New Chemistry for the Sol-Gel Process: Acetone as a New Condensation Reagent

1992 ◽  
Vol 271 ◽  
Author(s):  
Subhash C. Goel ◽  
Michael Y. Chiang ◽  
Patrick C. Gibbons ◽  
William E. Buhro
Keyword(s):  
Aldol Condensation ◽  
Sol Gel ◽  
Metal Alkoxide ◽  
Sol Gel Process ◽  
New Process ◽  
Gel Processing ◽  
Alkoxide Precursors

ABSTRACTA nonhydrolytic sol-gel process that uses acetone as the condensation reagent is described. In the new process, the hydrocarbon soluble Zn(OCEt3)2 is converted to a rigid, transparent gel and then to ZnO by an aldol-condensation-elimination sequence. The chemical pathway for the transformation has been established, and differs completely from the pathway for the conventional hydrolytic sol-gel processing of alkoxide precursors. The new, nonhydrolytic strategy may prove applicable to a variety of metal-alkoxide systems.

New insight in the role of modifying ligands in the sol-gel processing of metal alkoxide precursors: A possibility to approach new classes of materials

2006 ◽  
Vol 40 (2-3) ◽  
pp. 163-179 ◽  
Author(s):  
Vadim G. Kessler ◽  
Gerald I. Spijksma ◽  
Gulaim A. Seisenbaeva ◽  
Sebastian Håkansson ◽  
Dave H. A. Blank ◽  
...  
Keyword(s):  
Sol Gel ◽  
Metal Alkoxide ◽  
Gel Processing ◽  
Alkoxide Precursors

Preparation and Characterization of Sol-Gel Derived Heteroepitaxial LiNbO3 and LiTaO3 Thin Films

1993 ◽  
Vol 310 ◽  
Author(s):  
Keiichi Nashimoto
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
Metal Alkoxide ◽  
Bulk Single Crystal ◽  
Rocking Curve ◽  
X Ray ◽  
Sapphire Substrates ◽  
Sol Gel Process ◽  
Alkoxide Precursors

AbstractDense epitaxial LiNbO3 thin films without any misoriented plane on sapphire substrates were obtained with a sol-gel process utilizing 2-methoxyethanol based metal alkoxide precursors without pre-hydrolysis and rapid thermal annealing. Epitaxial LiNbO3 films annealed at 700°C were transparent and showed refractive indices close to bulk single crystal values. Epitaxial and transparent LiTaO3 films crystallized successfully on sapphire substrates with single orientations with the present process. X-ray rocking curve full widths at half maximum of epitaxial LiNbO3 and LiTaO3 films on sapphire (110) substrates and annealed at 700°C were less than 0.4 degree.

Amorphous Thin Film Ruthenium Oxide as an Electrode Material for Electrochemical Capacitors

1995 ◽  
Vol 393 ◽  
Author(s):  
T.R. Jow ◽  
J.P. Zheng
Keyword(s):  
Specific Capacitance ◽  
Chloride Solution ◽  
Sol Gel ◽  
Ruthenium Oxide ◽  
Metal Alkoxide ◽  
Oxide Electrode ◽  
Preparation Temperature ◽  
Amorphous Thin Film ◽  
Sol Gel Process ◽  
Alkoxide Precursor

ABSTRACTRuthenium oxide thin films of an amorphous phase were successfully prepared on a titanium (Ti) substrate at temperatures below 160 °C. The sol-gel process using metal alkoxide precursor in nonaqueous solvents was used to prepare these films. The preliminary results showed that a specific capacitance of 430 F/g can be achieved for amorphous ruthenium oxide electrode in sulfuric acid. Films prepared by this method are compared with the films prepared by the thermal decomposition of the aqueous ruthenium chloride solution at temperatures above 300 °C. The specific capacitance, the crystalline structure, and the surface morphology of these films as a function of the preparation temperature were also discussed.

Introduction of Organic Moieties into Transition-Metal Oxide Matrices via Phosphonate Groups

1998 ◽  
Vol 519 ◽  
Author(s):  
P.H. Mutin ◽  
C. Delenne ◽  
D. Medoukali ◽  
R. Corriu ◽  
A. Vioux
Keyword(s):  
Transition Metal ◽  
Metal Oxide ◽  
Phosphonic Acid ◽  
Sol Gel ◽  
Transition Metal Oxide ◽  
Metal Alkoxide ◽  
Hydrolytic Condensation ◽  
Metal Phosphonates ◽  
Or Groups ◽  
Sol Gel Process

AbstractTransition metal oxide / phenylphosphonate hybrids with M/P ratios ranging from 1 to 5, (M= Ti, Zr) and metal phosphonates (M/P = 0.5) have been prepared by a sol-gel process involving in a first step the non-hydrolytic condensation between metal alkoxide and phosphonic acid leading to M-O-P bonds, followed by the hydrolysis-condensation of the remaining M-OR groups. The composition, texture and structure of the materials were investigated using EDX, TGA, XRD, IR and 31P NMR.

