No abstract

The preparation of colloidal dispersions containing spherical cerium(IV) oxide sols of narrow size distribution can be accomplished by hydrolytic deprotonation of cerium(IV) ions in the presence of diluted sulfuric acid. At higher sulfate ion content, rodlike particles of ceric basic sulfate are formed. It was found that the particle morphology could be altered by reactant concentrations and the nature of anions in solution. These particles show definite crystallinity by X-ray diffraction analysis yet consist of much smaller uniform subunits. The materials so obtained were characterized in terms of size distribution, electrokinetics, surface area, and optical properties.

No abstract

Colloidal dispersions of uniform spherical particles of yttrium basic carbonate and rodlike particles of yttrium ammine carbonate were prepared by aging at elevated temperatures yttrium salt solutions in the presence of urea. Different composition and morphology were achieved by altering the aging temperature and time. Coprecipitation in mixed solutions of yttrium(II1) and cerium(II1) salts under similar experimental conditions yielded composite spherical particles of basic carbonate. The content of the two metals in the solids followed closely the initial composition of the reacting solutions. On calcination all prepared solids converted to their corresponding oxides while retaining their particle morphology. The soprepared powders were characterized by various techniques.