Potentialities of an Innovative Technique Like 129Xe NMR and of Saxs for the Characterization of Microporous Sol-Gel Derived SiO2

1996 ◽  
Vol 431 ◽  
Author(s):  
L. C. de Menorval ◽  
A. Julbe ◽  
H. Jobic ◽  
J. A. Dalmon ◽  
C. Guizard

AbstractAddition of surfactants in TEOS derived sols leads to micro- or mesoporous materials whose porous texture can be varied by changing the surfactant quantity and/or chain length. This series of materials, with a relatively narrow pore size distribution, is well adapted to study the potentialities of an innovative characterization technique like 129Xe Nuclear Magnetic Resonance in comparison with Small Angle X-ray Scattering and N2 adsorption. SAXS revealed a high surface rugosity of the materials and a good correlation with pore hydraulic radius distributions measured by N2 adsorption. Using 129Xe NMR, we have studied the Xe chemical shifts (δXe,) as a function of pXe, and have pointed out several original results showing the importance, for microporous materials, of the NMR line shapes and of the slope of the lines δXe.=f(pXe).

1995 ◽  
Vol 385 ◽  
Author(s):  
Barry J. Bauer ◽  
Catheryn L. Jackson ◽  
Da-Wei Liu

ABSTRACTInterpenetrating polymer networks have been synthesized by performing sol-gel chemistry and conventional organic polymerizations in mixtures of the monomers. The organic polymers were acrylates, and the inorganic phase was SiO2 formed by hydrolysis of orthosilicates. Polymerizations were conducted at a variety of relative rates, and the chemistry was designed to allow different amounts of grafting between the components. The morphology was characterized by transmission electron microscopy and small angle neutron and x-ray scattering. Wide variations in morphology were observed depending on the polymerization conditions, ranging from grossly phase separated to dendritic to finely divided structures (at a 100Å size scale). The phases ranged from mixtures of the two components to relatively pure phases. The interface between the phases ranged from very narrow to relatively broad.


2017 ◽  
Vol 3 (1) ◽  
pp. 20-26
Author(s):  
Atik Setyani ◽  
Emas Agus Prastyo Wibowo

Nanotubes received great attention because it has a high surface area. In this study, TiO2 nanotubes fabricated via hydrothermal method from  synthesis of TiO2 nanoparticles via sol-gel method. Catalysts that have been synthesized later in the characterization by X-Ray Diffraction (XRD) to obtain the crystal size and crystallinity. Crystal size of TiO2 nanoparticles at a temperature of 450C is 13.78 nm. Then characterized by Transmission Electron Microscopy (TEM) to look at the formation of nanotubes. Characterization of TiO2 nanotubes with TEM shows that the structure of the tubes had already been formed TNTs although the growth has not been perfect. It can be seen from the structure TNTs who tend to be short and yet so irregular.DOI: http://dx.doi.org/10.15408/jkv.v0i0.5036  


1986 ◽  
Vol 73 ◽  
Author(s):  
J. Covino ◽  
R. A. Nissan

ABSTRACTAl2O3 has been synthesized from aluminum propionate [A1(CO2CH2CH3)3] bySol-Gel techniques. Methods of characterization include: x-ray powder diffraction, scanning electron microscopy (SEM) and nuclear magnetic resonance(NMR). Solution and solid state 13C and 27Al NMR data is coupled with bothx-ray diffraction powder data and SEM in order to understand the transitionfrom sol + gel + amorphous powder + crystalline powder In the sonicated andunsonicated aluminum propionate precursor, and A12O3 powders. Resultsindicate that the sonicated dried powder is crystalline, having the γA12O3structure while the unsonicated dried powder is amorphous and crystallizesat 800°C with the a A12O3 structure. These differences in crystallinity arefurther substantiated by solid state 27AL NMR chemical shifts and linewidths at half height.


1981 ◽  
Vol 46 (7) ◽  
pp. 1675-1681 ◽  
Author(s):  
Josef Baldrian ◽  
Božena N. Kolarz ◽  
Henrik Galina

Porosity variations induced by swelling agent exchange were studied in a styrene-divinylbenzene copolymer. Standard methods were used in the characterization of copolymer porosity in the dry state and the results were compared with related structural parameters derived from small angle X-ray scattering (SAXS) measurements as developed for the characterization of two-phase systems. The SAXS method was also used for porosity determination in swollen samples. The differences in the porosity of dry samples were found to be an effect of the drying process, while in the swollen state the sample swells and deswells isotropically.


