scholarly journals Study of Multifunctional Nanocomposites Formed by Cobalt Ferrite Dispersed in a Silica Matrix Prepared by Sol-Gel Process

10.5772/51154 ◽  
2012 ◽  
Author(s):  
Nelcy Della Santina Mohallem ◽  
Juliana Batista ◽  
Gabriel L. Tacchi Nascimento ◽  
Victor L.
Keyword(s):  
Cobalt Ferrite ◽  
Sol Gel ◽  
Silica Matrix ◽  
Sol Gel Process ◽  
Multifunctional Nanocomposites

Cobalt ferrite dispersed in a silica matrix prepared by sol–gel process

2004 ◽  
Vol 272-276 ◽  
pp. E1851-E1853 ◽  
Author(s):  
J.B. Silva ◽  
C.F. Diniz ◽  
J.D. Ardinson ◽  
A.I.C. Persiano ◽  
N.D.S. Mohallem
Keyword(s):  
Cobalt Ferrite ◽  
Sol Gel ◽  
Silica Matrix ◽  
Sol Gel Process

Formation Study of Nanocomposite Thin Films of Ferrite Dispersed in a Silica Matrix Prepared by sol-Gel Process

2003 ◽  
Vol 775 ◽  
Author(s):  
Nelcy D. S. Mohallem ◽  
Luciana M. Seara
Keyword(s):  
Thin Films ◽  
Saturation Magnetization ◽  
Cobalt Ferrite ◽  
Amorphous Matrix ◽  
Sol Gel ◽  
Dip Coating ◽  
Silica Matrix ◽  
Coating Process ◽  
Sol Gel Process ◽  
Nanocomposite Thin Films

AbstractMagnetic nanocomposite thin films formed by cobalt ferrite dispersed in silica matrix were prepared by sol-gel process using tetraethylorthosilicate (TEOS) as a precursor of silica, and metallic nitrates as precursors of the ferrite. The films were prepared with 5–50 wt. % ferrite contents and deposited on substrate using the dip-coating process. The films obtained were adherent, transparent, homogeneous and free of microcracks, with thickness between 30 and 500 nm. The films obtained presented crystalline CoFe2O4 phases dispersed in SiO2 amorphous matrix and saturation magnetization of approximately 9 emu/g considering the composite mass and 30 emu/g considering the ferrite mass.

Leaching Behavior of Edta In A Silica Sol-Gel Matrix

1994 ◽  
Vol 346 ◽  
Author(s):  
Kris S. Oka ◽  
J.D. Mackenzie
Keyword(s):  
Pore Volume ◽  
Sol Gel ◽  
Silica Matrix ◽  
Silica Gels ◽  
Volume Distribution ◽  
Leaching Behavior ◽  
Sol Gel Process ◽  
The Matrix ◽  
Physical Changes ◽  
Hydrolysis Of

ABSTRACTEthylene diamine tetra-acetic acid (EDTA) doped silica gels were made by the sol-gel process for the potential application as a filter for heavy metal ions in wastewater. The behavior of the organic molecule in the matrix was studied by investigating the percentage of EDTA leached out with a variation in the timing of addition of the EDTA molecule into the starting silica gel solution. Leach tests using water as the medium were performed for 2, 12 and 24 hours in order to determine the amount of EDTA trapped in the pores or in the matrix. A minimum amount of EDTA leached from the gels was detected in the samples to which EDTA was added 4 hours after initial hydrolysis of TEOS. This result was correlated to having a greater percentage of pore volume in the range of 15–20 Å, which was further substantiated with density measurements. The physical changes in the silica matrix altering the pore volume distribution were attributed to the addition of the water into which the EDTA molecule was initially dissolved.

scholarly journals Facile Synthesis of Lanthanum Strontium Cobalt Ferrite (LSCF) Nanopowders Employing an Ion-Exchange Promoted Sol-Gel Process

