Hydration Properties and Interlayer Organization of Water and Ions in Synthetic Na-Smectite with Tetrahedral Layer Charge. Part 2. Toward a Precise Coupling between Molecular Simulations and Diffraction Data

2011 ◽  
Vol 115 (5) ◽  
pp. 1867-1881 ◽  
Author(s):  
Eric Ferrage ◽  
Boris A. Sakharov ◽  
Laurent J. Michot ◽  
Alfred Delville ◽  
Allan Bauer ◽  
...  
Keyword(s):  
Diffraction Data ◽  
Molecular Simulations ◽  
Layer Charge ◽  
Hydration Properties ◽  
Tetrahedral Layer ◽  
Charge Part

Tungusite: new data, relationship with gyrolite and structural model

1995 ◽  
Vol 59 (396) ◽  
pp. 535-543 ◽  
Author(s):  
Giovanni Ferraris ◽  
Alessandro Pavese ◽  
Svetlana V. Soboleva
Keyword(s):  
Solid Solution ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structural Model ◽  
Substitutional Solid Solution ◽  
Chemical Analyses ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Tetrahedral Layer ◽  
The Ideal

AbstractNew chemical analyses, electron and X-ray powder diffraction data, and comparison with gyrolite and reyerite show that tungusite has the ideal formula , symmetry P and a = 9.714(9), b = 9.721(9), c = 22.09(3), α = 90.13(1)°, β = 98.3(2)°, γ = 120.0(1)°, Z = 1. A structural model for tungusite is derived by splitting the double tetrahedral layer of reyerite and inserting a trioctahedral X sheet which is ideally occupied by Fe2+. Polytypism phenomena due to different relative positions between tetrahedral and X sheets are discussed. A substitutional solid solution represented by the formula [Ca14(OH)8]Si24−yAlyO60[NaxM9−(x+z)□z(OH)14−(x+y+2z)·(x+y+2z)H2O] includes tungusite (x = y = z = 0, M = Fe2+ and gyrolite (x = 1, y = 1, z = 6, M = Ca).

The site occupancy of Mg in the brownmillerite structure and its effect on hydration properties: an X-ray/neutron diffraction and EXAFS study

2001 ◽  
Vol 34 (1) ◽  
pp. 55-61 ◽  
Author(s):  
A. C. Jupe ◽  
J. K. Cockcroft ◽  
P. Barnes ◽  
S. L. Colston ◽  
G. Sankar ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Diffraction Data ◽  
Site Occupancy ◽  
Pure Form ◽  
Site Preference ◽  
Data Sets ◽  
Hydration Properties ◽  
Time Resolved ◽  
X Ray ◽  
Mg Doping

Samples of pure (Ca2FeAlO5) and lightly doped (Ca2Fe0.95Al0.95Mg0.05Si0.05O5) brownmillerite have been synthesized. Synchrotron X-ray and neutron diffraction data have been collected so that the structures can be refined using, simultaneously, both diffraction data sets and known compositional information; this overcomes the problem of under-determinacy resulting from multi-occupation of the tetrahedrally and octahedrally coordinated sites in the structure. For the pure form, a 2.7:1 iron/aluminium preference for octahedral/tetrahedral (respectively) occupation is obtained. This trend is reflected also in the doped brownmillerite, though, because of the low level of Mg doping, the occupancy of Mg is only resolved through the additional use of Mg EXAFS (extended X-ray absorption fine structure) data, which shows that Mg displays a distinct octahedral site preference rather than a disordered occupation between the octahedral/tetrahedral sites. The consequences of Mg doping are then examined using time-resolved multi-angle energy-dispersive powder X-ray diffraction studies of the mineral undergoing hydration; this shows that the pure form is more active than the doped form.

