Discretization of the Water Uptake Process of Na-Montmorillonite Undergoing Atmospheric Stress: XRD Modeling Approach

This work focuses on the water-montmorillonite interaction under variable atmospheric conditions in order to characterize the interlamellar space (IS) configuration for possible use in the context of geological barrier for radioactive and industrial waste confinement. Atmospheric stress is achieved by applying, for Na-rich montmorillonite, a water sorption/desorption constraint, created at the laboratory scale. This hydrological disturbance allows the “demolition” of the clay history and to highlight the clay hydrous performance. The structural analysis is achieved using modeling of XRD profiles, which allowed us to determine the optimal structural parameters describing the IS configuration along thec∗axis. During the “in situ” XRD analysis, a sorption/desorption cycle is envisaged by variation of the relative humidity rate (%RH) from the saturated condition (94 %RH) towards extremely dry ones (2-3 %RH). Qualitatively, a new hydration hysteresis behavior of the “stressed” sample appears. Structural analysis achieved before and after perturbation allowed us to identify, respectively, the homogeneous hydration states, the hydrous transition domains, and the hydration heterogeneity degree. This latter parameter is characterized, quantitatively, by variable relative abundances of mixed-layer structure (MLS) population discerned over a wide explored RH range. Using the optimum structural parameter, the water molecule distribution versus the applied hydrous strain was quantified.

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How the Solid/Liquid Ratio Affects the Cation Exchange Process and Porosity in the Case of Dioctahedral Smectite: Structural Analysis?

Adsorption Science & Technology ◽

10.1155/2021/9732092 ◽

2021 ◽

Vol 2021 ◽

pp. 1-24

Author(s):

Chadha Mejri ◽

Walid Oueslati ◽

Abdesslem Ben Haj Amara

Keyword(s):

Structural Analysis ◽

Cation Exchange ◽

Layer Structure ◽

Structural Parameters ◽

Exchange Process ◽

Xrd Analysis ◽

Exchangeable Cations ◽

Structural Parameter ◽

Liquid Ratio ◽

Solid Liquid

The performance of a clay mineral geomembrane used in the context of a geological barrier for industrial and radioactive waste confinement must pass through the understanding of its hydrous response as well as the limits of the cation exchange process which are closely related to the solid/liquid ratio constraint. The Na-rich montmorillonite is used, as starting material, to evaluate the link between the applied external constraint (variable solid/liquid ratio) and the structural response of the material. The geochemical constraint is realized at the laboratory scale, and the possible effects are investigated in the cases of Ba2+ and Ni2+ heavy metal cations. The structural analysis is achieved using the XRD profile modeling approach to quantify the interlayer space (IS) deformation. The quantitative XRD analysis, which consists of the comparison of experimental 001 reflections with the calculated ones deduced from structural models, allowed us to determine the optimal structural parameters describing IS configuration along the c ∗ axis. The obtained result showed an interstratified hydration character, for both studied exchangeable cations, regardless of the solid/liquid ratio being described probably by a partial cation exchange process. The theoretical mixed layer structure (MLS) suggests the coexistence of more one cristallite species saturated by more than one exchangeable cations, indicating a partial saturation of all exchangeable sites. The optimum structural parameter values, from the theoretical model, allowed us to follow the evolution of several intrinsic properties versus the applied constraint strength. The variable solid/liquid ratio effect on the material porosity is examined by the BET-specific surface area and BJH pore size distribution (PSD) analyses. The adsorption measurement outcomes confirm XRD results concerning mainly the link between several intrinsic clay properties and the constraint strength.

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The Effect on Physical, Electrical and Structural Parameters of RF Sputtered Molybdenum Thin Film

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.403-408.5092 ◽

2011 ◽

Vol 403-408 ◽

pp. 5092-5096 ◽

Cited By ~ 1

Author(s):

Mukter Zaman ◽

Gunawan Witjaksono ◽

Teh Aun Shih ◽

Shabiul Islam ◽

Masuri Othman ◽

...