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1800
Author(s):  
Sri Rahayu ◽  
Adi Ab Fatah ◽  
Girish M. Kale
Keyword(s):  
Ion Exchange ◽  
Calcination Temperature ◽  
Cobalt Ferrite ◽  
Exchange Process ◽  
Sol Gel ◽  
Simultaneous Thermal Analysis ◽  
High Catalytic Activity ◽  
Ion Exchange Process ◽  
Lanthanum Strontium ◽  
Sol Gel Process

The perovskite nanopowders of lanthanum strontium cobalt ferrite (LSCF) have been synthesized using the alginate mediated ion-exchange process. This perovskite-based material is a promising cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs) due to its high electrical conductivity, low polarizability, high catalytic activity for oxygen reduction, enhanced chemical stability at an elevated temperature in high oxygen potential environment and high compatibility with the ceria based solid electrolytes. Phase pure LSCF 6428, LSCF 6455, and LSCF 6482 corresponding to La0.6Sr0.4Co0.2Fe0.8O3-δ, La0.6Sr0.4Co0.5Fe0.5O3-δ, and La0.6Sr0.4Co0.8Fe0.2O3-δ, respectively were successfully synthesized. The simultaneous thermal analysis (DSC-TGA) and XRD were used to determine the optimum calcination temperature for the dried ion-exchanged beads. Single phase nanopowders of LSCF (6428, 6455, and 6482) have been successfully prepared at a calcination temperature of 700 °C. The TGA analysis showed that every ton of LSCF-ALG dried beads can potentially yield 360 kg of LSCF nanopowders suggesting a potential for scaling-up of the process of manufacturing nanopowders of LSCF.

scholarly journals Incorporation of Organic Compound into Silica Matrix by a Sol-Gel Process for NLO Applications

1993 ◽  
Vol 101 (1169) ◽  
pp. 76-77 ◽  
Author(s):  
Yong-Gun SHUL ◽  
Dong-Jo LEE ◽  
Jae-Suk LEE ◽  
Tatsuo WADA
Keyword(s):  
Organic Compound ◽  
Sol Gel ◽  
Silica Matrix ◽  
Sol Gel Process

Synthesis of tin oxide nanosized crystals embedded in silica matrix through sol–gel process using alkoxide precursors

2009 ◽  
Vol 355 (16-17) ◽  
pp. 951-959 ◽  
Author(s):  
Y.C. Wu ◽  
W. Hamd ◽  
E. Thune ◽  
A. Boulle ◽  
C. Rochas ◽  
...  
Keyword(s):  
Tin Oxide ◽  
Sol Gel ◽  
Silica Matrix ◽  
Sol Gel Process ◽  
Alkoxide Precursors ◽  
Nanosized Crystals

Preparation of core shell particles consisting of cobalt ferrite and silica by sol–gel process

2006 ◽  
Vol 415 (1-2) ◽  
pp. 257-260 ◽  
Author(s):  
Shuping Zhang ◽  
Dawei Dong ◽  
Yu Sui ◽  
Zhiguo Liu ◽  
Hongxia Wang ◽  
...  
Keyword(s):  
Cobalt Ferrite ◽  
Sol Gel ◽  
Core Shell ◽  
Sol Gel Process ◽  
Shell Particles

Structure and chemistry of Ag‒Cu nanoclusters in a silica matrix by the sol-gel process

1997 ◽  
Vol 76 (4) ◽  
pp. 621-628 ◽  
Author(s):  
M. Catalano ◽  
E. Carlino ◽  
G. De ◽  
L. Tapfer ◽  
F. Gonella ◽  
...  
Keyword(s):  
Sol Gel ◽  
Silica Matrix ◽  
Sol Gel Process ◽  
Cu Nanoclusters

Synthesis and Characterization of Silicon Oxycarbide Derived Nanocomposites Obtained through Ceramic Processing of TEOS/PDMS Preceramic Materials

