Synthesis of BN-coated CeO2 fine powder as a new UV blocking material

A new UV-blocking material consisting of cerium oxide (ceria) and turbostra tic boron nitride (t-BN) has been synthesized. The surface of the ceria pow ders was coated with a t-BN layer by means of reaction between boric acid a nd urea on the surface of ceria. The thickness of the t-BN layer estimated by high resolution transmission electron microscopy was ca. 10 nm. The BN-c oating was very effective in reducing the catalytic activity of the ceria a nd the resulting matrial showed good light scattering and absorption of UV light. BN-coated ceria particles included in an organic thin film showed hi gher transparency and blocked UV light more effectively than conventional m icronized titanium dioxide or zinc oxide particles, two inorganic materials in common use in cosmetics and in many other applications as UV blocking m aterials.