Etude de la repartition de l'eau dans des argiles saturees Mg2+ aux fortes teneurs en eau

Clay Minerals ◽  
1990 ◽  
Vol 25 (2) ◽  
pp. 217-233 ◽  
Author(s):  
O. Touret ◽  
C. H. Pons ◽  
D. Tessier ◽  
Y. Tardy
Keyword(s):  
Particle Size ◽  
Aggregate Size ◽  
High Water ◽  
Hydration Mechanism ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Particle Aggregate ◽  
Sample Water ◽  
Particle Size And Shape ◽  
Water Contents

AbstractPowdered 2:1 Mg-clay samples were rehydrated up to the maximum hydration. Both scanning and transmission electron microscopy were used to characterize their structural organization i.e. particle arrangement, texture and crystal structure. Low-angle X-ray scattering experiments were carried out to quantify the microstructure of the system. The results showed that sample water contents reached at saturation are not directly related to changes in layer distance. The hydration mechanism is rather correlated to particle size and particle aggregate size. It is also shown that the a, b plane extension of the layers influences particle size and shape. Finally, it appears that for a better understanding of clay swelling mechanisms, at high water contents, it is necessary to take into account all organization levels and that the contribution of interlayer space to the total water content, for Mg-smectites, is small.

Silica Nanoparticle Synthesis and Multi-Method Characterisation

2019 ◽  
Vol 947 ◽  
pp. 82-90
Author(s):  
Pirutchada Musigapong ◽  
Sophie Marie Briffa ◽  
Iseult Lynch ◽  
Siriwat Soontaranon ◽  
N. Chanlek ◽  
...  
Keyword(s):  
Particle Size ◽  
Sol Gel ◽  
Nanoparticle Synthesis ◽  
Size Control ◽  
Silica Nanoparticle ◽  
Radius Of Gyration ◽  
Hydrodynamic Diameter ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Diameter Core

The information provided by different characterisation methods when measuring particle size varies depending on the chosen technique and analytical approach (e.g. light scattering, transmission electron microscopy, spectroscopy, x-ray scattering). This in turn has an impact on the accuracy of the results as well as comparability between methods and overall confidence on the analyses. The present study used a common sol-gel reaction to synthesise amorphous silica nanoparticles (aSiNPs) and characterised the product purity and homogeneity. The reaction involved hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in the presence of lysine, which acted as catalyst for the silica production and also as a capping agent for particle size control in a suspension kept at pH 8-10. According to DLS data, the stock suspension was stable for at least 6 months in Milli Q water without surfactant when kept at 4°C. This study focused on multi-method size and shape characterisation of the aSiNPs, involving the following techniques: DLS, TEM, FTIR, STEM and SAXS. These techniques provided information on hydrodynamic diameter, core particle dimensions, sphere equivalent size, and radius of gyration. Our results show two particle populations, one around 2 nm and the other around 7 nm in diameter. Notably, these two populations are not resolved (i.e. “visible”) by all methods used.

scholarly journals Obtaining Highly Crystalline Barium Sulphate Nanoparticles via Chemical Precipitation and Quenching in Absence of Polymer Stabilizers

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Ángela B. Sifontes ◽  
Edgar Cañizales ◽  
Jhoan Toro-Mendoza ◽  
Edward Ávila ◽  
Petra Hernández ◽  
...  
Keyword(s):  
Particle Size ◽  
Fourier Transforms ◽  
Aggregate Size ◽  
Chemical Precipitation ◽  
Barium Sulphate ◽  
Degree Of Crystallinity ◽  
Transmission Electron ◽  
Lattice Images ◽  
Scherrer Formula ◽  
Polymer Stabilizers

Here we report the synthesis of barium sulphate (BaSO4) nanoparticles from Ba(OH)2/BaCl2solutions by a combined method of precipitation and quenching in absence of polymer stabilizers. Transmission electron microscopy (HRTEM), Fourier transforms infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were employed to characterize the particles. The Scherrer formula was applied to estimate the particle size using the width of the diffraction peaks. The obtained results indicate that the synthesized material is mainly composed of nanocrystalline barite, with nearly spherical morphology, and diameters ranging from 4 to 92 nm. The lattice images of nanoparticles were clearly observed by HRTEM, indicating a high degree of crystallinity and phase purity. In addition, agglomerates with diameters between 20 and 300 nm were observed in both lattice images and dynamic light scattering measurements. The latter allowed obtaining the particle size distribution, the evolution of the aggregate size in time of BaSO4in aqueous solutions, and the sedimentation rate of these solutions from turbidimetry measurements. A short discussion on the possible medical applications is presented.

Effect of Electron Microscope Magnification on the Determination of Particle Size and Shape by Image Analysis

2007 ◽  
Vol 121-123 ◽  
pp. 893-896
Author(s):  
Zheng Min Li
Keyword(s):  
Particle Size ◽  
Image Analysis ◽  
Standard Sample ◽  
Standard Specimen ◽  
Particle Diameter ◽  
Value Change ◽  
Size And Shape ◽  
Transmission Electron ◽  
Particle Size And Shape

To investigate the effect of magnification (M) on determination of particle size and shape by transmission electron microscopy (TEM) and image analysis. The calibration curve and its simulative equation of TEM magnification are obtained by measurement of a grating replica standard specimen at different magnifications. Based on the analysis of TEM images at a series of magnifications for a 350nm-sphere standard sample, It has been found that the two errors of its size measurement, caused by one pixel change of the pixel number per particle diameter (Np) and by one gray value change during thresholding, is smaller, and the shape of ‘circle’ particles are close to the standard one, while Np is larger than 35. It can be seen that the suitable TEM magnification is in inverse proportion to particle size and it can be calculated by given equation.

