Abstract: For aluminum disks and glass-made hard disks, those disks having a mean waviness of less than 3 Å are being desired in order to increase the density of memory capacity. The present invention provides polishing compositions that can give smoothly polished surfaces for the disks. The polishing compositions are polishing compositions for aluminum disks or substrates having silica on the surface thereof, which contain colloidal silica particle groups having different particle size distributions and have a SiO2 concentration of 0.5 to 50% by weight.

Abstract: The present invention provides an abrasive compound suitable for polishing the surface of a glass substrate for an optical disk platter or a magnetic disk platter. More specifically, the present invention provides an abrasive compound for a glass hard disk platter, characterized as comprising a stable slurry having water and, dispersed therein as an abrasive, cerium(IV) oxide particles having an average secondary particle size of 0.1 to 0.5 &mgr;m and containing CeO2 in a concentration of 0.2 to 30 wt %. Preferably, the present invention provides the above abrasive compound in which cerium amounts for 95% or more in terms of oxides of the total amount of rare earth elements in the abrasive.

Abstract: Substantially monodisperse crystalline ceric oxide sols and processes for producing such sols are provided. Sols include crystalline ceric oxide particles having a particle size I (particle size converted from specific surface area by gas absorption method) ranging from 10 nm to 200 nm and a ratio of particle size II (particle size measured by dynamic light scattering method) to particle size I ranging from 2 to 6. Sols can be prepared by reacting a cerium (III) salt with an alkaline substance in an aqueous medium under an inert gas atmosphere to obtain a suspension of cerium (III) hydroxide, immediately blowing oxygen or a gas containing oxygen into the suspension to obtain a sol comprising crystalline ceric oxide particles, and wet grinding the resulting sol. Sols are also prepared by calcining cerium carbonate at a temperature of 300 to 1100° C. to give cerium oxide particles, and wet-grinding the resulting particles.

Abstract: For aluminum disks and glass-made hard disks, those disks having a mean waviness of less than 3 Å are being desired in order to increase the density of memory capacity. The present invention provides polishing compositions that can give smoothly polished surfaces for the disks.

Abstract: There is provided a crystalline ceric oxide sol that is approximately monodisperse, and a process for producing the sol.

Abstract: Production of an alumina powder characterized by having a single or multiple crystal structure selected from the group consisting of &ggr;, &dgr; and &thgr;-forms, a primary particle size of 10 to 50 nm, a mean secondary particle size of 100 to 500 nm, and a granular primary particle shape, or an alumina powder characterized by having an a-form crystal structure, a primary particle size of 60 to 150 nm, a mean secondary particle size of 200 to 500 nm, and a granular primary particle shape, using as a raw material an alumina hydrate comprising rectangular plate-like primary particles having a boehmite structure and having a length of one side of 10 to 50 nm; and preparation of a polishing composition comprising the alumina powder, water and a polishing accelerator.

Abstract: There is provided an abrasive used for polishing a substrate which comprises silica as a main component, for example a rock crystal, a quartz glass for photomask, for CMP of an organic film, Inter Layer Dielectric (ILD) and shallow trench isolation of a semiconductor device, or for polishing a hard disk made of glass.

Abstract: The present invention relates to a polishing composition for polishing alumina disks, polishing substrates having silica surfaces and semiconductor wafers, comprising a stable aqueous silica sol containing moniliform colloidal silica particles having a ratio (D1/D2) of a particle diameter D1 nm (as measured by dynamic light scattering method) to a mean particle diameter D2 (as measured by nitrogen absorption method) of 3 or more, wherein D1 is between 50 to 800 nm and D2 is between 10 to 120 nm, said moniliform colloidal silica particles being composed of spherical colloidal silica particles and a metal oxide-containing silica bond which bonds these spherical colloidal silica particles together, wherein the spherical colloidal silica particles are linked together in rows in only one plane by observation through an electron microscope, and further wherein said polishing composition contains 0.5 to 50% by weight of said moniliform colloidal silica particles.

Abstract: According to the present invention, a process is provided for producing crystalline ceric oxide particles having a particle diameter of 0.005 to 5 &mgr;m, which comprises the steps of reacting a cerium (III) salt with an alkaline substance in an (OH)/(Ce3+) molar ratio of 3 to 30 in an aqueous medium in an inert gas atmosphere to produce a suspension of cerium (III) hydroxide, and blowing oxygen or a gas containing oxygen into the suspension at a temperature of 10 to 95° C. and at an atmospheric pressure.

Abstract: A sensor for detecting a gas comprises a gas detecting portion comprising an anhydrous zinc antimonate semiconductor. The sensor for detecting a gas is preferably hydrogen sulfide. A method for producing the sensor for detecting a gas comprising the steps of: mixing a zinc compound with colloidal antimony oxide in a ZnO/Sb2O5 molar ratio of 0.8 to 1.2; calcining the mixture at 300 to 680° C. and grinding the mixture to form electroconductive anhydrous zinc antimonate powder; preparing a sol of the electroconductive anhydrous zinc antimonate; coating the sol of the electroconductive anhydrous zinc antimonate on a substrate of a device; and heating the substrate at a temperature exceeding 680° C., but below 1,000° C.

