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

A new UV-blocking material consisting of cerium oxide (ceria) and turbostratic boron nitride (t-BN) has been synthesized. The surface of the ceria powders was coated with a t-BN layer by means of reaction between boric acid and 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-coating was very effective in reducing the catalytic activity of the ceria and the resulting matrial showed good light scattering and absorption of UV light. BN-coated ceria particles included in an organic thin film showed higher transparency and blocked UV light more effectively than conventional micronized titanium dioxide or zinc oxide particles, two inorganic materials in common use in cosmetics and in many other applications as UV blocking materials.