2011 ◽  
Vol 14 ◽  
pp. 27-38 ◽  
Author(s):  
J.L. Oteo ◽  
M. Alejandra Mazo ◽  
Cristina Palencia ◽  
F. Rubio ◽  
Juan Rubio
Keyword(s):  
Silicon Carbide ◽  
Sol Gel ◽  
Silica Matrix ◽  
Silicon Oxycarbide ◽  
Glassy Matrix ◽  
Ceramic Processing ◽  
Carbon Phase ◽  
Graphite Phase ◽  
Sol Gel Process ◽  
Silicon Oxycarbide Glasses

Bulk silicon oxycarbide derived ceramic nanocomposites have been prepared by the application of the conventional ceramic processing to preceramic materials. Tetraethylortosilicate/ polydimethylsiloxane preceramic materials obtained by sol-gel process were thermally treated and attrition milled to 4 micrometers. Subsequently, the preceramic powders were pyrolized at 1100 °C to obtain silicon oxycarbide powders that were pressed and sintered at 1550 °C up to 16 hours. Silicon oxycarbide glasses obtained at 1100 °C from pyrolysis of preceramic materials consist of a Si-O-C network and a carbon like graphite phase well dispersed. At annealing temperatures higher than 1100°C silicon oxycarbide glasses undergo a rearrangement which involves a phase separation to silica and silicon carbide and a segregation of carbon like graphite phase. At these temperatures the material can be considered as a glassy matrix nanocomposite. At temperatures higher than 1500 °C the carbothermal reduction occurs with the consumption of both silica and free carbon phase. However, the nanocomposite structure is maintained but with different constituents. The silicon oxycarbide glasses obtained at 1100 °C are amorphous. However, as a result of all involving processes taken place during the ceramic process, the nanocomposites formed at 1550 °C comprise a silica matrix and nanodomains of carbon like graphite and silicon carbide both of them displaying an incipient crystallization. Structure and crystalline size evolution, from preceramic materials to silicon oxycarbide derived nanocomposites, have been determined by FT-IR and Raman spectroscopies, XRD and 29Si-MASNMR.

scholarly journals CO2 Hydrogenation to Methanol with Ga- and Zn-Doped Mesoporous Cu/SiO2 Catalysts Prepared by the Aerosol-Assisted Sol-Gel Process

2020 ◽  
Author(s):  
Charlie Paris ◽  
Alejandro Karelovic ◽  
Raydel Manrique ◽  
Solène Le Bras ◽  
François Devred ◽  
...  
Keyword(s):  
Heterogeneous Catalysts ◽  
Continuous Production ◽  
Sol Gel ◽  
Active Phase ◽  
High Specific Surface Area ◽  
Silica Matrix ◽  
Promoting Effect ◽  
Process Step ◽  
Sol Gel Process ◽  
One Step

The preparation of copper-based heterogeneous catalysts dedicated to the hydrogenation of CO2 to methanol typically relies on multi-step procedures carried out in batch. These steps are precisely tailored to introduce the active phase (Cu) and the promoters (e.g. zinc, gallium) onto a preformed support, to maximize catalyst performance. However, each process step – often carried out in batch – can be associated with the formation of waste and with the consumption of energy, thereby negatively impacting the environmental performance of the overall catalyst preparation procedure. Here, we propose a direct and continuous production process for the synthesis of efficient catalysts for the CO2 to methanol reaction. Gallium- and zinc-promoted mesoporous Cu-SiO2 catalysts are prepared in one step by the aerosol-assisted sol-gel process. The catalysts consist of spherical microparticles and feature high specific surface area and pore volume, with interconnected pores of about 6 nm. A strong promoting effect of Ga and Zn is highlighted, boosting the selectivity for methanol at the expense of CO. Upon calcination, we show that Cu species – initially trapped in the silica matrix – undergo a migration towards the catalyst surface and a progressive sintering. After optimization, the catalysts obtained via such direct route compete with the best catalysts reported in the literature and obtained via multi-step approaches. <br>

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