Structure and Characterization of Sol-gel and Aerogel Materials and Oxidation Products from the Reaction of (CH3O)4Si and C16H33Si(OCH3)3

2002 ◽  
Vol 740 ◽  
Author(s):  
Thomas M. Tillotson ◽  
John G. Reynolds
Keyword(s):  
Sol Gel ◽  
Supercritical Drying ◽  
Spectroscopic Characterization ◽  
Carbon Chain ◽  
Oxidation Products ◽  
Surface Areas ◽  
Potential Applications ◽  
Different Temperatures ◽  
Stable Forms

ABSTRACTReactions of (CH3O)4Si and C16H33Si(OCH3)3 at various mole ratios were performed in methanol using base and acid catalysis. Sol-gel materials were formed that have low surface areas (∼10 m2/g). Subsequent supercritical drying using CO2 at 40 °C produced materials that are very different than traditional aerogels, with surface areas around the same values as the corresponding sol-gels, as well as no detectable meso-pore features. In some cases, the aerogels even melted upon heating. Spectroscopic characterization, using IR, 29Si and 13C NMR revealed normal Si-O substitution as well as incorporation of the carbon chain into the Si framework.Heating of the stable forms of the materials in air at different temperatures yielded, depending upon oxidation conditions, several materials with much higher surface areas, typical of aerogels. Pore size distribution measurements revealed meso-pore features with a narrow distribution around 35Å. Spectroscopic characterization revealed the disappearance of the R-Si substitution and the appearance of an oxidized intermediate.This paper will describe the chemistry and characterization of these unusual sol-gels, aerogels, and oxidation products, as well as potential applications.

Characterization of Nano-Porous Silica-Zirconia Aerogels

2007 ◽  
Vol 121-123 ◽  
pp. 1289-1292
Author(s):  
Xiao Dong He ◽  
He Xin Zhang ◽  
Yao Li ◽  
Chang Qing Hong
Keyword(s):  
Sol Gel ◽  
Porous Silica ◽  
Supercritical Drying ◽  
Homogeneous Distribution ◽  
Zirconyl Nitrate ◽  
Surface Areas ◽  
Porous Sio2 ◽  
Ft Ir ◽  
Specific Surface Areas

Highly Nano-porous SiO2-ZrO2 aerogels were manufactured with tetraethylorthosilicate (TEOS) and zirconyl nitrate dihydrate (ZrO(NO3)2 .5H2O) by the sol-gel method followed by supercritical drying technique. The prepared aerogels are performed by SEM, FT-IR and BET to characterize and analyze the morphology and pore structure of SiO2-ZrO2 aerogels. The results showed that:(i) The areogels are the typical of nano pores in the interval between 1<Dp<30 nm; (ii) the specific surface areas varied from 300 to 620 m2/g with (SBET)MAX = 615.5 m2/g with 35wt% Zirconia and the surface areas decreased with the increase of zirconia; The thermal conductivity attains 0.015 W/(m.k) ; (iii) a mass of Si-O-Zr bands existed in the aerogels indicating a homogeneous distribution of the components on the nano scale.

scholarly journals High-level ab initio quartic force fields and spectroscopic characterization of C2N−

2021 ◽  
Author(s):  
Carlos M. Rocha ◽  
H V J Linnartz
Keyword(s):  
Ab Initio ◽  
Force Fields ◽  
Electron Attachment ◽  
Spectroscopic Characterization ◽  
Carbon Chain ◽  
Molecular Anions ◽  
High Level

While it is now well established that large carbon chain species and radiative electron attachment (REA) are key ingredients triggering interstellar anion chemistry, the role played by smaller molecular anions,...

