Methods for forming and controlling morphology cracks in silicon dioxide (SiO.sub.2) film comprising: preparing SiO.sub.2precursor solution comprising solvent, precursor of SiO.sub.2, precursor of metal oxide nanocrystals, water, and acid; coating the solution onto substrate; drying the solution atop the substrate at a temperature between about 20° C. to 100° C. between 1 minute to 24 hours to form SiO.sub.2 film having uniformly dispersed metal oxide nanocrystals, wherein shorter drying times yield substantially spherical shaped metal oxide nanocrystals and longer drying times yield rod and disc shaped metal oxide nanocrystals; and thermally treating the SiO.sub.2 film between about 60° C. to 500° C. between 1 minute to 24 hours to form cracked mesh SiO.sub.2 film, wherein two cracks initiate from rod shaped metal oxide nanocrystals, three to four cracks initiate from spherical shaped metal oxide nanocrystals, and four or more cracks initiate from disc shaped metal oxide nanocrystals. Other embodiments are described and claimed.

A polishing composition that can not only achieve high polishing speed, but also can improve the surface smoothness (surface quality) of a polished substrate and reduce defects is provided. That is, provided is a polishing composition comprising silica particles and a water soluble polymer, wherein the contained silica particles satisfy the following requirements (a) to (c): (a) the primary particle diameter based on the specific surface area is 5 to 300 nm; (b) the coefficient of variation in the particle diameter is 10% or less; and (c) the Sears number Y is 10.0 to 12.0.

A polishing composition that can not only achieve high polishing speed, but also can improve the surface smoothness (surface quality) of a polished substrate and reduce defects is provided. That is, provided is a polishing composition comprising silica particles and a water soluble polymer, wherein the contained silica particles satisfy the following requirements (a) to (c): (a) the primary particle diameter based on the specific surface area is 5 to 300 nm; (b) the coefficient of variation in the particle diameter is 10% or less; and (c) the Sears number Y is 10.0 to 12.0.

Modified silanized colloidal silica particles are reaction products of silanized colloidal silica particles having epoxy moieties with nitrogen of amines to form stable and tunable modified silanized colloidal silica particles. The modified silanized colloidal silica particles can be used as an abrasive in chemical mechanical polishing of various substrates.

The invention relates to a water based composition to be used for the preparation of anti-abrasion coatings on ophthalmic lenses. The composition comprises: the product of hydrolysis of an epoxyalkoxysilane SiXY.sub.3, wherein X represents a monovalent organic group linked to the silicon atom through a carbon atom and containing at least one epoxy function and Y represents an alkoxy group; cationic nanoparticles comprising silica, wherein a water sol of said cationic particles is stable at acidic pH; an inorganic non-hydrogen Lewis acid; a surfactant such that a water solution of 15 wt % of said surfactant exhibits a static surface tension below 25 mN/m at 20° C.; less than 0.5 wt % of a water miscible organic solvent less volatile than water. Moreover, the composition comprises no organic solvents other than said water miscible organic solvent less volatile than water and other than organic solvents that are a product of hydrolysis of the epoxyalkoxysilane.

A method for producing a liquid dispersion containing irregular-shaped silica particles in which two or more primary particles are linked together, by simultaneously adding a liquid A containing silane alkoxide and a liquid B containing an alkali catalyst and water to a liquid I consisting substantially of an organic solvent to cause hydrolysis and polycondensation of the silane alkoxide, wherein the period from the start of the addition until the silica concentration of the reaction system at the end of the addition reaches 70% is 20% or less of the full reaction time period.

A method for producing a liquid dispersion containing irregular-shaped silica particles in which two or more primary particles are linked together, by simultaneously adding a liquid A containing silane alkoxide and a liquid B containing an alkali catalyst and water to a liquid I consisting substantially of an organic solvent to cause hydrolysis and polycondensation of the silane alkoxide, wherein the period from the start of the addition until the silica concentration of the reaction system at the end of the addition reaches 70% is 20% or less of the full reaction time period.

A silica-containing resin composition, characterized by containing a resin and silica particles in an amount of 5 to 300 parts by mass, with respect to 100 parts by mass of the resin, wherein the silica particles satisfy the following requirements (a) to (c): (a) the silica particles have a specific surface area, as determined through a nitrogen absorption method, of 20 to 500 m.sup.2/g; (b) the silica particles have a percent moisture absorption of 5.0 mass % or less at a relative humidity of 50%; and (c) the silica particles contain substantially no metallic impurity or halogen.

A silica-containing resin composition, characterized by containing a resin and silica particles in an amount of 5 to 300 parts by mass, with respect to 100 parts by mass of the resin, wherein the silica particles satisfy the following requirements (a) to (c): (a) the silica particles have a specific surface area, as determined through a nitrogen absorption method, of 20 to 500 m.sup.2/g; (b) the silica particles have a percent moisture absorption of 5.0 mass % or less at a relative humidity of 50%; and (c) the silica particles contain substantially no metallic impurity or halogen.

Surface-treated fumed silica, with a tribo-electro static charge of −500 μC/g to +500 μC/g, a ratio of the tribo-electro static charge to BET surface area of −3.5 μC/m.sup.2 to +3.5 μC/m.sup.2, a methanol wettability of at least 20% by volume methanol in methanol/water mixture, a ratio of carbon content to BET surface area of at most 0.020 wt. %*g/m.sup.2, a process for its preparation and the use thereof.