Abstract: A process for producing a lithium-containing composite oxide for a positive electrode active material for use in a lithium secondary battery, the oxide having the formula LipQqNxMyOzFa (wherein Q is at least one element selected from the group consisting of titanium, zirconium, niobium and tantalum, N is at least one element selected from the group consisting of Co, Mn and Ni, M is at least one element selected from the group consisting of Al, alkaline earth metal elements and transition metal elements other than Q and N, 0.9?p?1.1, 0?q<0.03, 0.97?x?1.00, 0?y<0.03, 1.9?z?2.1, q+x+y=1 and 0?a?0.02), which comprises firing a mixture of a lithium, Q element source and N element sources, and an M element source and/or fluorine source when these elements are present, in an oxygen-containing atmosphere, wherein the Q element source is a Q element compound aqueous solution having a pH of from 0.5 to 11.

Abstract: It is to provide a positive electrode active material for a lithium secondary battery, which has a large volume capacity density and high safety, is excellent in uniform coating properties and is excellent in the charge and discharge cyclic durability and low temperature characteristics even at a high charge voltage. A process for producing a lithium-containing composite oxide represented by the formula LipQqNxMyOzFa (wherein Q is at least one element selected from the group consisting of titanium, zirconium, niobium and tantalum, N is at least one element selected from the group consisting of Co, Mn and Ni, M is at least one element selected from the group consisting of Al, alkaline earth metal elements and transition metal elements other than the Q element and the N element, 0.9?p?1.1, 0<q?0.03, 0.97?x<1.00, 0?y<0.03, 1.9?z?2.1, q+x+y=1 and 0?a?0.

Abstract: A floor polishing composition containing a film-formable organic high molecular material as the main component, which further contains at least scaly particles.

Abstract: A process for producing a hardenable composition with high storage stability containing scaly silica particles which consist essentially of foliar secondary silica particles and have a laminated structure, said process comprising: (1) a step of subjecting a silica sol, a silica hydrogel or hydrous silicic acid to hydrothermal treatment in the presence of an alkali metal salt to form tertiary agglomerated particles of the scaly silica in the form of porous three-dimensional disorderly agglomerates of foliar secondary silica particles, each secondary particle being formed by a parallel face-to-face alignment of a plurality of flaky primary particles which are overlaid one on another, and (2) a step of disintegrating and dispersing the tertiary agglomerated particles of silica in an organic polymer in the form of an aqueous emulsion by a wet method.

Abstract: Scaly silica particles having a laminated structure, consisting essentially of secondary particles of foliar silica, each formed by a plurality of flaky primary particles of scaly silica which are overlaid one on another and aligned face-to-face in parallel with one another, said secondary particles being present independent of one another.

Abstract: Fine particulate silica gel having the following characteristics (1) to (3): (1) average particle size: from 1 to 200 &mgr;m; (2) oil absorption in accordance with JIS K5101: from 100 to 300 ml/100 g; and (3) hygroscopicity represented by moisture adsorption under a relative humidity of 90% at 25° C. in accordance with JIS Z0701: not more than 20 wt %.

Abstract: A process for producing a hardenable composition with high storage stability containing scaly silica particles which consist essentially of foliar secondary silica particles and have a laminated structure, said process comprising:

Abstract: A floor polishing composition containing a film-formable organic high molecular material as the main component, which further contains at least scaly particles.

Abstract: Scaly silica particles having a laminated structure, consisting essentially of secondary particles of foliar silica, each formed by a plurality of flaky primary particles of scaly silica which are overlaid one on another and aligned face-to-face in parallel with one another, said secondary particles being present independent of one another.

Abstract: A silica-metal oxide particulate composite comprising silica agglomerates having voids formed by random stacking of scaly silica primary particles, and metal oxide particulates supported on the surfaces, and the inner surfaces in the voids, of the silica agglomerates.

Abstract: An alumina sol having an alumina solid content of at least 10 wt % and a viscosity of not higher than 5 Pa.s measured by a Brookfield viscometer and containing a cation other than a hydrogen ion in a total ion equivalent concentration in the range of from 2.0.times.10.sup.-4 to 1.0.times.10.sup.-1 N and a method of preparing the same.

Abstract: A process for producing zinc oxide-containing spherical silica, which comprises emulsifying, in an organic solvent containing a surfactant, a dispersion having zinc oxide with a particle size of from 0.005 to 0.5 .mu.m dispersed in an aqueous alkali metal silicate solution in an amount of from 10 to 70 wt % based on the total amount of zinc oxide and SiO.sub.2 in the aqueous alkali metal silicate solution, followed by gelation of the resulting emulsion with carbon dioxide gas.

Abstract: A process for preparing hydrogen fluoride, which comprises (i) reacting calcium fluoride with sulfuric acid to produce a gypsum and a gas containing hydrogen fluoride, (ii) separating hydrogen fluoride from said gas containing hydrogen fluoride, (iii) absorbing said hydrogen fluoride-separated gas with water to obtain an aqueous solution containing hydrogen fluoride and silicofluoric acid, (iv) reacting calcium carbonate with said aqueous solution to obtain a suspension containing silicic acid and calcium fluoride, (v) adding an alkaline substance to said suspension to make pH at least 8, thereby stabilizing the silicic acid as a colloidal solution, (vi) separating a calcium fluoride solid and the colloidal solution of silicic acid from said suspension, and (vii) recycling the separated calcium fluoride as a starting calcium fluoride.

Abstract: A method for treating a waste gas containing a fluorine component and/or a chlorine component, which comprises contacting the waste gas with magnesium oxide particles having a specific surface area of from 100 to 200 m.sup.2 /g.

Abstract: A dry-etching process comprising dry-etching treatment of semiconductor material by action of a gas and, if necessary, cleaning treatment, characterized in that at least one of the dry-etching and cleaning treatments is conducted under action of a gas composed essentially of a fluorinated ether.

Abstract: A method for synthesizing amorphous silicon nitride, wherein silicon halide and ammonia are reacted in a reaction vessel at a high temperature in the absence of oxygen to thereby synthesize powder of amorphous silicon nitride, then the powder is separated from a gas containing therein gaseous ammonia halide which has been produced simultaneously with said amorphous silicon nitride by use of a collecting means, comprises directly mixing, in advance of the separation, cool gas containing therein neither oxygen nor moisture into said gas to cool down said powder and gas so that both substances may be put in said collecting means without deposition of ammonium halide to the inner wall of the reaction vessel, and other component parts.

Abstract: A process for synthesizing silicon nitride by reacting a silicon halide and ammonia at a high temperature, which is characterized in that at least while the reaction product is amorphous, hydrogen and chlorine are burned in the reaction zone where a halogen containing inorganic silicon compound and ammonia are reacting, and the reaction of said reactants is effected by the heat of combustion thus obtained.