Synthesis of CeO2-ZrO2 solid solutions by hydrolysis

Ceria-zirconia (CeO2-ZrO2) solid solutions were prepared from acidic aqueous solutions of ZrOCl2 and Ce (SO4)(2) .2(NH4)(2)SO4 by hydrolysis under a hydrothermal condition. The morphology, crystallite size, lattice parameter, and lattice strain of the solid solutions changed depending on the composition of the CeO2-ZrO2 system. Spherical agglomeration of primary particles was one of the distinctive morphological features of solid solution precipitates with cubic and/or tetragonal fluorite structure, their agglomeration size ranging from 50 to 500 nm, depending on composition. With increasing ZrO2 content, the lattice parameter of the solid solutions decreased and the crystallite size (i.e., primary particle size) of the solid solutions also decreased from 22 to 14 nm. The morphology and crystalline phase of directly formed precipitates in the CeO2-ZrO2 system were greatly influenced by the nature of anion constituent of cerium and zirconium salts.