Abstract: The invention concerns a colloidal dispersion of a phosphate of a rare earth and a process for its preparation. The dispersion is characterized in that it comprises anisotropic and disaggregated or disaggregatable particles of a phosphate of at least one rare earth and an anion of a monobasic acid, soluble in water and with a pKa of at least 2.5. It is prepared by a process in which a solution of a salt of at least one rare earth is mixed with phosphate ions while controlling the pH of the reaction medium to a value in the range 4 to 9 and in the presence of a monobasic acid, soluble in water and with a pKa of at least 2.5; the mixture obtained optionally undergoes a maturing step; the precipitate is then separated from the reaction medium; and said precipitate is then dispersed in water.

Abstract: The invention provides separated calcium phosphate platelets with a length of between 250 nm and 800 nm. The invention also provides dispersions comprising the platelets according to the invention or colloidal dispersions obtained by resuspending the said platelets in the presence of a dispersing agent. The invention also relates to a process for preparing platelets according to the invention. Finally, another subject-matter of the invention is the use of the abovementioned platelets as reinforcing filler, polishing agent, building materials, additive for oral formulations, in particular dentifrices, or encapsulating agent.

Abstract: The invention relates to a mesostructural material, preferably thermally stable, comprising a mineral phase within which nano-scale particles of a metallic oxide are dispersed, selected from a cerium, zirconium, titanium or rare earth metal oxide other than that of cerium. Said oxide comprises at least one metallic element M in a cationic form in a solid solution within the crystalline structure of said oxide. The invention further relates to a method for production of such a material, particularly in the form of heterogeneous catalysts or as a support for catalytic species.

Abstract: The invention relates to an aqueous colloidal dispersion of a compound of cerium and at least one other element M chosen from among the rare earths other than cerium; titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, aluminium, gallium and zirconium. This dispersion is characterized in that it displays a conductivity of at most 5 mS/cm. It is obtained by a process in which there is reacted with a base a mixture of at least one salt of cerium with at least one salt of an element M mentioned above and in the presence of an acid in a quantity such that the atomic ratio H+/(Ce+M) is greater than 0.1, then the precipitate from the preceding reaction is re-dispersed in water. The dispersions of this type cane be used in catalysis, in lubrication, in ceramics, in the manufacture of luminophorous compounds, in cosmetics and as anticorrosion agents.

Abstract: The invention concerns an organic colloidal dispersion comprising: particles of at least a compound based on at least a rare earth, at least an acid, and at least a diluent, characterised in that at least 90% of the particles are monocrystalline. The invention also concerns the method for preparing said dispersion and its use as additive of diesel fuel for internal combustion engines.

Abstract: The invention relates to a partially crystalline mesostructured material which consists essentially of a compound chosen from cerium oxide, zirconium oxide, titanium oxide or a mixture of these compounds, and which is characterized in that it comprises at least one element M in solid solution in said oxide. This material is obtained by means of a process in which (a) a partially crystalline mesostructured starting material is brought into contact with a solution of the element M which has a concentration of this element of at most 2 mol/l; and then (b) the material obtained after this process of bringing into contact with said solution is calcinated at a temperature of at most 500° C.; steps (a) and (b) being repeated, where appropriate, until a material having the desired content of element M is obtained. The material can be used as a catalyst.

Abstract: The invention relates to an ordered mesoporous or mesostructured compound comprising a mineral phase of aluminium in which at least partially crystalline particles of a cerium, titanium or zirconium compound are dispersed. The inventive compound is characterised in that the chemical consistency thereof is such that the heterogeneity domains are at most 100 nm2 The invention also relates to the aforementioned ordered mesoporous or mesostructured compound which comprises at least one element M in solid solution in said particles. Moreover, the invention relates to the methods of preparing said ordered mesoporous or mesostructured compounds. The inventive materials can be used, for example, in the field of catalysis.

Abstract: The invention concerns a heat-stable ordered mesoporous or mesostructured material comprising a mineral phase wherein are dispersed particles of nanometric dimension at least partly crystaline, the global crystallinity index of said mesostructured or ordered mesoporous material being less than 10% in volume. The invention also concern a method for obtaining such a material.

Abstract: The colloidal dispersion of the invention is characterized in that it comprises an organic phase; particles of an iron compound in its amorphous form; and at least one amphiphilic agent. It is prepared by a process in which either an iron salt in the presence of an iron complexing agent or an iron complex is reacted with a base, maintaining the pH of the reaction medium at a value of at most 8 to obtain a precipitate, the iron complexing agent being selected from hydrosoluble carboxylic acids with a complexing constant K such that the pK is at least 3 and the iron complex being selected from the products of reacting iron salts with said acids; then the precipitate obtained or a suspension containing said precipitate is brought into contact with an organic phase in the presence of an amphiphilic agent to obtain the dispersion in an organic phase. The dispersion of the invention can be used as a combustion additive in liquid fuel or motor fuel.

Abstract: The invention concerns a colloidal dispersion of a vanadate or a phosphovanadate of at least a rare earth characterized in that it comprises either a complex-forming agent having a pK (cologarithm of the dissociation constant of the complex formed by the complex-forming agent and said rare earth) higher than 2.5, or an anion of a monovalent acid, soluble-in water and having a pKa ranging between 2.5 and 5. In the case of a vanadate dispersion, the particles have an average size of not more than 6 nm. The inventive dispersion is obtained by a method which consists in contacting a colloidal dispersion or a dispersion of initial complexes comprising at least a rare earth compound and at least a complex-forming agent or an anion of said monovalent acid and whereof the pH has been adjusted to a value of at least 7, with vanadate ions and, if required, with phosphate ions, then in adjusting the pH of the resulting medium to a value of at least 9 and heating.

