scholarly journals Characterization of FeOOH Nanoparticles and Amorphous Silica Matrix in an FeOOH-SiO2Nanocomposite

2008 ◽  
Vol 2008 ◽  
pp. 1-6 ◽  
Author(s):  
Guido Ennas ◽  
Maria F. Casula ◽  
Sergio Marras ◽  
Gabriele Navarra ◽  
Alessandra Scano ◽  
...  
Keyword(s):  
Hydrochloric Acid ◽  
Amorphous Silica ◽  
Diffraction Data ◽  
Silica Matrix ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Matrix ◽  
Curve Method ◽  
Hydrolysis Of

A nanocomposite with an FeOOH/SiO2ratio equal to 17.7 wt% and the pertinent matrix, obtained by etching away the nanoparticles through reaction with hydrochloric acid, were investigated by XRD, TGA-DTA, heliostereopicnometry, BET, and TEM techniques. The study shows the presence in the nanocomposite of ferrihydrite nanoparticles phase with average dimensions around 4 nm. The FeOOH nanoparticles structure was analyzed by synchrotron X-ray diffraction data using the distribution difference curve method. The porous structure of the matrix resulting by etching away the nanoparticles differs significantly from that of a pureSiO2sample obtained by hydrolysis of TEOS under the same operative conditions followed in the nanocomposite preparation.

Characterization and genesis of horizontal banding in Brazilian agate: an X-ray diffraction, thermogravimetric and electron microprobe study

2013 ◽  
Vol 77 (3) ◽  
pp. 227-248 ◽  
Author(s):  
T. Moxon ◽  
C. M. Petrone ◽  
S. J. B. Reed
Keyword(s):  
Amorphous Silica ◽  
Electron Microprobe ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wall Lining ◽  
Defect Site ◽  
Site Water ◽  
Stage Process ◽  
Upper Chamber

AbstractCharacterization of Brazilian agates containing a lower horizontally banded section and an upper chamber with bands parallel to the walls shows that these agates formed much later than the 135 Ma Paraná basalt host rock. Age differentiation between the two types of banding shows that the horizontal bands formed between 43 to 63 Ma ago with a final infill of wall-lining bands between 7 and 27 Ma later. The horizontal bands have a higher Al3+ concentration and a greater crystallite size than the wall-lining layers; they have a lower mogánite content and defect-site water content. The formation of these agates appears to be the result of a three-stage process. After the separate formation of horizontally banded and wall-lining agate, a silica infill seals the gap between the agate and the cavity wall. The detection of cristobalite in some specimens indicates that genesis of both the horizontally banded and wall-lining deposits in the Brazilian samples proceeds along an amorphous silica → opal-CT → opal-C → chalcedony pathway.

scholarly journals Synthesis and Crystallographic Characterization of X-Substituted 2,4-Dinitrophenyl-4′-phenylbenzenesulfonates

Chemistry ◽  
2020 ◽  
Vol 2 (2) ◽  
pp. 591-599
Author(s):  
Brock A. Stenfors ◽  
Richard J. Staples ◽  
Shannon M. Biros ◽  
Felix N. Ngassa
Keyword(s):  
Diffraction Data ◽  
Pyridinium Salt ◽  
Environmentally Benign ◽  
Pyridinium Salts ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Range ◽  
Aqueous Environments ◽  
Aqueous Base

Treatment of 2,4-dinitrophenol with sulfonyl chlorides in the presence of pyridine results in the formation of undesired pyridinium salts. In non-aqueous environments, the formation of the insoluble pyridinium salt greatly affects the formation of the desired product. A facile method of producing the desired sulfonate involves the use of an aqueous base with a water-miscible solvent. Herein, we present the optimization of methods for the formation of sulfonates and its application in the production of desired x-substituted 2,4-dinitrophenyl-4′-phenylbenzenesulfonates. This strategy is environmentally benign and supports a wide range of starting materials. Additionally, the intermolecular interactions of these sulfonate compounds were investigated using single-crystal x-ray diffraction data.

