that they were calculated correctly. All calculations were performed for 298.15 K. The density of dry ammonium sulfate was taken as 1.77 g/cm 3 (Johnston & Adams, 1912;Minevich et al, 2004;Schlemper & Hamilton, 1966), that of dry sodium chloride as 2.17 g/cm 3 (Johnston & Hutchison, 1942;Nickels et al, 1949;Wollam & Wallace, 1956), and that of pure sulfuric acid as 1.83 g/cm 3 (Gillespie & Wasif, 1953;Greenwood & Thompson, 1959;Rhodes & Barbour, 1923). Molal masses are calculated from Wieser (2007).…”