Structural study on monosize CeO2-x nano-particles

Electron diffraction patterns are obtained for monosize ceria nano-particle s produced by a size-fractionation method with surfactants. A dependency of lattice parameters estimated by the least squares method on crystalline pa rticle sizes strongly suggests that a C-type cerium sesquioxide, which has never been reported in the bulk crystal, exists in the particle 1.5 nm in d iameter. Chemical reactions responsible for the valence change of cerium io ns near the surface are proposed for the existence of the sesquioxide in a strong acid sol. (C) 1999 Acta Metallurgica Inc.