scholarly journals Influence of Tetrahedral Layer Charge on the Fixation of Cesium in Synthetic Smectite

2017 ◽  
Vol 121 (42) ◽  
pp. 23422-23435 ◽  
Author(s):  
Liva Dzene ◽  
Heloïse Verron ◽  
Alfred Delville ◽  
Laurent J. Michot ◽  
Jean-Louis Robert ◽  
...  
Keyword(s):  
Layer Charge ◽  
Tetrahedral Layer

Influence of Tetrahedral Layer Charge on the Organization of Interlayer Water and Ions in Synthetic Na-Saturated Smectites

2015 ◽  
Vol 119 (8) ◽  
pp. 4158-4172 ◽  
Author(s):  
Baptiste Dazas ◽  
Bruno Lanson ◽  
Alfred Delville ◽  
Jean-Louis Robert ◽  
Sridhar Komarneni ◽  
...  
Keyword(s):  
Layer Charge ◽  
Interlayer Water ◽  
Tetrahedral Layer

scholarly journals Rb1.66Cs1.34Tb[Si5.43Ge0.57O15]·H2O, a New Member of the OD-Family of Natural and Synthetic Layered Silicates: Topology-Symmetry Analysis and Structure Prediction

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 395
Author(s):  
Anastasiia Topnikova ◽  
Elena Belokoneva ◽  
Olga Dimitrova ◽  
Anatoly Volkov ◽  
Dina Deyneko
Keyword(s):  
Structure Prediction ◽  
Symmetry Analysis ◽  
Layered Silicates ◽  
Water Molecules ◽  
Structural Variants ◽  
X Ray ◽  
A Chain ◽  
Multi Component System ◽  
Tetrahedral Layer ◽  
Natural And Synthetic

Crystals of new silicate-germanate Rb1.66Cs1.34Tb[Si5.43Ge0.57O15]·H2O have been synthesized hydrothermally in a multi-component system TbCl3:GeO2:SiO2 = 1:1:5 at T = 280 °C and P = 100 atm. K2CO3, Rb2CO3 and Cs2CO3 were added to the solution as mineralizers. The crystal structure was solved using single crystal X-ray data: a = 15.9429(3), b = 14.8407(3), c = 7.2781(1) Å, sp. gr. Pbam. New Rb,Cs,Tb-silicate-germanate consists of a [Si5.43Ge0.57O15]∞∞ corrugated tetrahedral layer combined by isolated TbO6 octahedra into the mixed microporous framework as in synthetic K3Nd[Si6O15]·2H2O, K3Nd[Si6O15] and K3Eu[Si6O15]·2H2O with the cavities occupied by Cs, Rb atoms and water molecules. Luminescence spectrum on new crystals was obtained and analysed. A comparison with the other representatives of related layered natural and synthetic silicates was carried out based on the topology-symmetry analysis by the OD (order-disorder) approach. The wollastonite chain was selected as the initial structural unit. Three symmetrical ways of forming ribbon from such a chain and three ways of further connecting ribbons to each other into the layer were revealed and described with symmetry groupoids. Hypothetical structural variants of the layers and ribbons in this family were predicted.

Crystallochemical classifications of phyllosilicates based on the unified system of projection of chemical composition: I. The mica group

Clay Minerals ◽  
1990 ◽  
Vol 25 (1) ◽  
pp. 73-81 ◽  
Author(s):  
A. Wiewióra
Keyword(s):  
Chemical Composition ◽  
Divalent Cations ◽  
Layer Charge ◽  
Vector Representation ◽  
Similar Formula ◽  
Crystallochemical Formula ◽  
Trivalent Cations ◽  
Image Position ◽  
Composition I ◽  
Unit Vectors

