Preparation and characterization of cerium oxide ultrafine particles dispersed in polymer thin films

Cerium(IV) oxide ultrafine particles were prepared using the thermal relaxation technique known as the relaxative auto-dispersion (RAD) process. The ultrafine particles obtained were characterized by high-resolution electron microscope (HREM) observations and ultraviolet-visible spectra measurements. HREM micrographs revealed that cerium oxide ultrafine particles were uniformly dispersed and individually isolated in the matrix. The size distribution of the nm-sized cerium oxide particles was fairly narrow. Selected-area electron diffraction patterns of the particles were completely indexed as those of cerium(IV) oxide with cubic fluorite structure, and the lattice constant calculated from the radii of the Debye-Sherrer rings was 5.41 Angstrom. Absorption spectra of the ultrafine particles in the composite film were compared with those of the bulk material. However, there were no size quantization effects on the absorption edge of CeO2. (C) 1997 Elsevier Science S.A.