Formation of precursor for ceria by two homogeneous precipitation reactions - (cerium chloride + urea at 95 deg C - called reaction A and cerium chloride + hexamethylenetetramine at 85 deg C - called reaction B) has been studied. The variation of size of the colloidal particles formed and the zeta potential of the suspensions with progress of reactions exhibited similar trends for both the precipitation processes. Particle size increased from 100 to 300 nm with increasing temperature and extent of reaction. The precipitation in the he pH range of 5-7. Filtration and drying led to agglomeration of the fine particles in the case of the precursor from Reaction B. The as-formed precursors were crystalline - a basic carbonate in the case of reaction A and hydrous oxide in case of reaction B.