Abstract: A method of producing electroconductive anhydrous zinc antimonate, comprising the steps of mixing a zinc compound and a colloidal antimony oxide in a ZnO/Sb.sub.2 O.sub.5 molar ratio of 0.8 to 1.2; and calcining the mixture of 300 to 680.degree. C. in a gas containing steam to produce an electroconductive anhydrous zinc antimonate having a ZnO/Sb.sub.2 O.sub.5 molar ratio of 0.8 to 1.2 and a primary particle diameter of 5 to 100 nm. The substance is useful as an antistatic agent, an ultraviolet absorbent, a heat ray absorbent, and a sensor, for example.

Abstract: A polishing composition for an aluminum disk includes water, an alumina abrasive agent and a polishing accelerator. The polishing accelerator is preferably basic aluminum nitrate. A process for polishing an aluminum disk using the polishing composition is also provided.

Abstract: According to the present invention, a process is provided for producing crystalline ceric oxide particles having a particle diameter of 0.005 to 5 .mu.m, which comprises the steps of reacting a cerium (III) salt with an alkaline substance in an (OH)/(Ce.sup.3+) molar ratio of 3 to 30 in an aqueous medium in an inert gas atmosphere to produce a suspension of cerium (III) hydroxide, and blowing oxygen or a gas containing oxygen into the suspension at a temperature of 10 to 95.degree. C. and at an atmospheric pressure.

Abstract: The present invention is to provide a process for preparing ceric oxide particles used as an abrasive or polishing material for producing semiconductors or as a UV ray-absorbing material for plastics, glass and the like.The present invention relates to a process for preparing cerium (IV) oxide particles having a particle size of from 0.03 .mu.m to 5 .mu.m, which comprises adjusting an aqueous medium containing cerium (IV) hydroxide and a nitrate to a pH of from 8 to 11 with an alkaline substance and heating the aqueous medium at a temperature of from 100.degree. to 200.degree. C. under pressure.

Abstract: A method for producing fine particles of barium ferrite, which comprises reacting an aqueous solution comprising an iron compound, a barium compound and an alkaline substance, wherein the molar ratio of hydroxyl groups of the alkaline substance to the total of anions of the iron compound and the barium compound in the aqueous solution is from 1 to 4, and the reaction is carried out at a temperature of at least 250.degree. C. under a pressure of at least 200 kg/cm.sup.2 using a flow type reactor.

Abstract: A liquid crystal display comprises as liquid crystal panel having a liquid crystal layer disposed between electrode layers, polarizers disposed at both sides of the panel, and a solid birefringent film having the maximum refractive index direction varying with its depth and disposed at at least one side of the liquid crystal panel between the polarizers. The solid birefringent film conpensates the dependence of the polarization characteristic on wave length, thus being capable of obtaining either a monochrome display or a display having an extremely low coloration.

Abstract: A nonlinear diode which is easy to manufacture and has sharply nonlinear voltage-current characteristic and a matrix display unit in which it is used has a diode structure in which an amorphous semiconductor layer is disposed between a bus bar and a pixel electrode formed on a substrate so as to thereby provide an electrical connection therebetween. The amorphous semiconductor layer is made of a compound of arsenic and at least one of selenium and sulphur; a compound of nitrogen and at least one of boron; silicon; aluminium and gallium, a compound of carbon and silicon; or boron.

Abstract: A driving method in accordance with the present invention permits the simple time sharing driving of a ferroelectric liquid crystal matrix panel at high scanning frequency and high multiplexing ratio. A predetermined pulse is applied to a scanning electrode when another scanning electrode is selected to reset the pixel. The pixel is inverted or kept by the action of a pulse applied to the pixel when selected and, under this condition, a desired brightness is written in a short scanning period. Besides, the representation of a number of grey levels is obtained by multiple scanning at reset timing varying with the scanning.

Abstract: An improved driving method capable of achieving high-quality display even in simple matrix addressing for a ferroelectric liquid crystal matrix panel at a high multiplex ratio applies pulses of a frequency higher than that of a scanning voltage in an addressed condition to a scanning electrode in a non-addressed condition to gain either a surface stabilizing effect or an AC field stabilizing effect, hence ensuring high-contrast display. And the panel is so driven that the temporal average of the voltage applied to each pixel becomes zero, thereby averting deterioration of the liquid crystal.

Abstract: A method of producing a substrate structure for a large size display panel. The method involves conveying a transparent substrate from a transparent substrate storage means in a conveying path through a vacuum chamber, and while conveying the substrate, forming at least a patterned transparent conductive film on a surface of the substrate by depositing strips of conductive film on the substrate through a pattern containing member extending in a direction orthogonal to the substrate conveying direction and having strip forming openings therein at intervals along the lengths thereof, and storing the transparent substrates with the strips thereon at the end of the conveying path.