The Microstructural Characterization of Nanocrystalline CeO₂ Ceramics Produced by the Sol−Gel Method

Abstract

CeO₂ ceramics were manufactured in the form of surface coatings deposited onto various substrates by sol-gel technology. The size of the CeO₂ crystallites, dried at room temperature, was about 5 nm and did not change significantly after heating, up to 680 K. Further increase of the temperature resulted in a rapid growth of crystallites. The process of growth depends also on the film thickness and nature of substrate. The results obtained using thermogravimetric analysis (TGA) and infrared spectroscopy (IR) demonstrated that the thermal decomposition of gel was completed at about 750 K. There was no evident texture in both the as-deposited state and after heat-treatment. X-ray diffraction (XRD), the atomic force microscopy (AFM), and transmission electron microscopy (TEM) were used to characterize the structure of coatings. The examples of application of CeO₂ ceramics as coatings for high temperature corrosion protection are presented. The role of size of CeO₂ particles in modification of grain boundary transport is discussed.