Variation in Density and Colour of Cerium Oxide

Abstract

R. C. VICKERY has stated¹ that evidence for more than one crystal structure has been obtained when preparing cerium oxide by igniting various salts of cerium. He classified some preparations he had made into four groups on the basis of density measurements and colour estimations. Referring to work by Wyrouboff and Verneuil, who have suggested that three polymorphic varieties of this oxide might exist, Vickery claimed that a fourth may be indicated as a result of his work. He prepared various salts, starting with the same source of cerium, and fired these for 1 hour at 1,200° C. to secure complete conversion to the oxide. If by this process oxides of different crystal structure are really produced, important and far-reaching effects on solid reactions generally can be envisaged.