Compositional Stresses in Polycrystalline Ceria Films

Abstract

Nanocrystalline ceria generally has significantly higher defect concentrations and more oxygen nonstoichiometry than coarse grained material that is equilibrated at the same temperature and oxygen partial pressure. The volume changes associated with such high nonstoichiometry can lead to significant stresses in constrained ceria films. This may have significant implications for applications such as solid electrolytes, where stresses can lead to mechanical failures. To systematically study these compositionally induced stresses, ceria films with varying film thickness were grown by MOCVD and in situ stress measurements were made by monitoring changes in the curvature. The results show that nanocrystalline films exhibit significantly higher compositional stresses than coarse grained films. The film thickness also appears to have a measurable effect on the observed compositional stresses.