Interaction of octahedral Mg(II) and tetrahedral Al(III) substitutions in aluminium-rich dioctahedral smectites

Lavikainen, Lasse P.; Hirvi, Janne T.; Kasa, Seppo; Pakkanen, Tapani A.

doi:10.1007/s00214-016-1846-4

Cited by 8 publications

(6 citation statements)

References 34 publications

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“…Accordingly, these substitutions tend to be dispersed in the layer structure . Various arrangements of octahedral and tetrahedral substitutions in both tv and cv structures of 2:1 dioctahedral smectites and illites were examined by DFT calculations. − Arrangements with dispersed Mg octahedral substitutions were energetically preferred, as were structures where Fe substitutions and Mg octahedral cations were not in close proximity in agreement with other studies. , Fe substitutions were shown to prefer neighboring positions to each other, confirming the segregation effect found earlier by means of Monte Carlo simulations . Energy differences between tv and cv structures were calculated as well, but no correlation was obtained between the number and type of cation substitutions on the one hand and the tv/cv preference on the other .…”

Section: Introductionsupporting

confidence: 85%

“…Monte Carlo simulations applying empirical interatomic potentials to smectite and Illite models with various arrangements of Al, Fe, and Mg cations in the octahedral sheet were carried out. − It was shown that Mg cations are preferentially dispersed, whereas Fe cations tend to form either clusters or chains . Recently, Lavikainen and co-workers used the density functional theory (DFT) approach to study the interaction of octahedral and tetrahedral charged substitutions in tv dioctahedral smectites. Accordingly, these substitutions tend to be dispersed in the layer structure .…”

Section: Introductionmentioning

confidence: 99%

“…Recently, Lavikainen and co-workers used the density functional theory (DFT) approach to study the interaction of octahedral and tetrahedral charged substitutions in tv dioctahedral smectites. Accordingly, these substitutions tend to be dispersed in the layer structure . Various arrangements of octahedral and tetrahedral substitutions in both tv and cv structures of 2:1 dioctahedral smectites and illites were examined by DFT calculations. − Arrangements with dispersed Mg octahedral substitutions were energetically preferred, as were structures where Fe substitutions and Mg octahedral cations were not in close proximity in agreement with other studies. , Fe substitutions were shown to prefer neighboring positions to each other, confirming the segregation effect found earlier by means of Monte Carlo simulations .…”

Section: Introductionmentioning

confidence: 99%

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Crystal-Chemical Composition of Dicoctahedral Smectites: An Energy-Based Assessment of Empirical Relations

Kaufhold

Kremleva

Krüger

et al. 2017

ACS Earth Space Chem.

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The experimental characterization of various dioctahedral smectites reveals weak correlations between the ratio of cis- and trans-vacant layer structures, fraction of charge in the tetrahedral sheet, and iron content. These correlations are demonstrated by two independent sample sets examined in different laboratories and, hence, are considered to be significant. For these relations to be rationalized and corroborated, accurate relative energies and ion exchange energies of a set of model minerals were determined by quantum chemical density functional calculations. Accordingly, one may trace these empirical correlations mainly back to energy relations and rationalize some deviating smectites by their particular history of formation.

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Section: Introductionsupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Crystal-Chemical Composition of Dicoctahedral Smectites: An Energy-Based Assessment of Empirical Relations

Kaufhold

Kremleva

Krüger

et al. 2017

ACS Earth Space Chem.

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“…Substitution Energies for the Second Heteroatoms (E sub2 , kcal/mol), Their Differences from the First Substitution Energies (ΔE sub , kcal/mol), and Relative Energies (RE, kcal/mol) for the Double Substituted MMT Models as Well as Average K−O S Distances (R K−Os , Å), Charge Transfers (q tr , |e|), and Adsorption Energies (E ad , kcal/mol) for the Adsorption of K + on these MMT Models 3 and Figure 6). Priority is generally given to two T sites with larger distances; 25,28,53,54 3). In all cases, the K− O S distances of double substitutions are less than those of mono substitutions (both octahedral and tetrahedral, see Table 2) suggesting the reinforced adsorption.…”

