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: Finely divided, homogeneous and easily sintered superconducting powders of at least one rare earth element, e.g., yttrium and/or lanthanum, at least one alkaline earth metal, e.g., barium, calcium and/or strontium, and at least one transition metal, e.g., copper, nickel, manganese, cobalt and/or iron, and oxygen, are produced by (a) solubilizing, in water, the nitrates and/or acetates of at least one rare earth element, at least one alkaline earth metal, and at least one transition metal; (b) atomizing such solution to dryness; (c) calcining the dried product; and, optionally; (d) grinding the calcined material.

Abstract: Finely divided, homogeneous and easily sintered superconducting powders of at least one rare earth element, e.g., yttrium and/or lanthanum, at least one alkaline earth metal, e.g., barium, calcium and/or strontium, and at least one transition metal, e.g., copper, nickel, manganese, cobalt and/or iron, and oxygen, are produced by (a) intimately admixing a sol of a rare earth element and an aqueous solution of at least one alkaline earth metal nitrate and of at least one nitrate of a transition metal, with the pH of the resulting mixture being adjusted to a value such that said nitrates remain solubilized therein; (b) drying the resulting mixture; (c) calcining the dried product; and, optionally; (d) grinding the calcined material.

Abstract: Highly concentrated, aqueous colloidal dispersions of a cerium (IV) compound, adapted for the impregnation of catalyst supports, are prepared by reacting an aqueous solution of a cerium (IV) salt with a base, to precipitate a certain cerium hydroxynitrate, separating and washing said precipitate, and then dispersing the washed precipitate in an aqueous acid medium.

Abstract: A neodymium hydroxynitrate, readily calcined into, e.g., neodymium oxide, Nd.sub.2 O.sub.3, has the formula (I):Nd(OH).sub.2 NO.sub.3.1H.sub.

Abstract: Rare earth hydroxides are recovered from the rare earth ores, e.g., monazite, xenotime and/or bastnasite, by treating the ore with an aqueous solution of an alkali metal hydroxide, under agitation and essentially constant pressure, at a temperature of from about 100.degree. to 220.degree. C., and wherein the ratio by weight of alkali metal hydroxide/ore ranges from about 1.4 to 0.5, e.g., a weight ratio of sodium hydroxide/ore of from about 1 to 0.5, or a weight ratio of potassium hydroxide/ore of from about 1.4 to 0.7.

Abstract: Zeolites of type ZSM-5, well suited as absorbents/catalysts, are facilely prepared by (i) intimately admixing a source of alumina with a source of silica, in aqueous reaction medium having a pH ranging from 1 to 7 and wherein the molar ratio SiO.sub.2 /Al.sub.2 O.sub.3 ranges from 5 to 100, (ii) adding a source of alkali metal oxide to the reaction mixture resulting from said stage (i), said combined reaction mixture having a pH ranging from 8 to 12, and thence (iii) crystallizing a zeolite of type ZSM-5 therefrom.

Abstract: Morphologically improved ceric oxide particulates have a BET specific surface, measured after calcination at a temperature of from 350.degree. to 450.degree. C., of at least 100 m.sup.2 /g, a total pore volume of at least 0.3 cm.sup.3 /g, and the pores of which having a mean diameter larger than 50 .ANG.. The improved ceric oxide particulates are prepared by reacting a cerium salt with a strong base in the presence of carboxylate ions, or a cerium carboxylate with a strong base; separating the precipitate of true cerium hydroxide thus produced; and washing, heat-treating, and calcining such precipitate.

Abstract: A fine powder of stabilized zirconia a process for its preparation and application of the powder in ceramic compositions to obtain good mechanical, thermomechanical and electrical properties.A zirconia hydrate sol having a pH between 0.5 and 5 and containing elementary acicular crystals having dimensions of from about 10 to 500 .ANG. which are agglomerated into submicron aggregates of from abuot 100 to 5000 .ANG. in diameter is mixed with a solution of a stabilizing agent, preferably yttrium; the suspension is dried; the dried suspension is calcined at a temperature of from about 700.degree. C. to 1,300.degree. C. for preferably from about 30 minutes to 24 hours; and if needed, the powder obtained is milled.

Abstract: Submicronic zirconia particulates containing stabilizing amounts of yttrium or cerium, well adapted for ceramics applications, are produced by (i) admixing an aqueous suspension of zirconium fluosulfate particles having a pH of from about 0 to 3 with an aqueous solution of a salt of yttrium or cerium, (ii) neutralizing the resulting mixture at a pH of at least 7, (iii) separating a mixture of zirconium/yttrium or zirconium/cerium hydroxides from the medium of neutralization, (iv) washing said mixture of hydroxides to eliminate sulfate and fluoride ions therefrom, and then (v) calcining said mixture of hydroxides.

