Method for the preparation of a rare earth oxide powder

Abstract

An improved method is proposed for the preparation of a powder of a rare earth oxide having good dispersibility containing no agglomerates of particles even without undertaking disintegration indispensable heretofore. The improved method comprises precipitation of a rare earth carbonate by the admixture of an aqueous solution of an inorganic rare earth salt with an aqueous solution of ammonium hydrogen carbonate in an excess amount over the stoichiometrically equivalent amount to give a slurry of the rare earth carbonate which is subjected to heating treatment in two steps each under specified conditions to effect aging of the carbonate precipitates. Characteristically, the aqueous slurry after the first aging treatment is subjected to an adjustment in three differently specified ways prior to the second aging treatment including, first, admixture of an additional amount of ammonium hydrogen carbonate, second, addition of water to decrease the solid content in the slurry and, third, addition of an inorganic acid to decrease the pH of the slurry.