Temperature dependence of the growth of cerium oxide nanoparticles investigated by SAXS and XANES

The growth process of cerium oxide nanoparticles has been investigated by synchrotron Small-Angle x-ray scattering (SAXS) and x-ray absorption near edge spectroscopy (XANES) as a function of the annealing temperature in the range from 298 K to 973 K in atmosphere. The SAXS experimental intensity increases dramatically with increasing annealing temperature, corresponding the nucleation and growth of CeO2 nanoparticles. SAXS also indicates that the growth of CeO2 nanoparticles shows a fractal behaviour. When the annealing temperature increases CeO2 nanoparticles changes from a volume to surface fractal index. The XANES of CeO2 nanoparticles at the Ce L3 edge reveals the increase of the relative intensity of the transition from Ce 2p to 4f1 5d egL, with increasing temperature up to 873 K. Because XANES does not show any significant change for temperature higher than 873 K, this result supports the fractal growth properties of CeO2 nanoparticles addressed by SAXS.