Sol-gel formation of heteropolysiloxanes from diethylphosphatoethyltriethoxysilane and tetraethoxysilane

The study of submicroscopic particles in already known systems has resulted in a renewed interest due to the large differences found in their properties when the particle size is reduced, and because of possible new technological applications. In this work we report the preparation of LaFeO3 particles by the sol-gel route, starting from a solution of the corresponding metallic nitrates and using urea as gelificant agent. Gels were decomposed at 200 °C and calcined 3 h at several temperatures, T, in the range 250–1000 °C. The samples were structurally characterized by x-ray diffraction (XRD) showing that the orthoferrite crystallizes at T as low as 315 °C. From the x-ray diffraction peak broadening, the particle size was determined. The size increases from 60 to 300 nm as the calcination T increases. Infrared spectroscopy was used to characterize gels and calcined samples. From these studies a mechanism for the gel formation is proposed. Study of the magnetic properties of LaFeO3 particles shows the presence of a ferromagnetic component which diminishes as the calcination temperature increases, vanishing at T = 1000 °C.

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pH Affects Sol–Gel Formation of Core–Shell Mesoporous Silica Coatings on Polyamide

Industrial & Engineering Chemistry Research ◽

10.1021/ie302580q ◽

2013 ◽

Vol 52 (2) ◽

pp. 779-784 ◽

Cited By ~ 1

Author(s):

Junia N. M. Batista ◽

Emerson H. de Faria ◽

Paulo S. Calefi ◽

Katia J. Ciuffi ◽

Eduardo J. Nassar ◽

...

Keyword(s):

Mesoporous Silica ◽

Sol Gel ◽

Core Shell ◽

Gel Formation ◽

Silica Coatings

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Viscoelastic Relaxation of Polyurethane at Different Stages of the Gel Formation. 2. Sol−Gel Transition Dynamics

Macromolecules ◽

10.1021/ma9617936 ◽

1997 ◽

Vol 30 (19) ◽

pp. 5897-5904 ◽

Cited By ~ 19

Author(s):

Taco Nicolai ◽

Hery Randrianantoandro ◽

Frederic Prochazka ◽

Dominique Durand

Keyword(s):

Sol Gel ◽

Viscoelastic Relaxation ◽

Gel Formation ◽

Transition Dynamics ◽

Sol Gel Transition ◽

Gel Transition

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Oxometalate-Glass Composites and Thin Films

MRS Proceedings ◽

10.1557/proc-180-595 ◽

1990 ◽

Vol 180 ◽

Cited By ~ 1

Author(s):

Karin Moller ◽

Thomas Bein ◽

C. Jeffrey Brinker

Keyword(s):

Thin Films ◽

Ion Exchange ◽

Sol Gel ◽

Composite Films ◽

Exchange Capacity ◽

Exafs Spectroscopy ◽

Gel Formation ◽

Ion Exchange Capacity ◽

Glass Composites ◽

Exchange Properties

ABSTRACTNew glass-composites with ion exchange properties have been developed. Ammonium 12-molybdophosphate (AMP) (NH4)3PMo12O40, and ammonium 12-tungstophosphate (AWP) (NH4)3PW12O40, known for their ion exchange capabilities, are included either in preformed aerogels with defined pore size, or are added to sol-gel mixtures during the process of gel formation. Characterization is carried out by FTIR, Raman and EXAFS spectroscopy. Ion exchange capacities for the oxometalate precursors are determined for silver and rubidium and are compared to those of the glass composites. Glass composites show high ion exchange capacity, but some portion of the metalate complexes leaches from the glass during the procedure. This is in contrast to thin composite films, which have almost no porosity and do not show loss of metalate. EXAFS spectroscopy demostrates that the oxometalate microstructure is maintained in glass composites and that rubidium ions after ion exchange in glasses occupy similar cation positions as in the precursor compounds.

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Sol-Gel Synthesis of Nanocrystalline Ni-Ferrite and Co-Ferrite Redox Materials for Thermochemical Production of Solar Fuels

MRS Proceedings ◽

10.1557/opl.2014.866 ◽

2014 ◽

Vol 1675 ◽

pp. 203-208 ◽

Cited By ~ 15

Author(s):

Rahul R. Bhosale ◽

Ivo Alxneit ◽

Leo L. P. van den Broeke ◽

Anand Kumar ◽

Mehak Jilani ◽

...

Keyword(s):

Sol Gel ◽

Solar Fuels ◽

Bet Surface Area ◽

Mixed Solution ◽

Gel Formation ◽

Thermochemical Cycles ◽

X Ray ◽

Thermogravimetric Analyzer ◽

Sol Gel Synthesis

ABSTRACTIn this contribution, we report the synthesis and characterization of NixFe3-xO4 and CoxFe3-xO4 redox nanomaterials using sol-gel method. These materials will be used to produce solar fuels such as H2 or syngas from H2O and/or CO2 via solar thermochemical cycles (STCs). For the sol-gel synthesis of ferrites, the Ni, Co, Fe precursor salts were dissolved in ethanol and propylene oxide (PO) was added dropwise to the well mixed solution as a gelation agent to achieve gel formation. Freshly synthesized gels were aged, dried, and calcined by heating them to 600°C in air. The calcined powders were characterized by powder x-ray diffractometer (XRD), BET surface area, as well as scanning (SEM) and transmission (TEM) electron microscopy. Their suitability to be used in STCs for the production of solar fuels was assessed by performing several reduction/re-oxidation cycles using a thermogravimetric analyzer (TGA).

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Creation and Preparation of a Barium Lanthanyloxalate Composite Substance Based on Sol-Gel Technology

Bulletin of Science and Practice ◽

10.33619/2414-2948/57/05 ◽

2020 ◽

Vol 6 (8) ◽

pp. 45-49

Author(s):

Y. Tashpolotov ◽

E. Ysmanov ◽

A. Atambekova

Keyword(s):

Acidic Medium ◽

Sol Gel ◽

Component Composition ◽

Gel Formation ◽

Mechanical Stirring

This article explored a method for producing a compound of the type perovskite composition. Ba0.5X×Ox1X (where X=0.5:0.5=1). A multi-component composition was obtained during coagulation and gel formation (xerogel) of pH 5.5, acidic medium, at a temperature of 45–50 °C, mechanical stirring for 10 hours. The sol–gel crystallization of the compound was determined at a temperature of 400–500 °C and the previously obtained substance was named Barium Lanthanyloxalate.

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