Abstract: A composition based on cerium oxide and on zirconium oxide and, optionally, on a yttrium, scandium or rare-earth metal oxide. The cerium/zirconium atomic proportion is at least 1. The compound exhibits a specific surface, after calcination for 6 hours at 900° C. of at least 35 m2/g and an oxygen storage capacity at 400° C. of at least 1.5 ml of O2/g. The composition is prepared by mixing, in a liquid medium, a cerium compound, a zirconium compound and, if appropriate, a yttrium, scandium or rare-earth metal compound; heating and calcining the precipitate obtained; and using a zirconium solution having an amount of base necessary to reach the equivalent point during an acid/base titration of the solution having a molar ratio of OH−/Zr≦1.65. The composition thus obtained is used in the manufacture of multi-functional catalysts.

Abstract: The present invention concerns a sulfide of a rare earth and an alkali, a process for its preparation and its use as a colored pigment. The sulfide is characterized in that it has the formula ABS2 where A represents at least one alkali and B represents at least one rare earth and in that it is constituted by grains with an average size of 1.5 &mgr;m at most. The preparation process for the sulfide is characterized in that at least one rare earth carbonate or hydroxycarbonate is brought into the presence of at least one gas selected from hydrogen sulfide or carbon disulfide. The product obtained is optionally deagglomerated. The sulfide can be used as a pigment in plastics, paints, finishes, rubbers, ceramics, glazes, paper, inks, cosmetics, dyes, laminated coatings and materials based on or obtained from at least one inorganic binder.

Abstract: The invention relates to a composition based on zirconium oxide and comprising cerium oxide which has a specific surface of at least 30 m2/g after calcination for 6 hours at 900° C. and which is provided in the form of a pure solid solution of cerium oxide in zirconium oxide. According to another embodiment, this composition can additionally comprise a doping element and can exhibit a specific surface of at least 25 m2g after calcination for 6 hours at 1000° C. A process for the preparation of these compositions comprises the following stages: a mixture is prepared, in liquid medium, containing a zirconium compound and a cerium(IV) compound; the said mixture is heated at a temperature greater than 100° C.