2021 ◽  
Vol 92 (1) ◽  
pp. 013102
Author(s):  
Roberto Daniel Pérez ◽  
Juan José Leani ◽  
José Ignacio Robledo ◽  
Héctor Jorge Sánchez

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2058
Author(s):  
Jordi Fraxedas ◽  
Antje Vollmer ◽  
Norbert Koch ◽  
Dominique de Caro ◽  
Kane Jacob ◽  
...  

The metallic and semiconducting character of a large family of organic materials based on the electron donor molecule tetrathiafulvalene (TTF) is rooted in the partial oxidation (charge transfer or mixed valency) of TTF derivatives leading to partially filled molecular orbital-based electronic bands. The intrinsic structure of such complexes, with segregated donor and acceptor molecular chains or planes, leads to anisotropic electronic properties (quasi one-dimensional or two-dimensional) and morphology (needle-like or platelet-like crystals). Recently, such materials have been synthesized as nanoparticles by intentionally frustrating the intrinsic anisotropic growth. X-ray photoemission spectroscopy (XPS) has emerged as a valuable technique to characterize the transfer of charge due to its ability to discriminate the different chemical environments or electronic configurations manifested by chemical shifts of core level lines in high-resolution spectra. Since the photoemission process is inherently fast (well below the femtosecond time scale), dynamic processes can be efficiently explored. We determine here the fingerprint of partial oxidation on the photoemission lines of nanoparticles of selected TTF-based conductors.


2020 ◽  
Vol 49 (7) ◽  
pp. 823-825
Author(s):  
Yojiro Oba ◽  
Ryuhei Motokawa ◽  
Masahiro Hino ◽  
Nozomu Adachi ◽  
Yoshikazu Todaka ◽  
...  

2020 ◽  
Vol 43 (1) ◽  
pp. 26-42 ◽  
Author(s):  
Zahra Hajian Karahroudi ◽  
Kambiz Hedayati ◽  
Mojtaba Goodarzi

AbstractThis study presents a preparation of SrFe12O19– SrTiO3 nanocomposite synthesis via the green auto-combustion method. At first, SrFe12O19 nanoparticles were synthesized as a core and then, SrTiO3 nanoparticles were prepared as a shell for it to manufacture SrFe12O19–SrTiO3 nanocomposite. A novel sol-gel auto-combustion green synthesis method has been used with lemon juice as a capping agent. The prepared SrFe12O19–SrTiO3 nanocomposites were characterized by using several techniques to characterize their structural, morphological and magnetic properties. The crystal structures of the nanocomposite were investigated via X-ray diffraction (XRD). The morphology of SrFe12O19– SrTiO3 nanocomposite was studied by using a scanning electron microscope (SEM). The elemental composition of the materials was analyzed by an energy-dispersive X-ray (EDX). Magnetic properties and hysteresis loop of nanopowder were characterized via vibrating sample magnetometer (VSM) in the room temperature. Fourier transform infrared spectroscopy (FTIR) spectra of the samples showed the molecular bands of nanoparticles. Also, the photocatalytic behavior of nanocomposites has been checked by the degradation of azo dyes under irradiation of ultraviolet light.


2005 ◽  
Vol 38 (1) ◽  
pp. 211-216 ◽  
Author(s):  
Pang-Hung Liu ◽  
Kuei-Jung Chao ◽  
Xing-Jian Guo ◽  
Kuo-Ying Huang ◽  
Yen-Ru Lee ◽  
...  

A continuous silica film with well aligned mesochannels parallel to the Si(001) surface was found to be formed through sol–gel dip-coating of a silica precursor with nonionic ethylene oxide surfactant. Two two-dimensional mesoporous structures in centered and non-centered rectangular symmetries and with the short axes of elongated ellipsoidal pores normal to the surface were observed by X-ray and electron diffraction. Detailed transmission electron microscopy investigations were employed to view the direction dependence of the channel or pore packing in the continuous film.


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