PROCEDE DE PREPARATION DE PRECURSEURS D'OXYDES DE TERRES RARES ET PRODUITS OBTENUS

1. Process for obtaining precursors of oxygen-containing derivatives of rare earths, characterized in that it consists in : - simultaneously and continuously mixing an aqueous solution of at least one salt of a trivalent rare earth with a base under conditions such that the molar ratio of the concentration of OH**- ions of the base to the concentration of rare earth salt, expressed as rare earth cation, is constant and less than 5, - separating off the precipitate obtained - and, optionally, thermally treating the precipitate.