Keyword(s):

Thin Film ◽

Deposition Rate ◽

Rate Increase ◽

Structural Parameters ◽

Rf Sputtering ◽

Xrd Analysis ◽

Device Fabrication ◽

Structural Parameter ◽

Rf Power ◽

Deposition Parameters

In this study, the physical, electrical, and structural parameter on radio frequency (RF) sputtered molybdenum thin film is investigated as a function of two deposition parameters: rf power, and argon (Ar) pressure. Films are sputtered onto the substrates nominally held in room temperature in a RF sputtering system at partial argon (Ar) pressure. A number of 10 films are deposited at 8 sccm of Ar pressure while varying the rf power from 90 to 360 watt. Besides, another set of 7 films are deposited at 240 watt RF power while varying the Ar pressure from 8 to 32 watts. All the films are characterized using FESEM, AFM, XRD, and four points probe. The analysis results substantiate that, to fabricate a low resistive thin layer of molybdenum (Mo) both sputtering power, and deposition time Ar pressure plays significant rules. It is found that, with the increase of the RF power (90 to 280 watt) the deposition rate increase from 1.2 A0/sec to 4.4 A0/sec. But at a RF power higher than 280 watt the deposition rate saturated and it does not increase as linear as before. Also resistivity continuously decreases as the RF power increases from 90 watt up to 270 watt, after that the resistivity remain almost same regardless the RF power increased. Besides, by varying the Ar pressure it is found that with the increase of the Ar pressure the deposition rate increase until 20 sccm (up to 2.4 A0/sec). With further increase of the Ar pressure deposition rate start reducing and reached 2.1 A0/sec at 32 sccm. Based on the above investigation and analysis optimized film is deposited and further analyzed. The surface roughness is analyzed using AFM characterization tool and found 27.4519 nm. The FESEM and XRD analysis along with the resistivity of the film is used to measure the strain of the deposited film and found a strain of less than 0.01% on the optimized film, which is essential for MEMS/NEMS device fabrication and energy harvesting applications.

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STRUCTURAL ANALYSIS OF ZINC OXIDE THIN FILMS PREPARED BY THERMAL EVAPORATION TECHNIQUE

Kongunadu Research Journal ◽

10.26524/krj224 ◽

2017 ◽

Vol 4 (3) ◽

pp. 7-9

Author(s):

Balaganesh A.s ◽

Chandar Shekar B

Keyword(s):

Thin Films ◽

Zinc Oxide ◽

Structural Analysis ◽

Thermal Evaporation ◽

Structural Parameters ◽

Xrd Analysis ◽

Zno Films ◽

Thermal Evaporation Technique ◽

Oxide Thin Films ◽

Evaporation Technique

Zinc oxide thin films of 800nm were successfully prepared by thermal evaporation technique. XRD analysis revealed polycrystalline nature of the as prepared ZnO films. The structural parameters such as crystallite size, dislocation density and micro strain were evaluated and discussed.

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Effect of mechanical constraint on the hydration properties of Na-montmorillonite: study under extreme relative humidity conditions

Powder Diffraction ◽

10.1017/s088571561700046x ◽

2017 ◽

Vol 32 (S1) ◽

pp. S160-S167 ◽

Cited By ~ 1

Author(s):

Walid Oueslati ◽

Nejmeddine Chorfi ◽

Mohamed Abdelwahed

Keyword(s):

Relative Humidity ◽

Structural Changes ◽

Water Layer ◽

Xrd Analysis ◽

Household Waste ◽

Atmospheric Conditions ◽

Hydration Properties ◽

Clay Matrix ◽

Geological Barrier ◽

Mechanical Constraint

The evaluation of the performance of a geological barrier, consisting essentially of a clay matrix, in the context of industrial and household waste confinement must go with the study of its hydration behavior respectively under extreme atmospheric conditions and variable mechanical soil constraints. Na-montmorillonite (Swy-2) is used, as starting materials, in order to establish the link between applied externals strain (variable relative humidity rate %RH and axial mechanical constraint) and the hydration material response. All constraints are realized at the laboratory scale. This work is achieved using oedometric testing and quantitative X-ray diffraction (XRD) analysis, based on the modeling approach, which consists in the comparison of experimental 00l reflections with the calculated ones deduced from structural models. This approach allows us to quantify the interlamellar space configuration and all structural changes along the c* axis. Obtained results show a decrease for the void ratio e value along the compaction/reswelling process. The “insitu” XRD analysis realized at 5%RH demonstrates hydration shift, from dehydrated water layer (i.e. 0W) to monohydrated water layer (i.e. 1W), attributed to the applied mechanical constraint. At 90%RH, the sample hydration state remains at tri-hydrated water layer (3W) with a clear interstratified trends.

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Exo⇔Endo Isomerism, MEP/DFT, XRD/HSA-Interactions of 2,5-Dimethoxybenzaldehyde: Thermal, 1BNA-Docking, Optical, and TD-DFT Studies

Molecules ◽

10.3390/molecules25245970 ◽

2020 ◽

Vol 25 (24) ◽

pp. 5970

Author(s):

Nabil Al-Zaqri ◽

Mohammed Suleiman ◽

Anas Al-Ali ◽

Khaled Alkanad ◽

Karthik Kumara ◽

...

