Homogeneity of Lanthanide Doped Ceria Nanocrystal Dispersions Using High-resolution Transmission Electron Microscopy

Aqueous sols of crystalline solid solutions of the general formula Ce1-xLnxO2-x/2□x/2 [Ln = entire lanthanide range, x = 0–0.50 and square = anion vacancy] were synthesised using inorganic materials. The nanocrystals were dispersed on an amorphous silica support and individual crystals examined for composition and structure by high-resolution transmission electron microscopy (HREM) and energy dispersive analysis of X-rays (EDX). High-resolution pictures showed the nanocrystals to be mainly between 5 and 10 nm in size, rarely elongated and with atomically clean faceted surfaces. Diffractograms were used to measure the lattice parameters of the face-centre-cubic (fcc) fluorite structures giving values, depending on dopant species and concentration of dopant, in the range 5.5–5.8 A. EDX analysis of individual crystals with the same nominal composition compared closely to each other and to that of an average over a large area indicating good homogeneity from the preparation method.