Nanoparticles of Pd: Synthesis by Microwave-Solvothermal Method and Optical Properties

2008 ◽  
Vol 8 (8) ◽  
pp. 3930-3935 ◽  
Author(s):  
Dongsheng Li ◽  
Sridhar Komarneni
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Pd Nanoparticles ◽  
Absorption Bands ◽  
Reaction Conditions ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Particle Size And Morphology ◽  
Particle Size And Shape ◽  
Size And Morphology

Well-dispersed Pd nanoparticles were synthesized by microwave-assisted solvothermal technique using methanol and ethanol. Particle size and morphology were controlled mainly by the reaction temperature. Particle size of Pd nanoparticles was controlled in the range of 2 to 11 nm by manipulating the reaction conditions. The Pd nanoparticles were characterized by transmission electron microscopy for particle size and shape and UV-Vis spectroscopy for optical properties. UV-Vis spectra showed that synthesized Pd nanoparticles stabilized with PVP had absorption bands at around 280 to 290 nm.

scholarly journals Process for Producing Nano-Alpha-Alumina Powder

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Fatemeh Mirjalili ◽  
Luqman Chuah Abdullah ◽  
Hasmaliza Mohamad ◽  
A. Fakhru'l-Razi ◽  
A. B. Dayang Radiah ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Sol Gel ◽  
Alumina Nanoparticles ◽  
Alumina Powder ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Stirring Time ◽  
Particle Size And Shape

This paper is trying to explore the effect of stirring time on the synthesis of nano-α-Alumina particles. In this study, alumina nanoparticles were synthesized through alkoxide route using sol-gel method, where aqueous solutions of aluminum isopropoxide and 0.5 M aluminum nitrate nanohydrate were used for preparing alumina sol. Sodium dodecylbenzen sulfonate (SDBS) was used as the surfactant stabilizing agent. The prepared solution was stirred at different times (24, 36, 48, and 60 hours) at 60°C. The Samples were, then, characterized by X-ray diffraction, thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and Transmission Electron Microscopy(TEM) . The introduction of different stirring times affected the particle size and shape and the degree of aggregation. By increasing the stirring time, (starting from 24 to 48 hours) the particle size decreased, but agglomeration became hard for 60 hours of stirring time. The finest particle size (20–30 nm) was obtained at 48-hour stirring time.

scholarly journals Получение аблированных частиц CeO-=SUB=-2-=/SUB=- с нанодисперсным распределением по составу

2020 ◽  
Vol 46 (20) ◽  
pp. 38
Author(s):  
М.А. Пугачевский ◽  
В.А. Мамонтов ◽  
Ней Вин Аунг ◽  
А.С. Чекаданов ◽  
А.П. Кузьменко
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Colloidal Solution ◽  
Vacancy Defects ◽  
X Ray ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Electron Energy Loss ◽  
Content Of Oxygen

A technique for the preparation of ablated particles of CeO2 of a nanosized composition has been developed. Using transmission electron microscopy and Small Angle X-ray Scattering, it has been found that the maximal particle size in a colloidal solution does not exceed 30 nm. According to Electron Energy Loss Spectroscopy, the content of oxygen vacancy defects increases with a decrease in the size of ablated nanoparticles.

scholarly journals Morphology and Raman spectra of aerodynamically classified soot samples

2019 ◽  
Vol 12 (8) ◽  
pp. 4339-4346 ◽  
Author(s):  
Alberto Baldelli ◽  
Steven Nicholas Rogak
Keyword(s):  
Particle Size ◽  
Primary Particle ◽  
Particle Diameter ◽  
Size Control ◽  
Aggregate Size ◽  
Aerodynamic Diameter ◽  
Carbon Nanostructure ◽  
Transmission Electron ◽  
Primary Particles ◽  
Combustion Processes

Abstract. Airborne soot is emitted from combustion processes as aggregates of primary particles. The size of the primary particles and the overall aggregate size control soot transport properties, and prior research shows that these parameters may be related to the soot nanostructure. In this work, a laminar, inverted nonpremixed burner has been used as a source of soot that is almost completely elemental carbon. The inverted burner was connected to an electrical low-pressure impactor, which collected particles on stages according to the aerodynamic diameter, from 0.03 to 10 µm. The morphology was analyzed using a transmission electron microscope followed by image processing to extract projected area and average primary particle size for each aggregate (approximately 1000 aggregates analyzed in total for the nine impactor stages). Carbon nanostructure was analyzed using a Raman spectrometer, and five vibrational bands (D4, D1, D3, G, and D2) were fitted to the spectra to obtain an estimate of the carbon disorder. The average primary particle diameter increases from 15 to 30 nm as the impactor stage aerodynamic diameter increases. The D1, D3, D2, and D4 bands decreased (relative to the G band) with the particle size, suggesting that the larger aggregates have larger graphitic domains.

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