Spectroscopic characterization of sol–gel synthesized Tm:Lu2O3 nanocrystals

2011 ◽  
Vol 106 (2) ◽  
pp. 409-417 ◽  
Author(s):  
E. W. Barrera ◽  
M. C. Pujol ◽  
C. Cascales ◽  
C. Zaldo ◽  
K. H. Park ◽  
...  
Keyword(s):  
Sol Gel ◽  
Spectroscopic Characterization

Spectroscopic characterization of CuO /TiO2–ZrO2 catalysts prepared by a-step sol–gel method

2015 ◽  
Vol 489 ◽  
pp. 218-225 ◽  
Author(s):  
F. Morales Anzures ◽  
F. Chávez Rivas ◽  
J. Hernández Ventura ◽  
P. Salinas Hernández ◽  
G. Berlier ◽  
...  
Keyword(s):  
Sol Gel ◽  
Spectroscopic Characterization ◽  
Gel Method ◽  
Sol Gel Method

Design, preparation and characterization of aerogel NiO–CuO–CoO/SiO2 nanocomposite as a reusable catalyst for C–N cross-coupling reaction

2020 ◽  
Vol 44 (13) ◽  
pp. 5056-5063
Author(s):  
Amir Hossein Ghasemi ◽  
Hossein Naeimi
Keyword(s):  
Sol Gel ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Supercritical Drying ◽  
Reusable Catalyst ◽  
Drying Method ◽  
Cross Coupling Reaction ◽  
Powerful Process

The aerogel nanocomposite produces using the sol–gel and supercritical drying method processes. The CO2 supercritical drying (SCD) was taken as the most powerful process, ensuring the best properties of the product.

Effect of the drying on morphology and texture of aerogels and zirconia cryogels

MRS Advances ◽  
2019 ◽  
Vol 4 (64) ◽  
pp. 3513-3521
Author(s):  
Tzipatly A. Esquivel-Castro ◽  
Antonia Martínez-Luévanos ◽  
Luis Alfonso García-Cerda ◽  
Juan C. Contreras-Esquivel ◽  
Pascual Bartolo Pérez ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Cetyltrimethylammonium Bromide ◽  
Sol Gel ◽  
Three Dimensional ◽  
Supercritical Drying ◽  
Sem Images ◽  
Texture Properties ◽  
Dimensional Network ◽  
Zirconia Aerogel

ABSTRACTDue to their excellent properties, aerogel has attracted the attention of the scientific community to use it in the biomedical area as a drug delivery system. This work reports on the synthesis and characterization of ZrO2 aerogels and cryogels obtained by the sol-gel method. The influence of different cetyltrimethylammonium bromide (CTAB) and the type of drying on structural, morphological and texture properties of ZrO2 aerogels and cryogels was investigated. SEM images reveal that a porous interconnected three-dimensional network was formed into aerogels due to supercritical drying. Zirconia aerogel sample has a specific surface area (SBET) larger than zirconia cryogels. Therefore, our results indicate that zirconia aerogel is an adequate material for applications in drug delivery systems.

LUMINESCENT PROPERTIES OF SOL-GEL DEPOSITED Eu:TiO2 THIN FILMS

2001 ◽  
Vol 15 (17n19) ◽  
pp. 769-773 ◽  
Author(s):  
M. GARCIA-ROCHA ◽  
A. CONDE-GALLARDO ◽  
I. HERNANDEZ-CALDERON ◽  
R. PALOMINO-MERINO
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
Luminescent Properties ◽  
X Ray Diffraction ◽  
Si Substrates ◽  
Glass Substrates ◽  
Corning Glass ◽  
Different Temperatures ◽  
Hecd Laser

In this work we show the results on tile growth and optical characterization of TiO 2 thin films doped with Eu atoms. Eu:TiO2 films were grown at room temperature with different Eu concentrations by sol-gel on Si Corning glass substrates. A different crystalline structure is developed for the films deposited on Corning glass than those deposited on Si as observed from x-ray diffraction experiments. Room and low temperature photoluminescence (PL) was measured by using two different lines (325 and 442 nm) of a HeCd laser. A strong PL signal associated to the 5 D 0→7 F 2 transition from Eu +3 was observed. A better emission was obtained from those films deposited on Si substrates, Finally, the evolution of the PL signal is studied when the samples are annealed at different temperatures in O 2 atmosphere.

Spectroscopic characterization of sol-gel processing

1988 ◽  
Vol 106 (1-3) ◽  
pp. 170-173 ◽  
Author(s):  
Florence Babonneau ◽  
Clément Sanchez ◽  
Jacques Livage
Keyword(s):  
Sol Gel ◽  
Spectroscopic Characterization ◽  
Gel Processing
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