Phase diagram of kaolinite from Molecular Dynamics calculations

Benazzouz, B.K.; Zaoui, A.

doi:10.1016/j.physb.2012.03.047

Cited by 18 publications

(9 citation statements)

References 36 publications

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“…Elastic constant is an important parameter used to express the mechanical properties of solid materials. As stress and strain have three tensile and shear components, the elastic constant forms a 6 × 6 matrix with 36 independent components [37]. According to the symmetry of the triclinic system of montmorillonite, the elastic constant is reduced to 21 independent components, including (C .…”

Section: Methodsmentioning

confidence: 99%

Investigation on Atomic Structure and Mechanical Property of Na- and Mg-Montmorillonite under High Pressure by First-Principles Calculations

et al. 2021

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Montmorillonite is an important layered phyllosilicate material with many useful physicochemical and mechanical properties, which is widely used in medicine, environmental protection, construction industry, and other fields. In order to a get better understanding of the behavior of montmorillonite under high pressure, we studied its atomic structure, electronic and mechanical properties using density functional theory (DFT), including dispersion corrections, as function of the interlayer Na and Mg cations. At ideal condition, the calculations of lattice constants, bond length, band structure, and elastic modulus of Na- and Mg-montmorillonite are in good agreement with the experimental values. Under high pressure, the lattice constants and major bond lengths decreased with increasing pressure. The calculated electronic properties and band structure show only a slight change under 20 GPa, indicating that the effect of pressure on the electronic properties of Na- and Mg-montmorillonite is weak. The bulk modulus, shear modulus, Young’s modulus, shear wave velocity and compression wave velocity of Na- and Mg-montmorillonite are positively correlated with the external pressure, and the other mechanical parameters have a little change. The calculated studies will be useful to explore experiments in the future from a purely scientific point of view.

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Section: Methodsmentioning

confidence: 99%

Investigation on Atomic Structure and Mechanical Property of Na- and Mg-Montmorillonite under High Pressure by First-Principles Calculations

et al. 2021

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“…To describe the Montmorillonite (001)/calcite (104) interface, we have developed existing models for calcite and clay by adding terms describing the interatomic interactions between constituents of calcite and clay at the interface. We have used the ClayFF potential model 37 , well tested for clays 38 39 40 41 42 43 44 45 46 47 48 49 and the Xiao forcefield for calcite 50 , that we have previously used in the analysis of bulk and surface state of calcite rock 51 . This is a new forcefield taking into account the aqueous environment using the TIP3P water model 52 .…”

Section: Methods Summarymentioning

confidence: 99%

Can clays ensure nuclear waste repositories?

Zaoui

Sekkal

2015

Sci Rep

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Research on argillite as a possible host rock for nuclear waste disposal is still an open subject since many issues need to be clarified. In the Underground Research Laboratories constructed for this purpose, a damaged zone around the excavation has been systematically observed and characterized by the appearance of micro-fissures. We analyse here -at nanoscale level- the calcite/clay assembly, the main constituents of argillite, under storage conditions and show the fragility of the montmorillonite with respect to calcite. Under anisotropic stress, we have observed a shear deformation of the assembly with the presence of broken bonds in the clay mineral, localised in the octahedral rather than the tetrahedral layers. The stress/strain curve leads to a failure strength point at 18.5 MPa. The obtained in-plane response of the assembly to perpendicular deformation is characterized by smaller perpendicular moduli Ez = 48.28 GPa compared to larger in-plane moduli Ex = 141.39 GPa and Ey = 134.02 GPa. Our calculations indicate the instability of the assembly without water molecules at the interface in addition to an important shear deformation.

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“…Elastic property is the inherent property of the material, which represents the deformation extent of the material under the applied stress. For the triclinic system of pyrophyllite, 21 independent elastic stiffness constants [40]…”

Section: Effect Of Pressure On the Mechanical Properties Of Pyrophyllitementioning

confidence: 99%

Atomic Structure, Electronic and Mechanical Properties of Pyrophyllite under Pressure: A First-Principles Study

et al. 2020

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Pyrophyllite is extensively used in the high-pressure synthesis industry as a pressure-transmitting medium because of its outstanding pressure transmission, machinability, and insulation. Therefore, the atomic structure, electronic, and mechanical behavior of pyrophyllite [Al4Si8O20(OH)4] under high pressure should be discussed deeply and systematically. In the present paper, the lattice parameters, bond length, the electronic density of states, band structure, elastic constants, and mechanical parameters of pyrophyllite are investigated using density functional theory (DFT) from a microscopic perspective. The pressure dependence of atomic structure, electronic, and mechanical properties of pyrophyllite is analyzed for a wide range of pressure (from 0 GPa to 13.87 GPa). Under high pressure, the major bond lengths and layer thicknesses decrease slightly, and mechanical properties are improved with increasing pressure. The calculated electronic and band structures show only a slight change with increasing pressure, implying that the effect of pressure on the electronic property of pyrophyllite is weak, and pyrophyllite still has good stability under high pressure. The theoretical calculations presented here clarify the electronic and mechanical properties of natural pyrophyllite that are difficult to obtain experimentally because of their small particle size.

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Phase diagram of kaolinite from Molecular Dynamics calculations

Cited by 18 publications

References 36 publications

Investigation on Atomic Structure and Mechanical Property of Na- and Mg-Montmorillonite under High Pressure by First-Principles Calculations

Investigation on Atomic Structure and Mechanical Property of Na- and Mg-Montmorillonite under High Pressure by First-Principles Calculations

Can clays ensure nuclear waste repositories?

Atomic Structure, Electronic and Mechanical Properties of Pyrophyllite under Pressure: A First-Principles Study

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