PREPARATION AND CHARACTERIZATION OF CERIUM OXIDE ULTRAFINE PARTICLES DISPERSED IN POLYMER THIN-FILMS

Cerium(IV) oxide ultrafine particles were prepared using the thermal r elaxation technique known as the relaxative auto-dispersion (RAD) proc ess. The ultrafine particles obtained were characterized by high-resol ution electron microscope (HREM) observations and ultraviolet-visible spectra measurements. HREM micrographs revealed that cerium oxide ultr afine particles were uniformly dispersed and individually isolated in the matrix. The size distribution of the nm-sized cerium oxide particl es was fairly narrow. Selected-area electron diffraction patterns of t he particles were completely indexed as those of cerium(IV) oxide with cubic fluorite structure, and the lattice constant calculated from th e radii of the Debye-Sherrer rings was 5.41 Angstrom. Absorption spect ra 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.