Keyword(s):

Density Functional ◽

Energy Gap ◽

Structural Parameters ◽

Population Analysis ◽

Xrd Analysis ◽

X Ray Diffraction ◽

Optical Energy Gap ◽

Functional Theory ◽

Reactivity Descriptors ◽

Td Dft

The exo⇔endo isomerization of 2,5-dimethoxybenzaldehyde was theoretically studied by density functional theory (DFT) to examine its favored conformers via sp2–sp2 single rotation. Both isomers were docked against 1BNA DNA to elucidate their binding ability, and the DFT-computed structural parameters results were matched with the X-ray diffraction (XRD) crystallographic parameters. XRD analysis showed that the exo-isomer was structurally favored and was also considered as the kinetically preferred isomer, while several hydrogen-bonding interactions detected in the crystal lattice by XRD were in good agreement with the Hirshfeld surface analysis calculations. The molecular electrostatic potential, Mulliken and natural population analysis charges, frontier molecular orbitals (HOMO/LUMO), and global reactivity descriptors quantum parameters were also determined at the B3LYP/6-311G(d,p) level of theory. The computed electronic calculations, i.e., TD-SCF/DFT, B3LYP-IR, NMR-DB, and GIAO-NMR, were compared to the experimental UV–Vis., optical energy gap, FTIR, and 1H-NMR, respectively. The thermal behavior of 2,5-dimethoxybenzaldehyde was also evaluated in an open atmosphere by a thermogravimetric–derivative thermogravimetric analysis, indicating its stability up to 95 °C.

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Vision-Based Structural FE Model Updating Using Genetic Algorithm

Applied Sciences ◽

10.3390/app11041622 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1622

Author(s):

Gun Park ◽

Ki-Nam Hong ◽

Hyungchul Yoon

Keyword(s):

Genetic Algorithm ◽

Model Updating ◽

Structural Parameters ◽

Fe Model ◽

Structural Members ◽

Stiffness Reduction ◽

Before And After ◽

Scale Test ◽

Fe Model Updating ◽

Story Building

Structural members can be damaged from earthquakes or deterioration. The finite element (FE) model of a structure should be updated to reflect the damage conditions. If the stiffness reduction is ignored, the analysis results will be unreliable. Conventional FE model updating techniques measure the structure response with accelerometers to update the FE model. However, accelerometers can measure the response only where the sensor is installed. This paper introduces a new computer-vision based method for structural FE model updating using genetic algorithm. The system measures the displacement of the structure using seven different object tracking algorithms, and optimizes the structural parameters using genetic algorithm. To validate the performance, a lab-scale test with a three-story building was conducted. The displacement of each story of the building was measured before and after reducing the stiffness of one column. Genetic algorithm automatically optimized the non-damaged state of the FE model to the damaged state. The proposed method successfully updated the FE model to the damaged state. The proposed method is expected to reduce the time and cost of FE model updating.

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Effect of pH of coating solution on the adhesion strength and corrosion resistance of hydroxyapatite and octacalcium phosphate coated WE43 alloy

Journal of Biomaterials Applications ◽

10.1177/08853282211012525 ◽

2021 ◽

pp. 088532822110125

Author(s):

Tuyet Thi Anh Ngo ◽

Sachiko Hiromoto ◽

Linh Chi Do ◽

Hanh Hong Pham ◽

Le Hanh

Keyword(s):

