Microstrain and self-limited grain growth in nanocrystalline ceria ceramics

The grain coarsening in dense nanocrystalline gadolinia-doped ceria (CGO) and CeO2 was studied for the grain size regime from 10 to 250 nm. Dense ceria-based thin films were prepared by spray pyrolysis and pulsed laser deposition on sapphire substrates. The small grain-sized CGO and CeO2 microstructures were surprisingly stable and showed self-limited grain growth and relaxation of the microstrain with time. In this regime, material transport occurs via grain boundary diffusion leading to densification and grain coarsening in the thin films. A continuous transition to common grain growth kinetics was observed for larger grains at higher temperatures.