scholarly journals Structural Aspects of Some Modified Metal-Alkoxides and Related Molecular Precursors to Ceramic Materials by the Sol—Gel Processing

ChemInform ◽  
2005 ◽  
Vol 36 (47) ◽  
Author(s):  
Rakesh Bohra
Keyword(s):  
Sol Gel ◽  
Ceramic Materials ◽  
Metal Alkoxides ◽  
Molecular Precursors ◽  
Gel Processing ◽  
Structural Aspects

scholarly journals Silane Primers as Adhesion Promotors for Coatings

Proceedings ◽  
2019 ◽  
Vol 29 (1) ◽  
pp. 73
Author(s):  
François Perrin ◽  
Anthony Grard ◽  
Lénaïk Belec
Keyword(s):  
Low Temperatures ◽  
Sol Gel ◽  
Ceramic Materials ◽  
Soft Chemistry ◽  
Molecular Precursors ◽  
Chemistry Method ◽  
Gel Processing

Sol-gel processing is a soft-chemistry method to obtain ceramic materials at low temperatures starting from molecular precursors in solution. [...]

Sol-gel processing and automation of tunable ceramic materials

1993 ◽  
Author(s):  
Fathi Selmi ◽  
Vasundara V. Varadan ◽  
B. Herner ◽  
Vijay K. Varadan
Keyword(s):  
Sol Gel ◽  
Ceramic Materials ◽  
Gel Processing

Catalytic Materials by Design from Hybrid Organic-Inorganics

1998 ◽  
Vol 519 ◽  
Author(s):  
Joël ◽  
J.E. Moreau ◽  
Michel Wong Chi Man
Keyword(s):  
Heterogeneous Catalysts ◽  
Sol Gel ◽  
Inorganic Materials ◽  
Hybrid Network ◽  
Intrinsic Properties ◽  
Reaction Conditions ◽  
Molecular Precursors ◽  
Catalytic Materials ◽  
Materials By Design ◽  
Gel Processing

AbstractThe sol-gel processing of appropriated molecular precursors easily leads to a variety of hybrid organic-inorganic materials with intrinsic properties. This approach is increasingly becoming an interesting way to prepare heterogeneous catalysts. The paper will focus on the use of hybrids for the preparation of selective catalytic materials. Two examples of the use of hybrid polysilsesquioxanes polymers will be given. i) The tailoring of the pore structure of silicas, under mild reaction conditions, based on the temporary introduction of different organic substructures in the hybrid network of polysilsesquioxane gels will be discussed. ii) Also the preparation of new chiral hybrid supports for enantioselective catalysis will be presented.

Sol-Gel Processing of Glasses and Glass-Ceramics for Microelectronic Packaging

1991 ◽  
Vol 249 ◽  
Author(s):  
M.A. Sriram ◽  
P.N. Kumta
Keyword(s):  
Dielectric Constant ◽  
Thermal Analyses ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Signal Propagation ◽  
Ceramic Materials ◽  
X Ray Diffraction ◽  
Low Dielectric ◽  
Heat Treated ◽  
Gel Processing

In recent years considerable progress has been made in electronic packaging substrate technology. The future need of miniaturization of devices to increase the signal processing speeds calls for an increase in the device density requiring the substrates to be designed for better thermal, mechanical and electrical efficiency.Fast signal propagation with minimum delay requires the substrate to possess very low dielectric constant. Several glasses and glass-ceramic materials have been identified over the years which show good promise as candidate substrate materials. Among these borophosphate and borophosphosilicate glass-ceramics have been recently identified to have the lowest dielectric constant (3.8). Sol-gel processing has been used to synthesize borosilicate, borophosphosilicate and borophosphate glasses and glass-ceramics using inexpensive boron oxide and phosphorus pentoxide precursors. Preliminary results of the processing of these gels and the effect of volatility of boron alkoxide and its modification on the gel structure are described. X-ray diffraction, Differential thermal analyses and FTIR have been used to characterize the as-prepared and heat treated gels.

Sol-Gel Processing of Transparent MgAl2O4

1988 ◽  
Vol 121 ◽  
Author(s):  
Yuan-Fu Yu ◽  
Sangvavann Heng ◽  
Tai-Il Mah ◽  
Edward E. Hermes
Keyword(s):  
Sol Gel ◽  
Ceramic Materials ◽  
Metal Alkoxide ◽  
Solvent Ratio ◽  
Processing Conditions ◽  
Chemical Additives ◽  
Control Chemical ◽  
High Degree ◽  
Gel Processing ◽  
Hydrolysis Of

ABSTRACTHigh-purity, transparent monolithic spinel (MgAl2O4) was synthesized via the hydrolytic thermal decomposition of mixed alkoxide organo-metallic precursors. Several factors, such as the metal alkoxide concentration in various solvents, the water to solvent ratio, and the reaction temperatures affect the hydrolysis of the mixed alkoxides. These factors also influence the transparency of the resulting sols and gels. The degree of transparency of the sols and gels is also influenced by such factors as pH and drying control chemical additives. Variations in the processing conditions during drying, aging, and sintering of the gels produced ceramic materials with high degree of transparency.

