Abstract: The present invention relates to a Si2O glass characterized by a high homogeneity, prepared through a sol-gel procedure.

Abstract: Sol-gel process for the production of optical fiber preforms or overcladdings by preparing a sol, gelling the sol, drying the wet gel to a dry porous gel and densifying the dry gel to fully dense glass, wherein during the calcination treatment from 350° C. to 900° C. to remove organic impurities in the dry gel, it is carried out at least one reduced-pressure phase at a pressure comprised between about 0.01 and 0.5 bar.

Abstract: Glassy articles are prepared by subjecting to hydrolysis and policondensation a solution or suspension of a suitable precursor, mainly comprising a silicon alkoxide, and by drying the obtained gel in a pressure chamber, the gel solvent having been substituted by a non-protic solvent, mainly acetone, under nitrogen flowing, at temperature and pressure conditions lower than the gel solvent critical values. The dried gel is then densified by a thermal treatment.

Abstract: A method for the preparation of aerogels that involves the exchange of the liquid present in the aquagel with xenon and the subsequent extraction thereof.

Abstract: This invention concerns a method and the product derived from applying this method, for flatting moulded thermoplastic polymers parts and powder paints, of the type that requires particles to be added to said thermoplastic polymers and paints, in which said particles to be added to said thermoplastic polymers and paints are coated with a carrier that has a melting point that is lower than the melting point for said thermoplastic polymers and paints. The particles have a glass transition temperature that is at least equal to the moulding temperature of said thermoplastic polymers, are made of material able to withstand the polymerisation temperature used for said paints and have a glass transition temperature that is at least equal to the polymerisation temperature used for said paints.

Abstract: This invention concerns an agglomeration of particles to be used as additives for moulding thermoplastic polymers or paints, said agglomeration being in the form of chips, flakes, powder or paste in which a coating with a carrier of said particles is provided that moves in between the particles to keep them essentially separate from one another, said particles being substantially coated all over their surface.

Abstract: Process for the preparation and the deposition of vitreous films on substrates comprising: the dissolution of one or more metal alkoxides in aprotic solvent, the hydrolysis of the resulting solution, yhe eventual removal of the formed alcohol, the deposition of the resulting sol on the substrate surface of interest and the final drying of the film.

Abstract: A sol-gel process allowing preparation, on a substrate, of glassy films of silicon oxide or mixed oxides based on silicon oxide, of thickness above 1 micrometer, generally between 2 and 20 micrometers and characterized by absence of defects, that turn out to be particularly suitable as waveguides in flat optical devices.

Abstract: A sol-gel process is described that allows dry gels to be produced, and where necessary, the corresponding dense vitreous bodies, around an incompressible insert. A particular feature of the process is the step of rotating a container holding the sol and incompressible insert throughout the gelling step under such conditions that a wet gel adhering to the insert is produced, which is then dried. The process is useful particularly for the production of preforms for optical fibers, which are also claimed.

Abstract: It is described a process based on sol-gel chemistry suitable to the production of nanocomposite materials being photoluminescent at ambient temperature, comprising silicon grains of dimension of nanometers embedded in a silica matrix.

Abstract: It is described a process based on sol-gel chemistry suitable to the production of nanocomposite materials being photoluminescent at ambient temperature, comprising silicon grains of dimension of nanometers embedded in a silica matrix.

Abstract: It is described a sol-gel process that allows to obtain dry gels, and possibly the corresponding dense glassy bodies, having higher dimensions compared to similar known processes.

Abstract: A sol-gel process allowing the preparation, on a substrate, of glassy films of silicon oxide or mixed oxides based on silicon oxide, of thickness above 1 micrometer, generally between 2 and 20 micrometers and characterized by absence of defects, that turn out to be particularly suitable as waveguides in flat optical devices.

Abstract: An optical article, which is a preform for an optical lens, which is isotropic, consisting essentially of silicon oxide or silicon oxide in combination with one or more oxides of elements belonging to Groups III to VI of the Periodic Table, the article having a dimensional precision which has tolerance to surface roughness and profilometric accuracy required in the spectral interval of 200-800 nm of the electromagnetic spectrum, the tolerance being between one-half and one-tenth wavelength corresponding to the range of about 0.350-0.02 &mgr;m.

Abstract: It is described a process based on sol-gel chemistry suitable to the production of nanocomposite materials being photoluminescent at ambient temperature, comprising silicon grains of dimension of nanometers embedded in a silica matrix.

Abstract: A sol-gel process allowing the preparation, on a substrate, of glassy films of silicon oxide or mixed oxides based on silicon oxide, of thickness above 1 micrometer, generally between 2 and 20 micrometers and characterized by absence of defects, that turn out to be particularly suitable as waveguides in flat optical devices.

Abstract: A sol-gel process is described that allows dry gels to be produced, and where necessary, the corresponding dense vitreous bodies, around an incompressible insert. A particular feature of the process is the step of a rotating a container holding the sol and incompressible insert throughout the gelling step under such conditions that a wet gel adhering to the insert is produced, which is then dried. The process is useful particularly for the production of preforms for optical fibers, which are also claimed.

Abstract: Sol-gel process for the production of optical fiber preforms or overcladdings by preparing a sol, gelling the sol, drying the wet gel to a dry porous gel and densifying the dry gel to fully dense glass, wherein during the calcination treatment from 350° C. to 900° C. to remove organic impurities in the dry gel, it is carried out at least one reduced-pressure phase at a pressure comprised between about 0.01 and 0.5 bar.

Abstract: An optical article, which is a preform for an optical lens, which is an isotropically miniaturized, amorphous monolithic aerogel, consisting essentially of silicon oxide or silicon oxide in combination with one or more oxides of elements belonging to Groups III to VI of the Periodic Table, the article having a surface having a dimensional precision which has tolerance to surface roughness and profilometric accuracy required in the spectral interval of 200-800 nm of the electromagnetic spectrum, the tolerance being between one-half and one-tenth wavelength corresponding to the range of about 0.350-0.02 &mgr;m.

Abstract: A process for producing a linearly-miniaturized, densified optical product, which entails a) cold filling a mould with a liquid colloidal dispersion formed from a chemical precursor; b) polycondensing the liquid colloidal dispersion to obtain a gel; c) supercritically drying the gel to form an amorphous aerogel having dimensions corresponding to the mould; and d) isotropically miniaturizing the amorphous monolithic aerogel obtained.