Porosity of Synthetic Saponites with Variable Layer Charge Pillared by Al13 Polycations

Langmuir ◽  
1995 ◽  
Vol 11 (8) ◽  
pp. 2849-2852 ◽  
Author(s):  
L. Bergaoui ◽  
J. F. Lambert ◽  
M. A. Vicente-Rodriguez ◽  
L. J. Michot ◽  
F. Villieras
Keyword(s):  
Layer Charge ◽  
Variable Layer

Spectral Properties of Rhodamine 3B Adsorbed on the Surface of Montmorillonites with Variable Layer Charge

Langmuir ◽  
2007 ◽  
Vol 23 (4) ◽  
pp. 1851-1859 ◽  
Author(s):  
Juraj Bujdák ◽  
Virginia Martínez Martínez ◽  
Fernando López Arbeloa ◽  
Nobuo Iyi
Keyword(s):  
Spectral Properties ◽  
Layer Charge ◽  
Variable Layer

Preparation and infrared spectroscopic characterization of reduced-charge montmorillonite with various Li contents

Clay Minerals ◽  
1996 ◽  
Vol 31 (2) ◽  
pp. 233-241 ◽  
Author(s):  
J. Madejová ◽  
J. Bujdák ◽  
W. P. Gates ◽  
P. Komadel
Keyword(s):  
Infrared Spectroscopy ◽  
Spectroscopic Characterization ◽  
Layer Charge ◽  
Preparation Temperature ◽  
Oh Groups ◽  
Tetrahedral Sheet ◽  
Increasing Temperature ◽  
Octahedral Cations ◽  
Variable Layer

AbstractA series of reduced-charge montmorillonites (RCMs) was prepared from Li-montmorillonite from Jelšový Potok (Slovakia) by heating at various temperatures (105–210°C for 24 h. The amount of fixed Li, 0.09–0.67 per O20(OH)4, increased with increasing temperature, confirming preparation of a set of samples of variable layer charge from the same parent Li-montmorillonite by varying only the preparation temperature. Infrared spectroscopy revealed that Li was trapped in the hexagonal cavities of the tetrahedral sheet at all temperatures. Partial deprotonation of the samples, reflected in the decrease of the intensities of the OH-bending bands, was observed after treatments above 120°C. Analysis of the OH-stretching region showed Li in the previously vacant octahedra in the samples heated above 150°C. Weak inflections near 660 and 720 cm−1 confirmed development of local trioctahedral character of octahedral cations coordinated with OH groups in the sample heated at 210°C. Gradual decrease of the layer charge due to Li fixation led to a shift of the Si-O stretching band to higher frequencies and to the appearance of new, pyrophyllite-like bands at 1120 and 419 cm−1.

Pillaring of Layered Double Hydroxides Possessing Variable Layer Charge with Vanadium Polyoxoanions

1994 ◽  
Vol 371 ◽  
Author(s):  
F. Kooli ◽  
V. Rives ◽  
M.A. Ulibarri ◽  
W. Jones
Keyword(s):  
Surface Area ◽  
Layered Double Hydroxides ◽  
Layer Charge ◽  
Second Phase ◽  
Textural Characteristics ◽  
Al Content ◽  
Complete Exchange ◽  
Double Hydroxides ◽  
Charge Balancing ◽  
Variable Layer

AbstractA range of layered double hydroxides (LDHs) with Ni/Al and Mg/Al as the M(II)/M(III) cations and containing carbonate as the charge balancing anion have been synthesised. A variation in the M(II)/M(III) ratio between 2 and 6 has been attempted with the influence of the M(II)/M(III) ratio upon the subsequent exchange of carbonate by [V10O28]6- (at pH 4.5) examined. Complete exchange is obtained for all ratios, although the crystallinity of the products varies. For M(II)/M(III) ratios > 4, the product crystallinity is poor. In addition, a second phase is detected for all ratios. In the case of Ni/Al, the amount of vanadium incorporated is found to depend upon the Al content whereas for Mg/Al the amount incorporated is constant. Overall, the replacement of carbonate by decavanadate does not appear to have any significant effect on the textural characteristics (e.g. surface area or porosity) of the pillared products.

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.

Interfacial Engineering of Mo/Hf0.3Zr0.7O2/Si Capacitor Using Direct Scavenging Effect of Thin Ti layer

2021 ◽  
Author(s):  
Se Hyun Kim ◽  
Geun Taek Yu ◽  
Geun Hyeong Park ◽  
Dong Hyun Lee ◽  
Ju-Yong Park ◽  
...  
Keyword(s):  
Sacrificial Layer ◽  
Charge Trapping ◽  
Layer Charge ◽  
Tio2 Layer ◽  
Interfacial Engineering ◽  
Scavenging Effect

An antiferroelectric Mo/Hf0.3Zr0.7O2/SIOx/Si capacitor was engineered using the direct scavenging effect of a sputtered Ti sacrificial layer. Charge trapping could be mitigated with the oxidized TiO2 layer, and the endurance...

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