Abstract: An organic sol is disclosed comprising titanium oxide particles; an organic liquid phase and at least am amphiphilic compound selected among polyethylene phosphate alkyl ethers. In a first embodiment, the method for preparing said sol mixes said amphiphilic compound and the organic liquid phase, and disperses the titanium oxide particles in the resulting mixture. In a second embodiment, the method forms a mixture of titanium oxide and at least said amphiphilic compound, then disperses said mixture in said liquid phase. A solid compound comprising a mixture of titanium oxide particles and at least an amphiphilic compound selected among these mentioned above is also disclosed.

Abstract: The invention concerns a heat-stable mesostructured material, for use as heterogeneous catalyst, wherein the mesostructured walls comprise: (a) a mineral matrix; and (b) dispersed within said mineral matrix (a), particles of nanometric dimensions based on at least a rare earth T and on at least a transition element M different from said rare earth. The invention also concerns a method for obtaining such a material.

Abstract: The invention concerns a stable aqueous colloidal dispersion of colloids with apatite structure, having a pH ranging between 5 and 10, consisting of oblong colloids with an average number length ranging between 20 and 250 nm and an equivalent aspect ratio (number average length/equivalent diameter ratio) ranging between 1 and 300 or in spherical shape having a diameter ranging between 10 and 100 nm, and comprising one or several amino acids optionally in ionized form, as stabilising agents for said colloids with apatite structure corresponding to formula (I): Ca10−x(HPO4)x(PO4)6−x(J)2−x, wherein: x and J are such as defined in claim 1.

Abstract: The invention concerns a stable aqueous colloidal dispersion of colloids with apatite structure, having a pH ranging between 5 and 10.5, comprising a bifunctionalised stabilising agent having a first amine or ammonium function and a second function capable of complexing calcium, and consisting of oblong colloids with an average number length ranging between 5 and 100 nm and an equivalent aspect ratio (number average length/equivalent diameter ratio) ranging between 2 and 300, said colloids with apatite structure corresponding to the formula: Ca10-x(HPO4)x(PO4)6-x(J)2-x, wherein x and J are such as defined in claim 1.

Abstract: The invention concerns a stable aqueous colloidal dispersion with apatite structure, having a pH ranging between 3.5 and 9,5, oblong-shaped with average length between 20 and 200 nm and an equivalent aspect ratio (average length/equivalent diameter ratio) between 5 and 500, and comprising as stabilising agent a compound of formula (I), a compound of formula (II) or a compound of formula (III), such as defined below, optionally in ionized form, or a mixture of said compounds, said colloids with apatite structure corresponding to formula (IV): Ca10-x(HPO4)x(PO4)6-x(J)2-x, wherein x and J are such as defined in claim 1, the stabilising agents corresponding to formula (I), wherein p, X, G1, n, R and m are such as defined in claim 1; the stabilising agents corresponding to formula (II), wherein A, X′″, K, n′ and R′ are such as defined in claim 1; the stabilising agents corresponding to formula (III), wherein X, G1, n and R are such as described in claim 1.

Abstract: The invention concerns a colloidal dispersion of a phosphate of a rare earth and a process for its preparation. The dispersion is characterized in that it comprises anisotropic and disaggregated or disaggregatable particles of a phosphate of at least one rare earth and an anion of a monobasic acid, soluble in water and with a pKa of at least 2.5. It is prepared by a process in which a solution of a salt of at least one rare earth is mixed with phosphate ions while controlling the pH of the reaction medium to a value in the range 4 to 9 and in the presence of a monobasic acid, soluble in water and with a pKa of at least 2.5; the mixture obtained optionally undergoes a maturing step; the precipitate is then separated from the reaction medium; and said precipitate is then dispersed in water.

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.

Abstract: The invention concerns a surfactant formed by at least a particle with nanometric dimensions based on a metal oxide, hydroxide and/or oxy hydroxide, at the surface of which are bound hydrophobic organic chains, the bonds between said chains and said particle surface being non-homogeneously distributed on said surface, such that the resulting modified surface particle has an actual amphiphilic character. The invention also concerns emulsifying compositions comprising surface-modified particles with nanometric dimensions which can be said type of surfactants, and methods for preparing said emulsifying compositions.

Abstract: An organic sol containing: cerium oxide particles; an organic liquid phase; and at least one amphiphilic compound chosen from polyoxyethylenated alkyl ethers of carboxylic acids, polyoxyethylenated alkyl ether phosphates, dialkyl sulphosuccinates and quaternary ammonium compounds. A process for preparing the sol is characterized in that the abovementioned amphiphilic compound and the organic liquid phase are mixed together and the cerium oxide particles are then dispersed in the mixture obtained. According to a second variant, a mixture of cerium oxide and of at least one abovementioned amphiphilic compound is formed and the said mixture is then dispersed in the organic liquid phase.

Abstract: The invention concerns a colloidal dispersion of a cerium compound or of a cerium compound and at least another element selected among titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, aluminum, gallium, zirconium and rare earths other than cerium. The invention is characterised in that it comprises an amino acid, said acid being at least bound to particles constituting the dispersion. Said dispersion can be used on a substrate as anticorrosive agent, for preparing polymer films, in a cosmetic composition, in catalysis particularly for motor vehicle post-combustion catalysis, for lubrication and in ceramics.