In situ Synthesis of High Refractive Index PDMS/Metal Oxide Nanocomposites

2012 ◽  
Vol 1400 ◽  
Author(s):  
Qiaoyu Lu ◽  
Michael E. Mullins
Keyword(s):  
Refractive Index ◽  
Metal Oxide ◽  
Hybrid Materials ◽  
Sol Gel ◽  
Heat Stability ◽  
Ceramic Materials ◽  
High Refractive Index ◽  
Oxide Content ◽  
Metal Alkoxides ◽  
Silicone Polymers

ABSTRACTOrganic-inorganic hybrids have been prepared with tailorable and enhanced properties which are unachievable using polymers or ceramics alone. By combining the flexibility of polymers with the electronic and optical properties of ceramic materials, these hybrids offer great potential for many optical, electrical and mechanical applications. Silicone polymers because of their desirable surface properties, excellent physical properties, heat stability, and high resistance to chemical and UV attack, have been widely used. Hybrid siloxane-metal oxide gels have been prepared via sol-gel techniques, by using hydroxyl-terminated polydimethylsiloxanes (PDMS) crosslinked by metallic alkoxides, M(OR)n. In this technique, the use of organic solvents permits organic and inorganic components to be combined at a molecular level with the desired composition. By varying the type and percentage of metal alkoxides during synthesis, transparent and homogeneous organic-inorganic hybrid materials with unique properties were obtained. Also a secondary metal oxide species was introduced to synthesize binary metal oxide-PDMS hybrids. Systematic experiments were carried out to study the effect of the reaction conditions and metal alkoxides-PDMS ratios on the properties of the final hybrids. These hybrids were spin coating on silicon wafers or molded into bulk films to be tested. The composition and the properties of the transparent inorganic-organic hybrids were investigated and characterized by ellipsometer and Fourier Transform Infrared (FTIR) spectroscopy. Experimental results showed that the refractive index of the hybrid materials exhibits a proportional relationship with the metal oxide content, the higher the metal oxide content the higher the refractive index. The refractive index was increased from 1.4 of PDMS to 1.7 of metal oxide-PDMS hybrid with highest prepared metal oxide loading. From the FTIR spectra, the structures of the hybrids for various metal oxide-PDMS compositions were examined.

Sol-Gel Strategies for Controlled Porosity Ceramic Materials: Thin Film and Bulk

1994 ◽  
Vol 368 ◽  
Author(s):  
C. Jeffrey Brinker ◽  
Rakesh Sehgal ◽  
Narayan K. Raman ◽  
Sai S. Prakash ◽  
Laurent Delatire
Keyword(s):  
Thin Film ◽  
Sol Gel ◽  
Ceramic Materials ◽  
Particle Packing ◽  
Membrane Reactors ◽  
Organic Templates ◽  
Controlled Porosity ◽  
Processing Techniques ◽  
Catalytic Membrane Reactors ◽  
Gel Processing

ABSTRACTUsing sol-gel processing techniques it is possible to vary the condensation pathway over wide ranges to form primary species ranging in structure from oligomers to polymers to particles. The porosity of the corresponding dry gels depends on the size and structure of the primary species, the organization of these structures, often by aggregation, to form a gel, and the collapse of the gel by drying. This paper reviews these ideas in the context of forming thin film or bulk specimens. Several strategies are introduced to control porosity on length scales of interest for catalysis and catalytic membrane reactors: 1) aggregation of fractals; 2) management of capillary pressure; 3) surface derivatization; 4) relative rates of condensation and evaporation; 5) the use of organic templates and 6) sintering. These strategies are contrasted with the more traditional particle packing approach to preparing controlled porosity materials.

Preparation of Stoichiometric Crystalline Lithium Niobate Fibers by Sol-Gel Processing with Metal Alkoxides

1989 ◽  
Vol 72 (4) ◽  
pp. 707-709 ◽  
Author(s):  
Shin-ichi Hirano ◽  
Takashi Hayashi ◽  
Katsutoshi Nosaki ◽  
Kazumi Kato
Keyword(s):  
Lithium Niobate ◽  
Sol Gel ◽  
Metal Alkoxides ◽  
Gel Processing

Chemical Synthesis of Fine Powders

MRS Bulletin ◽  
1990 ◽  
Vol 15 (1) ◽  
pp. 18-25 ◽  
Author(s):  
J. Livage ◽  
M. Henry ◽  
J.P. Jolivet ◽  
C. Sanchez
Keyword(s):  
High Performance ◽  
Colloidal Particles ◽  
Sol Gel ◽  
Solid Material ◽  
Narrow Particle Size Distribution ◽  
Molecular Precursors ◽  
Inorganic Oxides ◽  
Fine Powders ◽  
Sol Gel Process ◽  
Gel Processing

Interest in the synthesis of submicron monodispersed powders is increasing. Such powders find applications in the ceramic industry when high performance materials are required. Sintering time and temperature can be significantly reduced with powders of narrow particle-size distribution. Fine colloidal particles can be made by a variety of methods, from the vapor phase or the liquid phase.The sol gel process offers new approaches to the synthesis of fine powders. Starting from molecular precursors, such as metal alkoxides or aqueous solutions, an oxide network is obtained via inorganic polymerization reactions. These reactions occur in solution, and the term “sol-gel processing” is often used to describe the synthesis of inorganic oxides by wet chemical methods. It offers many advantages compared to the conventional powder route. One unique advantage is the ability to go all the way from the molecular precursor to the solid material, permitting better control of the entire process and allowing synthesis of “tailor-made” powders.

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