The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 04, 2009
Filed:
Mar. 27, 2007
Jean-yves Chane-ching, Eaubonne, FR;
Jean-Yves Chane-Ching, Eaubonne, FR;
Rhodia Electronics & Catalysis, La Rochelle, FR;
Abstract
The invention concerns an aqueous colloidal dispersion of isotropic particles of a phosphate of at least one rare earth and is characterized in that it comprises either a complexing agent with a pK (cologarithm of the dissociation constant of the complex formed by the complexing agent and said rare earth) of more than 2.5; or an anion of a monobasic acid, soluble in water and with a pKa in the range 2.5 to 5; or said complexing agent and/or said anion of a monobasic acid. In the case of cerium and lanthanum, the mean particle size is at most 20 nm. The dispersions can have a degree of colloid agglomeration of less than 40%.This dispersion can be prepared by forming an aqueous mixture comprising at least one rare earth salt and the complexing agent or monobasic acid anion; by adding a base then phosphate ions to the mixture formed; and heating the mixture obtained. A precipitate is obtained that is re-dispersed in water.