Preparation and characterization of poly(3-glycidoxypropyltrimethoxysilane) nanocomposite using organophilic montmorillonite clay (Mag-cetyltrimethylammonium)

2019 ◽  
Vol 53 (28-30) ◽  
pp. 4313-4322 ◽  
Author(s):  
Nadia Embarek ◽  
Nabahat Sahli ◽  
Mohammed Belbachir
Keyword(s):  
Thermal Properties ◽  
Preparation Method ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
X Ray ◽  
The Matrix ◽  
Organophilic Clay ◽  
Linear Poly ◽  
Organophilic Montmorillonite

Nanocomposites of linear poly(3-glycidoxypropyltrimethoxysilane) based on Algerian natural organophilic clay: montmorillonite–cetyltrimethylammonium named Maghnite-CTA were prepared by enhancing the dispersion of the matrix polymer in sheets of the organoclay. The effect of the organoclay, used with different amounts (3, 5, and 7% by weight) and the preparation method were studied in order to determine and evaluate their structural, morphological and thermal properties. X-ray diffraction analysis of obtained nanocomposites showed a significant change in the distance interlayer of montmorillonite–cetyltrimethylammonium. Therefore, interlayer expansion and exfoliation of linear poly(3-glycidoxypropyltrimethoxysilane) between layers of montmorillonite–cetyltrimethylammonium were observed. The thermal properties of the prepared nanocomposites were given by thermogravimetric analysis. The structure and morphology of the obtained materials were determined respectively by Fourier transform infrared spectroscopy and scanning electronic microscopy. The results obtained have approved the privilege of the intercalation of linear poly(3-glycidoxypropyltrimethoxysilane) in the interface of montmorillonite–cetyltrimethylammonium and the best quantity of organoclay required to prepare nanocomposite with a high thermal stability is 5% (by weight).

Synthesis and Characterization of ALaFeNi0.5W0.5O6 (A= Sr or Ca), a New Structure Distorted Double Perovskite

2013 ◽  
Vol 717 ◽  
pp. 133-138
Author(s):  
A. Awad Allah ◽  
M. Elhadi ◽  
O.A. Yassien
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Double Perovskite ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
Absorption Bands ◽  
X Ray ◽  
Perovskite Materials ◽  
Ftir Spectrometer

The crystal structure of both samples has been solved by powder X-ray diffraction, data in the tetragonal space group I4/m (a= b= 5.55182 Å, c =7.86955 A0) for SrLaFeNi0.5W0.5O6sample and (a=b= 5.49129Å, c= 7.82233Å) for CaLaFeNi0.5W0.5O6 sample, and shows an almost perfect ordering between Ni2+ and W5+ cations at the B-site of the perovskite structure. The FTIR spectrometer used of the powders showed that the spectra of both are very similar, showing two strong and well-defined absorption bands, typical of perovskite materials.

Scheme of hydrolysis of five-coordinate chlorosilanes by X-ray diffraction data

2011 ◽  
Vol 81 (12) ◽  
pp. 2428-2439 ◽  
Author(s):  
A. G. Shipov ◽  
E. P. Kramarova ◽  
T. P. Murasheva ◽  
A. A. Korlyukov ◽  
S. A. Pogozhikh ◽  
...  
Keyword(s):  
Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrolysis Of

scholarly journals Microstructural evolution of a modified HP alloy: experimental and complementary computational study

2017 ◽  
pp. 5141-5145
Author(s):  
Sandra Simonetti ◽  
C. Lanz ◽  
G. Brizuela ◽  
A. Juan
Keyword(s):  
Computational Study ◽  
Microstructural Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Eutectic Carbides ◽  
The Matrix ◽  
Secondary Precipitates ◽  
M23c6 Carbides ◽  
Cast Condition

In this work is presented results of the microstructural characterization of austenitic stainless steel (HP series) modified with Nb, aged at temperatures of 750, 800, 850, 900 and 950oC in air at different times. Microstructural changes were analyzed using optical microscopy, scanning electron microscopy (SEM) equipped with (EDS), x-ray diffraction and Vickers hardness. In the as-cast condition, the microstructure consists of an austenitic matrix and eutectic carbides network, Cr, Nb-rich carbides. The Cr-rich carbides are M7C3 type, whereas, those rich in Nb are NbC. During aging, there is a second precipitation in the matrix of very fine needle form of M23C6 carbides, which leads to an increase in hardness. After that, the decreasing in hardness is associated with a coalescence phenomenon of the secondary precipitates. Computational modeling shows that M23C6 is lesser stable than M7C3 carbide.

scholarly journals Characterization of microcrystalline cellulose from fast-growing species Artocarpus elasticus

2021 ◽  
Vol 5 (1) ◽  
pp. 1-8
Author(s):  
Sunardi Sunardi ◽  
Wiwin Tyas Istikowati ◽  
Norhidayah Norhidayah ◽  
Dahlena Ariyani ◽  
Azlan Kamari
Keyword(s):  
Hydrochloric Acid ◽  
Microcrystalline Cellulose ◽  
Crystallinity Index ◽  
Cellulosic Material ◽  
X Ray Diffraction ◽  
Cellulose I ◽  
X Ray ◽  
Artocarpus Elasticus ◽  
Fast Growing Species

