scholarly journals DFT Study of Electronic Structure and Optical Properties of Kaolinite, Muscovite, and Montmorillonite

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 618
Author(s):  
Layla Shafei ◽  
Puja Adhikari ◽  
Wai-Yim Ching
Keyword(s):  
Mechanical Properties ◽  
Optical Properties ◽  
Electronic Structure ◽  
Hydrogen Bonds ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Bond Order ◽  
Deep Understanding ◽  
Pharmaceutical Applications ◽  
Structure Properties

Clay mineral materials have attracted attention due to their many properties and applications. The applications of clay minerals are closely linked to their structure and composition. In this paper, we studied the electronic structure properties of kaolinite, muscovite, and montmorillonite crystals, which are classified as clay minerals, by using DFT-based ab initio packages VASP and the OLCAO. The aim of this work is to have a deep understanding of clay mineral materials, including electronic structure, bond strength, mechanical properties, and optical properties. It is worth mentioning that understanding these properties may help continually result in new and innovative clay products in several applications, such as in pharmaceutical applications using kaolinite for their potential in cancer treatment, muscovite used as insulators in electrical appliances, and engineering applications that use montmorillonite as a sealant. In addition, our results show that the role played by hydrogen bonds in O-H bonds has an impact on the hydration in these crystals. Based on calculated total bond order density, it is concluded that kaolinite is slightly more cohesive than montmorillonite, which is consistent with the calculated mechanical properties.

Effects of Drying on the Mechanical Properties of Paper and their Relationship to the Treatment Of Paper

1992 ◽  
Vol 267 ◽  
Author(s):  
Timothy Vitale
Keyword(s):  
Mechanical Properties ◽  
Optical Properties ◽  
Hydrogen Bonds ◽  
Water Immersion ◽  
Treatment Method ◽  
Elevated Pressure ◽  
Wetting And Drying ◽  
Wet Pressing ◽  
Air Bag ◽  
Drying Conditions

ABSTRACTThe effects of drying on paper after water immersion are explored by evaluating mechanical properties. When paper is wet, structural interfiber hydrogen bonds are disrupted; drying reverses this process. However, some “as manufactured” mechanical properties are lost after wetting and drying. The method of drying was found to be critical for regaining the mechanical properties of a dried sheet.The effects of (1) wet-pressing (weight on paper during drying) and (2) wet-straining during drying are assessed. Application of incremental increases of the two variables results in changes of the mechanical properties which eventally reach and exceed the original mechanical properties which are lost during standard water immersion and drying treatments.The treatment method which most closely reproduces the “as manufactured” properties involves wet-pressing and wet-stretching. In particular, friction stretch-drying in an air-bag press can approximate original drying conditions. However, alterations of optical properties of the paper and design media due to elevated pressure prevents endorsement of the methodology.

Clays are not created equal – effects of clay mineral type on soil hydraulic and mechanical properties

2021 ◽  
Author(s):  
Peter Lehmann ◽  
Ben Leshchinsky ◽  
Surya Gupta ◽  
Ben Mirus ◽  
Samuel Bickel ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Internal Friction ◽  
Specific Surface ◽  
Surface Area ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Specific Surface Area ◽  
Friction Angle ◽  
Tropical Soils ◽  
Mineral Type

<p>Clay minerals dominate the soil colloidal fraction and often carry the largest specific surface area – a property that controls various soil hydraulic and mechanical properties (SHMPs; e.g. water retention, permeability, and internal friction). Differences in microscale structure among clay mineral types in tropical and temperate regions affect the specific surface area and result in higher permeability and internal friction angle values for tropical soils with inactive kaolinite clay minerals. Presently, the soil clay size fraction used to parameterize SHMPs with pedotransfer functions (PTFs) ignores clay mineral type, leading to inconsistent parameter representation. In this study, we present new PTFs informed by clay minerals, enabling enhanced estimation of friction angle and saturated hydraulic conductivity. To capture higher conductivity and lower air entry values in tropical soils, we developed a hierarchical packing model and validated this new PTF approach using literature data from various tropical regions. We leveraged recent global maps of clay minerals to demonstrate that a strong climatic and spatial segregation of active and inactive clays enable spatially resolved consideration of clay mineral type in SHMP estimation. We applied these clay-informed PTFs to improve SHMP representation regionally with implications for a wide range of hydrological and geomechanical Earth surface processes.</p>

Influence of Clay Mineral Content on the Mechanical Properties and Microfabrics of Tailings

2021 ◽  
Author(s):  
Chao Zhang ◽  
Zhenkai Pan ◽  
Changkun Ma ◽  
Lei Ma ◽  
Xueting Li
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Mineral Content ◽  
Triaxial Compression ◽  
Clay Content ◽  
Nitrogen Adsorption ◽  
Confining Pressure ◽  
Compression Tests