Abstract: A fine powder of neodymium titanate or barium neodymium titanate, a process for its preparation and applications in ceramic compositions. A suspension of particles is formed by mixing a solution of neodymium nitrate or a solution of barium and neodymium nitrates with a sol of titania having a pH of from about 0.8 to 2.5 which contains elementary crystallites of TiO.sub.2 having a size of from about 10 to about 100 .ANG. in diameter which are agglomerated into submicron masses of from about 200 to about 1,000 .ANG. in diameter. The suspension obtained is dried, and the dried product is calcined at a temperature between 800.degree. C. and 1,300.degree. C., preferably for about 1 to 24 hours. If necessary, the powder obtained is milled. The fine powder obtained has a low fritting temperature and its density after heating for 2 hours at 1,300.degree. C. is greater than or equal to 95% of the theoretical density of the desired titanate powder.

Abstract: Finely divided powders of alkaline earth metal titanates, well suited for the fabrication of, e.g., ceramic resistors and condensers, are facilely prepared by (i) admixing a solution of an alkaline earth metal nitrate with a titanium sol having a pH ranging from 0.8 to 2.5 and which comprises elementary crystallites of TiO.sub.2 having particle sizes ranging from 10 to 100 .ANG., agglomerated into submicronic masses having particle sizes ranging from 200 to 1000 .ANG., (ii) next drying the suspension which results, (iii) calcining said dried suspension at a temperature ranging from 700.degree. to 1300.degree. C. for from 30 minutes to 24 hours, under a NO.sub.x partial pressure decreasing from 1 to 0, and then (iv) optionally grinding the powder resulting from said step (iii).

Abstract: A novel neodymium hydroxy/ammonium nitrate, readily calcined into, e.g., neodymium oxide, Nd.sub.2 O.sub.3, has the formula (I):Nd(OH).sub.x (NO.sub.3).sub.y.n NH.sub.4 NO.sub.3.z H.sub.2 O (I)wherein 2.ltoreq.x.ltoreq. 2.3,0.7.ltoreq. y.ltoreq.1.0,0.8.ltoreq. z.ltoreq.1.25; and 0.8.ltoreq. n.ltoreq. 1.25.

Abstract: A catalyst support and process for preparing same are provided wherein a metal substrate is coated with a layer of adherent alumina with a layer of chromium interposed between the alumina catalyst support and the metal substrate. The catalyst supports of the invention are especially useful in catalytic converters for the purification and control of exhaust gas emissions from internal combustion engines by the active catalyst oxidation/reduction of carbon monoxide, unburned hydrocarbons and nitrogen oxides.

Abstract: A novel anhydrous sodium tripolyphosphate, well adapted for detergency applications, has an X-ray diffraction pattern essentially characterizing a phase I sodium tripolyphosphate; a viscosity, in aqueous medium, characterizing a phase II sodium tripolyphosphate; a rate of hydration characterizing a phase I sodium tripolyphosphate; and which exhibits an ROH at 1 minute of greater than about 90.degree. C.

Abstract: A novel sodium orthophosphate has the formula Na.sub.5 H.sub.4 (PO.sub.4).sub.3 wherein the Na/P ratio thereof is essentially 5/3, and which is characterized by but a single crystalline phase and a characteristic X-ray diffraction pattern.

Abstract: A novel anhydrous sodium tripolyphosphate, well adapted as an additive for foodstuffs and detergent compositions, has an Na/P ratio of essentially 1.667.+-.0.01, an apparent density of from 0.5 to 1.1, a mean agglomerate size of less than 100 microns, a phase I content ranging from 15 to 6% by weight, is devoid of insoluble fraction, and displays zero solidification or caking in a quiescent solvent medium.

Abstract: A process for treating a rock essentially constituted by calcium aluminophosphate, comprising the treatment of the ground rock with a concentrated sulfuric acid in stoichiometric excess with respect to calcium and aluminum, at a temperature of above about 120.degree. C., for a time between a few minutes and about 5 hours, followed by controlled water take-up. Subsequently, a residue containing substantially all the calcium and the aluminum of the rock and a solution of the acids serving to digest a tricalciumphosphate charge are separated. The process is particularly suitable for the treatment of Thies phosphate ore.