In situ size-strain analysis of nanocrystalline ceria growth

A xerogel produced from cerium isopropoxide is shown to be made of nanocrystalline ceria domains (ca. 2 nm in diameter), already formed by condensation of the hydrolysed precursor. In situ isothermal X-ray diffraction studies of the xerogel calcination reveal the occurrence of a second stage of nucleation, followed by growth of the grains up to a temperature-dependent asymptotic limit. The process, with an activation energy of 52(4) kJ/mol and an Avrami exponent 0.55–0.75, is interpreted in terms of coalescence of the existing nuclei.