Microcrystalline cellulose is an important derivative of cellulosic material obtained from wood and non-wood sources, and is used for pharmaceutical, food, cosmetics, and other industries. The aim of this study was to determine the effect of various hydrochloric acid concentrations on the characteristics of cellulose microcrystals isolated from terap wood (Artocarpus elasticus). The microcrystalline cellulose was hydrolyzed using hydrochloric acid, at concentrations of 1.5 N, 2.5 N, and 3.5 N for 15 minutes, and within a temperature range of 100-105o C. Thesamples were then analyzed for changes in color and functional groups with Fourier Transform Infrared spectroscopy (FTIR), while crystallinity index was evaluated through X-Ray Diffraction Analysis (X-RDF). The FTIR results showed similarity with commercial products, while X-Ray Diffraction confirms the highest crystallinity index in the 2.5 N of cellulose I (69.395 %) and cellulose II (82.73 %).

Nucleation and growth of iron oxides in olivines, (Mg,Fe)2SiO4

1970 ◽  
Vol 37 (291) ◽  
pp. 790-800 ◽  
Author(s):  
P. E. Champness
Keyword(s):  
Electron Microscopy ◽  
Iron Oxide ◽  
Amorphous Silica ◽  
Nucleation And Growth ◽  
X Ray Diffraction ◽  
Low Temperature Oxidation ◽  
Temperature Oxidation ◽  
X Ray ◽  
The Matrix ◽  
Equiaxed Grains

SummaryIron-rich olivines have been oxidized in air in the laboratory and the mechanism of their breakdown has been elucidated using X-ray diffraction and electron microscopy. Low-temperature oxidation (500–800 °C) produces well-oriented hematite- and magnetite-like precipitates together with amorphous silica. The reaction is a cellular one in which thin needles of oxide about 50–100 Å apart grow into the matrix separated by regions of amorphous silica. Nucleation of spherical colonies of the iron oxide and silica occurs on dislocations.Although the hematite or magnetite always shows the same topotactic relationship with the matrix, the direction in which the needle-like precipitates grow is determined by the orientation of the nucleating dislocation. The small size and highly distorted nature of these precipitates accounts for the diffuseness of their X-ray reflections.Oxidation at 1000 °C produces undistorted equiaxed grains of the oxides about 0·2 μm in size. They are surrounded by silica, which produces a disordered electron diffraction pattern. As the temperature is raised, the silica achieves more structural order and the oxide grains increase in size.

The characterization of serpentine minerals by X-ray diffraction

1956 ◽  
Vol 31 (233) ◽  
pp. 107-126 ◽  
Author(s):  
E. J. W. Whittaker ◽  
J. Zussman
Keyword(s):  
Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Serpentine Minerals ◽  
Serpentine Mineral

SummaryX-ray diffraction data on serpentine minerals are discussed. There arc three structural varieties of chrysotile: ortho-chrysotile, clino-chrysotile, and para-chrysotile. Methods are described for the estimation of the proportions of the first two of these in mixed specimens, and their distribution in nature is reviewed. The variations observed in powder photographs of serpentine minerals are interpreted in accordance with this classification. The criteria proposed by Selfridge for distinguishing between chrysotile and antigorite are shown to be unreliable, but valid criteria are presented. The powder photographs also reveal the existence of a third serpentine mineral, distinct from chrysotile and antigorite, for which the name lizardite is proposed. Four samples of bastite are shown to consist of chrysotile or lizardite rather than antigorite. All the serpentine minerals examined consist either of antigorite or of one or more of the group comprising lizardite and the chrysotile varieties.

Eu3+-Doped Y2O3-SiO2 Nanocomposite Obtained by a Sol-Gel Method

2001 ◽  
Vol 676 ◽  
Author(s):  
Carla Cannas ◽  
Mariano Casu ◽  
Roberta Licheri ◽  
Anna Musinu ◽  
Giorgio Piccaluga ◽  
...  
Keyword(s):  
Amorphous Silica ◽  
Sol Gel ◽  
Silica Matrix ◽  
Luminescence Spectroscopy ◽  
X Ray Diffraction ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Excited Luminescence ◽  
The Eu

ABSTRACTA Y2O3-SiO2 nanocomposite doped with Eu3+ was obtained by a sol-gel method and characterized by X-ray diffraction, IR, 29Si NMR and laser-excited luminescence spectroscopy. It was found that small (2-3 nm) yttria nanoparticles are homogeneously dispersed in, and interacting with, the amorphous silica matrix. Luminescence spectroscopy indicates that the Eu3+ ion is preferentially located inside or at the surface of highly disordered Y2O3 nanoparticles. These luminescent nanocomposites form a class of materials which could find applications in the field of phosphors.

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