AbstractA unified system of vector representation of chemical composition is proposed for the phyllosilicates based on projection of the composition, as given by crystallochemical formula, onto a field with orthogonal axes chosen for octahedral divalent cations, R2+, and Si (X, Y, respectively), and oblique axes for octahedral trivalent cations, R3+, and vacancies, □, (V, Z, respectively). Point coordinates for each set of axes were used to define the direction and length of the unit vectors for phyllosilicates belonging to different groups. Parallel to these fundamental directions the composition isolines were drawn in the projection fields. Applied to micas, this system enables control of the chemical composition by the general crystallochemical formula covering all varieties of Li-free dioctahedral and trioctahedral micas:where z (number of vacancies) = (y-x+ m)/2; m (layer charge) =1; u+y+z = 3. There is a similar formula for vacancy-free lithian micas:where w = m — x+y;m=1; u+y+w = 3, and for Li-free brittle micas:where z = (y — x+m)/2; m = 2; u+y+z = 3. Projection fields were used to classify micas.

scholarly journals Lightning in the Anvils of Supercell Thunderstorms

2012 ◽  
Vol 140 (7) ◽  
pp. 2064-2079 ◽  
Author(s):  
Stephanie A. Weiss ◽  
Donald R. MacGorman ◽  
Kristin M. Calhoun
Keyword(s):  
Warm Season ◽  
Opposite Polarity ◽  
Layer Charge ◽  
Supercell Storm ◽  
Lightning Detection ◽  
Supercell Storms ◽  
Mapping Array ◽  
Storm Dynamics ◽  
Supercell Thunderstorms

Abstract This study uses data from the Oklahoma Lightning Mapping Array (OK-LMA), the National Lightning Detection Network, and the Norman, Oklahoma (KOUN), prototype Weather Surveillance Radar-1988 Doppler (WSR-88D) radar to examine the evolution and structure of lightning in the anvils of supercell storms as they relate to storm dynamics and microphysics. Several supercell storms within the domain of the OK-LMA were examined to determine whether they had lightning in the anvil region, and if so, the time and location of the initiation of the anvil flashes were determined. Every warm-season supercell storm had some flashes that were initiated in or near the stronger reflectivities of the parent storm and propagated 40–70 km downstream to penetrate well into the anvil. Some supercell storms also had flashes that were initiated within the anvil itself, 40–100 km beyond the closest 30-dBZ contour of the storm. These flashes were typically initiated in one of three locations: 1) coincident with a local reflectivity maximum, 2) between the uppermost storm charge and a screening-layer charge of opposite polarity near the cloud boundary, or 3) in a region in which the anvils from two adjoining storms intersected. In some storms, anvil flashes struck ground beneath a reflectivity maximum in which reflectivity ≥20 dBZ had extended below the 0°C isotherm, possibly leading to the formation of embedded convection. This relationship may be useful for identifying regions in which there is a heightened risk for cloud-to-ground strikes beneath anvil clouds. In one storm, however, anvil lightning struck ground even though this reflectivity signature was absent.

Influence of Layer Charge and Modifier on Wettability of Organo-Montmorillonite

2014 ◽  
Vol 1030-1032 ◽  
pp. 90-94
Author(s):  
Zhong Xin Luo ◽  
Mang Lai Gao ◽  
Ya Ge Ye
Keyword(s):  
Synergistic Effect ◽  
Chain Length ◽  
Quaternary Ammonium ◽  
Capillary Rise ◽  
Quaternary Ammonium Salts ◽  
Deionized Water ◽  
Ammonium Salts ◽  
Layer Charge ◽  
Oil Reservoir ◽  
Capillary Rise Method

To study the influence of layer charge and modifier on wettability plays an important role on the diagnosis of oil reservoir. In this paper, two quaternary ammonium salts (QASs) with different chain-length were used singularly or in compound form to modify the reduced-charge montmorillonites (RCMs). The wettability alterations of the organo-RCMs for deionized water and cyclohexane were studied based on capillary rise method. The results showed that RCMs singularly modified by QASs show different wettability characteristics. Moreover, there is a synergistic effect on the wettability when the RCMs are compound modified by two QASs and the organo-RCMs turn to more hydrophilic. The results of this work also indicated that it is possible to regulate the wettability of the RCMs by choosing different recipe of QASs, which is helpful to provide theoretical guidance for the oil production.

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