Abstract Clay mineral content has an important influence on the mechanical behavior of tailings, and the mechanical behavior of tailings directly affects the stability of tailings dams. XRF and XRD tests were carried out on tailings from three different regions. The chemical and mineral compositions of the tailings are analyzed. The strength and failure deformation of tailings were studied by carrying out laboratory triaxial compression tests. The effect of clay content on the stress path of tailings was investigated. The microfabric of tailings samples was examined with scanning electron microscopy (SEM) and nitrogen adsorption tests. The results show that the confining pressure corresponding to the samples exhibiting strain hardening increases with increasing clay mineral content in the tailings. The cohesion of tailings increases linearly, and the specific surface area decreases as the content of clay minerals increases. Nitrogen adsorption test results reveal from a microscopic point of view that changes in pore structure are associated with the content of clay minerals. The higher the content of clay minerals is, the higher the proportion of micropores (aggregated interior). Macroscopically, the overall porosity decreases and the fineness of the pores increases with clay content, which will directly affect the mechanical properties of tailings.

Structural/Property Relationships for Optical Materials

1993 ◽  
Vol 329 ◽  
Author(s):  
Vivien D.
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Electronic Structure ◽  
Chemical Composition ◽  
Field Strength ◽  
Optical Materials ◽  
Site Occupancy ◽  
Laser Materials ◽  
Crystal Field Strength ◽  
The Matrix

AbstractIn this paper the relationships between the crystal structure, chemical composition and electronic structure of laser materials, and their optical properties are discussed. A brief description is given of the different laser activators and of the influence of the matrix on laser characteristics in terms of crystal field strength, symmetry, covalency and phonon frequencies. The last part of the paper lays emphasis on the means to optimize the matrix-activator properties such as control of the oxidation state and site occupancy of the activator and influence of its concentration.

scholarly journals Controlling the non-linear optical properties of MgO by tailoring the electronic structure

2020 ◽  
Vol 126 (3) ◽  
Author(s):  
Mukhtar Hussain ◽  
Hugo Pires ◽  
Willem Boutu ◽  
Dominik Franz ◽  
Rana Nicolas ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Non Linear ◽  
Linear Optical Properties ◽  
Linear Optical

scholarly journals Sensitivity of Intra- and Intermolecular Interactions of Benzo[h]quinoline from Car–Parrinello Molecular Dynamics and Electronic Structure Inspection

2021 ◽  
Vol 22 (10) ◽  
pp. 5220
Author(s):  
Jarosław J. Panek ◽  
Joanna Zasada ◽  
Bartłomiej M. Szyja ◽  
Beata Kizior ◽  
Aneta Jezierska
Keyword(s):  
Molecular Dynamics ◽  
Electronic Structure ◽  
Hydrogen Bonds ◽  
Density Functional ◽  
Quantum Effects ◽  
Potential Of Mean Force ◽  
Probability Density Distribution ◽  
Donor And Acceptor ◽  
Nuclear Quantum Effects ◽  
Vibrational Features

The O-H...N and O-H...O hydrogen bonds were investigated in 10-hydroxybenzo[h]quinoline (HBQ) and benzo[h]quinoline-2-methylresorcinol complex in vacuo, solvent and crystalline phases. The chosen systems contain analogous donor and acceptor moieties but differently coupled (intra- versus intermolecularly). Car–Parrinello molecular dynamics (CPMD) was employed to shed light onto principle components of interactions responsible for the self-assembly. It was applied to study the dynamics of the hydrogen bonds and vibrational features as well as to provide initial geometries for incorporation of quantum effects and electronic structure studies. The vibrational features were revealed using Fourier transformation of the autocorrelation function of atomic velocity and by inclusion of nuclear quantum effects on the O-H stretching solving vibrational Schrödinger equation a posteriori. The potential of mean force (Pmf) was computed for the whole trajectory to derive the probability density distribution and for the O-H stretching mode from the proton vibrational eigenfunctions and eigenvalues incorporating statistical sampling and nuclear quantum effects. The electronic structure changes of the benzo[h]quinoline-2-methylresorcinol dimer and trimers were studied based on Constrained Density Functional Theory (CDFT) whereas the Electron Localization Function (ELF) method was applied for all systems. It was found that the bridged proton is localized on the donor side in both investigated systems in vacuo. The crystalline phase simulations indicated bridged proton-sharing and transfer events in HBQ. These effects are even more pronounced when nuclear quantization is taken into account, and the quantized Pmf allows the proton to sample the acceptor area more efficiently. The CDFT indicated the charge depletion at the bridged proton for the analyzed dimer and trimers in solvent. The ELF analysis showed the presence of the isolated proton (a signature of the strongest hydrogen bonds) only in some parts of the HBQ crystal simulation. The collected data underline the importance of the intramolecular coupling between the donor and acceptor moieties.

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