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 Investigation of dioctahedral smectite hydration properties by modeling of X-ray diffraction profiles: Influence of layer charge and charge location

2007 ◽  
Vol 92 (10) ◽  
pp. 1731-1743 ◽  
Author(s):  
E. Ferrage ◽  
B. Lanson ◽  
B. A. Sakharov ◽  
N. Geoffroy ◽  
E. Jacquot ◽  
...  
Keyword(s):  
Layer Charge ◽  
X Ray Diffraction ◽  
Hydration Properties ◽  
X Ray ◽  
Dioctahedral Smectite

scholarly journals Influence of layer charge on hydration properties of synthetic octahedrally-charged Na-saturated trioctahedral swelling phyllosilicates

2020 ◽  
Vol 184 ◽  
pp. 105404 ◽  
Author(s):  
Doriana Vinci ◽  
Baptiste Dazas ◽  
Eric Ferrage ◽  
Martine Lanson ◽  
Valérie Magnin ◽  
...  
Keyword(s):  
Layer Charge ◽  
Hydration Properties

scholarly journals Effect of Layer Charge Density on Hydration Properties of Montmorillonite: Molecular Dynamics Simulation and Experimental Study

2019 ◽  
Vol 20 (16) ◽  
pp. 3997 ◽  
Author(s):  
Jun Qiu ◽  
Guoqing Li ◽  
Dongliang Liu ◽  
Shan Jiang ◽  
Guifang Wang ◽  
...  
Keyword(s):  
Charge Density ◽  
The Self ◽  
Dynamics Simulation ◽  
Central Axis ◽  
Layer Charge ◽  
Water Molecules ◽  
Hydration Properties ◽  
Self Diffusion ◽  
Simulation Results ◽  
Self Diffusion Coefficient

Four kinds of Ca-montmorillonite with different layer charge density were used to study the effect of charge density on their hydration properties by molecular dynamics simulation and experiments. The research results of Z-density distribution of water molecules, Hw (hydrogen in water molecules), and Ca in the interlayer of montmorillonite show that the hydration properties of montmorillonite are closely related to its layer charge density. If the charge density is low, the water molecules in the interlayers are mainly concentrated on the sides of the central axis about –1.3 Å and 1.5 Å. As the charge density increases from 0.38semi-cell to 0.69semi-cell, the water molecules are distributed −2.5 Å and 2.4 Å away from the siloxane surface (Si-O), the concentration of water molecules near the central axis decreases, and at the same time, Ca2+ appears to gradually shift from the vicinity of the central axis to the Si-O surface on both sides in the montmorillonite layer. The simulation results of the radial distribution function (RDF) of the Ca-Hw, Ca-Ow (oxygen in water molecules), and Ca-Ot (the oxygen in the tetrahedron) show that the Ca2+ and Ow are more tightly packed together than that of Hw; with the increase of the charge density, due to the fact that the negative charge sites on the Si-O surface increase, under the action of electrostatic attraction, some of the Ca2+ are pulled towards the Si-O surface, which is more obvious when the layer charge density of the montmorillonite is higher. The results of the RDF of the Ot-Hw show that with the increase of charge density, the number of hydrogen bonds formed by Ot and Hw in the interlayers increase, and under the action of hydrogen bonding force, the water molecules near the central axis are pulled towards the two sides of Si-O surface. As a result, the arrangement of water molecules is more compact, and the structure is obvious. Correspondingly, the self-diffusion coefficient shows that the higher the layer charge density, the lower the self-diffusion coefficient of water molecules in interlayers is and the worse the hydration performance of montmorillonite. The experimental results of the experiments fit well with the above simulation results.

Hydration of methane intercalated in Na-smectites with distinct layer charge: Insights from molecular simulations

2011 ◽  
Vol 355 (1) ◽  
pp. 237-242 ◽  
Author(s):  
Qing Zhou ◽  
Xiancai Lu ◽  
Xiandong Liu ◽  
Lihu Zhang ◽  
Hongping He ◽  
...  
Keyword(s):  
Molecular Simulations ◽  
Layer Charge
Sign in / Sign up

Export Citation Format

Share Document