Corrosion Resistance ◽

Adhesion Strength ◽

Corrosion Current ◽

Xrd Analysis ◽

Octacalcium Phosphate ◽

Solution Deposition ◽

Chemical Solution Deposition Method ◽

Before And After ◽

Coating Layers ◽

We43 Alloy

Hydroxyapatite (HAp) and octacalcium phosphate (OCP) layers were formed on Mg- 4mass% Y- 3mass% rare earth (WE43) alloy by a chemical solution deposition method at various pH values of pH 5.5, 6.2, 7.5, and 8.6. Adhesion strength of HAp and OCP layers was evaluated before and after immersing in a medium for 14 days by a pull-off test. The corrosion resistance of these coatings was measured by polarization tests performed in a simulated body fluid (SBF). XRD analysis demonstrated that HAp coating layers were formed at pH 7.5 and 8.6, while OCP coating layers were formed at pH 5.5 and 6.2. Adhesion test results showed that the as-coated pH7.5-HAp layer had the highest adhesion strength of 8.6 MPa, which was attributed to the very dense structure of the coating layer. The as-coated pH8.6-HAp layer showed the adhesion strength of 6.5 MPa. The adhesion strength of the as-coated pH5.5- and pH6.2-OCP layers was 3.9 and 7.1 MPa, respectively, that was governed by the thick and fragile property of the layers. After immersing in the medium for 14 days, the adhesion strength of pH7.5- and pH8.6-specimens decreased to 5.8 and 5.6 MPa, respectively. The pitting corrosion and formation of Mg(OH)2 under the HAp layers were responsible for the decrease of adhesion strength. The polarization tests in SBF at 37 °C showed that the corrosion current density decreased with the HAp and OCP coatings, indicating the improvement of the corrosion resistance of WE43 alloy. The HAp coatings improved the corrosion resistance more efficiently than the OCP coatings.

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Zirconium phase transformations observed by “in-situ” XRD analysis

Vacuum ◽

10.1016/j.vacuum.2011.07.009 ◽

2012 ◽

Vol 86 (6) ◽

pp. 785-788 ◽

Cited By ~ 2

Author(s):

Jan Riha ◽

Pavol Sutta ◽

Andrej Vincze ◽

Rostislav Medlin

Keyword(s):

Phase Transformations ◽

Xrd Analysis ◽

In Situ Xrd

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Analysis of Activation Process of Carbon Black Based on Structural Parameters Obtained by XRD Analysis

Crystals ◽

10.3390/cryst11020153 ◽

2021 ◽

Vol 11 (2) ◽

pp. 153

Author(s):

Sang-Min Lee ◽

Sang-Hye Lee ◽

Jae-Seung Roh

Keyword(s):

Carbon Black ◽

Early Stage ◽

Structural Parameters ◽

Xrd Analysis ◽

Activation Process ◽

Co2 Gas ◽

Carbon Black Surface ◽

Black Surface ◽

Last Stage ◽

Pore Properties

In the present study, carbon black activated by CO2 gas was examined through XRD analysis, especially with regard to changes in its structural parameters. Based on the results, its activation process was thoroughly analyzed. The activation process was controlled by isothermally activating the carbon black inside a reaction tube through which CO2 gas flowed. With this approach, the degree of activation was varied as desired. At an early stage of the activation process, the amorphous fraction on the carbon black surface was preferentially activated, and later the less-developed crystalline carbon (LDCC) region inside the carbon black particles started to be activated. The latter process was attributable to the formation of pores inside the carbon black particles. As the activation process proceeded further, the more-developed crystalline carbon (MDCC) region started to be activated, thereby causing the pores inside the carbon black particles to grow larger. At the last stage of the activation process, La was found to be decreased to about 40 Å. This implied that the edges of the graphite crystals had been activated, thus causing the internal pores to grow and coalesce into larger pores. Activated conductive Super-P with enhanced pore properties is expected to have wide applications.

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Effects of Cr+ ion implantation on the oxidation of Ni3Al

Journal of Materials Research ◽

10.1557/jmr.1993.0734 ◽

1993 ◽

Vol 8 (4) ◽

pp. 734-740 ◽

Cited By ~ 5

Author(s):

M. Chen ◽

S. Patu ◽

J.N. Shen ◽

C.X. Shi

Keyword(s):

Oxidation Resistance ◽

Layer Structure ◽

Surface Region ◽

Optical Microscope ◽

Al Alloy ◽

Temperature Oxidation ◽

Intermediate Layers ◽

Air Interface ◽

Before And After ◽

High Temperature Oxidation Behavior

Ni3Al samples were implanted with different doses of 150 keV Cr+ ions to modify the surface region. The high temperature oxidation behavior was tested. The surface layer structure was investigated by AES, TEM, XRD, and optical microscope before and after the test. The experimental results show that chromium ions turn a small amount of ordered superlattice Ni3Al phase into a disordered Ni–Al–Cr phase. Also there is a bcc chromium phase in the implanted sample. Implanted Ni3Al alloy has better oxidation resistance than the unimplanted one at 900 °C. The oxide layer is of a multilayer structure after 50 h oxidation, composed of a NiO inner layer, Cr2O3, spinel NiAl2O4 intermediate layers, and an α–Al2O3 external layer at the oxide/air interface. The α-Al2O3 and Cr2O3 are independent scale-like layers. The two protective layers improve the oxidation resistance significantly. The effects of implanted elements and possible reaction mechanisms are discussed.

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