Sol-Gel Process form Heterometallic Alkoxides to Incorporate Alkaline- and Rare Earths in Alumina for automotive Applications

1996 ◽  
Vol 431 ◽  
Author(s):  
C. K. Narula
Keyword(s):  
Elevated Temperatures ◽  
Sol Gel ◽  
Automotive Applications ◽  
Automotive Catalysts ◽  
Heterometallic Alkoxides ◽  
Sol Gel Process ◽  
Alkaline Earths ◽  
Cost Of Materials ◽  
Gel Processing

AbstractThe high cost of materials prepared by sol-gel processing and the loss of useful surface properties at elevated temperature has prevented the application of sol-gel processed materials in automotive exhaust reduction catalyst formulations. In this report, we briefly describe the important developments needed in the next generation automotive catalysts and the role of sol-gel processed materials. We will also discuss the application of heterometallic alkoxides as sol-gel precursors to achieve the molecular distribution of lanthanides and alkaline earths in alumina matrices needed for the stabilization of alumina based materials at elevated temperatures.

Preparation and Microstructural Evolution of Sol-Gel-Derived Enstatite Fibers

2008 ◽  
Vol 368-372 ◽  
pp. 1007-1009
Author(s):  
M.T. Tsai ◽  
P.J. Tsai ◽  
H.C. Chang
Keyword(s):  
Microstructural Evolution ◽  
Sol Gel ◽  
Optical Transmittance ◽  
Ceramic Fiber ◽  
Visible Range ◽  
Metal Alkoxide ◽  
Ceramic Fibers ◽  
Bridging Ligands ◽  
Sol Gel Process ◽  
Infrared Studies

Homogeneous and transparent enstatite fibers were prepared via the sol-gel process of metal alkoxide precursors. The gel-to-ceramic conversion was characterized. The solution compositions had a significant influence on the microstructural evolution of gel fibers. Infrared studies indicated that bidentate bridging ligands were formed between acetate and metal ions, which enhanced spinnability remarkably. The as-drawn fibers were essentially microporous. On heating to 800 oC, enstatite ceramic fibers exhibited mesoporous structures with nanocrystals in size. The optical transmittance of enstatite ceramic fiber in the visible range was around 90 % after heating at 800 oC.

Physical-Chemical Properties of TiO2 Membranes Controlled By Sol-Gel Processing

1988 ◽  
Vol 132 ◽  
Author(s):  
Qunyin Xu ◽  
Marc A. Anderson
Keyword(s):  
Primary Particle ◽  
Sol Gel ◽  
Chemical Properties ◽  
Primary Particle Size ◽  
Chemical Processes ◽  
Gel Structure ◽  
Physical Chemical ◽  
Membrane Porosity ◽  
Gel Processing ◽  
Alkoxide Precursors

ABSTRACTParticulate TiO2 membranes have been prepared by sol-gel techniques from alkoxide precursors. The degree of aggregation, which is controlled by physical chemical processes during sol preparation influences the gelling volume and gel structure. While three types of gel structures have been proposed, the porosity of the final membrane seems to be little affected by these hydrogel structures. Firing temperature is a much more critical parameter. It is concluded that the primary particle size determines the final membrane porosity in this TiO2 system.

Sol-gel processing of PbTiO3 and Pb(Zr0.52Ti0.48)O3 fibers

1992 ◽  
Vol 7 (4) ◽  
pp. 992-996 ◽  
Author(s):  
Ulagaraj Selvaraj ◽  
A.V. Prasadarao ◽  
Sridhar Komarneni ◽  
Keith Brooks ◽  
Stewart Kurtz
Keyword(s):  
Heat Treatment ◽  
Sol Gel ◽  
Dielectric Constants ◽  
Heat Treated ◽  
Viscous Solutions ◽  
Gel Processing ◽  
Alkoxide Precursors

Homogeneous and stoichiometric PbTiO3 and PbZr0.52Ti0.48O3 gel fibers were drawn from viscous solutions prepared by sol-gel processing of alkoxide precursors. The fibrous gels on heating at 450 and 600 °C, respectively, formed the well-crystallized phases of PbTiO3 and PbZr0.52Ti0.48O3. Fibers heat treated at 700 °C are a few centimeters long and 50 to 150 μm in diameter. PbZr0.52Ti0.48O3 fibers subjected to heat treatment at 700 °C for 1 h consisted of fully dense submicron grains (0.15 to 0.2 μm). However, PbTiO3 fibers under analogous conditions showed a few micropores with grains of ∼0.1 μm. Dielectric constants of these PbTiO3 and PbZr0.52Ti0.48O3 fibers were approximately 300 and 800, respectively.

The Effects of Aluminum Alkoxides on the Synthesis of Composite Powders of Alumina and Titania

1989 ◽  
Vol 155 ◽  
Author(s):  
Michael T. Harris ◽  
Charles H. Byers ◽  
Ronald R. Brunson
Keyword(s):  
Sol Gel ◽  
Particle Morphology ◽  
Ceramic Materials ◽  
Metal Alkoxide ◽  
Oxide Ceramic ◽  
Powder Synthesis ◽  
Composite Powders ◽  
Sol Gel Process ◽  
Hydrolysis Of ◽  
Uniform Composition

ABSTRACTThe synthesis of mixed oxide ceramic powders that consist of very fine (submicron)-monodisperse particles with uniform composition is desirable in the improvement of existing ceramics and the development of new ceramic materials. Metal alkoxide hydrolysis is a very attractive method for the synthesis of ultrapure composite powders at low temperatures by the sol-gel process.The present study investigates the effects of the hydrolysis of aluminum alkoxides and the condensation products on the growth kinetics and morphology of composite particles containing alumina and titania. Alkoxides of titanium and aluminum are employed; therefore, powders of high purity are produced. Since various solvents are used as media for powder synthesis, the effect of the solvent on particle morphology will also be discussed.

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