Sol-gel

About: Sol-gel is a research topic. Over the lifetime, 11843 publications have been published within this topic receiving 262454 citations.

Tailoring Molecular Precursors for Multicomponent Oxides

Abstract: Simple ways to build up mixed-metal molecules which can act as potential single-source precursors to multimetallic oxides are reviewed. Emphasis is given to Lewis acid-base reactions metal alkoxides M(OR) n , and between metal alkoxides and more accessible oxide precursors, carboxylates M'(O₂CR) n and β-diketonates M'(β-dik) n . Characterization of the precursors is achieved in the solid state (single crystal X-ray diffraction, FT-IR) and by multinuclear NMR in solution. The reactions proceed toward the formation of aggregates in which the different metals display their usual coordinations numbers, often six for transition metals, as shown. Strategies for fixing the stoichiometry between the metals are developed. The reactivity of the MM'species (dislocation, effects of chemical modifiers, of other metallic species, hydrolytic or non-hydrolytic condensation, etc.) will be indicated. Transformations into oxides are illustrated on precursors for titanates or niobates.

Alkali-resistant coating for light metals, in particular aluminum

Abstract: A method for producing a coated light metal substrate, in particular an aluminum substrate, includes steps a) wet chemical application of a coating composition to the light metal substrate, and b) thermal hardening of the coating material, the coating composition containing a sol gel material having the composition indicated in the description.

Sol-gel synthesis of magnetic sorbents based on porous iron oxides for the removal of U(VI) from aqueous solution

Abstract: An original synthetic route to nanostructured iron oxides with porous structure and to their reduced derivatives, prospective for uranium (VI) uptake from water media, is presented. The uniqueness of method includes combination of sol-gel technology, which used for generating inorganic framework, and template synthesis for porous structure formation with the help of poreforming agent (polymer latex). Method of consolidating porous iron oxides and its influence on such characteristics as porosity, magnetization, morphology, phase composition and sorption properties are described. Sorption properties of the materials based on iron oxides and their reduced derivatives with respect to uranium (VI) from water media of different acidity has been investigated. Mechanism of uranium (VI) sorption on the obtained materials has been determined. The interaction of the sorbents with uranyl-ions was shown to change depending on phase composition and structure of the solid matrix.

DFT Investigation of the Mechanism and Chemical Kinetics for the Gelation of Colloidal Silica

Abstract: The mechanism for the gelation reaction of colloidal silica, Si(OH)4 +Si(OH)3 (O)- ----> Si2O8H5 - + H2O, by an anionic pathway was investigated using density functional theory(DFT). Using transition state theory, the rate constants were obtained by analyzing the potential energy surface at the reactants, saddle point, and the products. In addition, reaction rate constants were investigated in the presence of ammonium chloride (NH4Cl) and sodium chloride (NaCl). These salts act as catalysts to induce gelation by destabilizing the double layer of colloidal silica to allow for Van der Waal interactions. Furthermore, it was observed that ammonium chloride plays an important role by initiating a hydride transfer allowing the reaction to proceed from the second transition state to the final product.