Structure and Chemical Characteristics of Modified Clays

1999 ◽  
pp. 3-18 ◽  
Author(s):  
P. Komadel
Keyword(s):  
Chemical Characteristics ◽  
Modified Clays

Characterization of defects in tabular silver halide grains

1990 ◽  
Vol 48 (4) ◽  
pp. 1046-1047
Author(s):  
C. Goessens ◽  
D. Schryvers ◽  
J. Van Landuyt ◽  
A. Verbeeck ◽  
R. De Keyzer
Keyword(s):  
Radiation Damage ◽  
Silver Halide ◽  
Chemical Characteristics ◽  
X Ray ◽  
Free Region ◽  
Central Defect ◽  
Crystallographic Defects ◽  
Physical And Chemical ◽  
Two Sides

Silver halide grains (AgX, X=Cl,Br,I) are commonly recognized as important entities in photographic applications. Depending on the preparation specifications one can grow cubic, octahedral, tabular a.o. morphologies, each with its own physical and chemical characteristics. In the present study crystallographic defects introduced by the mixing of 5-20% iodide in a growing AgBr tabular grain are investigated. X-ray diffractometry reveals the existence of a homogeneous Ag(Br1-xIx) region, expected to be formed around the AgBr kernel. In fig. 1 a two-beam BF image, taken at T≈100 K to diminish radiation damage, of a triangular tabular grain is presented, clearly showing defect contrast fringes along four of the six directions; the remaining two sides show similar contrast under relevant diffraction conditions. The width of the central defect free region corresponds with the pure AgBr kernel grown before the mixing with I. The thickness of a given grain lies between 0.15 and 0.3 μm: as indicated in fig. 2 triangular (resp. hexagonal) grains exhibit an uneven (resp. even) number of twin interfaces (i.e., between + and - twin variants) parallel with the (111) surfaces. The thickness of the grains and the existence of the twin variants was confirmed from CTEM images of perpendicular cuts.

Inorganic and organic chemical characteristics and sources of suspended particulate matters in Ulaanbaatar, Mongolia

2020 ◽  
Vol 54 (4) ◽  
pp. 267-276
Author(s):  
Koshi Yamamoto ◽  
Yuta Suzuki ◽  
Gochoobazar Oyunjargal ◽  
Hiroyuki Fukuda ◽  
Munkhtsetseg Oidov ◽  
...  
Keyword(s):  
Organic Chemical ◽  
Chemical Characteristics ◽  
Particulate Matters ◽  
Suspended Particulate ◽  
Suspended Particulate Matters ◽  
Inorganic And Organic

Solution chemistry effects on the solvation shell of metal ions

2020 ◽  
Author(s):  
Xiangwen Wang ◽  
Dimitrios Toroz ◽  
Seonmyeong Kim ◽  
Simon Clegg ◽  
Gun-Sik Park ◽  
...  
Keyword(s):  
Metal Ions ◽  
Pure Water ◽  
Solvation Shell ◽  
Solution Chemistry ◽  
Chemical Characteristics ◽  
Velocity Autocorrelation Function ◽  
Ionic Solvation ◽  
General Terms ◽  
Alkaline Earth Metal Ions ◽  
Wide Range

<div> <p>As natural aqueous solutions are far from being pure water, being rich in ions, the properties of solvated ions are of relevance for a wide range of systems, including biological and geochemical environments. We conducted ab initio and classical MD simulations of the alkaline earth metal ions Mg<sup>2+</sup> and Ca<sup>2+</sup> and of the alkali metal ions Li<sup>+</sup>, Na<sup>+</sup>, K<sup>+</sup> and Cs<sup>+</sup> in pure water and electrolyte solutions containing the counterions Cl<sup>–</sup> and SO<sub>4</sub><sup>2–</sup>. Through a detailed analysis of these simulations, this study reports on the effect of solution chemistry (composition and concentration of the solution) to the ion–water structural properties and interaction strength, and to the dynamics, hydrogen bond network, and low-frequency dynamics of the ionic solvation shell. Except for the ion–water radial distribution function, which is weakly dependent on the counter-ions and concentrations, we found that all other properties can be significantly influenced by the chemical characteristics of the solution. Calculation of the velocity autocorrelation function of magnesium ions, for example, shows that chlorine ions located in the second coordination shell of Mg<sup>2+</sup> weaken the Mg(H<sub>2</sub>O)<sub>6</sub><sup>2+</sup> hydration ‘cage’ of the cation. The result reported in this study suggest that ionic solvation shell can be significantly influenced by the interactions between other ions present in solution ions, especially those of opposite charge. In more general terms, the chemical characteristics of the solution, including the balance between ion-solvent and ion-ion interactions, could result in significant differences in behavior and function of the ionic solvation shell.</p> </div>

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