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.

Preparation and Structural Characterization of SiO2-ZrO2 Aerogels

2007 ◽  
Vol 336-338 ◽  
pp. 2282-2285
Author(s):  
Xiao Dong He ◽  
He Xin Zhang ◽  
Yao Li ◽  
Chang Qing Hong ◽  
Jiu Peng Zhao
Keyword(s):  
Average Pore Size ◽  
Supercritical Drying ◽  
X Ray Diffraction ◽  
Average Pore ◽  
Surface Areas ◽  
Fourier Transformed Infrared Spectroscopy ◽  
Transmission Electron ◽  
Ft Ir ◽  
Chemical Conditions

Low density SiO2-xZrO2 aerogels with x=35wt%, 65wt%, 75wt%, 90wt%, 95wt% were prepared by CO2 supercritical drying technique with tetraethylorthosilicate (TEOS) and zirconyl nitrate dihydrate (ZrO(NO3)2 .2H2O) by hydrolytic polycondensation under different chemical conditions. The prepared aerogels are performed by X-ray Diffraction (XRD), Transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FT-IR) and BET surface areas to characterize and analyze the morphology and pore structure of SiO2-ZrO2 aerogels. The results showed that the SiO2-ZrO2 areogels are the typical of nano mesopores and the average pore size is about 50 nm. The specific surface areas varied from 345.5 to 615.5 m2/g with (SBET)MAX = 615.5 m2/g with 20wt% Zirconia; Moreover a mass of Si-O-Zr bands formed in the aerogels and the formation mechanism of Si-O-Zr bands are also discussed.

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.

scholarly journals Synthesis and Characterization of ZnO-ZrO2 Nanocomposites for Photocatalytic Degradation and Mineralization of Phenol

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
M. C. Uribe López ◽  
M. A. Alvarez Lemus ◽  
M. C. Hidalgo ◽  
R. López González ◽  
P. Quintana Owen ◽  
...  
Keyword(s):  
Photocatalytic Degradation ◽  
Sol Gel ◽  
Tetragonal Zirconia ◽  
Synthesis Process ◽  
Monoclinic Structure ◽  
Surface Areas ◽  
Specific Surface Areas ◽  
Mineralization Degree ◽  
Xrd Patterns

ZnO-ZrO2 nanocomposites using zinc (II) acetylacetonate and different ZnO contents (13, 25, 50, and 75% mol) were synthesized through sol-gel method. The synthesis process was strongly related to nanocomposite properties especially on their structural composition. The obtained ZnO-ZrO2 nanomaterials presented tetragonal crystalline structure for zirconia whereas hexagonal one was formed in ZnO. Raman spectroscopy and XRD patterns confirmed the formation of tetragonal zirconia whereas inhibition of monoclinic structure was observed. Addition of ZnO affected the pore size distribution of the composite, and the measured specific surface areas were from 10 m2/g (for pure ZnO) to 46 m2/g (pristine ZrO2). Eg values of ZrO2 were modified by ZnO addition, since calculated values using Kubelka-Munk’s function varied from 4.73 to 3.76 eV. The morphology and size of the nanomaterials investigated by electron microscopy showed formation of nanorods for ZnO with sizes ranging from 50 nm to 300 nm while zirconia was formed by smaller particles (less than 50 nm). The main advantage of using the nanocomposite for photocatalytic degradation of phenol was the mineralization degree, since 75ZnO-ZrO2 nanocomposite surpassed mineralization reached by pure ZnO and also inhibited formation of undesirable intermediates.

Characterization of SrBi2Nb2O9 Thin Films Prepared by Sol Gel Technique

1996 ◽  
Vol 459 ◽  
Author(s):  
E. Ching-Prado ◽  
W. Pérez ◽  
A. Reynés-Figueroa ◽  
R. S. Katiyar ◽  
D. Ravichandran ◽  
...  
Keyword(s):  
Thin Films ◽  
Raman Band ◽  
Sol Gel ◽  
Orthorhombic Symmetry ◽  
X Ray Diffraction ◽  
Ft Ir ◽  
Gel Technique ◽  
High Degree ◽  
First Time

ABSTRACTThin films of SrBi2Nb2O9 (SBN) with thicknesses of 0.1, 0.2, and 0.4 μ were grown by Sol-gel technique on silicon, and annealed at 650°C. The SBN films were investigated by Raman scatering for the first time. Raman spectra in some of the samples present bands around 60, 167, 196, 222, 302, 451, 560, 771, 837, and 863 cm−1, which correspond to the SBN formation. The study indicates that the films are inhomogeneous, and only in samples with thicknesses 0.4 μ the SBN material was found in some places. The prominent Raman band around 870 cm−1, which is the A1g mode of the orthorhombic symmetry, is assigned to the symmetric stretching of the NbO6 octahedrals. The frequency of this band is found to shift in different places in the same sample, as well as from sample to sample. The frequency shifts and the width of the Raman bands are discussed in term of ions in non-equilibrium positions. FT-IR spectra reveal a sharp peak at 1260 cm−1, and two broad bands around 995 and 772 cm−1. The bandwidths of the latter two bands are believed to be associated with the presence of a high degree of defects in the films. The experimental results of the SBN films are compared with those obtained in SBT (T=Ta) films. X-ray diffraction and SEM techniques are also used for the structural characterization.

Textural characterization of porous silica films prepared by the sol–gel process

2004 ◽  
pp. 227-231
Author(s):  
G. L. T. Nascimento ◽  
L. M. Seara ◽  
B. R. A. Neves ◽  
N. D. S. Mohallem
Keyword(s):  
Sol Gel ◽  
Porous Silica ◽  
Silica Films ◽  
Textural Characterization ◽  
Sol Gel Process

FT-IR Characterization of the Acidic and Basic Sites on a Nanostructured Aluminum Nitride Surface

1996 ◽  
Vol 454 ◽  
Author(s):  
M.-I. Baraton ◽  
X. Chen ◽  
K. E. Gonsalves
Keyword(s):  
Aluminum Nitride ◽  
Organic Molecules ◽  
Sol Gel ◽  
Atomic Layer ◽  
Infrared Spectrometry ◽  
Nitride Powder ◽  
Fourier Transform Infrared Spectrometry ◽  
Basic Sites ◽  
Ft Ir

ABSTRACTA nanostructured aluminum nitride powder prepared by sol-gel type chemical synthesis is analyzed by Fourier transform infrared spectrometry. The surface acidic and basic sites are probed out by adsorption of several organic molecules. Resulting from the unavoidable presence of oxygen, the aluminum nitride surface is an oxinitride layer in fact, and its surface chemistry should present some analogies with alumina. Therefore, a thorough comparison between the acido-basicity of aluminum nitride and aluminum oxide is discussed. The remaining nitrogen atoms in the first atomic layer modify the acidity-basicity relative balance and reveals the specificity of the aluminum nitride surface.

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.

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