Rhodia Operations

Laurent Thiers

Valérie Buissette

Thierry Le-Mercier

Guillaume Criniere

Yvan Montardi

Olivier Le-Roux

Valerie Buissette

Phosphate particulates of at least one rare-earth metal (Ln), with Ln being at least one rare-earth metal selected from among cerium and terbium and optionally lanthanum are in the form of a suspension in a liquid phase of primary isotropic monocrystalline monazite particles having an average size of at least 25 nm and agglomerated into secondary particles having an average size of at most 400 nm; useful luminophores are produced from such phosphate particulates.

Suspensions of phosphates of at least one rare earth element selected from among cerium and terbium and optionally lanthanum and luminophores produced therefrom

The invention relates to a suspension of cerium oxide particles, of which the particles (secondary particles) have an average size of at most 200 nm, these secondary particles consisting of primary particles whose average size measured by TEM is of at most 150 nm with a standard deviation of at most 30% of the value of said average size, and for which the ratio of the average size measured by TEM to the average size measured by BET is at least 1.5. This suspension is prepared from a solution of a cerium III salt, comprising a colloidal dispersion of cerium IV, which is brought into contact, in the presence of nitrate ions and under an inert atmosphere, with a base; the medium obtained is subjected to a thermal treatment under an inert atmosphere and then acidified and washed. The suspension can be used for polishing.

Liquid suspensions and powders of cerium oxide particles and preparation and polishing applications thereof

Liquid phase suspensions of substantially monocrystalline rare-earth borate particles, the mean size thereof ranging from 100 to 400 nm, are prepared by roasting a rare earth borocarbonate or hydroxyborocarbonate at a temperature which is sufficient for forming a borate and obtaining a product whose specific surface area is equal to or greater than 3 m/g and then wet grinding the roasted product; such borates are useful in the form of luminophors, in particular, as luminescent transparent materials.

Submicron rare-earth borates and preparation/luminoshors thereof

Suspensions of cerium oxide particles, well suited for polishing applications, the particles (secondary particles) of which have an average size of at most 200 nm, these secondary particles are formed from primary particles whose average size measured by TEM is at most 150 nm with a standard deviation of at most 30% of the value of this average size, and for which the ratio of the average size measured by TEM to the average size measured by BET is at least 1.5. Such suspensions are prepared from solutions of a cerium III salt, comprising a colloidal dispersion of cerium IV, which are contacted, in the presence of nitrate ions and under an inert atmosphere, with a base, and the medium obtained is subjected to a thermal treatment under an inert atmosphere and then acidified and washed.

Submicronic barium and magnesium aluminates, useful as phosphors, are in the form of a liquid-phase suspension of substantially monocrystalline particles having an average particle size ranging from 80 to 400 nm; such aluminates are prepared by a process that includes: providing a liquid mixture containing compounds of aluminum and of other elements that are part of the aluminate composition; drying the mixture by atomization; calcining the dried product in a reducing atmosphere and wet-grinding this product.

Growing community of inventors

Savigny-sur-Orge, France

Laurent Thiers