Section: Double Substitutions In Mmtmentioning

confidence: 99%

Isomorphic Substitutions in Clay Materials and Adsorption of Metal Ions onto External Surfaces: A DFT Investigation

et al. 2017

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Clay materials show particular adsorption performances while the mechanisms and influencing factors remain largely elusive, which are presently tackled by DFT calculations. Isomorphic substitutions pervasive in clay materials may bring about critical impacts on the adsorption processes. Octahedral substitutions in montmorillonite occur preferentially at specific T sites (referred to as octahedral or tetrahedral sites) or evenly at different T sites, which depend strongly on the ionic radii of heteroatoms. Structural perturbations resulting from isomorphic substitutions and substitution energies generally increase with ionic radii, except Be2+/Al3+ substitutions that cause structural collapses. Octahedral rather than tetrahedral substitutions are preferred, and, compared with montmorillonite, octahedral substitutions in hectorite are more facile while tetrahedral substitutions are more difficult; furthermore, hectorite exhibits superior adsorption performances. The second heteroatoms are always more difficult to incorporate, and their locations depend significantly on the first heteroatoms. After analyzing the adsorption structures and energies, the various factors affecting the adsorption performances (identity of heteroatoms, crystallographically distinct T sites, structural alterations, quantity of negative charges, distance from charge centers to metal ions and source of negative charges) are discussed, with their respective contributions being estimated. Quantity of negative charges is the foremost factor that controls the adsorption performances, while other factors in certain circumstances can also play a critical role. Results are beneficial to understand the particular adsorption behaviors of clay materials.

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“…Moreover, the structures of MMTs are also influenced by different layer charge densities and layer charge distributions. For instance, the basal layer spacing and interlayer spacing can be affected by different layer charge densities and distributions (Peng et al, 2021) and the introduction of the substitutions generates structural tension to the layer structure leading to the structure expansion (Lavikainen et al, 2016). Since the anisotropic elastic properties of MMTs are strongly correlated with their structure (Zhong et al, 2021), the variation of structure may potentially cause a change in the anisotropic elastic properties of MMTs.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic Elastic Properties of Montmorillonite With Different Layer Charge Densities and Layer Charge Distributions Through Molecular Dynamic Simulation

Han

2022

Front. Earth Sci.

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The knowledge of the anisotropic elastic properties of clay minerals is of crucial importance for the exploration and development of shale oil and gas. Montmorillonite (MMT) is a common natural clay mineral with different layer charge densities and layer charge distributions due to different geological conditions. Therefore, it is important to understand the currently poorly known effect of layer charge density and layer charge distribution on the anisotropic elastic properties of MMTs. This work aims to obtain such knowledge by studying the anisotropic elastic properties of different MMTs under stratigraphic conditions through molecular dynamic simulations. We showed that the in-plane compressional coefficients C11, C22 and C12 decrease with the increasing layer charge density for MMTs with different layer charge distributions, and the MMTs with the layer charges distributed on the two tetrahedral (T) sheets were found to have the smallest C11, C22 and C12. We also showed that the out-of-plane compressional coefficients C33, C13 and C23 of the MMTs with the layer charges distributed in the two T sheets decrease, while those with the layer charges in the octahedral (O) sheet increase and those with layer charges distributed in both the O sheet and the T sheets do not vary much with the increasing layer charge density. The variations of the anisotropic compressional elastic coefficients with different layer charge densities and layer charge distributions were found to be a result of the impact of the density and distribution of layer charges on the molecular interactions within the MMT layer. We further demonstrated that the layer charge density and layer charge distribution do not influence significantly the shear coefficients C44, C55, and C66. The results revealed the mechanisms of how the density and distribution of layer charges affect the anisotropic elastic properties of MMTs and will contribute to the more successful exploration and development of unconventional resources in MMT bearing shale reservoirs.

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Interaction of octahedral Mg(II) and tetrahedral Al(III) substitutions in aluminium-rich dioctahedral smectites

Cited by 8 publications

References 34 publications

Crystal-Chemical Composition of Dicoctahedral Smectites: An Energy-Based Assessment of Empirical Relations

Crystal-Chemical Composition of Dicoctahedral Smectites: An Energy-Based Assessment of Empirical Relations

Isomorphic Substitutions in Clay Materials and Adsorption of Metal Ions onto External Surfaces: A DFT Investigation

Anisotropic Elastic Properties of Montmorillonite With Different Layer Charge Densities and Layer Charge Distributions Through Molecular Dynamic Simulation

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