Abstract: The present invention relates to the synthesis of luminophores and of reflective alumina for optimizing the emissive properties of a fluorescent layer.

Abstract: The present invention relates to the synthesis of luminophores and of reflective alumina for optimizing the emissive properties of a fluorescent layer.

Abstract: The invention relates to a heat-transporting fluid and to the use thereof. The heat-transporting fluid of the invention is formed of an aqueous colloidal sol including water and up to 58.8 wt %, relative to the total fluid weight, in a-Al2O3 particles, the thickness of which is the smallest dimension and less than or equal to 30 nm 90% to 95% of said a-Al2O3 particles have a size less than or equal to 210 nm, among which 50% have a size less than or equal to 160 nm. The invention is of use in the field of cooling, in particular nuclear reactor backup cooling.

Abstract: The present invention relates to the synthesis of luminophores and of reflective alumina for optimizing the emissive properties of a fluorescent layer.

Abstract: The invention relates to a heat-transporting fluid and to the use thereof. The heat-transporting fluid of the invention is formed of an aqueous colloidal sol including water and up to 58.8 wt %, relative to the total fluid weight, in a-Al2O3 particles, the thickness of which is the smallest dimension and less than or equal to 30 nm 90% to 95% of said a-Al2O3 particles have a size less than or equal to 210 nm, among which 50% have a size less than or equal to 160 nm. The invention is of use in the field of cooling, in particular nuclear reactor backup cooling.

Abstract: The invention relates to alpha-alumina with a purity of greater than or equal to 99.99%, in the form of spherical particles (1) with a size predominantly greater than or equal to 850 ?m. The invention also relates to the use of alpha-alumina as defined above, and to a related process for synthesizing and device.

Abstract: The present invention relates to the synthesis of luminophores and of reflective alumina for optimizing the emissive properties of a fluorescent layer.

Abstract: The present invention provides a slurry composition for chemical mechanical polishing comprising spinel particles having the formula AO•xZ2O3 wherein A is at least one divalent cation, Z is at least one trivalent cation, and 0.01≦x≦100. The present invention also includes a method of chemical mechanical polishing the surface of a substrate using slurry compositions that include these spinel particles. The slurry compositions of the present invention provide the desired level of planarization and selectivity for both metal and oxide surfaces. In addition, the slurry compositions of the invention can be prepared such that they are substantially free of alpha phase alumina particles and other high hardness particles to produce a scratch-free polished surface.

Abstract: A cerium oxide with pores having a uniform lamellar structure. The pores may be at least partially arranged in substantially parallel directions and may also extend throughout the grain. The method for preparing said cerium oxide comprises heat treating a compound that essentially consists of cerium carbonate octahydrate. The atmosphere in which the treatment is performed includes an air/steam or oxygen/steam mixture with a steam volume fraction of at least 40%. Said cerium oxide is particularly useful as a catalyst, especially in motor vehicle post-combustion catalysis.

Abstract: The invention relates to new compositions based on ceric oxide having an improved oxygen storage capacity, these compositions being characterized in that they contain, besides ceric oxide, at least one oxide of another metallic element M chosen from the group consisting of iron, bismuth, nickel, tin and chromium or one of their mixtures, this oxide preferably being in solid solution with the abovementioned cerium oxide. The process of synthesis of these compositions consists in first of all preparing an intimate mixture between (i) a ceric oxide or a ceric hydroxide and (ii) at least one additive consisting of a hydroxide or a salt, thermally decomposable to an oxide, of the metallic element M, and in then calcining this mixture so as to obtain the desired composition based on oxides. The compositions according to the invention are particularly useful in the manufacture of catalysts and/or catalyst supports, especially those intended for treating exhaust gases from internal combustion engines.

Abstract: The invention concerns a procedure for preparation of a precursor of a mixed cerium and zirconium oxide-based composition, characterized by the following steps:a liquid mixture is prepared containing cerium and zirconium compounds;the preceding mixture is placed in contact with carbonate or bicarbonate, thus forming a reactive medium exhibiting a neutral or basic pH during the reaction;the precipitate obtained is collected.A mixed cerium and zirconium oxide-based composition is obtained by calcining this precursor. This composition is characterized by the fact that it has a total pore volume of at least 0.6 cm.sup.3 /g, and that at least 40%, and more particularly at least 50%, of the total pore volume is composed of pores having a diameter of at most 1 .mu.m.

Abstract: Ceric oxide (ceria) particulates exhibiting a particularly small crystallite size, well suited for catalyst/catalyst carrier applications, include a specific surface-stabilizing amount of silicon values (preferably less than 1% by weight thereof, expressed as SiO.sub.2) and have a specific surface of at least 40 m.sup.2 /g after calcination at 800.degree. C. for 6 hours and of at least 20 m.sup.2 /g after calcination at 1,000.degree. C. for 6 hours; such CeO.sub.2 particulates are advantageously prepared by (a) suspending certain ceric hydroxides in a basic aqueous reaction medium containing a silicon compound, (b) autoclaving the resulting suspension, (c) cooling and depressurizing such medium of reaction, (d) separating a ceric hydroxide therefrom, and (e) calcining the ceric hydroxide thus separated.

Abstract: Thermally stable ceric oxide-based compositions, well suited as catalysts/catalyst supports for a wide variety of reactions, notably for the catalytic conversion of exhaust gases emanating from internal combustion engines, comprise particulates of immixture of a major amount of ceric oxide with at least one other metal oxide of magnesium, gallium, boron, scandium, or mixture thereof, and having a specific surface greater than 10 m.sup.2 /g after calcination at 800.degree. C.

Abstract: Organotin fluorides, notably dialkyltin difluorides, well adpated for the manufacture of coated insulating glassware and having controlled morphology, are prepared by reacting a stannic compound, e.g., an organotin chloride, with a fluorinating agent, e.g., hydrofluoric acid or an ammonium fluoride, admixing the organotin fluoride thus produced in a solvent that is immiscible with the fluorinating agent but which solubilizes the organotin fluoride therein, subsequently or simutaneously heating the solvent medium to a temperature sufficient to release unreacted fluorinating agent therefrom, and cooling such solvent medium and thereby crystallizing therefrom an organotin fluoride having a controlled morphology, e.g., well defined platelets having a characteristic DTA spectrum.